diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a60142f..732a73b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -674,6 +674,7 @@ SET (hs_SRCS
     src/compiler/compiler.h
     src/compiler/error.cpp
     src/compiler/error.h
+    src/compiler/expression_info.h
     src/fdr/engine_description.cpp
     src/fdr/engine_description.h
     src/fdr/fdr_compile.cpp
diff --git a/src/compiler/asserts.cpp b/src/compiler/asserts.cpp
index be836b06..44442226 100644
--- a/src/compiler/asserts.cpp
+++ b/src/compiler/asserts.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -42,6 +42,8 @@
  * word-to-word and word-to-nonword) are dropped.
  */
 #include "asserts.h"
+
+#include "compiler/compiler.h"
 #include "nfagraph/ng.h"
 #include "nfagraph/ng_prune.h"
 #include "nfagraph/ng_redundancy.h"
@@ -115,8 +117,8 @@ u32 conjunct(u32 flags1, u32 flags2) {
 typedef map<pair<NFAVertex, NFAVertex>, NFAEdge> edge_cache_t;
 
 static
-void replaceAssertVertex(NGWrapper &g, NFAVertex t, edge_cache_t &edge_cache,
-                         u32 &assert_edge_count) {
+void replaceAssertVertex(NGHolder &g, NFAVertex t, const ExpressionInfo &expr,
+                         edge_cache_t &edge_cache, u32 &assert_edge_count) {
     DEBUG_PRINTF("replacing assert vertex %zu\n", g[t].index);
 
     const u32 flags = g[t].assert_flags;
@@ -178,8 +180,7 @@ void replaceAssertVertex(NGWrapper &g, NFAVertex t, edge_cache_t &edge_cache,
                 edge_cache.emplace(cache_key, e);
                 g[e].assert_flags = flags;
                 if (++assert_edge_count > MAX_ASSERT_EDGES) {
-                    throw CompileError(g.expressionIndex,
-                                       "Pattern is too large.");
+                    throw CompileError(expr.index, "Pattern is too large.");
                 }
             } else {
                 NFAEdge e = ecit->second;
@@ -200,21 +201,23 @@ void replaceAssertVertex(NGWrapper &g, NFAVertex t, edge_cache_t &edge_cache,
 }
 
 static
-void setReportId(ReportManager &rm, NGWrapper &g, NFAVertex v, s32 adj) {
+void setReportId(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr,
+                 NFAVertex v, s32 adj) {
     // Don't try and set the report ID of a special vertex.
     assert(!is_special(v, g));
 
     // There should be no reports set already.
     assert(g[v].reports.empty());
 
-    Report r = rm.getBasicInternalReport(g, adj);
+    Report r = rm.getBasicInternalReport(expr, adj);
 
     g[v].reports.insert(rm.getInternalId(r));
     DEBUG_PRINTF("set report id for vertex %zu, adj %d\n", g[v].index, adj);
 }
 
 static
-void checkForMultilineStart(ReportManager &rm, NGWrapper &g) {
+void checkForMultilineStart(ReportManager &rm, NGHolder &g,
+                            const ExpressionInfo &expr) {
     vector<NFAEdge> dead;
     for (auto v : adjacent_vertices_range(g.start, g)) {
         if (!(g[v].assert_flags & POS_FLAG_MULTILINE_START)) {
@@ -238,7 +241,7 @@ void checkForMultilineStart(ReportManager &rm, NGWrapper &g) {
     for (const auto &e : dead) {
         NFAVertex dummy = add_vertex(g);
         g[dummy].char_reach.setall();
-        setReportId(rm, g, dummy, -1);
+        setReportId(rm, g, expr, dummy, -1);
         add_edge(source(e, g), dummy, g[e], g);
         add_edge(dummy, g.accept, g);
     }
@@ -263,7 +266,8 @@ bool hasAssertVertices(const NGHolder &g) {
  * Remove the horrors that are the temporary assert vertices which arise from
  * our construction method. Allows the rest of our code base to live in
  * blissful ignorance of their existence. */
-void removeAssertVertices(ReportManager &rm, NGWrapper &g) {
+void removeAssertVertices(ReportManager &rm, NGHolder &g,
+                          const ExpressionInfo &expr) {
     size_t num = 0;
 
     DEBUG_PRINTF("before: graph has %zu vertices\n", num_vertices(g));
@@ -285,12 +289,12 @@ void removeAssertVertices(ReportManager &rm, NGWrapper &g) {
 
     for (auto v : vertices_range(g)) {
         if (g[v].assert_flags & WORDBOUNDARY_FLAGS) {
-            replaceAssertVertex(g, v, edge_cache, assert_edge_count);
+            replaceAssertVertex(g, v, expr, edge_cache, assert_edge_count);
             num++;
         }
     }
 
-    checkForMultilineStart(rm, g);
+    checkForMultilineStart(rm, g, expr);
 
     if (num) {
         DEBUG_PRINTF("resolved %zu assert vertices\n", num);
diff --git a/src/compiler/asserts.h b/src/compiler/asserts.h
index b9ec80c7..b4d64c6c 100644
--- a/src/compiler/asserts.h
+++ b/src/compiler/asserts.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -35,8 +35,9 @@
 
 namespace ue2 {
 
+class ExpressionInfo;
 class ReportManager;
-class NGWrapper;
+class NGHolder;
 
 /** \brief Convert temporary assert vertices (from construction method) to
  * edge-based flags.
@@ -44,7 +45,8 @@ class NGWrapper;
  * Remove the horrors that are the temporary assert vertices which arise from
  * our construction method. Allows the rest of our code base to live in
  * blissful ignorance of their existence. */
-void removeAssertVertices(ReportManager &rm, NGWrapper &g);
+void removeAssertVertices(ReportManager &rm, NGHolder &g,
+                          const ExpressionInfo &expr);
 
 } // namespace ue2
 
diff --git a/src/compiler/compiler.cpp b/src/compiler/compiler.cpp
index 56ed5f41..49ed88f4 100644
--- a/src/compiler/compiler.cpp
+++ b/src/compiler/compiler.cpp
@@ -73,7 +73,6 @@ using namespace std;
 
 namespace ue2 {
 
-
 static
 void validateExt(const hs_expr_ext &ext) {
     static const unsigned long long ALL_EXT_FLAGS = HS_EXT_FLAG_MIN_OFFSET |
@@ -100,26 +99,18 @@ void validateExt(const hs_expr_ext &ext) {
 }
 
 ParsedExpression::ParsedExpression(unsigned index_in, const char *expression,
-                                   unsigned flags, ReportID actionId,
+                                   unsigned flags, ReportID report,
                                    const hs_expr_ext *ext)
-    : utf8(false),
-      allow_vacuous(flags & HS_FLAG_ALLOWEMPTY),
-      highlander(flags & HS_FLAG_SINGLEMATCH),
-      prefilter(flags & HS_FLAG_PREFILTER),
-      som(SOM_NONE),
-      index(index_in),
-      id(actionId),
-      min_offset(0),
-      max_offset(MAX_OFFSET),
-      min_length(0),
-      edit_distance(0) {
+    : expr(index_in, flags & HS_FLAG_ALLOWEMPTY, flags & HS_FLAG_SINGLEMATCH,
+           false, flags & HS_FLAG_PREFILTER, SOM_NONE, report, 0, MAX_OFFSET,
+           0, 0) {
     ParseMode mode(flags);
 
     component = parse(expression, mode);
 
-    utf8 = mode.utf8; /* utf8 may be set by parse() */
+    expr.utf8 = mode.utf8; /* utf8 may be set by parse() */
 
-    if (utf8 && !isValidUtf8(expression)) {
+    if (expr.utf8 && !isValidUtf8(expression)) {
         throw ParseError("Expression is not valid UTF-8.");
     }
 
@@ -147,7 +138,7 @@ ParsedExpression::ParsedExpression(unsigned index_in, const char *expression,
 
     // Set SOM type.
     if (flags & HS_FLAG_SOM_LEFTMOST) {
-        som = SOM_LEFT;
+        expr.som = SOM_LEFT;
     }
 
     // Set extended parameters, if we have them.
@@ -156,29 +147,29 @@ ParsedExpression::ParsedExpression(unsigned index_in, const char *expression,
         validateExt(*ext);
 
         if (ext->flags & HS_EXT_FLAG_MIN_OFFSET) {
-            min_offset = ext->min_offset;
+            expr.min_offset = ext->min_offset;
         }
         if (ext->flags & HS_EXT_FLAG_MAX_OFFSET) {
-            max_offset = ext->max_offset;
+            expr.max_offset = ext->max_offset;
         }
         if (ext->flags & HS_EXT_FLAG_MIN_LENGTH) {
-            min_length = ext->min_length;
+            expr.min_length = ext->min_length;
         }
         if (ext->flags & HS_EXT_FLAG_EDIT_DISTANCE) {
-            edit_distance = ext->edit_distance;
+            expr.edit_distance = ext->edit_distance;
         }
     }
 
     // These are validated in validateExt, so an error will already have been
     // thrown if these conditions don't hold.
-    assert(max_offset >= min_offset);
-    assert(max_offset >= min_length);
+    assert(expr.max_offset >= expr.min_offset);
+    assert(expr.max_offset >= expr.min_length);
 
     // Since prefiltering and SOM aren't supported together, we must squash any
     // min_length constraint as well.
-    if (flags & HS_FLAG_PREFILTER && min_length) {
+    if (flags & HS_FLAG_PREFILTER && expr.min_length) {
         DEBUG_PRINTF("prefiltering mode: squashing min_length constraint\n");
-        min_length = 0;
+        expr.min_length = 0;
     }
 }
 
@@ -187,25 +178,25 @@ ParsedExpression::ParsedExpression(unsigned index_in, const char *expression,
  * \brief Dumps the parse tree to screen in debug mode and to disk in dump
  * mode.
  */
-void dumpExpression(UNUSED const ParsedExpression &expr,
+void dumpExpression(UNUSED const ParsedExpression &pe,
                     UNUSED const char *stage, UNUSED const Grey &grey) {
 #if defined(DEBUG)
-    DEBUG_PRINTF("===== Rule ID: %u (internalID:  %u) =====\n", expr.id,
-                 expr.index);
+    DEBUG_PRINTF("===== Rule ID: %u (expression index: %u) =====\n",
+                 pe.expr.report, pe.expr.index);
     ostringstream debug_tree;
-    dumpTree(debug_tree, expr.component.get());
+    dumpTree(debug_tree, pe.component.get());
     printf("%s\n", debug_tree.str().c_str());
 #endif // DEBUG
 
 #if defined(DUMP_SUPPORT)
     if (grey.dumpFlags & Grey::DUMP_PARSE) {
         stringstream ss;
-        ss << grey.dumpPath << "Expr_" << expr.index << "_componenttree_"
+        ss << grey.dumpPath << "Expr_" << pe.expr.index << "_componenttree_"
            << stage << ".txt";
         ofstream out(ss.str().c_str());
-        out << "Component Tree for " << expr.id << endl;
-        dumpTree(out, expr.component.get());
-        if (expr.utf8) {
+        out << "Component Tree for " << pe.expr.report << endl;
+        dumpTree(out, pe.component.get());
+        if (pe.expr.utf8) {
             out << "UTF8 mode" << endl;
         }
     }
@@ -215,13 +206,13 @@ void dumpExpression(UNUSED const ParsedExpression &expr,
 
 /** \brief Run Component tree optimisations on \a expr. */
 static
-void optimise(ParsedExpression &expr) {
-    if (expr.min_length || expr.som) {
+void optimise(ParsedExpression &pe) {
+    if (pe.expr.min_length || pe.expr.som) {
         return;
     }
 
     DEBUG_PRINTF("optimising\n");
-    expr.component->optimise(true /* root is connected to sds */);
+    pe.component->optimise(true /* root is connected to sds */);
 }
 
 void addExpression(NG &ng, unsigned index, const char *expression,
@@ -238,34 +229,34 @@ void addExpression(NG &ng, unsigned index, const char *expression,
 
     // Do per-expression processing: errors here will result in an exception
     // being thrown up to our caller
-    ParsedExpression expr(index, expression, flags, id, ext);
-    dumpExpression(expr, "orig", cc.grey);
+    ParsedExpression pe(index, expression, flags, id, ext);
+    dumpExpression(pe, "orig", cc.grey);
 
     // Apply prefiltering transformations if desired.
-    if (expr.prefilter) {
-        prefilterTree(expr.component, ParseMode(flags));
-        dumpExpression(expr, "prefiltered", cc.grey);
+    if (pe.expr.prefilter) {
+        prefilterTree(pe.component, ParseMode(flags));
+        dumpExpression(pe, "prefiltered", cc.grey);
     }
 
     // Expressions containing zero-width assertions and other extended pcre
     // types aren't supported yet. This call will throw a ParseError exception
     // if the component tree contains such a construct.
-    checkUnsupported(*expr.component);
+    checkUnsupported(*pe.component);
 
-    expr.component->checkEmbeddedStartAnchor(true);
-    expr.component->checkEmbeddedEndAnchor(true);
+    pe.component->checkEmbeddedStartAnchor(true);
+    pe.component->checkEmbeddedEndAnchor(true);
 
     if (cc.grey.optimiseComponentTree) {
-        optimise(expr);
-        dumpExpression(expr, "opt", cc.grey);
+        optimise(pe);
+        dumpExpression(pe, "opt", cc.grey);
     }
 
     DEBUG_PRINTF("component=%p, nfaId=%u, reportId=%u\n",
-                 expr.component.get(), expr.index, expr.id);
+                 pe.component.get(), pe.expr.index, pe.expr.report);
 
     // You can only use the SOM flags if you've also specified an SOM
     // precision mode.
-    if (expr.som != SOM_NONE && cc.streaming && !ng.ssm.somPrecision()) {
+    if (pe.expr.som != SOM_NONE && cc.streaming && !ng.ssm.somPrecision()) {
         throw CompileError("To use a SOM expression flag in streaming mode, "
                            "an SOM precision mode (e.g. "
                            "HS_MODE_SOM_HORIZON_LARGE) must be specified.");
@@ -273,26 +264,26 @@ void addExpression(NG &ng, unsigned index, const char *expression,
 
     // If this expression is a literal, we can feed it directly to Rose rather
     // than building the NFA graph.
-    if (shortcutLiteral(ng, expr)) {
+    if (shortcutLiteral(ng, pe)) {
         DEBUG_PRINTF("took literal short cut\n");
         return;
     }
 
-    unique_ptr<NGWrapper> g = buildWrapper(ng.rm, cc, expr);
-
-    if (!g) {
+    auto built_expr = buildGraph(ng.rm, cc, pe);
+    if (!built_expr.g) {
         DEBUG_PRINTF("NFA build failed on ID %u, but no exception was "
-                     "thrown.\n", expr.id);
+                     "thrown.\n", pe.expr.report);
         throw CompileError("Internal error.");
     }
 
-    if (!expr.allow_vacuous && matches_everywhere(*g)) {
+    auto &g = *built_expr.g;
+    if (!pe.expr.allow_vacuous && matches_everywhere(g)) {
         throw CompileError("Pattern matches empty buffer; use "
                            "HS_FLAG_ALLOWEMPTY to enable support.");
     }
 
-    if (!ng.addGraph(*g)) {
-        DEBUG_PRINTF("NFA addGraph failed on ID %u.\n", expr.id);
+    if (!ng.addGraph(built_expr.expr, g)) {
+        DEBUG_PRINTF("NFA addGraph failed on ID %u.\n", pe.expr.report);
         throw CompileError("Error compiling expression.");
     }
 }
@@ -453,41 +444,42 @@ bool isSupported(const Component &c) {
 }
 #endif
 
-unique_ptr<NGWrapper> buildWrapper(ReportManager &rm, const CompileContext &cc,
-                                   const ParsedExpression &expr) {
-    assert(isSupported(*expr.component));
+BuiltExpression buildGraph(ReportManager &rm, const CompileContext &cc,
+                           const ParsedExpression &pe) {
+    assert(isSupported(*pe.component));
 
-    const unique_ptr<NFABuilder> builder = makeNFABuilder(rm, cc, expr);
+    const auto builder = makeNFABuilder(rm, cc, pe);
     assert(builder);
 
     // Set up START and ACCEPT states; retrieve the special states
-    const auto bs = makeGlushkovBuildState(*builder, expr.prefilter);
+    const auto bs = makeGlushkovBuildState(*builder, pe.expr.prefilter);
 
     // Map position IDs to characters/components
-    expr.component->notePositions(*bs);
+    pe.component->notePositions(*bs);
 
     // Wire the start dotstar state to the firsts
-    connectInitialStates(*bs, expr);
+    connectInitialStates(*bs, pe);
 
     DEBUG_PRINTF("wire up body of expr\n");
     // Build the rest of the FOLLOW set
     vector<PositionInfo> initials = {builder->getStartDotStar(),
                                      builder->getStart()};
-    expr.component->buildFollowSet(*bs, initials);
+    pe.component->buildFollowSet(*bs, initials);
 
     // Wire the lasts to the accept state
-    connectFinalStates(*bs, expr);
+    connectFinalStates(*bs, pe);
 
     // Create our edges
     bs->buildEdges();
 
-    auto g = builder->getGraph();
-    assert(g);
+    BuiltExpression built_expr = builder->getGraph();
+    assert(built_expr.g);
 
-    dumpDotWrapper(*g, "00_before_asserts", cc.grey);
-    removeAssertVertices(rm, *g);
+    dumpDotWrapper(*built_expr.g, built_expr.expr, "00_before_asserts",
+                   cc.grey);
+    removeAssertVertices(rm, *built_expr.g, built_expr.expr);
 
