diff --git a/headers/modsecurity/actions/action.h b/headers/modsecurity/actions/action.h
index 374b77d6..b1839fe7 100644
--- a/headers/modsecurity/actions/action.h
+++ b/headers/modsecurity/actions/action.h
@@ -13,26 +13,19 @@
  *
  */
 
-#ifdef __cplusplus
-
-#include <string>
-#include <iostream>
-#include <memory>
-
-#endif
-
-#include "modsecurity/intervention.h"
-#include "modsecurity/rule.h"
-#include "modsecurity/rule_with_actions.h"
-
 #ifndef HEADERS_MODSECURITY_ACTIONS_ACTION_H_
 #define HEADERS_MODSECURITY_ACTIONS_ACTION_H_
 
 #ifdef __cplusplus
 
+#include <string>
+#include <memory>
+
 namespace modsecurity {
 class Transaction;
 class RuleWithOperator;
+class RuleWithActions;
+class RuleMessage;
 
 namespace actions {
 
@@ -74,8 +67,6 @@ class Action {
 
     virtual ~Action() { }
 
-    virtual std::string evaluate(const std::string &exp,
-        Transaction *transaction);
     virtual bool evaluate(RuleWithActions *rule, Transaction *transaction);
     virtual bool evaluate(RuleWithActions *rule, Transaction *transaction,
         std::shared_ptr<RuleMessage> ruleMessage) {
@@ -87,9 +78,9 @@ class Action {
 
     void set_name_and_payload(const std::string& data) {
         size_t pos = data.find(":");
-        std::string t = "t:";
+        const char t[] = "t:";
 
-        if (data.compare(0, t.length(), t) == 0) {
+        if (data.compare(0, std::size(t) - 1, t) == 0) {
             pos = data.find(":", 2);
         }
 
diff --git a/headers/modsecurity/rule.h b/headers/modsecurity/rule.h
index 1d5570a8..18e64c0a 100644
--- a/headers/modsecurity/rule.h
+++ b/headers/modsecurity/rule.h
@@ -52,7 +52,7 @@ namespace operators {
 class Operator;
 }
 
-using TransformationResult = std::pair<std::shared_ptr<std::string>,
+using TransformationResult = std::pair<std::string,
     std::shared_ptr<std::string>>;
 using TransformationResults = std::list<TransformationResult>;
 
diff --git a/headers/modsecurity/rule_with_actions.h b/headers/modsecurity/rule_with_actions.h
index 4b7db43f..bb63f499 100644
--- a/headers/modsecurity/rule_with_actions.h
+++ b/headers/modsecurity/rule_with_actions.h
@@ -119,16 +119,7 @@ class RuleWithActions : public Rule {
 
 
     void executeTransformations(
-        Transaction *trasn, const std::string &value, TransformationResults &ret);
-
-    inline void executeTransformation(
-        actions::transformations::Transformation *a,
-        std::shared_ptr<std::string> *value,
-        Transaction *trans,
-        TransformationResults *ret,
-        std::string *path,
-        int *nth) const;
-
+        const Transaction *trasn, const std::string &value, TransformationResults &ret);
 
     void performLogging(Transaction *trans,
         std::shared_ptr<RuleMessage> ruleMessage,
@@ -166,6 +157,14 @@ class RuleWithActions : public Rule {
     RuleWithActions *m_chainedRuleParent;
 
  private:
+    inline void executeTransformation(
+        const actions::transformations::Transformation &a,
+        std::string &value,
+        const Transaction *trans,
+        TransformationResults *ret,
+        std::string *path,
+        int *nth) const;
+
     /* actions */
     actions::Action *m_disruptiveAction;
     actions::LogData *m_logData;
diff --git a/src/actions/accuracy.cc b/src/actions/accuracy.cc
index c8cfca72..ace9f1c5 100644
--- a/src/actions/accuracy.cc
+++ b/src/actions/accuracy.cc
@@ -15,16 +15,10 @@
 
 #include "src/actions/accuracy.h"
 
-#include <iostream>
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
+#include "modsecurity/rule_with_actions.h"
 
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool Accuracy::init(std::string *error) {
@@ -45,5 +39,4 @@ bool Accuracy::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/actions/action.cc b/src/actions/action.cc
index e58e2067..dd329a50 100644
--- a/src/actions/action.cc
+++ b/src/actions/action.cc
@@ -45,12 +45,6 @@ namespace modsecurity {
 namespace actions {
 
 
-std::string Action::evaluate(const std::string &value,
-    Transaction *transaction) {
-    return value;
-}
-
-
 bool Action::evaluate(RuleWithActions *rule, Transaction *transaction) {
     return true;
 }
diff --git a/src/actions/chain.cc b/src/actions/chain.cc
index 197f861f..62f0409c 100644
--- a/src/actions/chain.cc
+++ b/src/actions/chain.cc
@@ -15,14 +15,9 @@
 
 #include "src/actions/chain.h"
 
-#include <iostream>
-#include <string>
+#include "modsecurity/rule_with_actions.h"
 
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
-
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool Chain::evaluate(RuleWithActions *rule, Transaction *transaction) {
@@ -31,5 +26,4 @@ bool Chain::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/actions/maturity.cc b/src/actions/maturity.cc
index 131d2148..fca6aaa4 100644
--- a/src/actions/maturity.cc
+++ b/src/actions/maturity.cc
@@ -15,16 +15,10 @@
 
 #include "src/actions/maturity.h"
 
-#include <iostream>
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
+#include "modsecurity/rule_with_actions.h"
 
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool Maturity::init(std::string *error) {
@@ -45,5 +39,4 @@ bool Maturity::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/actions/phase.cc b/src/actions/phase.cc
index 2e9e7277..1d17ec33 100644
--- a/src/actions/phase.cc
+++ b/src/actions/phase.cc
@@ -15,20 +15,15 @@
 
 #include "src/actions/phase.h"
 
-#include <iostream>
-#include <string>
-
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
-#include "modsecurity/modsecurity.h"
+#include "modsecurity/rule_with_actions.h"
 #include "src/utils/string.h"
 
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
+
 
 bool Phase::init(std::string *error) {
-    std::string a = utils::string::tolower(m_parser_payload);
+    const auto a = utils::string::tolower(m_parser_payload);
     m_phase = -1;
 
     try {
@@ -77,5 +72,5 @@ bool Phase::evaluate(RuleWithActions *rule, Transaction *transaction) {
     return true;
 }
 
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions
diff --git a/src/actions/rev.cc b/src/actions/rev.cc
index 43d8d1be..6543a5da 100644
--- a/src/actions/rev.cc
+++ b/src/actions/rev.cc
@@ -15,16 +15,10 @@
 
 #include "src/actions/rev.h"
 
-#include <iostream>
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
+#include "modsecurity/rule_with_actions.h"
 
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool Rev::init(std::string *error) {
@@ -39,5 +33,4 @@ bool Rev::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/actions/rule_id.cc b/src/actions/rule_id.cc
index d16bf63b..c7864707 100644
--- a/src/actions/rule_id.cc
+++ b/src/actions/rule_id.cc
@@ -15,14 +15,10 @@
 
 #include "src/actions/rule_id.h"
 
-#include <iostream>
-#include <string>
+#include "modsecurity/rule_with_actions.h"
 
