Feb 15th 2023 update

external/graphqlparser/JsonVisitor.h

@@ -0,0 +1,121 @@
+/**
+ * Copyright 2019-present, GraphQL Foundation
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include "AstNode.h"
+#include "AstVisitor.h"
+
+#include <sstream>
+#include <vector>
+
+namespace facebook {
+namespace graphql {
+namespace ast {
+namespace visitor {
+
+/**
+ * Produces a JSON string describing the visited AST, in a format that
+ * would be a valid graphql-js AST when parsed.
+ */
+class JsonVisitor : public AstVisitor {
+ private:
+  using ChildrenList = std::vector<std::string>;
+  // Stack of lists of printed children.
+  // Postvisit method precondition: printed.back() contains strings
+  // for this node's children.
+  // Postvisit method postcondition: *(printed.rbegin() - 1) has had this
+  std::vector<ChildrenList> printed_;
+
+  // Interface to print fields for each kind of node.
+  // Note that, because of the post-order traversal for printing,
+  // field values need not be passed explicitly; they are grabbed from
+  // the passed-in visitor!
+  class NodeFieldPrinter {
+   private:
+    JsonVisitor &visitor_;
+    ChildrenList::const_iterator nextChild_;
+    std::ostringstream out_;
+
+    void printFieldSeparator();
+
+    // Prints a non-null array of n children from the given
+    // iterator. Does not update the iterator.
+    void printChildList(
+      std::ostringstream &out,
+      const std::vector<std::string>::const_iterator &childIterator,
+      size_t numChildren);
+
+    void printLocation(std::ostringstream &out, const yy::location &location);
+
+   public:
+    // Begin printing the fields for a node of the given kind at the
+    // given location.
+    NodeFieldPrinter(
+      JsonVisitor &visitor,
+      const char *nodeKind,
+      const Node &node);
+
+    std::string finishPrinting();
+
+    void printSingularPrimitiveField(const char *fieldName, const char *value);
+    void printSingularBooleanField(const char *fieldName, bool value);
+    void printSingularObjectField(const char *fieldName);
+    void printNullableSingularObjectField(const char *fieldName, const void *value);
+
+    template <typename T>
+      void printPluralField(
+        const char *fieldName,
+        const std::vector<std::unique_ptr<T>> &value) {
+      printFieldSeparator();
+      out_ << '"' << fieldName << "\":";
+      printChildList(out_, nextChild_, value.size());
+      nextChild_ += value.size();
+    }
+
+    template <typename T>
+    void printNullablePluralField(
+        const char *fieldName,
+        const std::vector<std::unique_ptr<T>> *value) {
+      printFieldSeparator();
+      out_ << '"' << fieldName << "\":";
+      if (value == nullptr) {
+        out_ << "null";
+      } else {
+        printChildList(out_, nextChild_, value->size());
+        nextChild_ += value->size();
+      }
+    }
+  };
+
+  // Must be called at the start of all visit methods for node types
+  // that have children. Maintains printed_.
+  void visitNode();
+
+  // Must be called at the end of all visit methods for node types
+  // that have children, passing the text for this node. Maintains
+  // printed_.
+  void endVisitNode(std::string &&str);
+
+  // Prints one of the many FooValue types that is prepresented with a
+  // single string.
+  template <typename ValueNode>
+  void endVisitValueRepresentedAsString(const char *valueKind, const ValueNode &value);
+
+public:
+  JsonVisitor();
+  ~JsonVisitor() {}
+
+  std::string getResult() const;
+
+  #include "JsonVisitor.h.inc"
+};
+
+}
+}
+}
+}