-    return g;
+    return built_expr;
 }
 
 } // namespace ue2
diff --git a/src/compiler/compiler.h b/src/compiler/compiler.h
index 48987fc3..8f5f9b65 100644
--- a/src/compiler/compiler.h
+++ b/src/compiler/compiler.h
@@ -35,8 +35,8 @@
 
 #include "ue2common.h"
 #include "database.h"
+#include "compiler/expression_info.h"
 #include "parser/Component.h"
-#include "som/som.h"
 
 #include <memory>
 #include <boost/core/noncopyable.hpp>
@@ -50,35 +50,32 @@ struct CompileContext;
 struct Grey;
 struct target_t;
 class NG;
+class NGHolder;
 class ReportManager;
-class NGWrapper;
 
-/** Class gathering together the pieces of a parsed expression.
- * Note: Owns the provided component.
- */
+/** \brief Class gathering together the pieces of a parsed expression. */
 class ParsedExpression : boost::noncopyable {
 public:
     ParsedExpression(unsigned index, const char *expression, unsigned flags,
-                     ReportID actionId, const hs_expr_ext *ext = nullptr);
+                     ReportID report, const hs_expr_ext *ext = nullptr);
 
-    bool utf8; //!< UTF-8 mode flag specified
+    /** \brief Expression information (from flags, extparam etc) */
+    ExpressionInfo expr;
 
-    /** \brief root node of parsed component tree. */
-    std::unique_ptr<ue2::Component> component;
+    /** \brief Root node of parsed component tree. */
+    std::unique_ptr<Component> component;
+};
 
-    const bool allow_vacuous;   //!< HS_FLAG_ALLOWEMPTY specified
-    const bool highlander;      //!< HS_FLAG_SINGLEMATCH specified
-    const bool prefilter;       //!< HS_FLAG_PREFILTER specified
-    som_type som;               //!< chosen SOM mode, or SOM_NONE
+/**
+ * \brief Class gathering together the pieces of an expression that has been
+ * built into an NFA graph.
+ */
+struct BuiltExpression {
+    /** \brief Expression information (from flags, extparam etc) */
+    ExpressionInfo expr;
 
-    /** \brief index in expressions array passed to \ref hs_compile_multi */
-    const unsigned index;
-
-    const ReportID id; //!< user-specified pattern ID
-    u64a min_offset;   //!< 0 if not used
-    u64a max_offset;   //!< MAX_OFFSET if not used
-    u64a min_length;   //!< 0 if not used
-    u32 edit_distance; //!< 0 if not used
+    /** \brief Built Glushkov NFA graph. */
+    std::unique_ptr<NGHolder> g;
 };
 
 /**
@@ -95,12 +92,12 @@ public:
  * @param ext
  *      Struct containing extra parameters for this expression, or NULL if
  *      none.
- * @param actionId
+ * @param report
  *      The identifier to associate with the expression; returned by engine on
  *      match.
  */
 void addExpression(NG &ng, unsigned index, const char *expression,
-                   unsigned flags, const hs_expr_ext *ext, ReportID actionId);
+                   unsigned flags, const hs_expr_ext *ext, ReportID report);
 
 /**
  * Build a Hyperscan database out of the expressions we've been given. A
@@ -128,9 +125,8 @@ struct hs_database *build(NG &ng, unsigned int *length);
  * @return
  *      nullptr on error.
  */
-std::unique_ptr<NGWrapper> buildWrapper(ReportManager &rm,
-                                        const CompileContext &cc,
-                                        const ParsedExpression &expr);
+BuiltExpression buildGraph(ReportManager &rm, const CompileContext &cc,
+                           const ParsedExpression &expr);
 
 /**
  * Build a platform_t out of a target_t.
diff --git a/src/compiler/expression_info.h b/src/compiler/expression_info.h
new file mode 100644
index 00000000..7775f59e
--- /dev/null
+++ b/src/compiler/expression_info.h
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2017, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ * \brief ExpressionInfo class for storing the properties of an expression.
+ */
+
+#ifndef COMPILER_EXPRESSION_INFO_H
+#define COMPILER_EXPRESSION_INFO_H
+
+#include "ue2common.h"
+#include "som/som.h"
+
+namespace ue2 {
+
+/** \brief Properties of an expression. */
+class ExpressionInfo {
+public:
+    ExpressionInfo(unsigned int index_in, bool allow_vacuous_in,
+                   bool highlander_in, bool utf8_in, bool prefilter_in,
+                   som_type som_in, ReportID report_in, u64a min_offset_in,
+                   u64a max_offset_in, u64a min_length_in, u32 edit_distance_in)
+        : index(index_in), report(report_in), allow_vacuous(allow_vacuous_in),
+          highlander(highlander_in), utf8(utf8_in), prefilter(prefilter_in),
+          som(som_in), min_offset(min_offset_in), max_offset(max_offset_in),
+          min_length(min_length_in), edit_distance(edit_distance_in) {}
+
+    /**
+     * \brief Index of the expression represented by this graph.
+     *
+     * Used:
+     * - down the track in error handling;
+     * - for identifying parts of an expression in highlander mode.
+     */
+    unsigned int index;
+
+    /** \brief Report ID specified by the user. */
+    ReportID report;
+
+    /** \brief Vacuous pattern is allowed. (HS_FLAG_ALLOWEMPTY) */
+    bool allow_vacuous;
+
+    /** \brief "Highlander" (single match) pattern. (HS_FLAG_SINGLEMATCH) */
+    bool highlander;
+
+    /** \brief UTF-8 pattern. (HS_FLAG_UTF8) */
+    bool utf8;
+
+    /** \brief Prefiltering pattern. (HS_FLAG_PREFILTER) */
+    bool prefilter;
+
+    /** \brief Start-of-match type requested, or SOM_NONE. */
+    som_type som;
+
+    /** \brief Minimum match offset extended parameter. 0 if not used. */
+    u64a min_offset;
+
+    /**
+     * \brief Maximum match offset extended parameter.
+     * MAX_OFFSET if not used.
+     */
+    u64a max_offset;
+
+    /** \brief Minimum match length extended parameter. 0 if not used. */
+    u64a min_length;
+
+    /**
+     * \brief Approximate matching edit distance extended parameter.
+     * 0 if not used.
+     */
+    u32 edit_distance;
+};
+
+}
+
+#endif // COMPILER_EXPRESSION_INFO_H
diff --git a/src/hs.cpp b/src/hs.cpp
index 6cd3a3ee..c1e1cdce 100644
--- a/src/hs.cpp
+++ b/src/hs.cpp
@@ -369,11 +369,13 @@ hs_error_t hs_expression_info_int(const char *expression, unsigned int flags,
         assert(pe.component);
 
         // Apply prefiltering transformations if desired.
-        if (pe.prefilter) {
+        if (pe.expr.prefilter) {
             prefilterTree(pe.component, ParseMode(flags));
         }
 
-        unique_ptr<NGWrapper> g = buildWrapper(rm, cc, pe);
+        auto built_expr = buildGraph(rm, cc, pe);
+        unique_ptr<NGHolder> &g = built_expr.g;
+        ExpressionInfo &expr = built_expr.expr;
 
         if (!g) {
             DEBUG_PRINTF("NFA build failed, but no exception was thrown.\n");
@@ -381,13 +383,13 @@ hs_error_t hs_expression_info_int(const char *expression, unsigned int flags,
         }
 
         // validate graph's suitability for fuzzing
-        validate_fuzzy_compile(*g, g->edit_distance, g->utf8, cc.grey);
+        validate_fuzzy_compile(*g, expr.edit_distance, expr.utf8, cc.grey);
 
         // fuzz graph - this must happen before any transformations are made
-        make_fuzzy(*g, g->edit_distance, cc.grey);
+        make_fuzzy(*g, expr.edit_distance, cc.grey);
 
-        handleExtendedParams(rm, *g, cc);
-        fillExpressionInfo(rm, *g, &local_info);
+        handleExtendedParams(rm, *g, expr, cc);
+        fillExpressionInfo(rm, *g, expr, &local_info);
     }
     catch (const CompileError &e) {
         // Compiler error occurred
diff --git a/src/nfagraph/ng.cpp b/src/nfagraph/ng.cpp
index 2f6d8cd7..eded7af2 100644
--- a/src/nfagraph/ng.cpp
+++ b/src/nfagraph/ng.cpp
@@ -27,10 +27,11 @@
  */
 
 /** \file
- * \brief NG, NGHolder, NGWrapper and graph handling.
+ * \brief NG and graph handling.
  */
-#include "grey.h"
 #include "ng.h"
+
+#include "grey.h"
 #include "ng_anchored_acyclic.h"
 #include "ng_anchored_dots.h"
 #include "ng_asserts.h"
@@ -62,6 +63,7 @@
 #include "ng_util.h"
 #include "ng_width.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "nfa/goughcompile.h"
 #include "rose/rose_build.h"
 #include "smallwrite/smallwrite_build.h"
@@ -100,16 +102,16 @@ NG::~NG() {
  * \throw CompileError if SOM cannot be supported for the component.
  */
 static
-bool addComponentSom(NG &ng, NGHolder &g, const NGWrapper &w,
+bool addComponentSom(NG &ng, NGHolder &g, const ExpressionInfo &expr,
                      const som_type som, const u32 comp_id) {
     DEBUG_PRINTF("doing som\n");
-    dumpComponent(g, "03_presom", w.expressionIndex, comp_id, ng.cc.grey);
+    dumpComponent(g, "03_presom", expr.index, comp_id, ng.cc.grey);
     assert(hasCorrectlyNumberedVertices(g));
-    assert(allMatchStatesHaveReports(w));
+    assert(allMatchStatesHaveReports(g));
 
     // First, we try the "SOM chain" support in ng_som.cpp.
 
-    sombe_rv rv = doSom(ng, g, w, comp_id, som);
+    sombe_rv rv = doSom(ng, g, expr, comp_id, som);
     if (rv == SOMBE_HANDLED_INTERNAL) {
         return false;
     } else if (rv == SOMBE_HANDLED_ALL) {
@@ -118,7 +120,7 @@ bool addComponentSom(NG &ng, NGHolder &g, const NGWrapper &w,
     assert(rv == SOMBE_FAIL);
 
     /* Next, Sombe style approaches */
-    rv = doSomWithHaig(ng, g, w, comp_id, som);
+    rv = doSomWithHaig(ng, g, expr, comp_id, som);
     if (rv == SOMBE_HANDLED_INTERNAL) {
         return false;
     } else if (rv == SOMBE_HANDLED_ALL) {
@@ -132,7 +134,7 @@ bool addComponentSom(NG &ng, NGHolder &g, const NGWrapper &w,
     vector<vector<CharReach> > triggers; /* empty for outfix */
 
     assert(g.kind == NFA_OUTFIX);
-    dumpComponent(g, "haig", w.expressionIndex, comp_id, ng.cc.grey);
+    dumpComponent(g, "haig", expr.index, comp_id, ng.cc.grey);
     makeReportsSomPass(ng.rm, g);
     auto haig = attemptToBuildHaig(g, som, ng.ssm.somPrecision(), triggers,
                                    ng.cc.grey);
@@ -145,7 +147,7 @@ bool addComponentSom(NG &ng, NGHolder &g, const NGWrapper &w,
     /* Our various strategies for supporting SOM for this pattern have failed.
      * Provide a generic pattern not supported/too large return value as it is
      * unclear what the meaning of a specific SOM error would be */
-    throw CompileError(w.expressionIndex, "Pattern is too large.");
+    throw CompileError(expr.index, "Pattern is too large.");
 
     assert(0); // unreachable
     return false;
@@ -200,21 +202,21 @@ void reduceGraph(NGHolder &g, som_type som, bool utf8,
 }
 
 static
-bool addComponent(NG &ng, NGHolder &g, const NGWrapper &w, const som_type som,
-                  const u32 comp_id) {
+bool addComponent(NG &ng, NGHolder &g, const ExpressionInfo &expr,
+                  const som_type som, const u32 comp_id) {
     const CompileContext &cc = ng.cc;
     assert(hasCorrectlyNumberedVertices(g));
 
     DEBUG_PRINTF("expr=%u, comp=%u: %zu vertices, %zu edges\n",
-                 w.expressionIndex, comp_id, num_vertices(g), num_edges(g));
+                 expr.index, comp_id, num_vertices(g), num_edges(g));
 
-    dumpComponent(g, "01_begin", w.expressionIndex, comp_id, ng.cc.grey);
+    dumpComponent(g, "01_begin", expr.index, comp_id, ng.cc.grey);
 
-    assert(allMatchStatesHaveReports(w));
+    assert(allMatchStatesHaveReports(g));
 
-    reduceGraph(g, som, w.utf8, cc);
+    reduceGraph(g, som, expr.utf8, cc);
 
-    dumpComponent(g, "02_reduced", w.expressionIndex, comp_id, ng.cc.grey);
+    dumpComponent(g, "02_reduced", expr.index, comp_id, ng.cc.grey);
 
     // There may be redundant regions that we can remove
     if (cc.grey.performGraphSimplification) {
@@ -231,12 +233,12 @@ bool addComponent(NG &ng, NGHolder &g, const NGWrapper &w, const som_type som,
 
     // Start Of Match handling.
     if (som) {
-        if (addComponentSom(ng, g, w, som, comp_id)) {
+        if (addComponentSom(ng, g, expr, som, comp_id)) {
             return true;
         }
     }
 
-    assert(allMatchStatesHaveReports(w));
+    assert(allMatchStatesHaveReports(g));
 
     if (splitOffAnchoredAcyclic(*ng.rose, g, cc)) {
         return true;
@@ -251,11 +253,11 @@ bool addComponent(NG &ng, NGHolder &g, const NGWrapper &w, const som_type som,
         return true;
     }
 
-    if (doViolet(*ng.rose, g, w.prefilter, false, ng.rm, cc)) {
+    if (doViolet(*ng.rose, g, expr.prefilter, false, ng.rm, cc)) {
         return true;
     }
 
-    if (splitOffPuffs(*ng.rose, ng.rm, g, w.prefilter, cc)) {
+    if (splitOffPuffs(*ng.rose, ng.rm, g, expr.prefilter, cc)) {
         return true;
     }
 
@@ -268,7 +270,7 @@ bool addComponent(NG &ng, NGHolder &g, const NGWrapper &w, const som_type som,
         return true;
     }
 
-    if (doViolet(*ng.rose, g, w.prefilter, true, ng.rm, cc)) {
+    if (doViolet(*ng.rose, g, expr.prefilter, true, ng.rm, cc)) {
         return true;
     }
 
@@ -283,7 +285,7 @@ bool addComponent(NG &ng, NGHolder &g, const NGWrapper &w, const som_type som,
 
 // Returns true if all components have been added.
 static
-bool processComponents(NG &ng, NGWrapper &w,
+bool processComponents(NG &ng, ExpressionInfo &expr,
                        deque<unique_ptr<NGHolder>> &g_comp,
                        const som_type som) {
     const u32 num_components = g_comp.size();
@@ -293,7 +295,7 @@ bool processComponents(NG &ng, NGWrapper &w,
         if (!g_comp[i]) {
             continue;
         }
-        if (addComponent(ng, *g_comp[i], w, som, i)) {
+        if (addComponent(ng, *g_comp[i], expr, som, i)) {
             g_comp[i].reset();
             continue;
         }
@@ -313,48 +315,48 @@ bool processComponents(NG &ng, NGWrapper &w,
     return false;
 }
 
-bool NG::addGraph(NGWrapper &w) {
+bool NG::addGraph(ExpressionInfo &expr, NGHolder &g) {
     // remove reports that aren't on vertices connected to accept.
-    clearReports(w);
+    clearReports(g);
 
-    som_type som = w.som;
-    if (som && isVacuous(w)) {
-        throw CompileError(w.expressionIndex, "Start of match is not "
+    som_type som = expr.som;
+    if (som && isVacuous(g)) {
+        throw CompileError(expr.index, "Start of match is not "
                            "currently supported for patterns which match an "
                            "empty buffer.");
     }
 
-    dumpDotWrapper(w, "01_initial", cc.grey);
-    assert(allMatchStatesHaveReports(w));
+    dumpDotWrapper(g, expr, "01_initial", cc.grey);
+    assert(allMatchStatesHaveReports(g));
 
     /* ensure utf8 starts at cp boundary */
-    ensureCodePointStart(rm, w);
+    ensureCodePointStart(rm, g, expr);
 
-    if (can_never_match(w)) {
-        throw CompileError(w.expressionIndex, "Pattern can never match.");
+    if (can_never_match(g)) {
+        throw CompileError(expr.index, "Pattern can never match.");
     }
 
     // validate graph's suitability for fuzzing before resolving asserts
-    validate_fuzzy_compile(w, w.edit_distance, w.utf8, cc.grey);
+    validate_fuzzy_compile(g, expr.edit_distance, expr.utf8, cc.grey);
 
-    resolveAsserts(rm, w);
-    dumpDotWrapper(w, "02_post_assert_resolve", cc.grey);
-    assert(allMatchStatesHaveReports(w));
+    resolveAsserts(rm, g, expr);
+    dumpDotWrapper(g, expr, "02_post_assert_resolve", cc.grey);
+    assert(allMatchStatesHaveReports(g));
 
-    make_fuzzy(w, w.edit_distance, cc.grey);
-    dumpDotWrapper(w, "02a_post_fuzz", cc.grey);
+    make_fuzzy(g, expr.edit_distance, cc.grey);
+    dumpDotWrapper(g, expr, "02a_post_fuzz", cc.grey);
 
-    pruneUseless(w);
-    pruneEmptyVertices(w);
+    pruneUseless(g);
+    pruneEmptyVertices(g);
 
-    if (can_never_match(w)) {
-        throw CompileError(w.expressionIndex, "Pattern can never match.");
+    if (can_never_match(g)) {
+        throw CompileError(expr.index, "Pattern can never match.");
     }
 
-    optimiseVirtualStarts(w); /* good for som */
+    optimiseVirtualStarts(g); /* good for som */
 
-    handleExtendedParams(rm, w, cc);
-    if (w.min_length) {
+    handleExtendedParams(rm, g, expr, cc);
+    if (expr.min_length) {
         // We have a minimum length constraint, which we currently use SOM to
         // satisfy.
         som = SOM_LEFT;
@@ -368,70 +370,70 @@ bool NG::addGraph(NGWrapper &w) {
     // first, we can perform graph work that can be done on an individual
     // expression basis.
 