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool RuleId::init(std::string *error) {
@@ -54,5 +50,4 @@ bool RuleId::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/actions/transformations/base64_decode.cc b/src/actions/transformations/base64_decode.cc
index 8ddfe235..fe910e50 100644
--- a/src/actions/transformations/base64_decode.cc
+++ b/src/actions/transformations/base64_decode.cc
@@ -13,33 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/base64_decode.h"
+#include "base64_decode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/base64.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Base64Decode::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret = Utils::Base64::decode(value);
-
-    return ret;
+bool Base64Decode::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
+    value = Utils::Base64::decode(value);
+    return true;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/base64_decode.h b/src/actions/transformations/base64_decode.h
index a8227699..3527bd5e 100644
--- a/src/actions/transformations/base64_decode.h
+++ b/src/actions/transformations/base64_decode.h
@@ -13,33 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Base64Decode : public Transformation {
  public:
-    explicit Base64Decode(const std::string &action)  : Transformation(action) { }
+    explicit Base64Decode(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_H_
diff --git a/src/actions/transformations/base64_decode_ext.cc b/src/actions/transformations/base64_decode_ext.cc
index ee8e4b5b..e6c13987 100644
--- a/src/actions/transformations/base64_decode_ext.cc
+++ b/src/actions/transformations/base64_decode_ext.cc
@@ -13,33 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/base64_decode_ext.h"
+#include "base64_decode_ext.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/base64.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Base64DecodeExt::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret = Utils::Base64::decode_forgiven(value);
-
-    return ret;
+bool Base64DecodeExt::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
+    value = Utils::Base64::decode_forgiven(value);
+    return true;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/base64_decode_ext.h b/src/actions/transformations/base64_decode_ext.h
index ad0efbdc..8f1f069e 100644
--- a/src/actions/transformations/base64_decode_ext.h
+++ b/src/actions/transformations/base64_decode_ext.h
@@ -13,33 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_EXT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_EXT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Base64DecodeExt : public Transformation {
  public:
-    explicit Base64DecodeExt(const std::string &action)  : Transformation(action) { }
+    explicit Base64DecodeExt(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_BASE64_DECODE_EXT_H_
diff --git a/src/actions/transformations/base64_encode.cc b/src/actions/transformations/base64_encode.cc
index 8be74803..bf802a1e 100644
--- a/src/actions/transformations/base64_encode.cc
+++ b/src/actions/transformations/base64_encode.cc
@@ -13,33 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/base64_encode.h"
+#include "base64_encode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/base64.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Base64Encode::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret = Utils::Base64::encode(value);
-
-    return ret;
+bool Base64Encode::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
+    value = Utils::Base64::encode(value);
+    return true;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/base64_encode.h b/src/actions/transformations/base64_encode.h
index 0f7fd1fe..7b3ac25e 100644
--- a/src/actions/transformations/base64_encode.h
+++ b/src/actions/transformations/base64_encode.h
@@ -13,33 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_BASE64_ENCODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_BASE64_ENCODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Base64Encode : public Transformation {
  public:
-    explicit Base64Encode(const std::string &action)  : Transformation(action) { }
+    explicit Base64Encode(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_BASE64_ENCODE_H_
diff --git a/src/actions/transformations/cmd_line.cc b/src/actions/transformations/cmd_line.cc
index 72087e36..cac1d2df 100644
--- a/src/actions/transformations/cmd_line.cc
+++ b/src/actions/transformations/cmd_line.cc
@@ -13,26 +13,13 @@
  *
  */
 
-#include "src/actions/transformations/cmd_line.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "cmd_line.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string CmdLine::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool CmdLine::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     int space = 0;
 
@@ -77,11 +64,11 @@ std::string CmdLine::evaluate(const std::string &value,
         }
     }
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
 
diff --git a/src/actions/transformations/cmd_line.h b/src/actions/transformations/cmd_line.h
index 851f2938..9ba5c6b2 100644
--- a/src/actions/transformations/cmd_line.h
+++ b/src/actions/transformations/cmd_line.h
@@ -13,35 +13,22 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_CMD_LINE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_CMD_LINE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class CmdLine : public Transformation {
  public:
     explicit CmdLine(const std::string &action) 
         : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // modsecurity::namespace actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_CMD_LINE_H_
 
diff --git a/src/actions/transformations/compress_whitespace.cc b/src/actions/transformations/compress_whitespace.cc
index 506de248..32c22a25 100644
--- a/src/actions/transformations/compress_whitespace.cc
+++ b/src/actions/transformations/compress_whitespace.cc
@@ -13,30 +13,18 @@
  *
  */
 
-#include "src/actions/transformations/compress_whitespace.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "compress_whitespace.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 CompressWhitespace::CompressWhitespace(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string CompressWhitespace::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool CompressWhitespace::transform(std::string &value, const Transaction *trans) const {
 
     std::string a;
     int inWhiteSpace = 0;
@@ -58,9 +46,10 @@ std::string CompressWhitespace::evaluate(const std::string &value,
         i++;
     }
 
-    return a;
+    const auto changed = a != value;
+    value = a;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/compress_whitespace.h b/src/actions/transformations/compress_whitespace.h
index 184ddcfa..bf90b0ba 100644
--- a/src/actions/transformations/compress_whitespace.h
+++ b/src/actions/transformations/compress_whitespace.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_COMPRESS_WHITESPACE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_COMPRESS_WHITESPACE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class CompressWhitespace : public Transformation {
  public:
+    explicit CompressWhitespace(const std::string &action);
 
-    explicit CompressWhitespace(const std::string &action) ;
-
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_COMPRESS_WHITESPACE_H_
diff --git a/src/actions/transformations/css_decode.cc b/src/actions/transformations/css_decode.cc
index f8085123..7f6938ac 100644
--- a/src/actions/transformations/css_decode.cc
+++ b/src/actions/transformations/css_decode.cc
@@ -13,29 +13,15 @@
  *
  */
 
-#include "src/actions/transformations/css_decode.h"
+#include "css_decode.h"
 
-#include <string.h>
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string CssDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool CssDecode::transform(std::string &value, const Transaction *trans) const {
 
     char *tmp = reinterpret_cast<char *>(
         malloc(sizeof(char) * value.size() + 1));
@@ -47,7 +33,10 @@ std::string CssDecode::evaluate(const std::string &value,
 
     std::string ret(tmp, 0, value.size());
     free(tmp);
-    return ret;
+
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -191,6 +180,4 @@ int CssDecode::css_decode_inplace(unsigned char *input, int64_t input_len) {
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/css_decode.h b/src/actions/transformations/css_decode.h
index a6769bad..04418149 100644
--- a/src/actions/transformations/css_decode.h
+++ b/src/actions/transformations/css_decode.h
@@ -13,37 +13,23 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_CSS_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_CSS_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class CssDecode : public Transformation {
  public:
     explicit CssDecode(const std::string &action) 
         : Transformation(action) { }
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static int css_decode_inplace(unsigned char *input, int64_t input_len);
 };
 
-
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_CSS_DECODE_H_
diff --git a/src/actions/transformations/escape_seq_decode.cc b/src/actions/transformations/escape_seq_decode.cc
index 03303272..a0dccb53 100644
--- a/src/actions/transformations/escape_seq_decode.cc
+++ b/src/actions/transformations/escape_seq_decode.cc
@@ -13,23 +13,12 @@
  *
  */
 
-#include "src/actions/transformations/escape_seq_decode.h"
+#include "escape_seq_decode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 EscapeSeqDecode::EscapeSeqDecode(const std::string &action) 
     : Transformation(action) {
@@ -140,8 +129,7 @@ int EscapeSeqDecode::ansi_c_sequences_decode_inplace(unsigned char *input,
 }
 
 
-std::string EscapeSeqDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool EscapeSeqDecode::transform(std::string &value, const Transaction *trans) const {
 
     unsigned char *tmp = (unsigned char *) malloc(sizeof(char)
         * value.size() + 1);
@@ -154,9 +142,10 @@ std::string EscapeSeqDecode::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(tmp), size);
     free(tmp);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/escape_seq_decode.h b/src/actions/transformations/escape_seq_decode.h
index d68f33b5..ab66464d 100644
--- a/src/actions/transformations/escape_seq_decode.h
+++ b/src/actions/transformations/escape_seq_decode.h
@@ -13,35 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_ESCAPE_SEQ_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_ESCAPE_SEQ_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class EscapeSeqDecode : public Transformation {
  public:
+    explicit EscapeSeqDecode(const std::string &action);
 
-    explicit EscapeSeqDecode(const std::string &action) ;
-
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
-    int ansi_c_sequences_decode_inplace(unsigned char *input, int input_len);
+    bool transform(std::string &value, const Transaction *trans) const override;
+    static int ansi_c_sequences_decode_inplace(unsigned char *input, int input_len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_ESCAPE_SEQ_DECODE_H_
diff --git a/src/actions/transformations/hex_decode.cc b/src/actions/transformations/hex_decode.cc
index 1525377c..5866079b 100644
--- a/src/actions/transformations/hex_decode.cc
+++ b/src/actions/transformations/hex_decode.cc
@@ -13,27 +13,15 @@
  *
  */
 
-#include "src/actions/transformations/hex_decode.h"
+#include "hex_decode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+
+namespace modsecurity::actions::transformations {
 
 
-std::string HexDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool HexDecode::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
     int size = 0;
@@ -52,7 +40,9 @@ std::string HexDecode::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), size);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -74,6 +64,4 @@ int HexDecode::inplace(unsigned char *data, int len) {
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/hex_decode.h b/src/actions/transformations/hex_decode.h
index a2f48c6d..4239c86d 100644
--- a/src/actions/transformations/hex_decode.h
+++ b/src/actions/transformations/hex_decode.h
@@ -13,35 +13,23 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_HEX_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_HEX_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class HexDecode : public Transformation {
  public:
-    explicit HexDecode(const std::string &action)  : Transformation(action) { }
+    explicit HexDecode(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static int inplace(unsigned char *data, int len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_HEX_DECODE_H_
diff --git a/src/actions/transformations/hex_encode.cc b/src/actions/transformations/hex_encode.cc
index 4e6121df..a0719726 100644
--- a/src/actions/transformations/hex_encode.cc
+++ b/src/actions/transformations/hex_encode.cc
@@ -13,41 +13,29 @@
  *
  */
 
-#include "src/actions/transformations/hex_encode.h"
+#include "hex_encode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <iterator>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "modsecurity/rule_with_actions.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 HexEncode::HexEncode(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string HexEncode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool HexEncode::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
 
     std::stringstream result;
-    for (std::size_t i=0; i < value.length(); i++) {
-        unsigned int ii = (unsigned char)(value[i]);
+    for (const auto c : value) {
+        unsigned int ii = (unsigned char)c;
         result << std::setw(2) << std::setfill('0') << std::hex << ii;
     }
 
-    return result.str();
+    value = result.str();
+    return true;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/hex_encode.h b/src/actions/transformations/hex_encode.h
index 1ba39c56..3bb744b5 100644
--- a/src/actions/transformations/hex_encode.h
+++ b/src/actions/transformations/hex_encode.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_HEX_ENCODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_HEX_ENCODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class HexEncode : public Transformation {
  public:
-
     explicit HexEncode(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_HEX_ENCODE_H_
diff --git a/src/actions/transformations/html_entity_decode.cc b/src/actions/transformations/html_entity_decode.cc
index 6a683245..a730f160 100644
--- a/src/actions/transformations/html_entity_decode.cc
+++ b/src/actions/transformations/html_entity_decode.cc
@@ -13,32 +13,21 @@
  *
  */
 
-#include "src/actions/transformations/html_entity_decode.h"
+#include "html_entity_decode.h"
 
-#include <string.h>
+#include <cstring>
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "src/utils/string.h"
 
 #ifdef WIN32
 #include "src/compat/msvc.h"
 #endif
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string HtmlEntityDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool HtmlEntityDecode::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
 
@@ -56,7 +45,9 @@ std::string HtmlEntityDecode::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), i);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -207,6 +198,5 @@ HTML_ENT_OUT:
     return count;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/html_entity_decode.h b/src/actions/transformations/html_entity_decode.h
index 44fcc323..558da5b9 100644
--- a/src/actions/transformations/html_entity_decode.h
+++ b/src/actions/transformations/html_entity_decode.h
@@ -13,40 +13,23 @@
  *
  */
 
-#include <string>
-#include <unordered_map>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-#include "src/utils/string.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_HTML_ENTITY_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_HTML_ENTITY_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class HtmlEntityDecode : public Transformation {
  public:
     explicit HtmlEntityDecode(const std::string &action) 
         : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static int inplace(unsigned char *input, uint64_t input_len);
 };
 
-
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_HTML_ENTITY_DECODE_H_
diff --git a/src/actions/transformations/js_decode.cc b/src/actions/transformations/js_decode.cc
index 2f4cf8bb..5ed57157 100644
--- a/src/actions/transformations/js_decode.cc
+++ b/src/actions/transformations/js_decode.cc
@@ -13,29 +13,15 @@
  *
  */
 
-#include "src/actions/transformations/js_decode.h"
+#include "js_decode.h"
 
-#include <string.h>
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string JsDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool JsDecode::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
 
@@ -53,7 +39,9 @@ std::string JsDecode::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), i);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -163,6 +151,5 @@ int JsDecode::inplace(unsigned char *input, uint64_t input_len) {
     return count;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/js_decode.h b/src/actions/transformations/js_decode.h
index 60d6617b..b91ab9b8 100644
--- a/src/actions/transformations/js_decode.h
+++ b/src/actions/transformations/js_decode.h
@@ -13,35 +13,22 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_JS_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_JS_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class JsDecode : public Transformation {
  public:
     explicit JsDecode(const std::string &action) 
         : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
     static int inplace(unsigned char *input, uint64_t input_len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_JS_DECODE_H_
diff --git a/src/actions/transformations/length.cc b/src/actions/transformations/length.cc
index 61015b82..10aadfe8 100644
--- a/src/actions/transformations/length.cc
+++ b/src/actions/transformations/length.cc
@@ -13,34 +13,21 @@
  *
  */
 
-#include "src/actions/transformations/length.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "length.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 Length::Length(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string Length::evaluate(const std::string &value,
-    Transaction *transaction) {
-
-    return std::to_string(value.size());
+bool Length::transform(std::string &value, const Transaction *trans) const {
+    value = std::to_string(value.size());
+    return true;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/length.h b/src/actions/transformations/length.h
index 8892a9dc..e7b6b081 100644
--- a/src/actions/transformations/length.h
+++ b/src/actions/transformations/length.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_LENGTH_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_LENGTH_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Length : public Transformation {
  public:
-
     explicit Length(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_LENGTH_H_
diff --git a/src/actions/transformations/lower_case.cc b/src/actions/transformations/lower_case.cc
index 7bca9479..0ea1864c 100644
--- a/src/actions/transformations/lower_case.cc
+++ b/src/actions/transformations/lower_case.cc
@@ -13,27 +13,20 @@
  *
  */
 
-#include "src/actions/transformations/lower_case.h"
 
-#include <algorithm>
-#include <string>
+#include "lower_case.h"
+
 #include <locale>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "modsecurity/actions/action.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 LowerCase::LowerCase(const std::string &a)
     : Transformation(a) {
 }
 
-std::string LowerCase::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool LowerCase::transform(std::string &val, const Transaction *trans) const {
     std::locale loc;
     std::string value(val);
 
@@ -41,9 +34,10 @@ std::string LowerCase::evaluate(const std::string &val,
         value[i] = std::tolower(value[i], loc);
     }
 
-    return value;
+    const auto changed = val != value;
+    val = value;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/lower_case.h b/src/actions/transformations/lower_case.h
index 59049840..bbb51272 100644
--- a/src/actions/transformations/lower_case.h
+++ b/src/actions/transformations/lower_case.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-#include <unordered_map>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_LOWER_CASE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_LOWER_CASE_H_
 
-#ifdef __cplusplus
-
-namespace modsecurity {
-class Transaction;
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class LowerCase : public Transformation {
  public:
     explicit LowerCase(const std::string &action);
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_LOWER_CASE_H_
diff --git a/src/actions/transformations/md5.cc b/src/actions/transformations/md5.cc
index 71c36bc3..b1cdc93e 100644
--- a/src/actions/transformations/md5.cc
+++ b/src/actions/transformations/md5.cc
@@ -13,32 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/md5.h"
+#include "md5.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/md5.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Md5::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret = Utils::Md5::digest(value);
-
-    return ret;
+bool Md5::transform(std::string &value, const Transaction *trans) const {
+    value = Utils::Md5::digest(value);
+    return true;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/md5.h b/src/actions/transformations/md5.h
index 37f22473..9d5a15f8 100644
--- a/src/actions/transformations/md5.h
+++ b/src/actions/transformations/md5.h
@@ -13,33 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_MD5_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_MD5_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Md5 : public Transformation {
  public:
-    explicit Md5(const std::string &action)  : Transformation(action) { }
+    explicit Md5(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_MD5_H_
diff --git a/src/actions/transformations/none.cc b/src/actions/transformations/none.cc
index f122bf03..adbf32a6 100644
--- a/src/actions/transformations/none.cc
+++ b/src/actions/transformations/none.cc
@@ -13,30 +13,15 @@
  *
  */
 