-    if (w.utf8) {
-        relaxForbiddenUtf8(w);
+    if (expr.utf8) {
+        relaxForbiddenUtf8(g, expr);
     }
 
-    if (w.highlander && !w.min_length && !w.min_offset) {
+    if (expr.highlander && !expr.min_length && !expr.min_offset) {
         // In highlander mode: if we don't have constraints on our reports that
         // may prevent us accepting our first match (i.e. extended params) we
         // can prune the other out-edges of all vertices connected to accept.
-        pruneHighlanderAccepts(w, rm);
+        pruneHighlanderAccepts(g, rm);
     }
 
-    dumpDotWrapper(w, "02b_fairly_early", cc.grey);
+    dumpDotWrapper(g, expr, "02b_fairly_early", cc.grey);
 
     // If we're a vacuous pattern, we can handle this early.
-    if (splitOffVacuous(boundary, rm, w)) {
+    if (splitOffVacuous(boundary, rm, g, expr)) {
         DEBUG_PRINTF("split off vacuous\n");
     }
 
     // We might be done at this point: if we've run out of vertices, we can
     // stop processing.
-    if (num_vertices(w) == N_SPECIALS) {
+    if (num_vertices(g) == N_SPECIALS) {
         DEBUG_PRINTF("all vertices claimed by vacuous handling\n");
         return true;
     }
 
     // Now that vacuous edges have been removed, update the min width exclusive
     // of boundary reports.
-    minWidth = min(minWidth, findMinWidth(w));
+    minWidth = min(minWidth, findMinWidth(g));
 
     // Add the pattern to the small write builder.
-    smwr->add(w);
+    smwr->add(g, expr);
 
     if (!som) {
-        removeSiblingsOfStartDotStar(w);
+        removeSiblingsOfStartDotStar(g);
     }
 
-    dumpDotWrapper(w, "03_early", cc.grey);
+    dumpDotWrapper(g, expr, "03_early", cc.grey);
 
     // Perform a reduction pass to merge sibling character classes together.
     if (cc.grey.performGraphSimplification) {
-        removeRedundancy(w, som);
-        prunePathsRedundantWithSuccessorOfCyclics(w, som);
+        removeRedundancy(g, som);
+        prunePathsRedundantWithSuccessorOfCyclics(g, som);
     }
 
-    dumpDotWrapper(w, "04_reduced", cc.grey);
+    dumpDotWrapper(g, expr, "04_reduced", cc.grey);
 
     // If we've got some literals that span the graph from start to accept, we
     // can split them off into Rose from here.
     if (!som) {
-        if (splitOffLiterals(*this, w)) {
+        if (splitOffLiterals(*this, g)) {
             DEBUG_PRINTF("some vertices claimed by literals\n");
         }
     }
 
     // We might be done at this point: if we've run out of vertices, we can
     // stop processing.
-    if (num_vertices(w) == N_SPECIALS) {
+    if (num_vertices(g) == N_SPECIALS) {
         DEBUG_PRINTF("all vertices claimed before calc components\n");
         return true;
     }
 
     // Split the graph into a set of connected components.
 
-    deque<unique_ptr<NGHolder>> g_comp = calcComponents(w);
+    deque<unique_ptr<NGHolder>> g_comp = calcComponents(g);
     assert(!g_comp.empty());
 
     if (!som) {
@@ -443,14 +445,14 @@ bool NG::addGraph(NGWrapper &w) {
         recalcComponents(g_comp);
     }
 
-    if (processComponents(*this, w, g_comp, som)) {
+    if (processComponents(*this, expr, g_comp, som)) {
         return true;
     }
 
     // If we're in prefiltering mode, we can run the prefilter reductions and
     // have another shot at accepting the graph.
 
-    if (cc.grey.prefilterReductions && w.prefilter) {
+    if (cc.grey.prefilterReductions && expr.prefilter) {
         for (u32 i = 0; i < g_comp.size(); i++) {
             if (!g_comp[i]) {
                 continue;
@@ -459,7 +461,7 @@ bool NG::addGraph(NGWrapper &w) {
             prefilterReductions(*g_comp[i], cc);
         }
 
-        if (processComponents(*this, w, g_comp, som)) {
+        if (processComponents(*this, expr, g_comp, som)) {
             return true;
         }
     }
@@ -469,7 +471,7 @@ bool NG::addGraph(NGWrapper &w) {
         if (g_comp[i]) {
             DEBUG_PRINTF("could not compile component %u with %zu vertices\n",
                          i, num_vertices(*g_comp[i]));
-            throw CompileError(w.expressionIndex, "Pattern is too large.");
+            throw CompileError(expr.index, "Pattern is too large.");
         }
     }
 
@@ -478,60 +480,60 @@ bool NG::addGraph(NGWrapper &w) {
 }
 
 /** \brief Used from SOM mode to add an arbitrary NGHolder as an engine. */
-bool NG::addHolder(NGHolder &w) {
-    DEBUG_PRINTF("adding holder of %zu states\n", num_vertices(w));
-    assert(allMatchStatesHaveReports(w));
-    assert(hasCorrectlyNumberedVertices(w));
+bool NG::addHolder(NGHolder &g) {
+    DEBUG_PRINTF("adding holder of %zu states\n", num_vertices(g));
+    assert(allMatchStatesHaveReports(g));
+    assert(hasCorrectlyNumberedVertices(g));
 
     /* We don't update the global minWidth here as we care about the min width
      * of the whole pattern - not a just a prefix of it. */
 
     bool prefilter = false;
-    //dumpDotComp(comp, w, *this, 20, "prefix_init");
+    //dumpDotComp(comp, g, *this, 20, "prefix_init");
 
     som_type som = SOM_NONE; /* the prefixes created by the SOM code do not
                                 themselves track som */
     bool utf8 = false; // handling done earlier
-    reduceGraph(w, som, utf8, cc);
+    reduceGraph(g, som, utf8, cc);
 
     // There may be redundant regions that we can remove
     if (cc.grey.performGraphSimplification) {
-        removeRegionRedundancy(w, som);
+        removeRegionRedundancy(g, som);
     }
 
     // "Short Exhaustible Passthrough" patterns always become outfixes.
-    if (isSEP(w, rm, cc.grey)) {
+    if (isSEP(g, rm, cc.grey)) {
         DEBUG_PRINTF("graph is SEP\n");
-        if (rose->addOutfix(w)) {
+        if (rose->addOutfix(g)) {
             return true;
         }
     }
 
-    if (splitOffAnchoredAcyclic(*rose, w, cc)) {
+    if (splitOffAnchoredAcyclic(*rose, g, cc)) {
         return true;
     }
 
-    if (handleSmallLiteralSets(*rose, w, cc)
-        || handleFixedWidth(*rose, w, cc.grey)) {
+    if (handleSmallLiteralSets(*rose, g, cc)
+        || handleFixedWidth(*rose, g, cc.grey)) {
         return true;
     }
 
-    if (handleDecoratedLiterals(*rose, w, cc)) {
+    if (handleDecoratedLiterals(*rose, g, cc)) {
         return true;
     }
 
-    if (doViolet(*rose, w, prefilter, false, rm, cc)) {
+    if (doViolet(*rose, g, prefilter, false, rm, cc)) {
         return true;
     }
-    if (splitOffPuffs(*rose, rm, w, prefilter, cc)) {
+    if (splitOffPuffs(*rose, rm, g, prefilter, cc)) {
         return true;
     }
-    if (doViolet(*rose, w, prefilter, true, rm, cc)) {
+    if (doViolet(*rose, g, prefilter, true, rm, cc)) {
         return true;
     }
 
     DEBUG_PRINTF("trying for outfix\n");
-    if (rose->addOutfix(w)) {
+    if (rose->addOutfix(g)) {
         DEBUG_PRINTF("ok\n");
         return true;
     }
@@ -586,26 +588,4 @@ bool NG::addLiteral(const ue2_literal &literal, u32 expr_index,
     return true;
 }
 
-NGWrapper::NGWrapper(unsigned int ei, bool highlander_in, bool utf8_in,
-                     bool prefilter_in, som_type som_in, ReportID r,
-                     u64a min_offset_in, u64a max_offset_in, u64a min_length_in,
-                     u32 edit_distance_in)
-    : expressionIndex(ei), reportId(r), highlander(highlander_in),
-      utf8(utf8_in), prefilter(prefilter_in), som(som_in),
-      min_offset(min_offset_in), max_offset(max_offset_in),
-      min_length(min_length_in), edit_distance(edit_distance_in) {
-    // All special nodes/edges are added in NGHolder's constructor.
-    DEBUG_PRINTF("built %p: expr=%u report=%u%s%s%s%s "
-                 "min_offset=%llu max_offset=%llu min_length=%llu "
-                 "edit_distance=%u\n",
-                 this, expressionIndex, reportId,
-                 highlander ? " highlander" : "",
-                 utf8 ? " utf8" : "",
-                 prefilter ? " prefilter" : "",
-                 (som != SOM_NONE) ? " som" : "",
-                 min_offset, max_offset, min_length, edit_distance);
-}
-
-NGWrapper::~NGWrapper() {}
-
 } // namespace ue2
diff --git a/src/nfagraph/ng.h b/src/nfagraph/ng.h
index d6e5d3c0..6693773e 100644
--- a/src/nfagraph/ng.h
+++ b/src/nfagraph/ng.h
@@ -27,7 +27,7 @@
  */
 
 /** \file
- * \brief NG, NGHolder, NGWrapper declarations.
+ * \brief NG declaration.
  */
 
 #ifndef NG_H
@@ -58,31 +58,7 @@ namespace ue2 {
 struct CompileContext;
 struct ue2_literal;
 
-class NGWrapper : public NGHolder {
-public:
-    NGWrapper(unsigned int expressionIndex, bool highlander, bool utf8,
-              bool prefilter, const som_type som, ReportID rid, u64a min_offset,
-              u64a max_offset, u64a min_length, u32 edit_distance);
-
-    ~NGWrapper() override;
-
-    /** index of the expression represented by this graph, used
-     * - down the track in error handling
-     * - identifying parts of an expression in highlander mode
-     */
-    const unsigned int expressionIndex;
-
-    const ReportID reportId; /**< user-visible report id */
-    const bool highlander; /**< user-specified single match only */
-    const bool utf8; /**< UTF-8 mode */
-    const bool prefilter; /**< prefiltering mode */
-    const som_type som; /**< SOM type requested */
-    u64a min_offset; /**< extparam min_offset value */
-    u64a max_offset; /**< extparam max_offset value */
-    u64a min_length; /**< extparam min_length value */
-    u32 edit_distance; /**< extparam edit_distance value */
-};
-
+class ExpressionInfo;
 class RoseBuild;
 class SmallWriteBuild;
 
@@ -94,14 +70,14 @@ public:
 
     /** \brief Consumes a pattern, returns false or throws a CompileError
      * exception if the graph cannot be consumed. */
-    bool addGraph(NGWrapper &w);
+    bool addGraph(ExpressionInfo &expr, NGHolder &h);
 
     /** \brief Consumes a graph, cut-down version of addGraph for use by SOM
      * processing. */
     bool addHolder(NGHolder &h);
 
-    /** \brief Adds a literal to Rose, used by literal shortcut passes (instead of
-     * using \ref addGraph) */
+    /** \brief Adds a literal to Rose, used by literal shortcut passes (instead
+     * of using \ref addGraph) */
     bool addLiteral(const ue2_literal &lit, u32 expr_index, u32 external_report,
                     bool highlander, som_type som);
 
@@ -128,7 +104,8 @@ public:
  *
  * Shared with the small write compiler.
  */
-void reduceGraph(NGHolder &g, som_type som, bool utf8, const CompileContext &cc);
+void reduceGraph(NGHolder &g, som_type som, bool utf8,
+                 const CompileContext &cc);
 
 } // namespace ue2
 
diff --git a/src/nfagraph/ng_asserts.cpp b/src/nfagraph/ng_asserts.cpp
index c2f0d68f..8812afad 100644
--- a/src/nfagraph/ng_asserts.cpp
+++ b/src/nfagraph/ng_asserts.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -47,6 +47,7 @@
 #include "ng_prune.h"
 #include "ng_redundancy.h"
 #include "ng_util.h"
+#include "compiler/compiler.h"
 #include "parser/position.h" // for POS flags
 #include "util/bitutils.h" // for findAndClearLSB_32
 #include "util/boundary_reports.h"
@@ -184,43 +185,45 @@ void findSplitters(const NGHolder &g, const vector<NFAEdge> &asserts,
 }
 
 static
-void setReportId(ReportManager &rm, NGWrapper &g, NFAVertex v, s32 adj) {
+void setReportId(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr,
+                 NFAVertex v, s32 adj) {
     // Don't try and set the report ID of a special vertex.
     assert(!is_special(v, g));
 
     // If there's a report set already, we're replacing it.
     g[v].reports.clear();
 
-    Report ir = rm.getBasicInternalReport(g, adj);
+    Report ir = rm.getBasicInternalReport(expr, adj);
 
     g[v].reports.insert(rm.getInternalId(ir));
     DEBUG_PRINTF("set report id for vertex %zu, adj %d\n", g[v].index, adj);
 }
 
 static
-NFAVertex makeClone(ReportManager &rm, NGWrapper &g, NFAVertex v,
-                    const CharReach &cr_mask) {
+NFAVertex makeClone(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr,
+                    NFAVertex v, const CharReach &cr_mask) {
     NFAVertex clone = clone_vertex(g, v);
     g[clone].char_reach &= cr_mask;
     clone_out_edges(g, v, clone);
     clone_in_edges(g, v, clone);
 
     if (v == g.startDs) {
-        if (g.utf8) {
+        if (expr.utf8) {
             g[clone].char_reach &= ~UTF_START_CR;
         }
 
         DEBUG_PRINTF("marked as virt\n");
         g[clone].assert_flags = POS_FLAG_VIRTUAL_START;
 
-        setReportId(rm, g, clone, 0);
+        setReportId(rm, g, expr, clone, 0);
     }
 
     return clone;
 }
 
 static
-void splitVertex(ReportManager &rm, NGWrapper &g, NFAVertex v, bool ucp) {
+void splitVertex(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr,
+                 NFAVertex v, bool ucp) {
     assert(v != g.start);
     assert(v != g.accept);
     assert(v != g.acceptEod);
@@ -232,14 +235,14 @@ void splitVertex(ReportManager &rm, NGWrapper &g, NFAVertex v, bool ucp) {
     auto has_no_assert = [&g](const NFAEdge &e) { return !g[e].assert_flags; };
 
     // Split v into word/nonword vertices with only asserting out-edges.
-    NFAVertex w_out = makeClone(rm, g, v, cr_word);
-    NFAVertex nw_out = makeClone(rm, g, v, cr_nonword);
+    NFAVertex w_out = makeClone(rm, g, expr, v, cr_word);
+    NFAVertex nw_out = makeClone(rm, g, expr, v, cr_nonword);
     remove_out_edge_if(w_out, has_no_assert, g);
     remove_out_edge_if(nw_out, has_no_assert, g);
 
     // Split v into word/nonword vertices with only asserting in-edges.
-    NFAVertex w_in = makeClone(rm, g, v, cr_word);
-    NFAVertex nw_in = makeClone(rm, g, v, cr_nonword);
+    NFAVertex w_in = makeClone(rm, g, expr, v, cr_word);
+    NFAVertex nw_in = makeClone(rm, g, expr, v, cr_nonword);
     remove_in_edge_if(w_in, has_no_assert, g);
     remove_in_edge_if(nw_in, has_no_assert, g);
 
@@ -250,7 +253,8 @@ void splitVertex(ReportManager &rm, NGWrapper &g, NFAVertex v, bool ucp) {
 }
 
 static
-void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
+void resolveEdges(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr,
+                  set<NFAEdge> *dead) {
     for (const auto &e : edges_range(g)) {
         u32 flags = g[e].assert_flags;
         if (!flags) {
@@ -363,7 +367,7 @@ void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
             } else if (v_w) {
                 /* need to add a word byte */
                 NFAVertex vv = add_vertex(g);
-                setReportId(rm, g, vv, -1);
+                setReportId(rm, g, expr, vv, -1);
                 g[vv].char_reach = CHARREACH_WORD;
                 add_edge(vv, g.accept, g);
                 g[e].assert_flags = 0;
@@ -372,7 +376,7 @@ void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
             } else {
                 /* need to add a non word byte or see eod */
                 NFAVertex vv = add_vertex(g);
-                setReportId(rm, g, vv, -1);
+                setReportId(rm, g, expr, vv, -1);
                 g[vv].char_reach = CHARREACH_NONWORD;
                 add_edge(vv, g.accept, g);
                 g[e].assert_flags = 0;
@@ -416,7 +420,7 @@ void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
             } else if (v_w) {
                 /* need to add a word byte */
                 NFAVertex vv = add_vertex(g);
-                setReportId(rm, g, vv, -1);
+                setReportId(rm, g, expr, vv, -1);
                 g[vv].char_reach = CHARREACH_WORD_UCP_PRE;
                 add_edge(vv, g.accept, g);
                 g[e].assert_flags = 0;
@@ -425,7 +429,7 @@ void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
             } else {
                 /* need to add a non word byte or see eod */
                 NFAVertex vv = add_vertex(g);
-                setReportId(rm, g, vv, -1);
+                setReportId(rm, g, expr, vv, -1);
                 g[vv].char_reach = CHARREACH_NONWORD_UCP_PRE;
                 add_edge(vv, g.accept, g);
                 g[e].assert_flags = 0;
@@ -450,7 +454,8 @@ void resolveEdges(ReportManager &rm, NGWrapper &g, set<NFAEdge> *dead) {
     }
 }
 
-void resolveAsserts(ReportManager &rm, NGWrapper &g) {
+void resolveAsserts(ReportManager &rm, NGHolder &g,
+                    const ExpressionInfo &expr) {
     vector<NFAEdge> asserts = getAsserts(g);
     if (asserts.empty()) {
         return;
@@ -460,20 +465,20 @@ void resolveAsserts(ReportManager &rm, NGWrapper &g) {
     map<u32, NFAVertex> to_split_ucp; /* by index, for determinism */
     findSplitters(g, asserts, &to_split, &to_split_ucp);
     if (to_split.size() + to_split_ucp.size() > MAX_CLONED_VERTICES) {
-        throw CompileError(g.expressionIndex, "Pattern is too large.");
+        throw CompileError(expr.index, "Pattern is too large.");
     }
 
     for (const auto &m : to_split) {
         assert(!contains(to_split_ucp, m.first));
-        splitVertex(rm, g, m.second, false);
+        splitVertex(rm, g, expr, m.second, false);
     }
 
     for (const auto &m : to_split_ucp) {
-        splitVertex(rm, g, m.second, true);
+        splitVertex(rm, g, expr, m.second, true);
     }
 
     set<NFAEdge> dead;
-    resolveEdges(rm, g, &dead);
+    resolveEdges(rm, g, expr, &dead);
 
     remove_edges(dead, g);
     renumber_vertices(g);
@@ -485,15 +490,16 @@ void resolveAsserts(ReportManager &rm, NGWrapper &g) {
     clearReports(g);
 }
 
-void ensureCodePointStart(ReportManager &rm, NGWrapper &g) {
+void ensureCodePointStart(ReportManager &rm, NGHolder &g,
+                          const ExpressionInfo &expr) {
     /* In utf8 mode there is an implicit assertion that we start at codepoint
      * boundaries. Assert resolution handles the badness coming from asserts.
      * The only other source of trouble is startDs->accept connections.
      */
     NFAEdge orig = edge(g.startDs, g.accept, g);
-    if (g.utf8 && orig) {
-        DEBUG_PRINTF("rectifying %u\n", g.reportId);
-        Report ir = rm.getBasicInternalReport(g);
+    if (expr.utf8 && orig) {
+        DEBUG_PRINTF("rectifying %u\n", expr.report);
+        Report ir = rm.getBasicInternalReport(expr);
         ReportID rep = rm.getInternalId(ir);
 
         NFAVertex v_a = add_vertex(g);
diff --git a/src/nfagraph/ng_asserts.h b/src/nfagraph/ng_asserts.h
index 8183490a..2534f571 100644
--- a/src/nfagraph/ng_asserts.h
+++ b/src/nfagraph/ng_asserts.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -36,12 +36,14 @@
 namespace ue2 {
 
 struct BoundaryReports;
-class NGWrapper;
+class ExpressionInfo;
+class NGHolder;
 class ReportManager;
 
-void resolveAsserts(ReportManager &rm, NGWrapper &g);
+void resolveAsserts(ReportManager &rm, NGHolder &g, const ExpressionInfo &expr);
 
-void ensureCodePointStart(ReportManager &rm, NGWrapper &g);
+void ensureCodePointStart(ReportManager &rm, NGHolder &g,
+                          const ExpressionInfo &expr);
 
 } // namespace ue2
 
diff --git a/src/nfagraph/ng_builder.cpp b/src/nfagraph/ng_builder.cpp
index 385e114f..60f667f4 100644
--- a/src/nfagraph/ng_builder.cpp
+++ b/src/nfagraph/ng_builder.cpp
@@ -28,11 +28,13 @@
 
 /** \file
  * \brief: NFA Graph Builder: used by Glushkov construction to construct an
- * NGWrapper from a parsed expression.
+ * NGHolder from a parsed expression.
  */
+
+#include "ng_builder.h"
+
 #include "grey.h"
 #include "ng.h"
-#include "ng_builder.h"
 #include "ng_util.h"
 #include "ue2common.h"
 #include "compiler/compiler.h" // for ParsedExpression
@@ -79,7 +81,7 @@ public:
     void cloneRegion(Position first, Position last,
                      unsigned posOffset) override;
 
-    unique_ptr<NGWrapper> getGraph() override;
+    BuiltExpression getGraph() override;
 
 private:
     /** fetch a vertex given its Position ID. */
@@ -94,8 +96,11 @@ private:
     /** \brief Greybox: used for resource limits. */
     const Grey &grey;
 
-    /** \brief Underlying NGWrapper graph. */
-    unique_ptr<NGWrapper> graph;
+    /** \brief Underlying graph. */
+    unique_ptr<NGHolder> graph;
+
+    /** \brief Underlying expression info. */
+    ExpressionInfo expr;
 
     /** \brief mapping from position to vertex. Use \ref getVertex for access.
      * */
@@ -108,13 +113,9 @@ private:
 } // namespace
 
 NFABuilderImpl::NFABuilderImpl(ReportManager &rm_in, const Grey &grey_in,
-                               const ParsedExpression &expr)
-    : rm(rm_in), grey(grey_in),
-      graph(ue2::make_unique<NGWrapper>(
-          expr.index, expr.highlander, expr.utf8, expr.prefilter, expr.som,
-          expr.id, expr.min_offset, expr.max_offset, expr.min_length,
-          expr.edit_distance)),
-      vertIdx(N_SPECIALS) {
+                               const ParsedExpression &parsed)
+    : rm(rm_in), grey(grey_in), graph(ue2::make_unique<NGHolder>()),
+      expr(parsed.expr), vertIdx(N_SPECIALS) {
 
     // Reserve space for a reasonably-sized NFA
     id2vertex.reserve(64);
@@ -151,7 +152,7 @@ void NFABuilderImpl::addVertex(Position pos) {
     (*graph)[v].index = pos;
 }
 
-unique_ptr<NGWrapper> NFABuilderImpl::getGraph() {
+BuiltExpression NFABuilderImpl::getGraph() {
     DEBUG_PRINTF("built graph has %zu vertices and %zu edges\n",
                  num_vertices(*graph), num_edges(*graph));
 
@@ -162,13 +163,13 @@ unique_ptr<NGWrapper> NFABuilderImpl::getGraph() {
         throw CompileError("Pattern too large.");
     }
 
-    return move(graph);
+    return { expr, move(graph) };
 }
 
 void NFABuilderImpl::setNodeReportID(Position pos, int offsetAdjust) {
-    Report ir = rm.getBasicInternalReport(*graph, offsetAdjust);
+    Report ir = rm.getBasicInternalReport(expr, offsetAdjust);
     DEBUG_PRINTF("setting report id on %u = (%u, %d, %u)\n",
-                 pos, graph->reportId, offsetAdjust, ir.ekey);
+                 pos, expr.report, offsetAdjust, ir.ekey);
 
     NFAVertex v = getVertex(pos);
     auto &reports = (*graph)[v].reports;
diff --git a/src/nfagraph/ng_builder.h b/src/nfagraph/ng_builder.h
index 5bd95ba9..df2e0dd8 100644
--- a/src/nfagraph/ng_builder.h
+++ b/src/nfagraph/ng_builder.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -28,7 +28,7 @@
 
 /** \file
  * \brief: NFA Graph Builder: used by Glushkov construction to construct an
- * NGWrapper from a parsed expression.
+ * NGHolder from a parsed expression.
  */
 
 #ifndef NG_BUILDER_H
@@ -44,8 +44,8 @@
 namespace ue2 {
 
 class CharReach;
-class NGWrapper;
 class ReportManager;
+struct BuiltExpression;
 struct CompileContext;
 
 class ParsedExpression;
@@ -83,10 +83,10 @@ public:
                              unsigned posOffset) = 0;
 
     /**
-     * \brief Returns the built NGWrapper graph.
+     * \brief Returns the built NGHolder graph and ExpressionInfo.
      * Note that this builder cannot be used after this call.
      */
-    virtual std::unique_ptr<NGWrapper> getGraph() = 0;
+    virtual BuiltExpression getGraph() = 0;
 };
 
 /** Construct a usable NFABuilder. */
diff --git a/src/nfagraph/ng_dump.cpp b/src/nfagraph/ng_dump.cpp
index fc840f25..094d2401 100644
--- a/src/nfagraph/ng_dump.cpp
+++ b/src/nfagraph/ng_dump.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -35,24 +35,25 @@
 
 #include "config.h"
 
-#include "ng_dump.h"
+#include "nfagraph/ng_dump.h"
 
-#include "hwlm/hwlm_build.h"
-#include "ng.h"
-#include "ng_util.h"
-#include "parser/position.h"
+#include "hs_compile.h" /* for HS_MODE_* flags */
 #include "ue2common.h"
+#include "compiler/compiler.h"
+#include "hwlm/hwlm_build.h"
 #include "nfa/accel.h"
 #include "nfa/nfa_internal.h" // for MO_INVALID_IDX
-#include "smallwrite/smallwrite_dump.h"
+#include "nfagraph/ng.h"
+#include "nfagraph/ng_util.h"
+#include "parser/position.h"
 #include "rose/rose_build.h"
 #include "rose/rose_internal.h"
+#include "smallwrite/smallwrite_dump.h"
 #include "util/bitutils.h"
 #include "util/dump_charclass.h"
 #include "util/report.h"
 #include "util/report_manager.h"
 #include "util/ue2string.h"
-#include "hs_compile.h" /* for HS_MODE_* flags */
 
 #include <cmath>
 #include <fstream>
@@ -287,13 +288,13 @@ void dumpGraphImpl(const char *name, const GraphT &g,
 // manual instantiation of templated dumpGraph above.
 template void dumpGraphImpl(const char *, const NGHolder &);
 
-void dumpDotWrapperImpl(const NGWrapper &nw, const char *name,
-                        const Grey &grey) {
+void dumpDotWrapperImpl(const NGHolder &g, const ExpressionInfo &expr,
+                        const char *name, const Grey &grey) {
     if (grey.dumpFlags & Grey::DUMP_INT_GRAPH) {
         stringstream ss;
-        ss << grey.dumpPath << "Expr_" << nw.expressionIndex << "_" << name << ".dot";
+        ss << grey.dumpPath << "Expr_" << expr.index << "_" << name << ".dot";
         DEBUG_PRINTF("dumping dot graph to '%s'\n", ss.str().c_str());
-        dumpGraphImpl(ss.str().c_str(), nw);
+        dumpGraphImpl(ss.str().c_str(), g);
     }
 }
 
diff --git a/src/nfagraph/ng_dump.h b/src/nfagraph/ng_dump.h
index b20d9f1b..077f07ce 100644
--- a/src/nfagraph/ng_dump.h
+++ b/src/nfagraph/ng_dump.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -48,7 +48,7 @@ namespace ue2 {
 
 class NGHolder;
 class NG;
-class NGWrapper;
+class ExpressionInfo;
 class ReportManager;
 
 // Implementations for stubs below -- all have the suffix "Impl".
@@ -61,7 +61,8 @@ void dumpGraphImpl(const char *name, const GraphT &g);
 template <typename GraphT>
 void dumpGraphImpl(const char *name, const GraphT &g, const ReportManager &rm);
 
-void dumpDotWrapperImpl(const NGWrapper &w, const char *name, const Grey &grey);
+void dumpDotWrapperImpl(const NGHolder &g, const ExpressionInfo &expr,
+                        const char *name, const Grey &grey);
 
 void dumpComponentImpl(const NGHolder &g, const char *name, u32 expr, u32 comp,
                        const Grey &grey);
@@ -88,10 +89,10 @@ static inline void dumpGraph(UNUSED const char *name, UNUSED const GraphT &g) {
 // Stubs which call through to dump code if compiled in.
 
 UNUSED static inline
-void dumpDotWrapper(UNUSED const NGWrapper &w, UNUSED const char *name,
-                    UNUSED const Grey &grey) {
+void dumpDotWrapper(UNUSED const NGHolder &g, UNUSED const ExpressionInfo &expr,
+                    UNUSED const char *name, UNUSED const Grey &grey) {
 #ifdef DUMP_SUPPORT
-    dumpDotWrapperImpl(w, name, grey);
+    dumpDotWrapperImpl(g, expr, name, grey);
 #endif
 }
 
diff --git a/src/nfagraph/ng_expr_info.cpp b/src/nfagraph/ng_expr_info.cpp
index 7419609b..1f601c61 100644
--- a/src/nfagraph/ng_expr_info.cpp
+++ b/src/nfagraph/ng_expr_info.cpp
@@ -27,8 +27,8 @@
  */
 
 /** \file
- * \brief Code for discovering properties of an NGWrapper used by
- * hs_expression_info.
+ * \brief Code for discovering properties of an NFA graph used by
+ * hs_expression_info().
  */
 #include "ng_expr_info.h"
 
@@ -58,42 +58,42 @@ namespace ue2 {
 
 /* get rid of leading \b and multiline ^ vertices */
 static
-void removeLeadingVirtualVerticesFromRoot(NGWrapper &w, NFAVertex root) {
+void removeLeadingVirtualVerticesFromRoot(NGHolder &g, NFAVertex root) {
     vector<NFAVertex> victims;
 
-    for (auto v : adjacent_vertices_range(root, w)) {
-        if (w[v].assert_flags & POS_FLAG_VIRTUAL_START) {
+    for (auto v : adjacent_vertices_range(root, g)) {
+        if (g[v].assert_flags & POS_FLAG_VIRTUAL_START) {
             DEBUG_PRINTF("(?m)^ vertex or leading \\[bB] vertex\n");
             victims.push_back(v);
         }
     }
 
     for (auto u : victims) {
-        for (auto v : adjacent_vertices_range(u, w)) {
-            add_edge_if_not_present(root, v, w);
+        for (auto v : adjacent_vertices_range(u, g)) {
+            add_edge_if_not_present(root, v, g);
         }
     }
 
-    remove_vertices(victims, w);
+    remove_vertices(victims, g);
 }
 
 static
-void checkVertex(const ReportManager &rm, const NGWrapper &w, NFAVertex v,
+void checkVertex(const ReportManager &rm, const NGHolder &g, NFAVertex v,
                  const vector<DepthMinMax> &depths, DepthMinMax &info) {
-    if (is_any_accept(v, w)) {
+    if (is_any_accept(v, g)) {
         return;
     }
-    if (is_any_start(v, w)) {
+    if (is_any_start(v, g)) {
         info.min = 0;
         info.max = max(info.max, depth(0));
         return;
     }
 
-    u32 idx = w[v].index;
+    u32 idx = g[v].index;
     assert(idx < depths.size());
     const DepthMinMax &d = depths.at(idx);
 
-    for (ReportID report_id : w[v].reports) {
+    for (ReportID report_id : g[v].reports) {
         const Report &report = rm.getReport(report_id);
         assert(report.type == EXTERNAL_CALLBACK);
 
@@ -118,7 +118,7 @@ void checkVertex(const ReportManager &rm, const NGWrapper &w, NFAVertex v,
             rd.max = min(rd.max, max_offset);
         }
 
-        DEBUG_PRINTF("vertex %zu report %u: %s\n", w[v].index, report_id,
+        DEBUG_PRINTF("vertex %zu report %u: %s\n", g[v].index, report_id,
                       rd.str().c_str());
 
         info = unionDepthMinMax(info, rd);
@@ -126,8 +126,8 @@ void checkVertex(const ReportManager &rm, const NGWrapper &w, NFAVertex v,
 }
 
 static
-bool hasOffsetAdjust(const ReportManager &rm, const NGWrapper &w) {
-    for (const auto &report_id : all_reports(w)) {
+bool hasOffsetAdjust(const ReportManager &rm, const NGHolder &g) {
+    for (const auto &report_id : all_reports(g)) {
         if (rm.getReport(report_id).offsetAdjust) {
             return true;
         }
@@ -135,28 +135,29 @@ bool hasOffsetAdjust(const ReportManager &rm, const NGWrapper &w) {
     return false;
 }
 
-void fillExpressionInfo(ReportManager &rm, NGWrapper &w, hs_expr_info *info) {
+void fillExpressionInfo(ReportManager &rm, NGHolder &g,
+                        const ExpressionInfo &expr, hs_expr_info *info) {
     assert(info);
 
     /* ensure utf8 starts at cp boundary */
-    ensureCodePointStart(rm, w);
-    resolveAsserts(rm, w);
-    optimiseVirtualStarts(w);
+    ensureCodePointStart(rm, g, expr);
+    resolveAsserts(rm, g, expr);
+    optimiseVirtualStarts(g);
 
-    removeLeadingVirtualVerticesFromRoot(w, w.start);
-    removeLeadingVirtualVerticesFromRoot(w, w.startDs);
+    removeLeadingVirtualVerticesFromRoot(g, g.start);
+    removeLeadingVirtualVerticesFromRoot(g, g.startDs);
 
     vector<DepthMinMax> depths;
-    calcDepthsFrom(w, w.start, depths);
+    calcDepthsFrom(g, g.start, depths);
 
     DepthMinMax d;
 
-    for (auto u : inv_adjacent_vertices_range(w.accept, w)) {
-        checkVertex(rm, w, u, depths, d);
+    for (auto u : inv_adjacent_vertices_range(g.accept, g)) {
+        checkVertex(rm, g, u, depths, d);
     }
 