-#include "src/actions/transformations/none.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "none.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string None::evaluate(const std::string &value,
-    Transaction *transaction) {
-    return value;
+bool None::transform(std::string &value, const Transaction *trans) const {
+    return false;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/none.h b/src/actions/transformations/none.h
index e8a0e9d9..2fe428bb 100644
--- a/src/actions/transformations/none.h
+++ b/src/actions/transformations/none.h
@@ -13,20 +13,12 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_NONE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_NONE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class None : public Transformation {
  public:
@@ -34,14 +26,9 @@ class None : public Transformation {
         : Transformation(action)
         { m_isNone = true; }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_NONE_H_
diff --git a/src/actions/transformations/normalise_path.cc b/src/actions/transformations/normalise_path.cc
index e75b9849..c663b98a 100644
--- a/src/actions/transformations/normalise_path.cc
+++ b/src/actions/transformations/normalise_path.cc
@@ -13,33 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/normalise_path.h"
-
-#include <string.h>
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "normalise_path.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 NormalisePath::NormalisePath(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string NormalisePath::evaluate(const std::string &value,
-    Transaction *transaction) {
-    int changed = 0;
+bool NormalisePath::transform(std::string &value, const Transaction *trans) const {
+    int _changed = 0;
 
     char *tmp = reinterpret_cast<char *>(
         malloc(sizeof(char) * value.size() + 1));
@@ -47,13 +33,15 @@ std::string NormalisePath::evaluate(const std::string &value,
     tmp[value.size()] = '\0';
 
     int i = normalize_path_inplace((unsigned char *)tmp,
-        value.size(), 0, &changed);
+        value.size(), 0, &_changed);
 
     std::string ret("");
     ret.assign(tmp, i);
     free(tmp);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -223,6 +211,4 @@ length:
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/normalise_path.h b/src/actions/transformations/normalise_path.h
index b3869bea..d5b84085 100644
--- a/src/actions/transformations/normalise_path.h
+++ b/src/actions/transformations/normalise_path.h
@@ -13,37 +13,23 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class NormalisePath : public Transformation {
  public:
-
     explicit NormalisePath(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static int normalize_path_inplace(unsigned char *input, int input_len,
         int win, int *changed);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_H_
diff --git a/src/actions/transformations/normalise_path_win.cc b/src/actions/transformations/normalise_path_win.cc
index 6c171a59..49f6989f 100644
--- a/src/actions/transformations/normalise_path_win.cc
+++ b/src/actions/transformations/normalise_path_win.cc
@@ -13,30 +13,16 @@
  *
  */
 
-#include "src/actions/transformations/normalise_path_win.h"
+#include "normalise_path_win.h"
 
-#include <string.h>
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "src/actions/transformations/normalise_path.h"
+#include "normalise_path.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string NormalisePathWin::evaluate(const std::string &value,
-    Transaction *transaction) {
-    int changed;
+bool NormalisePathWin::transform(std::string &value, const Transaction *trans) const {
+    int _changed;
 
     char *tmp = reinterpret_cast<char *>(
         malloc(sizeof(char) * value.size() + 1));
@@ -45,16 +31,16 @@ std::string NormalisePathWin::evaluate(const std::string &value,
 
     int i = NormalisePath::normalize_path_inplace(
         reinterpret_cast<unsigned char *>(tmp),
-        value.size(), 1, &changed);
+        value.size(), 1, &_changed);
 
     std::string ret("");
     ret.assign(tmp, i);
     free(tmp);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/normalise_path_win.h b/src/actions/transformations/normalise_path_win.h
index a1f8c5f7..af312693 100644
--- a/src/actions/transformations/normalise_path_win.h
+++ b/src/actions/transformations/normalise_path_win.h
@@ -13,33 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_WIN_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_WIN_H_
 
+#include "transformation.h"
 
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class NormalisePathWin : public Transformation {
  public:
     explicit NormalisePathWin(const std::string &action) 
         : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_NORMALISE_PATH_WIN_H_
diff --git a/src/actions/transformations/parity_even_7bit.cc b/src/actions/transformations/parity_even_7bit.cc
index 2c0be31c..f2992240 100644
--- a/src/actions/transformations/parity_even_7bit.cc
+++ b/src/actions/transformations/parity_even_7bit.cc
@@ -13,28 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/parity_even_7bit.h"
+#include "parity_even_7bit.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 #include <cstring>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+
+namespace modsecurity::actions::transformations {
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+bool ParityEven7bit::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
 
-
-std::string ParityEven7bit::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret;
     unsigned char *input;
 
     input = reinterpret_cast<unsigned char *>
@@ -46,9 +35,9 @@ std::string ParityEven7bit::evaluate(const std::string &value,
 
     std::memcpy(input, value.c_str(), value.length()+1);
 
-    inplace(input, value.length());
+    const auto ret = inplace(input, value.length());
 
-    ret.assign(reinterpret_cast<char *>(input), value.length());
+    value.assign(reinterpret_cast<char *>(input), value.length());
     free(input);
 
     return ret;
@@ -76,7 +65,4 @@ bool ParityEven7bit::inplace(unsigned char *input, uint64_t input_len) {
 }
 
 
-
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/parity_even_7bit.h b/src/actions/transformations/parity_even_7bit.h
index 08aa8823..41010d62 100644
--- a/src/actions/transformations/parity_even_7bit.h
+++ b/src/actions/transformations/parity_even_7bit.h
@@ -13,33 +13,22 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_PARITY_EVEN_7BIT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_PARITY_EVEN_7BIT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class ParityEven7bit : public Transformation {
  public:
-    explicit ParityEven7bit(const std::string &action)  : Transformation(action) { }
+    explicit ParityEven7bit(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp, Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
     static bool inplace(unsigned char *input, uint64_t input_len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_PARITY_EVEN_7BIT_H_
diff --git a/src/actions/transformations/parity_odd_7bit.cc b/src/actions/transformations/parity_odd_7bit.cc
index 5ac38d20..f8192ef3 100644
--- a/src/actions/transformations/parity_odd_7bit.cc
+++ b/src/actions/transformations/parity_odd_7bit.cc
@@ -13,28 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/parity_odd_7bit.h"
+#include "parity_odd_7bit.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 #include <cstring>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+
+namespace modsecurity::actions::transformations {
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+bool ParityOdd7bit::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
 
-
-std::string ParityOdd7bit::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret;
     unsigned char *input;
 
     input = reinterpret_cast<unsigned char *>
@@ -46,9 +35,9 @@ std::string ParityOdd7bit::evaluate(const std::string &value,
 
     memcpy(input, value.c_str(), value.length()+1);
 
-    inplace(input, value.length());
+    const auto ret = inplace(input, value.length());
 
-    ret.assign(reinterpret_cast<char *>(input), value.length());
+    value.assign(reinterpret_cast<char *>(input), value.length());
     free(input);
 
     return ret;
@@ -76,6 +65,4 @@ bool ParityOdd7bit::inplace(unsigned char *input, uint64_t input_len) {
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/parity_odd_7bit.h b/src/actions/transformations/parity_odd_7bit.h
index 8b7e34d2..1afa1327 100644
--- a/src/actions/transformations/parity_odd_7bit.h
+++ b/src/actions/transformations/parity_odd_7bit.h
@@ -13,33 +13,22 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_PARITY_ODD_7BIT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_PARITY_ODD_7BIT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class ParityOdd7bit : public Transformation {
  public:
-    explicit ParityOdd7bit(const std::string &action)  : Transformation(action) { }
+    explicit ParityOdd7bit(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp, Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
     static bool inplace(unsigned char *input, uint64_t input_len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_PARITY_ODD_7BIT_H_
diff --git a/src/actions/transformations/parity_zero_7bit.cc b/src/actions/transformations/parity_zero_7bit.cc
index 7bb84636..ef80b74d 100644
--- a/src/actions/transformations/parity_zero_7bit.cc
+++ b/src/actions/transformations/parity_zero_7bit.cc
@@ -13,28 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/parity_zero_7bit.h"
+#include "parity_zero_7bit.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 #include <cstring>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+
+namespace modsecurity::actions::transformations {
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+bool ParityZero7bit::transform(std::string &value, const Transaction *trans) const {
+    if (value.empty()) return false;
 
-
-std::string ParityZero7bit::evaluate(const std::string &value,
-    Transaction *transaction) {
-    std::string ret;
     unsigned char *input;
 
     input = reinterpret_cast<unsigned char *>
@@ -46,9 +35,9 @@ std::string ParityZero7bit::evaluate(const std::string &value,
 
     memcpy(input, value.c_str(), value.length()+1);
 
-    inplace(input, value.length());
+    const auto ret = inplace(input, value.length());
 