-    for (auto u : inv_adjacent_vertices_range(w.acceptEod, w)) {
-        checkVertex(rm, w, u, depths, d);
+    for (auto u : inv_adjacent_vertices_range(g.acceptEod, g)) {
+        checkVertex(rm, g, u, depths, d);
     }
 
     if (d.max.is_finite()) {
@@ -170,9 +171,9 @@ void fillExpressionInfo(ReportManager &rm, NGWrapper &w, hs_expr_info *info) {
         info->min_width = UINT_MAX;
     }
 
-    info->unordered_matches = hasOffsetAdjust(rm, w);
-    info->matches_at_eod = can_match_at_eod(w);
-    info->matches_only_at_eod = can_only_match_at_eod(w);
+    info->unordered_matches = hasOffsetAdjust(rm, g);
+    info->matches_at_eod = can_match_at_eod(g);
+    info->matches_only_at_eod = can_only_match_at_eod(g);
 }
 
 } // namespace ue2
diff --git a/src/nfagraph/ng_expr_info.h b/src/nfagraph/ng_expr_info.h
index dcc5a419..e518738c 100644
--- a/src/nfagraph/ng_expr_info.h
+++ b/src/nfagraph/ng_expr_info.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -27,7 +27,7 @@
  */
 
 /** \file
- * \brief Code for discovering properties of an NGWrapper used by
+ * \brief Code for discovering properties of an expression used by
  * hs_expression_info.
  */
 
@@ -36,14 +36,14 @@
 
 struct hs_expr_info;
 
-#include "ue2common.h"
-
 namespace ue2 {
 
-class NGWrapper;
+class ExpressionInfo;
+class NGHolder;
 class ReportManager;
 
-void fillExpressionInfo(ReportManager &rm, NGWrapper &w, hs_expr_info *info);
+void fillExpressionInfo(ReportManager &rm, NGHolder &g,
+                        const ExpressionInfo &expr, hs_expr_info *info);
 
 } // namespace ue2
 
diff --git a/src/nfagraph/ng_extparam.cpp b/src/nfagraph/ng_extparam.cpp
index a504ac50..31a1f81b 100644
--- a/src/nfagraph/ng_extparam.cpp
+++ b/src/nfagraph/ng_extparam.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -38,16 +38,19 @@
  * match given these constraints, or transform the graph in order to make a
  * constraint implicit.
  */
+
+#include "ng_extparam.h"
+
 #include "ng.h"
 #include "ng_depth.h"
 #include "ng_dump.h"
-#include "ng_extparam.h"
 #include "ng_prune.h"
 #include "ng_reports.h"
 #include "ng_som_util.h"
 #include "ng_width.h"
 #include "ng_util.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "parser/position.h"
 #include "util/compile_context.h"
 #include "util/compile_error.h"
@@ -129,7 +132,8 @@ DepthMinMax findMatchLengths(const ReportManager &rm, const NGHolder &g) {
 
 /** \brief Replace the graph's reports with new reports that specify bounds. */
 static
-void updateReportBounds(ReportManager &rm, NGWrapper &g, NFAVertex accept,
+void updateReportBounds(ReportManager &rm, NGHolder &g,
+                        const ExpressionInfo &expr, NFAVertex accept,
                         set<NFAVertex> &done) {
     for (auto v : inv_adjacent_vertices_range(accept, g)) {
         // Don't operate on g.accept itself.
@@ -153,16 +157,16 @@ void updateReportBounds(ReportManager &rm, NGWrapper &g, NFAVertex accept,
 
             // Note that we need to cope with offset adjustment here.
 
-            ir.minOffset = g.min_offset - ir.offsetAdjust;
-            if (g.max_offset == MAX_OFFSET) {
+            ir.minOffset = expr.min_offset - ir.offsetAdjust;
+            if (expr.max_offset == MAX_OFFSET) {
                 ir.maxOffset = MAX_OFFSET;
             } else {
-                ir.maxOffset = g.max_offset - ir.offsetAdjust;
+                ir.maxOffset = expr.max_offset - ir.offsetAdjust;
             }
             assert(ir.maxOffset >= ir.minOffset);
 
-            ir.minLength = g.min_length;
-            if (g.min_length && !g.som) {
+            ir.minLength = expr.min_length;
+            if (expr.min_length && !expr.som) {
                 ir.quashSom = true;
             }
 
@@ -196,22 +200,23 @@ bool hasVirtualStarts(const NGHolder &g) {
  * anchored and unanchored paths, but it's too tricky for the moment.
  */
 static
-bool anchorPatternWithBoundedRepeat(NGWrapper &g, const depth &minWidth,
+bool anchorPatternWithBoundedRepeat(NGHolder &g, const ExpressionInfo &expr,
+                                    const depth &minWidth,
                                     const depth &maxWidth) {
-    assert(!g.som);
-    assert(g.max_offset != MAX_OFFSET);
+    assert(!expr.som);
+    assert(expr.max_offset != MAX_OFFSET);
     assert(minWidth <= maxWidth);
     assert(maxWidth.is_reachable());
 
     DEBUG_PRINTF("widths=[%s,%s], min/max offsets=[%llu,%llu]\n",
-                 minWidth.str().c_str(), maxWidth.str().c_str(), g.min_offset,
-                 g.max_offset);
+                 minWidth.str().c_str(), maxWidth.str().c_str(),
+                 expr.min_offset, expr.max_offset);
 
-    if (g.max_offset > MAX_MAXOFFSET_TO_ANCHOR) {
+    if (expr.max_offset > MAX_MAXOFFSET_TO_ANCHOR) {
         return false;
     }
 
-    if (g.max_offset < minWidth) {
+    if (expr.max_offset < minWidth) {
         assert(0);
         return false;
     }
@@ -232,10 +237,10 @@ bool anchorPatternWithBoundedRepeat(NGWrapper &g, const depth &minWidth,
     u32 min_bound, max_bound;
     if (maxWidth.is_infinite()) {
         min_bound = 0;
-        max_bound = g.max_offset - minWidth;
+        max_bound = expr.max_offset - minWidth;
     } else {
-        min_bound = g.min_offset > maxWidth ? g.min_offset - maxWidth : 0;
-        max_bound = g.max_offset - minWidth;
+        min_bound = expr.min_offset > maxWidth ? expr.min_offset - maxWidth : 0;
+        max_bound = expr.max_offset - minWidth;
     }
 
     DEBUG_PRINTF("prepending ^.{%u,%u}\n", min_bound, max_bound);
@@ -315,7 +320,7 @@ NFAVertex findSingleCyclic(const NGHolder &g) {
 }
 
 static
-bool hasOffsetAdjust(const ReportManager &rm, NGWrapper &g,
+bool hasOffsetAdjust(const ReportManager &rm, NGHolder &g,
                      int *adjust) {
     const auto &reports = all_reports(g);
     if (reports.empty()) {
@@ -342,10 +347,11 @@ bool hasOffsetAdjust(const ReportManager &rm, NGWrapper &g,
  *     /foo.*bar/{min_length=100} --> /foo.{94,}bar/
  */
 static
-bool transformMinLengthToRepeat(const ReportManager &rm, NGWrapper &g) {
-    assert(g.min_length);
+bool transformMinLengthToRepeat(const ReportManager &rm, NGHolder &g,
+                                ExpressionInfo &expr) {
+    assert(expr.min_length);
 
-    if (g.min_length > MAX_MINLENGTH_TO_CONVERT) {
+    if (expr.min_length > MAX_MINLENGTH_TO_CONVERT) {
         return false;
     }
 
@@ -437,10 +443,10 @@ bool transformMinLengthToRepeat(const ReportManager &rm, NGWrapper &g) {
     DEBUG_PRINTF("width=%u, vertex %zu is cyclic\n", width,
                   g[cyclic].index);
 
-    if (width >= g.min_length) {
+    if (width >= expr.min_length) {
         DEBUG_PRINTF("min_length=%llu is guaranteed, as width=%u\n",
-                      g.min_length, width);
-        g.min_length = 0;
+                      expr.min_length, width);
+        expr.min_length = 0;
         return true;
     }
 
@@ -468,7 +474,7 @@ bool transformMinLengthToRepeat(const ReportManager &rm, NGWrapper &g) {
 
     const CharReach &cr = g[cyclic].char_reach;
 
-    for (u32 i = 0; i < g.min_length - width - 1; ++i) {
+    for (u32 i = 0; i < expr.min_length - width - 1; ++i) {
         v = add_vertex(g);
         g[v].char_reach = cr;
 
@@ -487,19 +493,19 @@ bool transformMinLengthToRepeat(const ReportManager &rm, NGWrapper &g) {
     renumber_edges(g);
     clearReports(g);
 
-    g.min_length = 0;
+    expr.min_length = 0;
     return true;
 }
 
 static
-bool hasExtParams(const NGWrapper &g) {
-    if (g.min_length != 0) {
+bool hasExtParams(const ExpressionInfo &expr) {
+    if (expr.min_length != 0) {
         return true;
     }
-    if (g.min_offset != 0) {
+    if (expr.min_offset != 0) {
         return true;
     }
-    if (g.max_offset != MAX_OFFSET) {
+    if (expr.max_offset != MAX_OFFSET) {
         return true;
     }
     return false;
@@ -535,7 +541,7 @@ const depth& minDistToAccept(const NFAVertexBidiDepth &d) {
 }
 
 static
-bool isEdgePrunable(const NGWrapper &g,
+bool isEdgePrunable(const NGHolder &g, const ExpressionInfo &expr,
                     const vector<NFAVertexBidiDepth> &depths,
                     const NFAEdge &e) {
     const NFAVertex u = source(e, g);
@@ -564,29 +570,29 @@ bool isEdgePrunable(const NGWrapper &g,
     const NFAVertexBidiDepth &du = depths.at(u_idx);
     const NFAVertexBidiDepth &dv = depths.at(v_idx);
 
-    if (g.min_offset) {
+    if (expr.min_offset) {
         depth max_offset = maxDistFromStart(du) + maxDistToAccept(dv);
-        if (max_offset.is_finite() && max_offset < g.min_offset) {
+        if (max_offset.is_finite() && max_offset < expr.min_offset) {
             DEBUG_PRINTF("max_offset=%s too small\n", max_offset.str().c_str());
             return true;
         }
     }
 
-    if (g.max_offset != MAX_OFFSET) {
+    if (expr.max_offset != MAX_OFFSET) {
         depth min_offset = minDistFromStart(du) + minDistToAccept(dv);
         assert(min_offset.is_finite());
 
-        if (min_offset > g.max_offset) {
+        if (min_offset > expr.max_offset) {
             DEBUG_PRINTF("min_offset=%s too large\n", min_offset.str().c_str());
             return true;
         }
     }
 
-    if (g.min_length && is_any_accept(v, g)) {
+    if (expr.min_length && is_any_accept(v, g)) {
         // Simple take on min_length. If we're an edge to accept and our max
         // dist from start is too small, we can be pruned.
         const depth &width = du.fromStart.max;
-        if (width.is_finite() && width < g.min_length) {
+        if (width.is_finite() && width < expr.min_length) {
             DEBUG_PRINTF("max width %s from start too small for min_length\n",
                          width.str().c_str());
             return true;
@@ -597,14 +603,14 @@ bool isEdgePrunable(const NGWrapper &g,
 }
 
 static
-void pruneExtUnreachable(NGWrapper &g) {
+void pruneExtUnreachable(NGHolder &g, const ExpressionInfo &expr) {
     vector<NFAVertexBidiDepth> depths;
     calcDepths(g, depths);
 
     vector<NFAEdge> dead;
 
     for (const auto &e : edges_range(g)) {
-        if (isEdgePrunable(g, depths, e)) {
+        if (isEdgePrunable(g, expr, depths, e)) {
             DEBUG_PRINTF("pruning\n");
             dead.push_back(e);
         }
@@ -621,8 +627,8 @@ void pruneExtUnreachable(NGWrapper &g) {
 /** Remove vacuous edges in graphs where the min_offset or min_length
  * constraints dictate that they can never produce a match. */
 static
-void pruneVacuousEdges(NGWrapper &g) {
-    if (!g.min_length && !g.min_offset) {
+void pruneVacuousEdges(NGHolder &g, const ExpressionInfo &expr) {
+    if (!expr.min_length && !expr.min_offset) {
         return;
     }
 
@@ -634,14 +640,14 @@ void pruneVacuousEdges(NGWrapper &g) {
 
         // Special case: Crudely remove vacuous edges from start in graphs with a
         // min_offset.
-        if (g.min_offset && u == g.start && is_any_accept(v, g)) {
+        if (expr.min_offset && u == g.start && is_any_accept(v, g)) {
             DEBUG_PRINTF("vacuous edge in graph with min_offset!\n");
             dead.push_back(e);
             continue;
         }
 
         // If a min_length is set, vacuous edges can be removed.
-        if (g.min_length && is_any_start(u, g) && is_any_accept(v, g)) {
+        if (expr.min_length && is_any_start(u, g) && is_any_accept(v, g)) {
             DEBUG_PRINTF("vacuous edge in graph with min_length!\n");
             dead.push_back(e);
             continue;
@@ -657,7 +663,8 @@ void pruneVacuousEdges(NGWrapper &g) {
 }
 
 static
-void pruneUnmatchable(NGWrapper &g, const vector<DepthMinMax> &depths,
+void pruneUnmatchable(NGHolder &g, const ExpressionInfo &expr,
+                      const vector<DepthMinMax> &depths,
                       const ReportManager &rm, NFAVertex accept) {
     vector<NFAEdge> dead;
 
@@ -676,16 +683,16 @@ void pruneUnmatchable(NGWrapper &g, const vector<DepthMinMax> &depths,
         d.min += adj.first;
         d.max += adj.second;
 
-        if (d.max.is_finite() && d.max < g.min_length) {
+        if (d.max.is_finite() && d.max < expr.min_length) {
             DEBUG_PRINTF("prune, max match length %s < min_length=%llu\n",
-                         d.max.str().c_str(), g.min_length);
+                         d.max.str().c_str(), expr.min_length);
             dead.push_back(e);
             continue;
         }
 
-        if (g.max_offset != MAX_OFFSET && d.min > g.max_offset) {
+        if (expr.max_offset != MAX_OFFSET && d.min > expr.max_offset) {
             DEBUG_PRINTF("prune, min match length %s > max_offset=%llu\n",
-                         d.min.str().c_str(), g.max_offset);
+                         d.min.str().c_str(), expr.max_offset);
             dead.push_back(e);
             continue;
         }
@@ -697,15 +704,16 @@ void pruneUnmatchable(NGWrapper &g, const vector<DepthMinMax> &depths,
 /** Remove edges to accepts that can never produce a match long enough to
  * satisfy our min_length and max_offset constraints. */
 static
-void pruneUnmatchable(NGWrapper &g, const ReportManager &rm) {
-    if (!g.min_length) {
+void pruneUnmatchable(NGHolder &g, const ExpressionInfo &expr,
+                      const ReportManager &rm) {
+    if (!expr.min_length) {
         return;
     }
 
     vector<DepthMinMax> depths = getDistancesFromSOM(g);
 
-    pruneUnmatchable(g, depths, rm, g.accept);
-    pruneUnmatchable(g, depths, rm, g.acceptEod);
+    pruneUnmatchable(g, expr, depths, rm, g.accept);
+    pruneUnmatchable(g, expr, depths, rm, g.acceptEod);
 
     pruneUseless(g);
 }
@@ -732,9 +740,9 @@ bool hasOffsetAdjustments(const ReportManager &rm, const NGHolder &g) {
     return false;
 }
 
-void handleExtendedParams(ReportManager &rm, NGWrapper &g,
+void handleExtendedParams(ReportManager &rm, NGHolder &g, ExpressionInfo &expr,
                           UNUSED const CompileContext &cc) {
-    if (!hasExtParams(g)) {
+    if (!hasExtParams(expr)) {
         return;
     }
 
@@ -751,50 +759,50 @@ void handleExtendedParams(ReportManager &rm, NGWrapper &g,
     DepthMinMax match_depths = findMatchLengths(rm, g);
     DEBUG_PRINTF("match depths %s\n", match_depths.str().c_str());
 
-    if (is_anchored && maxWidth.is_finite() && g.min_offset > maxWidth) {
+    if (is_anchored && maxWidth.is_finite() && expr.min_offset > maxWidth) {
         ostringstream oss;
         oss << "Expression is anchored and cannot satisfy min_offset="
-            << g.min_offset << " as it can only produce matches of length "
+            << expr.min_offset << " as it can only produce matches of length "
             << maxWidth << " bytes at most.";
-        throw CompileError(g.expressionIndex, oss.str());
+        throw CompileError(expr.index, oss.str());
     }
 
-    if (minWidth > g.max_offset) {
+    if (minWidth > expr.max_offset) {
         ostringstream oss;
-        oss << "Expression has max_offset=" << g.max_offset << " but requires "
-             << minWidth << " bytes to match.";
-        throw CompileError(g.expressionIndex, oss.str());
+        oss << "Expression has max_offset=" << expr.max_offset
+            << " but requires " << minWidth << " bytes to match.";
+        throw CompileError(expr.index, oss.str());
     }
 
-    if (maxWidth.is_finite() && match_depths.max < g.min_length) {
+    if (maxWidth.is_finite() && match_depths.max < expr.min_length) {
         ostringstream oss;
-        oss << "Expression has min_length=" << g.min_length << " but can "
+        oss << "Expression has min_length=" << expr.min_length << " but can "
             "only produce matches of length " << match_depths.max <<
             " bytes at most.";
-        throw CompileError(g.expressionIndex, oss.str());
+        throw CompileError(expr.index, oss.str());
     }
 
-    if (g.min_length && g.min_length <= match_depths.min) {
+    if (expr.min_length && expr.min_length <= match_depths.min) {
         DEBUG_PRINTF("min_length=%llu constraint is unnecessary\n",
-                     g.min_length);
-        g.min_length = 0;
+                     expr.min_length);
+        expr.min_length = 0;
     }
 
-    if (!hasExtParams(g)) {
+    if (!hasExtParams(expr)) {
         return;
     }
 
-    pruneVacuousEdges(g);
-    pruneUnmatchable(g, rm);
+    pruneVacuousEdges(g, expr);
+    pruneUnmatchable(g, expr, rm);
 
     if (!has_offset_adj) {
-        pruneExtUnreachable(g);
+        pruneExtUnreachable(g, expr);
     }
 
     // We may have removed all the edges to accept, in which case this
     // expression cannot match.
     if (in_degree(g.accept, g) == 0 && in_degree(g.acceptEod, g) == 1) {
-        throw CompileError(g.expressionIndex, "Extended parameter "
+        throw CompileError(expr.index, "Extended parameter "
                 "constraints can not be satisfied for any match from "
                 "this expression.");
     }
@@ -812,27 +820,28 @@ void handleExtendedParams(ReportManager &rm, NGWrapper &g,
 
     // If the pattern is completely anchored and has a min_length set, this can
     // be converted to a min_offset.
-    if (g.min_length && (g.min_offset <= g.min_length) && is_anchored) {
-        DEBUG_PRINTF("converting min_length to min_offset=%llu for "
-                     "anchored case\n", g.min_length);
-        g.min_offset = g.min_length;
-        g.min_length = 0;
+    if (expr.min_length && (expr.min_offset <= expr.min_length) &&
+        is_anchored) {
+        DEBUG_PRINTF("convertinexpr.min_length to min_offset=%llu for "
+                     "anchored case\n", expr.min_length);
+        expr.min_offset = expr.min_length;
+        expr.min_length = 0;
     }
 
-    if (g.min_offset && g.min_offset <= minWidth && !has_offset_adj) {
+    if (expr.min_offset && expr.min_offset <= minWidth && !has_offset_adj) {
         DEBUG_PRINTF("min_offset=%llu constraint is unnecessary\n",
-                     g.min_offset);
-        g.min_offset = 0;
+                     expr.min_offset);
+        expr.min_offset = 0;
     }
 
-    if (!hasExtParams(g)) {
+    if (!hasExtParams(expr)) {
         return;
     }
 
     // If the pattern has a min_length and is of "ratchet" form with one
     // unbounded repeat, that repeat can become a bounded repeat.
     // e.g. /foo.*bar/{min_length=100} --> /foo.{94,}bar/
-    if (g.min_length && transformMinLengthToRepeat(rm, g)) {
+    if (expr.min_length && transformMinLengthToRepeat(rm, g, expr)) {
         DEBUG_PRINTF("converted min_length to bounded repeat\n");
         // recalc
         minWidth = findMinWidth(g);
@@ -846,28 +855,28 @@ void handleExtendedParams(ReportManager &rm, NGWrapper &g,
     // Note that it is possible to handle graphs that have a combination of
     // anchored and unanchored paths, but it's too tricky for the moment.
 
-    if (g.max_offset != MAX_OFFSET && !g.som && !g.min_length &&
-                !has_offset_adj && isUnanchored(g)) {
-        if (anchorPatternWithBoundedRepeat(g, minWidth, maxWidth)) {
+    if (expr.max_offset != MAX_OFFSET && !expr.som && !expr.min_length &&
+        !has_offset_adj && isUnanchored(g)) {
+        if (anchorPatternWithBoundedRepeat(g, expr, minWidth, maxWidth)) {
             DEBUG_PRINTF("minWidth=%s, maxWidth=%s\n", minWidth.str().c_str(),
                          maxWidth.str().c_str());
             if (minWidth == maxWidth) {
                 // For a fixed width pattern, we can retire the offsets as they
                 // are implicit in the graph now.
-                g.min_offset = 0;
-                g.max_offset = MAX_OFFSET;
+                expr.min_offset = 0;
+                expr.max_offset = MAX_OFFSET;
             }
         }
     }
     //dumpGraph("final.dot", g);
 
-    if (!hasExtParams(g)) {
+    if (!hasExtParams(expr)) {
         return;
     }
 
     set<NFAVertex> done;
-    updateReportBounds(rm, g, g.accept, done);
-    updateReportBounds(rm, g, g.acceptEod, done);
+    updateReportBounds(rm, g, expr, g.accept, done);
+    updateReportBounds(rm, g, expr, g.acceptEod, done);
 }
 
 } // namespace ue2
diff --git a/src/nfagraph/ng_extparam.h b/src/nfagraph/ng_extparam.h
index d5df1cf6..798acd3f 100644
--- a/src/nfagraph/ng_extparam.h
+++ b/src/nfagraph/ng_extparam.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -37,10 +37,11 @@
 namespace ue2 {
 
 struct CompileContext;
-class NGWrapper;
+class ExpressionInfo;
+class NGHolder;
 class ReportManager;
 
-void handleExtendedParams(ReportManager &rm, NGWrapper &g,
+void handleExtendedParams(ReportManager &rm, NGHolder &g, ExpressionInfo &expr,
                           const CompileContext &cc);
 
 } // namespace ue2
diff --git a/src/nfagraph/ng_literal_component.cpp b/src/nfagraph/ng_literal_component.cpp
index e3cfe867..de05e490 100644
--- a/src/nfagraph/ng_literal_component.cpp
+++ b/src/nfagraph/ng_literal_component.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -30,12 +30,15 @@
  * \brief Literal Component Splitting. Identifies literals that span the
  * graph and moves them into Rose.
  */
+
+#include "ng_literal_component.h"
+
 #include "grey.h"
 #include "ng.h"
-#include "ng_literal_component.h"
 #include "ng_prune.h"
 #include "ng_util.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "rose/rose_build.h"
 #include "util/container.h"
 #include "util/graph.h"
@@ -47,8 +50,8 @@ using namespace std;
 namespace ue2 {
 
 static
-bool isLiteralChar(const NGWrapper &g, NFAVertex v,
-                   bool &nocase, bool &casefixed) {
+bool isLiteralChar(const NGHolder &g, NFAVertex v, bool &nocase,
+                   bool &casefixed) {
     const CharReach &cr = g[v].char_reach;
     const size_t num = cr.count();
     if (num > 2) {
@@ -93,7 +96,7 @@ void addToString(string &s, const NGHolder &g, NFAVertex v) {
 }
 
 static
-bool splitOffLiteral(NG &ng, NGWrapper &g, NFAVertex v, const bool anchored,
+bool splitOffLiteral(NG &ng, NGHolder &g, NFAVertex v, const bool anchored,
                      set<NFAVertex> &dead) {
     DEBUG_PRINTF("examine vertex %zu\n", g[v].index);
     bool nocase = false, casefixed = false;
@@ -185,7 +188,7 @@ bool splitOffLiteral(NG &ng, NGWrapper &g, NFAVertex v, const bool anchored,
 }
 
 /** \brief Split off literals. True if any changes were made to the graph. */
-bool splitOffLiterals(NG &ng, NGWrapper &g) {
+bool splitOffLiterals(NG &ng, NGHolder &g) {
     if (!ng.cc.grey.allowLiteral) {
         return false;
     }
diff --git a/src/nfagraph/ng_literal_component.h b/src/nfagraph/ng_literal_component.h
index dc177c40..1f284ce3 100644
--- a/src/nfagraph/ng_literal_component.h
+++ b/src/nfagraph/ng_literal_component.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -37,10 +37,10 @@
 namespace ue2 {
 
 class NG;
-class NGWrapper;
+class NGHolder;
 
 /** \brief Split off literals. True if any changes were made to the graph. */
-bool splitOffLiterals(NG &ng, NGWrapper &graph);
+bool splitOffLiterals(NG &ng, NGHolder &g);
 
 } // namespace ue2
 
diff --git a/src/nfagraph/ng_som.cpp b/src/nfagraph/ng_som.cpp
index 8d3d75a3..5bf52915 100644
--- a/src/nfagraph/ng_som.cpp
+++ b/src/nfagraph/ng_som.cpp
@@ -29,6 +29,9 @@
 /** \file
  * \brief SOM ("Start of Match") analysis.
  */
+
+#include "ng_som.h"
+
 #include "ng.h"
 #include "ng_dump.h"
 #include "ng_equivalence.h"
@@ -40,7 +43,6 @@
 #include "ng_redundancy.h"
 #include "ng_region.h"
 #include "ng_reports.h"
-#include "ng_som.h"
 #include "ng_som_add_redundancy.h"
 #include "ng_som_util.h"
 #include "ng_split.h"
@@ -49,6 +51,7 @@
 #include "ng_width.h"
 #include "grey.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "nfa/goughcompile.h"
 #include "nfa/nfa_internal.h" // for MO_INVALID_IDX
 #include "parser/position.h"
@@ -1584,8 +1587,9 @@ void dumpSomPlan(UNUSED const NGHolder &g, UNUSED const som_plan &p,
  * implement the full pattern.
  */
 static
-void implementSomPlan(NG &ng, const NGWrapper &w, u32 comp_id, NGHolder &g,
-                      vector<som_plan> &plan, const u32 first_som_slot) {
+void implementSomPlan(NG &ng, const ExpressionInfo &expr, u32 comp_id,
+                      NGHolder &g, vector<som_plan> &plan,
+                      const u32 first_som_slot) {
     ReportManager &rm = ng.rm;
     SomSlotManager &ssm = ng.ssm;
 
@@ -1598,14 +1602,14 @@ void implementSomPlan(NG &ng, const NGWrapper &w, u32 comp_id, NGHolder &g,
 
     // Root plan, which already has a SOM slot assigned (first_som_slot).
     dumpSomPlan(g, plan.front(), 0);
-    dumpSomSubComponent(*plan.front().prefix, "04_som", w.expressionIndex,
-                        comp_id, 0, ng.cc.grey);
+    dumpSomSubComponent(*plan.front().prefix, "04_som", expr.index, comp_id, 0,
+                        ng.cc.grey);
     assert(plan.front().prefix);
     if (plan.front().escapes.any() && !plan.front().is_reset) {
         /* setup escaper for first som location */
         if (!createEscaper(ng, *plan.front().prefix, plan.front().escapes,
                            first_som_slot)) {
-            throw CompileError(w.expressionIndex, "Pattern is too large.");
+            throw CompileError(expr.index, "Pattern is too large.");
         }
     }
 
@@ -1617,7 +1621,7 @@ void implementSomPlan(NG &ng, const NGWrapper &w, u32 comp_id, NGHolder &g,
     for (++it; it != plan.end(); ++it) {
         const u32 plan_num = it - plan.begin();
         dumpSomPlan(g, *it, plan_num);
-        dumpSomSubComponent(*it->prefix, "04_som", w.expressionIndex, comp_id,
+        dumpSomSubComponent(*it->prefix, "04_som", expr.index, comp_id,
                             plan_num, ng.cc.grey);
 
         assert(it->parent < plan_num);
@@ -1628,7 +1632,7 @@ void implementSomPlan(NG &ng, const NGWrapper &w, u32 comp_id, NGHolder &g,
 
         assert(!it->no_implement);
         if (!buildMidfix(ng, *it, som_slot_in, som_slot_out)) {
-            throw CompileError(w.expressionIndex, "Pattern is too large.");
+            throw CompileError(expr.index, "Pattern is too large.");
         }
         updateReportToUseRecordedSom(rm, g, it->reporters_in, som_slot_in);
         updateReportToUseRecordedSom(rm, g, it->reporters, som_slot_out);
@@ -1639,7 +1643,7 @@ void implementSomPlan(NG &ng, const NGWrapper &w, u32 comp_id, NGHolder &g,
         renumber_vertices(*plan.front().prefix);
         assert(plan.front().prefix->kind == NFA_OUTFIX);
         if (!ng.addHolder(*plan.front().prefix)) {
-            throw CompileError(w.expressionIndex, "Pattern is too large.");
+            throw CompileError(expr.index, "Pattern is too large.");
         }
     }
 }
@@ -1852,7 +1856,7 @@ bool doSomRevNfa(NG &ng, NGHolder &g, const CompileContext &cc) {
 }
 
 static
-u32 doSomRevNfaPrefix(NG &ng, const NGWrapper &w, NGHolder &g,
+u32 doSomRevNfaPrefix(NG &ng, const ExpressionInfo &expr, NGHolder &g,
                       const CompileContext &cc) {
     depth maxWidth = findMaxWidth(g);
 
@@ -1861,7 +1865,7 @@ u32 doSomRevNfaPrefix(NG &ng, const NGWrapper &w, NGHolder &g,
 
     auto nfa = makeBareSomRevNfa(g, cc);
     if (!nfa) {
-        throw CompileError(w.expressionIndex, "Pattern is too large.");
+        throw CompileError(expr.index, "Pattern is too large.");
     }
 
     if (ng.cc.streaming) {
@@ -2055,8 +2059,8 @@ void roseAddHaigLiteral(RoseBuild &tb, const shared_ptr<NGHolder> &prefix,
 }
 
 static
-sombe_rv doHaigLitSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
-                      som_type som,
+sombe_rv doHaigLitSom(NG &ng, NGHolder &g, const ExpressionInfo &expr,
+                      u32 comp_id, som_type som,
                       const ue2::unordered_map<NFAVertex, u32> &regions,
                       const map<u32, region_info> &info,
                       map<u32, region_info>::const_iterator lower_bound) {
@@ -2077,7 +2081,7 @@ sombe_rv doHaigLitSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
         // This is an optimisation: if we can't build a Haig from a portion of
         // the graph, then we won't be able to manage it as an outfix either
         // when we fall back.
-        throw CompileError(w.expressionIndex, "Pattern is too large.");
+        throw CompileError(expr.index, "Pattern is too large.");
     }
 
     while (1) {
@@ -2152,7 +2156,7 @@ sombe_rv doHaigLitSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
                 goto next_try;
             }
 
-            implementSomPlan(ng, w, comp_id, g, plan, som_loc);
+            implementSomPlan(ng, expr, comp_id, g, plan, som_loc);
 
             Report ir = makeCallback(0U, 0);
             assert(!plan.empty());
@@ -2877,7 +2881,7 @@ unique_ptr<NGHolder> makePrefixForChain(NGHolder &g,
     return prefix;
 }
 
-sombe_rv doSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
+sombe_rv doSom(NG &ng, NGHolder &g, const ExpressionInfo &expr, u32 comp_id,
                som_type som) {
     assert(som);
     DEBUG_PRINTF("som hello\n");
@@ -3001,7 +3005,7 @@ sombe_rv doSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
         /* create prefix to set the som_loc */
         updatePrefixReports(rm, *prefix, INTERNAL_SOM_LOC_SET_IF_UNSET);
         if (prefix_by_rev) {
-            u32 rev_comp_id = doSomRevNfaPrefix(ng, w, *prefix, cc);
+            u32 rev_comp_id = doSomRevNfaPrefix(ng, expr, *prefix, cc);
             updatePrefixReportsRevNFA(rm, *prefix, rev_comp_id);
         }
         renumber_vertices(*prefix);
@@ -3084,18 +3088,18 @@ sombe_rv doSom(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
         updatePrefixReports(rm, *prefix, INTERNAL_SOM_LOC_SET);
     }
     if (prefix_by_rev && !plan.front().no_implement) {
-        u32 rev_comp_id = doSomRevNfaPrefix(ng, w, *prefix, cc);
+        u32 rev_comp_id = doSomRevNfaPrefix(ng, expr, *prefix, cc);
         updatePrefixReportsRevNFA(rm, *prefix, rev_comp_id);
     }
 
-    implementSomPlan(ng, w, comp_id, g, plan, som_loc);
+    implementSomPlan(ng, expr, comp_id, g, plan, som_loc);
 
     DEBUG_PRINTF("success\n");
     return SOMBE_HANDLED_INTERNAL;
 }
 
-sombe_rv doSomWithHaig(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
-                       som_type som) {
+sombe_rv doSomWithHaig(NG &ng, NGHolder &g, const ExpressionInfo &expr,
+                       u32 comp_id, som_type som) {
     assert(som);
 
     DEBUG_PRINTF("som+haig hello\n");
@@ -3132,7 +3136,7 @@ sombe_rv doSomWithHaig(NG &ng, NGHolder &g, const NGWrapper &w, u32 comp_id,
     buildRegionMapping(g, regions, info, true);
 
     sombe_rv rv =
-        doHaigLitSom(ng, g, w, comp_id, som, regions, info, info.begin());
+        doHaigLitSom(ng, g, expr, comp_id, som, regions, info, info.begin());
     if (rv == SOMBE_FAIL) {
         clear_graph(g);
         cloneHolder(g, g_pristine);
diff --git a/src/nfagraph/ng_som.h b/src/nfagraph/ng_som.h
index 70710945..ecae4c67 100644
--- a/src/nfagraph/ng_som.h
+++ b/src/nfagraph/ng_som.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -34,12 +34,14 @@
 #define NG_SOM_H
 
 #include "som/som.h"
+#include "ue2common.h"
 
 namespace ue2 {
 
+class ExpressionInfo;
 class NG;
 class NGHolder;
-class NGWrapper;
+class ReportManager;
 struct Grey;
 
 enum sombe_rv {
@@ -63,14 +65,14 @@ enum sombe_rv {
  *  May throw a "Pattern too large" exception if prefixes of the
  * pattern are too large to compile.
  */
-sombe_rv doSom(NG &ng, NGHolder &h, const NGWrapper &w, u32 comp_id,
+sombe_rv doSom(NG &ng, NGHolder &h, const ExpressionInfo &expr, u32 comp_id,
                som_type som);
 