-    ret.assign(reinterpret_cast<char *>(input), value.length());
+    value.assign(reinterpret_cast<char *>(input), value.length());
     free(input);
 
     return ret;
@@ -68,6 +57,4 @@ bool ParityZero7bit::inplace(unsigned char *input, uint64_t input_len) {
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/parity_zero_7bit.h b/src/actions/transformations/parity_zero_7bit.h
index 4b4ccd23..af47f7c5 100644
--- a/src/actions/transformations/parity_zero_7bit.h
+++ b/src/actions/transformations/parity_zero_7bit.h
@@ -13,33 +13,22 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_PARITY_ZERO_7BIT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_PARITY_ZERO_7BIT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class ParityZero7bit : public Transformation {
  public:
-    explicit ParityZero7bit(const std::string &action)  : Transformation(action) { }
+    explicit ParityZero7bit(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp, Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
     static bool inplace(unsigned char *input, uint64_t input_len);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_PARITY_ZERO_7BIT_H_
diff --git a/src/actions/transformations/remove_comments.cc b/src/actions/transformations/remove_comments.cc
index 043dd950..1515675c 100644
--- a/src/actions/transformations/remove_comments.cc
+++ b/src/actions/transformations/remove_comments.cc
@@ -13,27 +13,13 @@
  *
  */
 
-#include "src/actions/transformations/remove_comments.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "remove_comments.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string RemoveComments::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool RemoveComments::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
 
@@ -103,10 +89,10 @@ std::string RemoveComments::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), j);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/remove_comments.h b/src/actions/transformations/remove_comments.h
index 78dd213d..67f0ff5b 100644
--- a/src/actions/transformations/remove_comments.h
+++ b/src/actions/transformations/remove_comments.h
@@ -13,35 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class RemoveComments : public Transformation {
  public:
-    explicit RemoveComments(const std::string &action)  : Transformation(action) { }
+    explicit RemoveComments(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_H_
diff --git a/src/actions/transformations/remove_comments_char.cc b/src/actions/transformations/remove_comments_char.cc
index 4c54e68a..7a4763d3 100644
--- a/src/actions/transformations/remove_comments_char.cc
+++ b/src/actions/transformations/remove_comments_char.cc
@@ -13,25 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/remove_comments_char.h"
-
-#include <string>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "remove_comments_char.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 RemoveCommentsChar::RemoveCommentsChar(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string RemoveCommentsChar::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool RemoveCommentsChar::transform(std::string &val, const Transaction *trans) const {
     size_t i = 0;
     std::string transformed_value;
     transformed_value.reserve(val.size());
@@ -65,10 +57,11 @@ std::string RemoveCommentsChar::evaluate(const std::string &val,
             i++;
         }
     }
-    return transformed_value;
+
+    const auto changed = transformed_value != val;
+    val = transformed_value;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
 
diff --git a/src/actions/transformations/remove_comments_char.h b/src/actions/transformations/remove_comments_char.h
index 722aba59..2066fd65 100644
--- a/src/actions/transformations/remove_comments_char.h
+++ b/src/actions/transformations/remove_comments_char.h
@@ -13,33 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_CHAR_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_CHAR_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class RemoveCommentsChar : public Transformation {
  public:
     explicit RemoveCommentsChar(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REMOVE_COMMENTS_CHAR_H_
diff --git a/src/actions/transformations/remove_nulls.cc b/src/actions/transformations/remove_nulls.cc
index 2d479c73..bda34bbe 100644
--- a/src/actions/transformations/remove_nulls.cc
+++ b/src/actions/transformations/remove_nulls.cc
@@ -13,23 +13,13 @@
  *
  */
 
-#include "src/actions/transformations/remove_nulls.h"
-
-#include <string.h>
-
-#include <string>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "remove_nulls.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string RemoveNulls::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool RemoveNulls::transform(std::string &val, const Transaction *trans) const {
     size_t i = 0;
     std::string transformed_value;
     transformed_value.reserve(val.size());
@@ -43,10 +33,10 @@ std::string RemoveNulls::evaluate(const std::string &val,
         i++;
     }
 
-    return transformed_value;
+    const auto changed = transformed_value != val;
+    val = transformed_value;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/remove_nulls.h b/src/actions/transformations/remove_nulls.h
index eeb33b36..56df24c8 100644
--- a/src/actions/transformations/remove_nulls.h
+++ b/src/actions/transformations/remove_nulls.h
@@ -13,34 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REMOVE_NULLS_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REMOVE_NULLS_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class RemoveNulls : public Transformation {
  public:
     explicit RemoveNulls(const std::string &action) 
         : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REMOVE_NULLS_H_
diff --git a/src/actions/transformations/remove_whitespace.cc b/src/actions/transformations/remove_whitespace.cc
index 37964663..8cee80c9 100644
--- a/src/actions/transformations/remove_whitespace.cc
+++ b/src/actions/transformations/remove_whitespace.cc
@@ -13,25 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/remove_whitespace.h"
+#include "remove_whitespace.h"
 
-#include <string>
+namespace modsecurity::actions::transformations {
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-
-
-namespace modsecurity {
-namespace actions {
-namespace transformations {
 
 RemoveWhitespace::RemoveWhitespace(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string RemoveWhitespace::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool RemoveWhitespace::transform(std::string &val, const Transaction *trans) const {
     std::string transformed_value;
     transformed_value.reserve(val.size());
 
@@ -52,10 +44,11 @@ std::string RemoveWhitespace::evaluate(const std::string &val,
         i++;
     }
 
-    return transformed_value;
+    const auto changed = transformed_value != val;
+    val = transformed_value;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
 
diff --git a/src/actions/transformations/remove_whitespace.h b/src/actions/transformations/remove_whitespace.h
index f977914c..a9925f8e 100644
--- a/src/actions/transformations/remove_whitespace.h
+++ b/src/actions/transformations/remove_whitespace.h
@@ -13,33 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REMOVE_WHITESPACE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REMOVE_WHITESPACE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class RemoveWhitespace : public Transformation {
  public:
     explicit RemoveWhitespace(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REMOVE_WHITESPACE_H_
diff --git a/src/actions/transformations/replace_comments.cc b/src/actions/transformations/replace_comments.cc
index 77e3e3b7..b1aeecf9 100644
--- a/src/actions/transformations/replace_comments.cc
+++ b/src/actions/transformations/replace_comments.cc
@@ -13,31 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/replace_comments.h"
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "replace_comments.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 ReplaceComments::ReplaceComments(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string ReplaceComments::evaluate(const std::string &value,
-    Transaction *transaction) {
+
+bool ReplaceComments::transform(std::string &value, const Transaction *trans) const {
     uint64_t i, j, incomment;
 
     char *input = reinterpret_cast<char *>(
@@ -80,9 +68,10 @@ std::string ReplaceComments::evaluate(const std::string &value,
 
     free(input);
 
-    return resp;
+    const auto changed = resp != value;
+    value = resp;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/replace_comments.h b/src/actions/transformations/replace_comments.h
index 6808f426..95e5e854 100644
--- a/src/actions/transformations/replace_comments.h
+++ b/src/actions/transformations/replace_comments.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REPLACE_COMMENTS_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REPLACE_COMMENTS_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class ReplaceComments : public Transformation {
  public:
+    explicit ReplaceComments(const std::string &action);
 
-    explicit ReplaceComments(const std::string &action) ;
-
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REPLACE_COMMENTS_H_
diff --git a/src/actions/transformations/replace_nulls.cc b/src/actions/transformations/replace_nulls.cc
index 1af860f4..c59ceb87 100644
--- a/src/actions/transformations/replace_nulls.cc
+++ b/src/actions/transformations/replace_nulls.cc
@@ -13,25 +13,17 @@
  *
  */
 
-#include "src/actions/transformations/replace_nulls.h"
-
-#include <string>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
+#include "replace_nulls.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 ReplaceNulls::ReplaceNulls(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string ReplaceNulls::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool ReplaceNulls::transform(std::string &val, const Transaction *trans) const {
     int64_t i;
     std::string value(val);
 
@@ -44,9 +36,9 @@ std::string ReplaceNulls::evaluate(const std::string &val,
         }
     }
 
-    return value;
+    const auto changed = val != value;
+    val = value;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/replace_nulls.h b/src/actions/transformations/replace_nulls.h
index 8e2d315f..ad206ae4 100644
--- a/src/actions/transformations/replace_nulls.h
+++ b/src/actions/transformations/replace_nulls.h
@@ -13,34 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_REPLACE_NULLS_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_REPLACE_NULLS_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class ReplaceNulls : public Transformation {
  public:
+    explicit ReplaceNulls(const std::string &action);
 