 /** Returns SOMBE_FAIL (and the original graph) if SOM cannot be established.
  * May also throw pattern too large if prefixes of the pattern are too large to
  * compile. */
-sombe_rv doSomWithHaig(NG &ng, NGHolder &h, const NGWrapper &w, u32 comp_id,
-                       som_type som);
+sombe_rv doSomWithHaig(NG &ng, NGHolder &h, const ExpressionInfo &expr,
+                       u32 comp_id, som_type som);
 
 void makeReportsSomPass(ReportManager &rm, NGHolder &g);
 
diff --git a/src/nfagraph/ng_utf8.cpp b/src/nfagraph/ng_utf8.cpp
index 383aa142..89500fe3 100644
--- a/src/nfagraph/ng_utf8.cpp
+++ b/src/nfagraph/ng_utf8.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -34,6 +34,7 @@
 #include "ng.h"
 #include "ng_prune.h"
 #include "ng_util.h"
+#include "compiler/compiler.h"
 #include "util/graph_range.h"
 #include "util/unicode_def.h"
 
@@ -45,14 +46,14 @@ using namespace std;
 namespace ue2 {
 
 static
-void allowIllegal(NGWrapper &w, NFAVertex v, u8 pred_char) {
-    if (in_degree(v, w) != 1) {
+void allowIllegal(NGHolder &g, NFAVertex v, u8 pred_char) {
+    if (in_degree(v, g) != 1) {
         DEBUG_PRINTF("unexpected pred\n");
         assert(0); /* should be true due to the early stage of this analysis */
         return;
     }
 
-    CharReach &cr = w[v].char_reach;
+    CharReach &cr = g[v].char_reach;
     if (pred_char == 0xe0) {
         assert(cr.isSubsetOf(CharReach(0xa0, 0xbf)));
         if (cr == CharReach(0xa0, 0xbf)) {
@@ -79,8 +80,8 @@ void allowIllegal(NGWrapper &w, NFAVertex v, u8 pred_char) {
  * above \\x{10ffff} or they represent overlong encodings. As we require valid
  * UTF-8 input, we have no defined behaviour in these cases, as a result we can
  * accept them if it simplifies the graph. */
-void relaxForbiddenUtf8(NGWrapper &w) {
-    if (!w.utf8) {
+void relaxForbiddenUtf8(NGHolder &g, const ExpressionInfo &expr) {
+    if (!expr.utf8) {
         return;
     }
 
@@ -88,12 +89,12 @@ void relaxForbiddenUtf8(NGWrapper &w) {
     const CharReach f0(0xf0);
     const CharReach f4(0xf4);
 
-    for (auto v : vertices_range(w)) {
-        const CharReach &cr = w[v].char_reach;
+    for (auto v : vertices_range(g)) {
+        const CharReach &cr = g[v].char_reach;
         if (cr == e0 || cr == f0 || cr == f4) {
             u8 pred_char = cr.find_first();
-            for (auto t : adjacent_vertices_range(v, w)) {
-                allowIllegal(w, t, pred_char);
+            for (auto t : adjacent_vertices_range(v, g)) {
+                allowIllegal(g, t, pred_char);
             }
         }
     }
diff --git a/src/nfagraph/ng_utf8.h b/src/nfagraph/ng_utf8.h
index e1b08e40..7c428833 100644
--- a/src/nfagraph/ng_utf8.h
+++ b/src/nfagraph/ng_utf8.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -35,7 +35,7 @@
 
 namespace ue2 {
 
-class NGWrapper;
+class ExpressionInfo;
 class NGHolder;
 
 /** \brief Relax forbidden UTF-8 sequences.
@@ -44,7 +44,7 @@ class NGHolder;
  * above \\x{10ffff} or they represent overlong encodings. As we require valid
  * UTF-8 input, we have no defined behaviour in these cases, as a result we can
  * accept them if it simplifies the graph. */
-void relaxForbiddenUtf8(NGWrapper &w);
+void relaxForbiddenUtf8(NGHolder &g, const ExpressionInfo &expr);
 
 /** \brief Contract cycles of UTF-8 code points down to a single cyclic vertex
  * where possible, based on the assumption that we will always be matching
diff --git a/src/nfagraph/ng_vacuous.cpp b/src/nfagraph/ng_vacuous.cpp
index 53672a1b..d1123dff 100644
--- a/src/nfagraph/ng_vacuous.cpp
+++ b/src/nfagraph/ng_vacuous.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -34,29 +34,31 @@
 #include "grey.h"
 #include "ng.h"
 #include "ng_util.h"
+#include "compiler/compiler.h"
 
 using namespace std;
 
 namespace ue2 {
 
 static
-ReportID getInternalId(ReportManager &rm, const NGWrapper &graph) {
-    Report ir = rm.getBasicInternalReport(graph);
+ReportID getInternalId(ReportManager &rm, const ExpressionInfo &expr) {
+    Report ir = rm.getBasicInternalReport(expr);
 
     // Apply any extended params.
-    if (graph.min_offset || graph.max_offset != MAX_OFFSET) {
-        ir.minOffset = graph.min_offset;
-        ir.maxOffset = graph.max_offset;
+    if (expr.min_offset || expr.max_offset != MAX_OFFSET) {
+        ir.minOffset = expr.min_offset;
+        ir.maxOffset = expr.max_offset;
     }
 
-    assert(!graph.min_length); // should be handled elsewhere.
+    assert(!expr.min_length); // should be handled elsewhere.
 
     return rm.getInternalId(ir);
 }
 
 static
-void makeFirehose(BoundaryReports &boundary, ReportManager &rm, NGWrapper &g) {
-    const ReportID r = getInternalId(rm, g);
+void makeFirehose(BoundaryReports &boundary, ReportManager &rm, NGHolder &g,
+                  const ExpressionInfo &expr) {
+    const ReportID r = getInternalId(rm, expr);
 
     boundary.report_at_0_eod.insert(r);
     boundary.report_at_0.insert(r);
@@ -81,8 +83,8 @@ void makeFirehose(BoundaryReports &boundary, ReportManager &rm, NGWrapper &g) {
 
 static
 void makeAnchoredAcceptor(BoundaryReports &boundary, ReportManager &rm,
-                          NGWrapper &g) {
-    boundary.report_at_0.insert(getInternalId(rm, g));
+                          NGHolder &g, const ExpressionInfo &expr) {
+    boundary.report_at_0.insert(getInternalId(rm, expr));
     remove_edge(g.start, g.accept, g);
     remove_edge(g.start, g.acceptEod, g);
     g[g.start].reports.clear();
@@ -90,8 +92,8 @@ void makeAnchoredAcceptor(BoundaryReports &boundary, ReportManager &rm,
 
 static
 void makeEndAnchoredAcceptor(BoundaryReports &boundary, ReportManager &rm,
-                             NGWrapper &g) {
-    boundary.report_at_eod.insert(getInternalId(rm, g));
+                             NGHolder &g, const ExpressionInfo &expr) {
+    boundary.report_at_eod.insert(getInternalId(rm, expr));
     remove_edge(g.startDs, g.acceptEod, g);
     remove_edge(g.start, g.acceptEod, g);
     g[g.start].reports.clear();
@@ -100,18 +102,18 @@ void makeEndAnchoredAcceptor(BoundaryReports &boundary, ReportManager &rm,
 
 static
 void makeNothingAcceptor(BoundaryReports &boundary, ReportManager &rm,
-                         NGWrapper &g) {
-    boundary.report_at_0_eod.insert(getInternalId(rm, g));
+                         NGHolder &g, const ExpressionInfo &expr) {
+    boundary.report_at_0_eod.insert(getInternalId(rm, expr));
     remove_edge(g.start, g.acceptEod, g);
     g[g.start].reports.clear();
 }
 
 bool splitOffVacuous(BoundaryReports &boundary, ReportManager &rm,
-                     NGWrapper &g) {
+                     NGHolder &g, const ExpressionInfo &expr) {
     if (edge(g.startDs, g.accept, g).second) {
         // e.g. '.*'; match "between" every byte
         DEBUG_PRINTF("graph is firehose\n");
-        makeFirehose(boundary, rm, g);
+        makeFirehose(boundary, rm, g, expr);
         return true;
     }
 
@@ -119,19 +121,19 @@ bool splitOffVacuous(BoundaryReports &boundary, ReportManager &rm,
 
     if (edge(g.start, g.accept, g).second) {
         DEBUG_PRINTF("creating anchored acceptor\n");
-        makeAnchoredAcceptor(boundary, rm, g);
+        makeAnchoredAcceptor(boundary, rm, g, expr);
         work_done = true;
     }
 
     if (edge(g.startDs, g.acceptEod, g).second) {
         DEBUG_PRINTF("creating end-anchored acceptor\n");
-        makeEndAnchoredAcceptor(boundary, rm, g);
+        makeEndAnchoredAcceptor(boundary, rm, g, expr);
         work_done = true;
     }
 
     if (edge(g.start, g.acceptEod, g).second) {
         DEBUG_PRINTF("creating nothing acceptor\n");
-        makeNothingAcceptor(boundary, rm, g);
+        makeNothingAcceptor(boundary, rm, g, expr);
         work_done = true;
     }
 
diff --git a/src/nfagraph/ng_vacuous.h b/src/nfagraph/ng_vacuous.h
index ebbc9d17..c33cb312 100644
--- a/src/nfagraph/ng_vacuous.h
+++ b/src/nfagraph/ng_vacuous.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -36,12 +36,13 @@
 namespace ue2 {
 
 struct BoundaryReports;
-class NGWrapper;
+class ExpressionInfo;
+class NGHolder;
 class ReportManager;
 
 // Returns true if a "vacuous" reporter was created.
 bool splitOffVacuous(BoundaryReports &boundary, ReportManager &rm,
-                     NGWrapper &graph);
+                     NGHolder &g, const ExpressionInfo &expr);
 
 } // namespace ue2
 
diff --git a/src/parser/shortcut_literal.cpp b/src/parser/shortcut_literal.cpp
index a7aa5d06..4539836a 100644
--- a/src/parser/shortcut_literal.cpp
+++ b/src/parser/shortcut_literal.cpp
@@ -159,13 +159,15 @@ public:
 ConstructLiteralVisitor::~ConstructLiteralVisitor() {}
 
 /** \brief True if the literal expression \a expr could be added to Rose. */
-bool shortcutLiteral(NG &ng, const ParsedExpression &expr) {
-    assert(expr.component);
+bool shortcutLiteral(NG &ng, const ParsedExpression &pe) {
+    assert(pe.component);
 
     if (!ng.cc.grey.allowLiteral) {
         return false;
     }
 
+    const auto &expr = pe.expr;
+
     // XXX: don't shortcut literals with extended params (yet)
     if (expr.min_offset || expr.max_offset != MAX_OFFSET || expr.min_length ||
         expr.edit_distance) {
@@ -175,8 +177,8 @@ bool shortcutLiteral(NG &ng, const ParsedExpression &expr) {
 
     ConstructLiteralVisitor vis;
     try {
-        assert(expr.component);
-        expr.component->accept(vis);
+        assert(pe.component);
+        pe.component->accept(vis);
         assert(vis.repeat_stack.empty());
     } catch (const ConstructLiteralVisitor::NotLiteral&) {
         DEBUG_PRINTF("not a literal\n");
@@ -196,7 +198,8 @@ bool shortcutLiteral(NG &ng, const ParsedExpression &expr) {
     }
 
     DEBUG_PRINTF("constructed literal %s\n", dumpString(lit).c_str());
-    return ng.addLiteral(lit, expr.index, expr.id, expr.highlander, expr.som);
+    return ng.addLiteral(lit, expr.index, expr.report, expr.highlander,
+                         expr.som);
 }
 
 } // namespace ue2
diff --git a/src/smallwrite/smallwrite_build.cpp b/src/smallwrite/smallwrite_build.cpp
index 108bca8a..7d340d79 100644
--- a/src/smallwrite/smallwrite_build.cpp
+++ b/src/smallwrite/smallwrite_build.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -30,6 +30,7 @@
 
 #include "grey.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "nfa/dfa_min.h"
 #include "nfa/mcclellancompile.h"
 #include "nfa/mcclellancompile_util.h"
@@ -74,7 +75,7 @@ public:
     // Construct a runtime implementation.
     aligned_unique_ptr<SmallWriteEngine> build(u32 roseQuality) override;
 
-    void add(const NGWrapper &w) override;
+    void add(const NGHolder &g, const ExpressionInfo &expr) override;
     void add(const ue2_literal &literal, ReportID r) override;
 
     set<ReportID> all_reports() const override;
@@ -171,26 +172,26 @@ bool pruneOverlong(NGHolder &g, const depth &max_depth,
     return modified;
 }
 
-void SmallWriteBuildImpl::add(const NGWrapper &w) {
+void SmallWriteBuildImpl::add(const NGHolder &g, const ExpressionInfo &expr) {
     // If the graph is poisoned (i.e. we can't build a SmallWrite version),
     // we don't even try.
     if (poisoned) {
         return;
     }
 
-    if (w.som || w.min_length || isVacuous(w)) { /* cannot support in smwr */
-        poisoned = true;
+    if (expr.som || expr.min_length || isVacuous(g)) {
+        poisoned = true; /* cannot support in smwr */
         return;
     }
 
-    DEBUG_PRINTF("w=%p\n", &w);
+    DEBUG_PRINTF("g=%p\n", &g);
 
     // make a copy of the graph so that we can modify it for our purposes
-    unique_ptr<NGHolder> h = cloneHolder(w);
+    unique_ptr<NGHolder> h = cloneHolder(g);
 
     pruneOverlong(*h, depth(cc.grey.smallWriteLargestBuffer), rm);
 
-    reduceGraph(*h, SOM_NONE, w.utf8, cc);
+    reduceGraph(*h, SOM_NONE, expr.utf8, cc);
 
     if (can_never_match(*h)) {
         DEBUG_PRINTF("graph can never match in small block\n");
diff --git a/src/smallwrite/smallwrite_build.h b/src/smallwrite/smallwrite_build.h
index 84c6df3a..3d7f3cb6 100644
--- a/src/smallwrite/smallwrite_build.h
+++ b/src/smallwrite/smallwrite_build.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -48,8 +48,9 @@ namespace ue2 {
 
 struct CompileContext;
 struct ue2_literal;
-class  NGWrapper;
-class  ReportManager;
+class ExpressionInfo;
+class NGHolder;
+class ReportManager;
 
 // Abstract interface intended for callers from elsewhere in the tree, real
 // underlying implementation is SmallWriteBuildImpl in smwr_build_impl.h.
@@ -61,16 +62,16 @@ public:
     // Construct a runtime implementation.
     virtual ue2::aligned_unique_ptr<SmallWriteEngine> build(u32 roseQuality) = 0;
 
-    virtual void add(const NGWrapper &w) = 0;
+    virtual void add(const NGHolder &g, const ExpressionInfo &expr) = 0;
     virtual void add(const ue2_literal &literal, ReportID r) = 0;
 
     virtual std::set<ReportID> all_reports() const = 0;
 };
 
 // Construct a usable SmallWrite builder.
-std::unique_ptr<SmallWriteBuild> makeSmallWriteBuilder(size_t num_patterns,
-                                                       const ReportManager &rm,
-                                                       const CompileContext &cc);
+std::unique_ptr<SmallWriteBuild>
+makeSmallWriteBuilder(size_t num_patterns, const ReportManager &rm,
+                      const CompileContext &cc);
 
 size_t smwrSize(const SmallWriteEngine *t);
 
diff --git a/src/util/report_manager.cpp b/src/util/report_manager.cpp
index 8377ea03..9c72da07 100644
--- a/src/util/report_manager.cpp
+++ b/src/util/report_manager.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -29,9 +29,12 @@
 /** \file
  * \brief ReportManager: tracks Report structures, exhaustion and dedupe keys.
  */
-#include "grey.h"
+
 #include "report_manager.h"
+
+#include "grey.h"
 #include "ue2common.h"
+#include "compiler/compiler.h"
 #include "nfagraph/ng.h"
 #include "rose/rose_build.h"
 #include "util/compile_error.h"
@@ -201,20 +204,21 @@ void ReportManager::registerExtReport(ReportID id,
     }
 }
 
-Report ReportManager::getBasicInternalReport(const NGWrapper &g, s32 adj) {
+Report ReportManager::getBasicInternalReport(const ExpressionInfo &expr,
+                                             s32 adj) {
     /* validate that we are not violating highlander constraints, this will
      * throw a CompileError if so. */
-    registerExtReport(g.reportId,
-                      external_report_info(g.highlander, g.expressionIndex));
+    registerExtReport(expr.report,
+                      external_report_info(expr.highlander, expr.index));
 
     /* create the internal report */
     u32 ekey = INVALID_EKEY;
-    if (g.highlander) {
+    if (expr.highlander) {
         /* all patterns with the same report id share an ekey */
-        ekey = getExhaustibleKey(g.reportId);
+        ekey = getExhaustibleKey(expr.report);
     }
 
-    return makeECallback(g.reportId, adj, ekey);
+    return makeECallback(expr.report, adj, ekey);
 }
 
 void ReportManager::setProgramOffset(ReportID id, u32 programOffset) {
diff --git a/src/util/report_manager.h b/src/util/report_manager.h
index 0eed2711..4b62e4b5 100644
--- a/src/util/report_manager.h
+++ b/src/util/report_manager.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -47,7 +47,7 @@ namespace ue2 {
 
 struct Grey;
 class RoseBuild;
-class NGWrapper;
+class ExpressionInfo;
 
 struct external_report_info {
     external_report_info(bool h, u32 fpi)
@@ -92,13 +92,13 @@ public:
     const std::vector<Report> &reports() const { return reportIds; }
 