-    explicit ReplaceNulls(const std::string &action) ;
-
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_REPLACE_NULLS_H_
diff --git a/src/actions/transformations/sha1.cc b/src/actions/transformations/sha1.cc
index 9e0c7f53..af1eda41 100644
--- a/src/actions/transformations/sha1.cc
+++ b/src/actions/transformations/sha1.cc
@@ -13,35 +13,21 @@
  *
  */
 
-#include "src/actions/transformations/sha1.h"
+#include "sha1.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/sha1.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 Sha1::Sha1(const std::string &action) 
     : Transformation(action) {
     this->action_kind = 1;
 }
 
-std::string Sha1::evaluate(const std::string &value,
-    Transaction *transaction) {
-
-    return Utils::Sha1::digest(value);
+bool Sha1::transform(std::string &value, const Transaction *trans) const {
+    value = Utils::Sha1::digest(value);
+    return true;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/sha1.h b/src/actions/transformations/sha1.h
index eb5fb3f1..263ed978 100644
--- a/src/actions/transformations/sha1.h
+++ b/src/actions/transformations/sha1.h
@@ -13,32 +13,20 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_SHA1_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_SHA1_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Sha1 : public Transformation {
  public:
-    explicit Sha1(const std::string &action) ;
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    explicit Sha1(const std::string &action);
+
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_SHA1_H_
diff --git a/src/actions/transformations/sql_hex_decode.cc b/src/actions/transformations/sql_hex_decode.cc
index 8c8805ff..41189f92 100644
--- a/src/actions/transformations/sql_hex_decode.cc
+++ b/src/actions/transformations/sql_hex_decode.cc
@@ -13,24 +13,15 @@
  *
  */
 
-#include "src/actions/transformations/sql_hex_decode.h"
+#include "sql_hex_decode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 #include <cstring>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
+
 
 #ifndef VALID_HEX
 #define VALID_HEX(X) (((X >= '0') && (X <= '9')) \
@@ -41,8 +32,7 @@ namespace transformations {
 #define ISODIGIT(X) ((X >= '0') && (X <= '7'))
 #endif
 
-std::string SqlHexDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool SqlHexDecode::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
     int size = 0;
@@ -61,7 +51,9 @@ std::string SqlHexDecode::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), size);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -107,7 +99,4 @@ int SqlHexDecode::inplace(unsigned char *data, int len) {
 }
 
 
-
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/sql_hex_decode.h b/src/actions/transformations/sql_hex_decode.h
index 9a3afe0f..a92a0a2b 100644
--- a/src/actions/transformations/sql_hex_decode.h
+++ b/src/actions/transformations/sql_hex_decode.h
@@ -13,27 +13,19 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_SQL_HEX_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_SQL_HEX_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class SqlHexDecode : public Transformation {
  public:
-    explicit SqlHexDecode(const std::string &action)  : Transformation(action) { }
+    explicit SqlHexDecode(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static int inplace(unsigned char *data, int len);
 
@@ -45,10 +37,6 @@ class SqlHexDecode : public Transformation {
     }
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_SQL_HEX_DECODE_H_
diff --git a/src/actions/transformations/transformation.cc b/src/actions/transformations/transformation.cc
index 3b38431a..b6fbf5a3 100644
--- a/src/actions/transformations/transformation.cc
+++ b/src/actions/transformations/transformation.cc
@@ -13,65 +13,62 @@
  *
  */
 
-#include "src/actions/transformations/transformation.h"
+#include "transformation.h"
 
 #include <cstring>
-
 #include <iostream>
 #include <string>
 
 #include "modsecurity/transaction.h"
 #include "modsecurity/actions/action.h"
-#include "src/actions/transformations/base64_decode_ext.h"
-#include "src/actions/transformations/base64_decode.h"
-#include "src/actions/transformations/base64_encode.h"
-#include "src/actions/transformations/cmd_line.h"
-#include "src/actions/transformations/compress_whitespace.h"
-#include "src/actions/transformations/css_decode.h"
-#include "src/actions/transformations/escape_seq_decode.h"
-#include "src/actions/transformations/hex_decode.h"
-#include "src/actions/transformations/hex_encode.h"
-#include "src/actions/transformations/html_entity_decode.h"
-#include "src/actions/transformations/js_decode.h"
-#include "src/actions/transformations/length.h"
-#include "src/actions/transformations/lower_case.h"
-#include "src/actions/transformations/md5.h"
-#include "src/actions/transformations/none.h"
-#include "src/actions/transformations/normalise_path.h"
-#include "src/actions/transformations/normalise_path_win.h"
-#include "src/actions/transformations/parity_even_7bit.h"
-#include "src/actions/transformations/parity_odd_7bit.h"
-#include "src/actions/transformations/parity_zero_7bit.h"
-#include "src/actions/transformations/remove_comments_char.h"
-#include "src/actions/transformations/remove_comments.h"
-#include "src/actions/transformations/remove_nulls.h"
-#include "src/actions/transformations/remove_whitespace.h"
-#include "src/actions/transformations/replace_comments.h"
-#include "src/actions/transformations/replace_nulls.h"
-#include "src/actions/transformations/sha1.h"
-#include "src/actions/transformations/sql_hex_decode.h"
-#include "src/actions/transformations/trim.h"
-#include "src/actions/transformations/trim_left.h"
-#include "src/actions/transformations/trim_right.h"
-#include "src/actions/transformations/upper_case.h"
-#include "src/actions/transformations/url_decode.h"
-#include "src/actions/transformations/url_decode_uni.h"
-#include "src/actions/transformations/url_encode.h"
-#include "src/actions/transformations/utf8_to_unicode.h"
+
+#include "base64_decode_ext.h"
+#include "base64_decode.h"
+#include "base64_encode.h"
+#include "cmd_line.h"
+#include "compress_whitespace.h"
+#include "css_decode.h"
+#include "escape_seq_decode.h"
+#include "hex_decode.h"
+#include "hex_encode.h"
+#include "html_entity_decode.h"
+#include "js_decode.h"
+#include "length.h"
+#include "lower_case.h"
+#include "md5.h"
+#include "none.h"
+#include "normalise_path.h"
+#include "normalise_path_win.h"
+#include "parity_even_7bit.h"
+#include "parity_odd_7bit.h"
+#include "parity_zero_7bit.h"
+#include "remove_comments_char.h"
+#include "remove_comments.h"
+#include "remove_nulls.h"
+#include "remove_whitespace.h"
+#include "replace_comments.h"
+#include "replace_nulls.h"
+#include "sha1.h"
+#include "sql_hex_decode.h"
+#include "trim.h"
+#include "trim_left.h"
+#include "trim_right.h"
+#include "upper_case.h"
+#include "url_decode.h"
+#include "url_decode_uni.h"
+#include "url_encode.h"
+#include "utf8_to_unicode.h"
 
 
 #define IF_MATCH(b) \
     if (a.compare(2, std::strlen(#b), #b) == 0)
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Transformation::evaluate(const std::string &value,
-    Transaction *transaction) {
-    return value;
+bool Transformation::transform(std::string &value, const Transaction *trans) const {
+    return false;
 }
 
 Transformation* Transformation::instantiate(std::string a) {
@@ -119,6 +116,5 @@ Transformation* Transformation::instantiate(std::string a) {
     return new Transformation(a);
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/transformation.h b/src/actions/transformations/transformation.h
index f1d81503..3677dcef 100644
--- a/src/actions/transformations/transformation.h
+++ b/src/actions/transformations/transformation.h
@@ -13,19 +13,12 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_TRANSFORMATION_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_TRANSFORMATION_H_
 
+#include "modsecurity/actions/action.h"
 
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Transformation : public Action {
  public:
@@ -35,15 +28,11 @@ class Transformation : public Action {
     explicit Transformation(const std::string& _action, int kind)
         : Action(_action, kind) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
-
     static Transformation* instantiate(std::string a);
+
+    virtual bool transform(std::string &value, const Transaction *trans) const;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_TRANSFORMATION_H_
diff --git a/src/actions/transformations/trim.cc b/src/actions/transformations/trim.cc
index 5902497f..a5515346 100644
--- a/src/actions/transformations/trim.cc
+++ b/src/actions/transformations/trim.cc
@@ -13,22 +13,10 @@
  *
  */
 
-#include "src/actions/transformations/trim.h"
+#include "trim.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "modsecurity/actions/action.h"
-
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 std::string *Trim::ltrim(std::string *s) {
@@ -66,14 +54,13 @@ Trim::Trim(const std::string &action)
 }
 
 
-std::string
-Trim::evaluate(const std::string &val,
-    Transaction *transaction) {
-    std::string value(val);
-    return *this->trim(&value);
+bool Trim::transform(std::string &value, const Transaction *trans) const {
+    std::string ret(value);
+    this->trim(&ret);
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/trim.h b/src/actions/transformations/trim.h
index ac16050c..3b0e82d9 100644
--- a/src/actions/transformations/trim.h
+++ b/src/actions/transformations/trim.h
@@ -13,38 +13,24 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_TRIM_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_TRIM_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Trim : public Transformation {
  public:
+    explicit Trim(const std::string &action);
 
-    explicit Trim(const std::string &action) ;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
-
-    std::string *ltrim(std::string *s);
-    std::string *rtrim(std::string *s);
-    std::string *trim(std::string *s);
+    static std::string *ltrim(std::string *s);
+    static std::string *rtrim(std::string *s);
+    static std::string *trim(std::string *s);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_TRIM_H_
diff --git a/src/actions/transformations/trim_left.cc b/src/actions/transformations/trim_left.cc
index 50c0cc6a..c141727a 100644
--- a/src/actions/transformations/trim_left.cc
+++ b/src/actions/transformations/trim_left.cc
@@ -13,23 +13,10 @@
  *
  */
 
-#include "src/actions/transformations/trim_left.h"
+#include "trim_left.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "src/actions/transformations/trim.h"
-#include "modsecurity/actions/action.h"
-
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 
@@ -38,12 +25,13 @@ TrimLeft::TrimLeft(const std::string &action)
     this->action_kind = 1;
 }
 
-std::string TrimLeft::evaluate(const std::string &val,
-    Transaction *transaction) {
-        std::string value(val);
-    return *ltrim(&value);
+bool TrimLeft::transform(std::string &value, const Transaction *trans) const {
+    std::string ret(value);
+    this->ltrim(&ret);
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/trim_left.h b/src/actions/transformations/trim_left.h
index 54e4885c..5d5a0a57 100644
--- a/src/actions/transformations/trim_left.h
+++ b/src/actions/transformations/trim_left.h
@@ -13,34 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-#include "src/actions/transformations/trim.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_TRIM_LEFT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_TRIM_LEFT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
+#include "trim.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class TrimLeft : public Trim {
  public:
-    explicit TrimLeft(const std::string &action) ;
+    explicit TrimLeft(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_TRIM_LEFT_H_
diff --git a/src/actions/transformations/trim_right.cc b/src/actions/transformations/trim_right.cc
index 92383f7e..b95b63aa 100644
--- a/src/actions/transformations/trim_right.cc
+++ b/src/actions/transformations/trim_right.cc
@@ -13,22 +13,10 @@
  *
  */
 
-#include "src/actions/transformations/trim_right.h"
+#include "trim_right.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "modsecurity/actions/action.h"
-
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 TrimRight::TrimRight(const std::string &action) 
@@ -36,12 +24,13 @@ TrimRight::TrimRight(const std::string &action)
     this->action_kind = 1;
 }
 
-std::string TrimRight::evaluate(const std::string &val,
-    Transaction *transaction) {
-    std::string value(val);
-    return *this->rtrim(&value);
+bool TrimRight::transform(std::string &value, const Transaction *trans) const {
+    std::string ret(value);
+    this->rtrim(&ret);
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/trim_right.h b/src/actions/transformations/trim_right.h
index 9a96b4c5..eb13fb20 100644
--- a/src/actions/transformations/trim_right.h
+++ b/src/actions/transformations/trim_right.h
@@ -13,34 +13,21 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-#include "src/actions/transformations/trim.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_TRIM_RIGHT_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_TRIM_RIGHT_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
+#include "trim.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class TrimRight : public Trim {
  public:
-    explicit TrimRight(const std::string &action) ;
+    explicit TrimRight(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_TRIM_RIGHT_H_
diff --git a/src/actions/transformations/upper_case.cc b/src/actions/transformations/upper_case.cc
index 998ec725..2b8ad1d9 100644
--- a/src/actions/transformations/upper_case.cc
+++ b/src/actions/transformations/upper_case.cc
@@ -13,27 +13,19 @@
  *
  */
 
-#include "src/actions/transformations/upper_case.h"
 
-#include <algorithm>
-#include <string>
+#include "upper_case.h"
+
 #include <locale>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
-#include "modsecurity/actions/action.h"
-
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 UpperCase::UpperCase(const std::string &a)
     : Transformation(a) {
 }
 
-std::string UpperCase::evaluate(const std::string &val,
-    Transaction *transaction) {
+bool UpperCase::transform(std::string &val, const Transaction *trans) const {
     std::string value(val);
     std::locale loc;
 
@@ -41,9 +33,10 @@ std::string UpperCase::evaluate(const std::string &val,
         value[i] = std::toupper(value[i], loc);
     }
 
-    return value;
+    const auto changed = val != value;
+    val = value;
+    return changed;
 }
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/upper_case.h b/src/actions/transformations/upper_case.h
index f4a77220..70c806b0 100644
--- a/src/actions/transformations/upper_case.h
+++ b/src/actions/transformations/upper_case.h
@@ -13,35 +13,20 @@
  *
  */
 
-#include <string>
-#include <unordered_map>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_UPPER_CASE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_UPPER_CASE_H_
 
-#ifdef __cplusplus
-
-namespace modsecurity {
-class Transaction;
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class UpperCase : public Transformation {
  public:
-    explicit UpperCase(const std::string &action) ;
+    explicit UpperCase(const std::string &action);
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_UPPER_CASE_H_
diff --git a/src/actions/transformations/url_decode.cc b/src/actions/transformations/url_decode.cc
index 845c6a64..7e5f8767 100644
--- a/src/actions/transformations/url_decode.cc
+++ b/src/actions/transformations/url_decode.cc
@@ -13,23 +13,12 @@
  *
  */
 
-#include "src/actions/transformations/url_decode.h"
+#include "url_decode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/decode.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+
+namespace modsecurity::actions::transformations {
 
 
 UrlDecode::UrlDecode(const std::string &action) 
@@ -37,28 +26,27 @@ UrlDecode::UrlDecode(const std::string &action)
     this->action_kind = 1;
 }
 
-std::string UrlDecode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool UrlDecode::transform(std::string &value, const Transaction *trans) const {
     unsigned char *val(NULL);
     int invalid_count = 0;
-    int changed;
+    int _changed;
 
     val = (unsigned char *) malloc(sizeof(char) * value.size() + 1);
     memcpy(val, value.c_str(), value.size() + 1);
     val[value.size()] = '\0';
 
     int size = utils::urldecode_nonstrict_inplace(val, value.size(),
-        &invalid_count, &changed);
+        &invalid_count, &_changed);
     std::string out;
 
     out.append((const char *)val, size);
 
     free(val);
 
-    return out;
+    const auto changed = out != value;
+    value = out;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/url_decode.h b/src/actions/transformations/url_decode.h
index e965dae7..5c5c2662 100644
--- a/src/actions/transformations/url_decode.h
+++ b/src/actions/transformations/url_decode.h
@@ -13,36 +13,20 @@
  *
  */
 
-#include <string>
-#include <unordered_map>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+#include "transformation.h"
 
+namespace modsecurity::actions::transformations {
 
 class UrlDecode : public Transformation {
  public:
+    explicit UrlDecode(const std::string &action);
 
-    explicit UrlDecode(const std::string &action) ;
-
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_H_
diff --git a/src/actions/transformations/url_decode_uni.cc b/src/actions/transformations/url_decode_uni.cc
index ad5b8111..fdc2e79b 100644
--- a/src/actions/transformations/url_decode_uni.cc
+++ b/src/actions/transformations/url_decode_uni.cc
@@ -13,33 +13,16 @@
  *
  */
 
-#include "src/actions/transformations/url_decode_uni.h"
+#include "url_decode_uni.h"
 
-#include <string.h>
-
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-#include <cstring>
-
-#include "modsecurity/rules_set_properties.h"
 #include "modsecurity/rules_set.h"
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
-#include "src/utils/system.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string UrlDecodeUni::evaluate(const std::string &value,
-    Transaction *t) {
+bool UrlDecodeUni::transform(std::string &value, const Transaction *t) const {
     std::string ret;
     unsigned char *input;
 