     /**
-     * Get a simple internal report corresponding to the wrapper. An ekey will
-     * be setup as required.
+     * Get a simple internal report corresponding to the expression. An ekey
+     * will be setup if required.
      *
      * Note: this function may throw a CompileError if constraints on external
      * match id are violated (mixed highlander status for example).
      */
-    Report getBasicInternalReport(const NGWrapper &g, s32 adj = 0);
+    Report getBasicInternalReport(const ExpressionInfo &expr, s32 adj = 0);
 
     /** \brief Register an external report and validate that we are not
      * violating highlander constraints (which will cause an exception to be
diff --git a/unit/internal/lbr.cpp b/unit/internal/lbr.cpp
index e40bda02..60bf8940 100644
--- a/unit/internal/lbr.cpp
+++ b/unit/internal/lbr.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -96,7 +96,8 @@ protected:
         const CompileContext cc(true, false, target, grey);
         ReportManager rm(cc.grey);
         ParsedExpression parsed(0, pattern.c_str(), flags, 0);
-        unique_ptr<NGWrapper> g = buildWrapper(rm, cc, parsed);
+        auto built_expr = buildGraph(rm, cc, parsed);
+        const auto &g = built_expr.g;
         ASSERT_TRUE(g != nullptr);
         clearReports(*g);
 
diff --git a/unit/internal/limex_nfa.cpp b/unit/internal/limex_nfa.cpp
index 804fcb1f..333c35f3 100644
--- a/unit/internal/limex_nfa.cpp
+++ b/unit/internal/limex_nfa.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -73,7 +73,8 @@ protected:
         CompileContext cc(false, false, target, Grey());
         ReportManager rm(cc.grey);
         ParsedExpression parsed(0, expr.c_str(), flags, 0);
-        unique_ptr<NGWrapper> g = buildWrapper(rm, cc, parsed);
+        auto built_expr = buildGraph(rm, cc, parsed);
+        const auto &g = built_expr.g;
         ASSERT_TRUE(g != nullptr);
         clearReports(*g);
 
@@ -306,7 +307,8 @@ protected:
         CompileContext cc(false, false, get_current_target(), Grey());
         ReportManager rm(cc.grey);
         ParsedExpression parsed(0, expr.c_str(), flags, 0);
-        unique_ptr<NGWrapper> g = buildWrapper(rm, cc, parsed);
+        auto built_expr = buildGraph(rm, cc, parsed);
+        const auto &g = built_expr.g;
         ASSERT_TRUE(g != nullptr);
         clearReports(*g);
 
@@ -365,7 +367,8 @@ protected:
         CompileContext cc(true, false, get_current_target(), Grey());
         ParsedExpression parsed(0, expr.c_str(), flags, 0);
         ReportManager rm(cc.grey);
-        unique_ptr<NGWrapper> g = buildWrapper(rm, cc, parsed);
+        auto built_expr = buildGraph(rm, cc, parsed);
+        const auto &g = built_expr.g;
         ASSERT_TRUE(g != nullptr);
         clearReports(*g);
 
diff --git a/unit/internal/nfagraph_common.h b/unit/internal/nfagraph_common.h
index d3aafc99..ca5554c4 100644
--- a/unit/internal/nfagraph_common.h
+++ b/unit/internal/nfagraph_common.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -40,18 +40,19 @@ namespace ue2 {
 
 // Helper function: construct a graph from an expression, flags and context.
 inline
-std::unique_ptr<NGWrapper> constructGraphWithCC(const std::string &expr,
-                                                CompileContext &cc,
-                                                unsigned flags) {
+std::unique_ptr<NGHolder> constructGraphWithCC(const std::string &expr,
+                                               CompileContext &cc,
+                                               unsigned flags) {
     ReportManager rm(cc.grey);
     ParsedExpression parsed(0, expr.c_str(), flags, 0);
-    return buildWrapper(rm, cc, parsed);
+    auto built_expr = buildGraph(rm, cc, parsed);
+    return std::move(built_expr.g);
 }
 
 // Helper function: construct a graph from an expression and its flags.
 inline
-std::unique_ptr<NGWrapper> constructGraph(const std::string &expr,
-                                          unsigned flags) {
+std::unique_ptr<NGHolder> constructGraph(const std::string &expr,
+                                         unsigned flags) {
     CompileContext cc(false, false, get_current_target(), Grey());
     return constructGraphWithCC(expr, cc, flags);
 }
diff --git a/unit/internal/nfagraph_equivalence.cpp b/unit/internal/nfagraph_equivalence.cpp
index 8fda9223..73aec1d7 100644
--- a/unit/internal/nfagraph_equivalence.cpp
+++ b/unit/internal/nfagraph_equivalence.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -54,7 +54,7 @@ TEST(NFAGraph, RemoveEquivalence1) {
     // The graph should be merged into: a(b|c)
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("(ab|ac)", cc, 0));
+    auto graph(constructGraphWithCC("(ab|ac)", cc, 0));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
     g.kind = NFA_SUFFIX;
@@ -115,7 +115,7 @@ TEST(NFAGraph, RemoveEquivalence2) {
     // The graph should be merged into: (b|c)a
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("(ba|ca)", cc, 0));
+    auto graph(constructGraphWithCC("(ba|ca)", cc, 0));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
     g.kind = NFA_SUFFIX;
@@ -176,8 +176,7 @@ TEST(NFAGraph, RemoveEquivalence3) {
     // The graph should be merged into: a(..)+(X|Y)
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("a(..)+X|a(..)+Y", cc,
-            HS_FLAG_DOTALL));
+    auto graph(constructGraphWithCC("a(..)+X|a(..)+Y", cc, HS_FLAG_DOTALL));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
     g.kind = NFA_SUFFIX;
@@ -266,8 +265,7 @@ TEST(NFAGraph, RemoveEquivalence4) {
     // The graph should be merged into: (X|Y)(..)+a
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("X(..)+a|Y(..)+a", cc,
-            HS_FLAG_DOTALL));
+    auto graph(constructGraphWithCC("X(..)+a|Y(..)+a", cc, HS_FLAG_DOTALL));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
     g.kind = NFA_SUFFIX;
@@ -363,8 +361,7 @@ TEST(NFAGraph, RemoveEquivalence5) {
     // The graph should be merged into: [^\x00]*[\x00]
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("[^\\x00][^\\x00]*[\\x00]",
-            cc, 0));
+    auto graph(constructGraphWithCC("[^\\x00][^\\x00]*[\\x00]", cc, 0));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
     g.kind = NFA_PREFIX;
@@ -420,7 +417,7 @@ TEST(NFAGraph, RemoveEquivalence5) {
 TEST(NFAGraph, RemoveEquivalence6) {
     // Build a small graph with two redundant vertices: ^(.*|.*)a
     // The graph should be merged into: a
-    unique_ptr<NGWrapper> graph(constructGraph("^(.*|.*)a", HS_FLAG_DOTALL));
+    auto graph(constructGraph("^(.*|.*)a", HS_FLAG_DOTALL));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
 
@@ -458,7 +455,7 @@ TEST(NFAGraph, RemoveEquivalence6) {
 TEST(NFAGraph, RemoveEquivalence7) {
     // Build a small graph with no redundant vertices: ^.+a
     // Make sure we don't merge anything
-    unique_ptr<NGWrapper> graph(constructGraph("^.+a", HS_FLAG_DOTALL));
+    auto graph(constructGraph("^.+a", HS_FLAG_DOTALL));
     ASSERT_TRUE(graph != nullptr);
     NGHolder &g = *graph;
 
diff --git a/unit/internal/nfagraph_find_matches.cpp b/unit/internal/nfagraph_find_matches.cpp
index 92c514d8..cd0cd796 100644
--- a/unit/internal/nfagraph_find_matches.cpp
+++ b/unit/internal/nfagraph_find_matches.cpp
@@ -208,7 +208,8 @@ TEST_P(MatchesTest, Check) {
     CompileContext cc(false, false, get_current_target(), Grey());
     ReportManager rm(cc.grey);
     ParsedExpression parsed(0, t.pattern.c_str(), t.flags, 0);
-    auto g = buildWrapper(rm, cc, parsed);
+    auto built_expr = buildGraph(rm, cc, parsed);
+    const auto &g = built_expr.g;
     bool utf8 = (t.flags & HS_FLAG_UTF8) > 0;
 
     set<pair<size_t, size_t>> matches;
diff --git a/unit/internal/nfagraph_redundancy.cpp b/unit/internal/nfagraph_redundancy.cpp
index be9527fd..c77045e0 100644
--- a/unit/internal/nfagraph_redundancy.cpp
+++ b/unit/internal/nfagraph_redundancy.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2016, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -53,7 +53,7 @@ TEST(NFAGraph, RemoveRedundancy1) {
     // The character reachability should be merged into: [ab]c
     CompileContext cc(false, false, get_current_target(), Grey());
 
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("(a|b)c", cc, 0));
+    auto graph(constructGraphWithCC("(a|b)c", cc, 0));
     ASSERT_TRUE(graph.get() != nullptr);
     NGHolder &g = *graph;
 
@@ -95,8 +95,7 @@ TEST(NFAGraph, RemoveRedundancy2) {
     // Build a small graph with a redundant vertex: a.*b?c
     // The dot-star should swallow the 'b?', leaving a.*c
     CompileContext cc(false, false, get_current_target(), Grey());
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("a.*b?c", cc,
-                                                     HS_FLAG_DOTALL));
+    auto graph(constructGraphWithCC("a.*b?c", cc, HS_FLAG_DOTALL));
     ASSERT_TRUE(graph.get() != nullptr);
     NGHolder &g = *graph;
 
@@ -152,8 +151,7 @@ TEST(NFAGraph, RemoveRedundancy2) {
 
 TEST(NFAGraph, RemoveRedundancy3) {
     CompileContext cc(false, false, get_current_target(), Grey());
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("foobar.*(a|b)?teakettle",
-                                                     cc, 0));
+    auto graph(constructGraphWithCC("foobar.*(a|b)?teakettle", cc, 0));
     ASSERT_TRUE(graph.get() != nullptr);
 
     unsigned countBefore = num_vertices(*graph);
@@ -166,7 +164,7 @@ TEST(NFAGraph, RemoveRedundancy3) {
 
 TEST(NFAGraph, RemoveRedundancy4) {
     CompileContext cc(false, false, get_current_target(), Grey());
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("foo([A-Z]|a|b|q)", cc, 0));
+    auto graph(constructGraphWithCC("foo([A-Z]|a|b|q)", cc, 0));
     ASSERT_TRUE(graph.get() != nullptr);
 
     unsigned countBefore = num_vertices(*graph);
@@ -178,8 +176,7 @@ TEST(NFAGraph, RemoveRedundancy4) {
 
 TEST(NFAGraph, RemoveRedundancy5) {
     CompileContext cc(false, false, get_current_target(), Grey());
-    unique_ptr<NGWrapper> graph(constructGraphWithCC("[0-9]?badgerbrush",
-            cc, 0));
+    auto graph(constructGraphWithCC("[0-9]?badgerbrush", cc, 0));
     ASSERT_TRUE(graph.get() != nullptr);
 
     unsigned countBefore = num_vertices(*graph);
diff --git a/unit/internal/nfagraph_width.cpp b/unit/internal/nfagraph_width.cpp
index 03508ea8..5cfb4c87 100644
--- a/unit/internal/nfagraph_width.cpp
+++ b/unit/internal/nfagraph_width.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Intel Corporation
+ * Copyright (c) 2015-2017, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -79,10 +79,10 @@ INSTANTIATE_TEST_CASE_P(NFAWidth, NFAWidthTest, ValuesIn(widthTests));
 TEST_P(NFAWidthTest, Check) {
     const WidthTest &t = GetParam();
     SCOPED_TRACE(testing::Message() << "Pattern: " << t.pattern);
-    unique_ptr<NGWrapper> w(constructGraph(t.pattern, 0));
+    auto g = constructGraph(t.pattern, 0);
 
-    ASSERT_EQ(t.minWidth, findMinWidth(*w));
-    ASSERT_EQ(t.maxWidth, findMaxWidth(*w));
+    ASSERT_EQ(t.minWidth, findMinWidth(*g));
+    ASSERT_EQ(t.maxWidth, findMaxWidth(*g));
 }
 
 // for google test
diff --git a/util/ng_corpus_generator.cpp b/util/ng_corpus_generator.cpp
index 9d75a7ad..19ab7edf 100644
--- a/util/ng_corpus_generator.cpp
+++ b/util/ng_corpus_generator.cpp
@@ -35,6 +35,7 @@
 #include "ng_corpus_generator.h"
 
 #include "ng_corpus_editor.h"
+#include "compiler/compiler.h"
 #include "nfagraph/ng.h"
 #include "nfagraph/ng_util.h"
 #include "ue2common.h"
@@ -219,8 +220,9 @@ namespace {
 /** \brief Concrete implementation */
 class CorpusGeneratorImpl : public CorpusGenerator {
 public:
-    CorpusGeneratorImpl(const NGWrapper &graph_in, CorpusProperties &props);
-    ~CorpusGeneratorImpl() {}
+    CorpusGeneratorImpl(const NGHolder &graph_in, const ExpressionInfo &expr_in,
+                        CorpusProperties &props);
+    ~CorpusGeneratorImpl() = default;
 
     void generateCorpus(vector<string> &data);
 
@@ -237,6 +239,9 @@ private:
      * bytes in length. */
     void addRandom(const min_max &mm, string *out);
 
+    /** \brief Info about this expression. */
+    const ExpressionInfo &expr;
+
     /** \brief The NFA graph we operate over. */
     const NGHolder &graph;
 
@@ -245,12 +250,13 @@ private:
     CorpusProperties &cProps;
 };
 
-CorpusGeneratorImpl::CorpusGeneratorImpl(const NGWrapper &graph_in,
+CorpusGeneratorImpl::CorpusGeneratorImpl(const NGHolder &graph_in,
+                                         const ExpressionInfo &expr_in,
                                          CorpusProperties &props)
-    : graph(graph_in), cProps(props) {
+    : expr(expr_in), graph(graph_in), cProps(props) {
     // if this pattern is to be matched approximately
-    if (graph_in.edit_distance && !props.editDistance) {
-        props.editDistance = props.rand(0, graph_in.edit_distance + 1);
+    if (expr.edit_distance && !props.editDistance) {
+        props.editDistance = props.rand(0, expr.edit_distance + 1);
     }
 }
 
@@ -392,8 +398,9 @@ hit_limit:
 /** \brief Concrete implementation for UTF-8 */
 class CorpusGeneratorUtf8 : public CorpusGenerator {
 public:
-    CorpusGeneratorUtf8(const NGWrapper &graph_in, CorpusProperties &props);
-    ~CorpusGeneratorUtf8() {}
+    CorpusGeneratorUtf8(const NGHolder &graph_in, const ExpressionInfo &expr_in,
+                        CorpusProperties &props);
+    ~CorpusGeneratorUtf8() = default;
 
     void generateCorpus(vector<string> &data);
 
@@ -410,19 +417,23 @@ private:
      * length. */
     void addRandom(const min_max &mm, vector<unichar> *out);
 
+    /** \brief Info about this expression. */
+    const ExpressionInfo &expr;
+
     /** \brief The NFA graph we operate over. */
-    const NGWrapper &graph;
+    const NGHolder &graph;
 
     /** \brief Reference to our corpus generator properties object (stores some
      * state) */
     CorpusProperties &cProps;
 };
 
-CorpusGeneratorUtf8::CorpusGeneratorUtf8(const NGWrapper &graph_in,
+CorpusGeneratorUtf8::CorpusGeneratorUtf8(const NGHolder &graph_in,
+                                         const ExpressionInfo &expr_in,
                                          CorpusProperties &props)
-    : graph(graph_in), cProps(props) {
+    : expr(expr_in), graph(graph_in), cProps(props) {
     // we do not support Utf8 for approximate matching
-    if (graph.edit_distance) {
+    if (expr.edit_distance) {
         throw CorpusGenerationFailure("UTF-8 for edited patterns is not "
                                       "supported.");
     }
@@ -681,11 +692,12 @@ CorpusGenerator::~CorpusGenerator() { }
 
 // External entry point
 
-unique_ptr<CorpusGenerator> makeCorpusGenerator(const NGWrapper &graph,
+unique_ptr<CorpusGenerator> makeCorpusGenerator(const NGHolder &graph,
+                                                const ExpressionInfo &expr,
                                                 CorpusProperties &props) {
-    if (graph.utf8) {
-        return ue2::make_unique<CorpusGeneratorUtf8>(graph, props);
+    if (expr.utf8) {
+        return ue2::make_unique<CorpusGeneratorUtf8>(graph, expr, props);
     } else {
-        return ue2::make_unique<CorpusGeneratorImpl>(graph, props);
+        return ue2::make_unique<CorpusGeneratorImpl>(graph, expr, props);
     }
 }
diff --git a/util/ng_corpus_generator.h b/util/ng_corpus_generator.h
index a02721bd..f230a10d 100644
--- a/util/ng_corpus_generator.h
+++ b/util/ng_corpus_generator.h
@@ -41,7 +41,8 @@
 
 namespace ue2 {
 
-class NGWrapper;
+class ExpressionInfo;
+class NGHolder;
 
 } // namespace ue2
 
@@ -68,6 +69,7 @@ public:
 /** \brief Build a concrete impl conforming to the \ref CorpusGenerator
  * interface. */
 std::unique_ptr<CorpusGenerator>
-makeCorpusGenerator(const ue2::NGWrapper &graph, CorpusProperties &props);
+makeCorpusGenerator(const ue2::NGHolder &g, const ue2::ExpressionInfo &expr,
+                    CorpusProperties &props);
 
 #endif