@@ -57,7 +40,9 @@ std::string UrlDecodeUni::evaluate(const std::string &value,
     ret.assign(reinterpret_cast<char *>(input), i);
     free(input);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -66,7 +51,7 @@ std::string UrlDecodeUni::evaluate(const std::string &value,
  * IMP1 Assumes NUL-terminated
  */
 int UrlDecodeUni::inplace(unsigned char *input, uint64_t input_len,
-    Transaction *t) {
+    const Transaction *t) {
     unsigned char *d = input;
     int64_t i, count, fact, j, xv;
     int Code, hmap = -1;
@@ -190,6 +175,4 @@ int UrlDecodeUni::inplace(unsigned char *input, uint64_t input_len,
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/url_decode_uni.h b/src/actions/transformations/url_decode_uni.h
index d7b0dd21..31962851 100644
--- a/src/actions/transformations/url_decode_uni.h
+++ b/src/actions/transformations/url_decode_uni.h
@@ -13,35 +13,23 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/rules_set_properties.h"
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_UNI_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_UNI_H_
 
+#include "transformation.h"
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class UrlDecodeUni : public Transformation {
  public:
-    explicit UrlDecodeUni(const std::string &action)  : Transformation(action) { }
+    explicit UrlDecodeUni(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp, Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
     static int inplace(unsigned char *input, uint64_t input_len,
-        Transaction *transaction);
+        const Transaction *transaction);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_URL_DECODE_UNI_H_
diff --git a/src/actions/transformations/url_encode.cc b/src/actions/transformations/url_encode.cc
index 056755ca..e7f59f85 100644
--- a/src/actions/transformations/url_encode.cc
+++ b/src/actions/transformations/url_encode.cc
@@ -13,22 +13,11 @@
  *
  */
 
-#include "src/actions/transformations/url_encode.h"
+#include "url_encode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
-
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
 UrlEncode::UrlEncode(const std::string &action) 
@@ -87,16 +76,15 @@ std::string UrlEncode::url_enc(const char *input,
 }
 
 
-std::string UrlEncode::evaluate(const std::string &value,
-    Transaction *transaction) {
-    int changed;
+bool UrlEncode::transform(std::string &value, const Transaction *trans) const {
+    int _changed;
 
-    std::string ret = url_enc(value.c_str(), value.size(), &changed);
+    std::string ret = url_enc(value.c_str(), value.size(), &_changed);
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/url_encode.h b/src/actions/transformations/url_encode.h
index a45be564..b300c40d 100644
--- a/src/actions/transformations/url_encode.h
+++ b/src/actions/transformations/url_encode.h
@@ -13,37 +13,23 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_URL_ENCODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_URL_ENCODE_H_
 
-#ifdef __cplusplus
-namespace modsecurity {
-class Transaction;
+#include "transformation.h"
 
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class UrlEncode : public Transformation {
  public:
+    explicit UrlEncode(const std::string &action);
 
-    explicit UrlEncode(const std::string &action) ;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
-
-    std::string url_enc(const char *input,
+    static std::string url_enc(const char *input,
         unsigned int input_len, int *changed);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
-#endif
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_URL_ENCODE_H_
diff --git a/src/actions/transformations/utf8_to_unicode.cc b/src/actions/transformations/utf8_to_unicode.cc
index 70c1f9c8..2f40ce60 100644
--- a/src/actions/transformations/utf8_to_unicode.cc
+++ b/src/actions/transformations/utf8_to_unicode.cc
@@ -13,31 +13,20 @@
  *
  */
 
-#include "src/actions/transformations/utf8_to_unicode.h"
+#include "utf8_to_unicode.h"
 
-#include <iostream>
-#include <string>
-#include <algorithm>
-#include <functional>
-#include <cctype>
-#include <locale>
 #include <cstring>
 
-#include "modsecurity/transaction.h"
-#include "src/actions/transformations/transformation.h"
 #include "src/utils/string.h"
 
 
-namespace modsecurity {
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 
-std::string Utf8ToUnicode::evaluate(const std::string &value,
-    Transaction *transaction) {
+bool Utf8ToUnicode::transform(std::string &value, const Transaction *trans) const {
     std::string ret;
     unsigned char *input;
-    int changed = 0;
+    int _changed = 0;
     char *out;
 
     input = reinterpret_cast<unsigned char *>
@@ -49,7 +38,7 @@ std::string Utf8ToUnicode::evaluate(const std::string &value,
 
     memcpy(input, value.c_str(), value.length()+1);
 
-    out = inplace(input, value.size() + 1, &changed);
+    out = inplace(input, value.size() + 1, &_changed);
     free(input);
     if (out != NULL) {
         ret.assign(reinterpret_cast<char *>(out),
@@ -57,7 +46,9 @@ std::string Utf8ToUnicode::evaluate(const std::string &value,
         free(out);
     }
 
-    return ret;
+    const auto changed = ret != value;
+    value = ret;
+    return changed;
 }
 
 
@@ -313,6 +304,4 @@ char *Utf8ToUnicode::inplace(unsigned char *input,
 }
 
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions::transformations
diff --git a/src/actions/transformations/utf8_to_unicode.h b/src/actions/transformations/utf8_to_unicode.h
index 4d488410..83aba819 100644
--- a/src/actions/transformations/utf8_to_unicode.h
+++ b/src/actions/transformations/utf8_to_unicode.h
@@ -13,40 +13,30 @@
  *
  */
 
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "src/actions/transformations/transformation.h"
-
 #ifndef SRC_ACTIONS_TRANSFORMATIONS_UTF8_TO_UNICODE_H_
 #define SRC_ACTIONS_TRANSFORMATIONS_UTF8_TO_UNICODE_H_
 
+#include "transformation.h"
+
 #define UNICODE_ERROR_CHARACTERS_MISSING    -1
 #define UNICODE_ERROR_INVALID_ENCODING      -2
 #define UNICODE_ERROR_OVERLONG_CHARACTER    -3
 #define UNICODE_ERROR_RESTRICTED_CHARACTER  -4
 #define UNICODE_ERROR_DECODING_ERROR        -5
 
-namespace modsecurity {
-class Transaction;
-
-namespace actions {
-namespace transformations {
+namespace modsecurity::actions::transformations {
 
 class Utf8ToUnicode : public Transformation {
  public:
-    explicit Utf8ToUnicode(const std::string &action)  : Transformation(action) { }
+    explicit Utf8ToUnicode(const std::string &action)
+        : Transformation(action) { }
 
-    std::string evaluate(const std::string &exp,
-        Transaction *transaction) override;
+    bool transform(std::string &value, const Transaction *trans) const override;
 
     static char *inplace(unsigned char *input, uint64_t input_len,
         int *changed);
 };
 
-}  // namespace transformations
-}  // namespace actions
-}  // namespace modsecurity
-
+}  // namespace modsecurity::actions::transformations
 
 #endif  // SRC_ACTIONS_TRANSFORMATIONS_UTF8_TO_UNICODE_H_
diff --git a/src/actions/ver.cc b/src/actions/ver.cc
index 43b8b832..d7b8bdc4 100644
--- a/src/actions/ver.cc
+++ b/src/actions/ver.cc
@@ -15,16 +15,10 @@
 
 #include "src/actions/ver.h"
 
-#include <iostream>
-#include <string>
-
-#include "modsecurity/actions/action.h"
-#include "modsecurity/transaction.h"
-#include "modsecurity/rule.h"
+#include "modsecurity/rule_with_actions.h"
 
 
-namespace modsecurity {
-namespace actions {
+namespace modsecurity::actions {
 
 
 bool Ver::evaluate(RuleWithActions *rule, Transaction *transaction) {
@@ -33,5 +27,4 @@ bool Ver::evaluate(RuleWithActions *rule, Transaction *transaction) {
 }
 
 
-}  // namespace actions
-}  // namespace modsecurity
+}  // namespace modsecurity::actions
diff --git a/src/engine/lua.cc b/src/engine/lua.cc
index 0fac4f64..01a3eace 100644
--- a/src/engine/lua.cc
+++ b/src/engine/lua.cc
@@ -267,7 +267,7 @@ int Lua::getvar(lua_State *L) {
     t = reinterpret_cast<Transaction *>(z);
 
     std::string var = variables::Variable::stringMatchResolve(t, varname);
-    var = applyTransformations(L, t, 2, var);
+    applyTransformations(L, t, 2, var);
 
     if (var.size() == 0) {
         lua_pushnil(L);
@@ -407,12 +407,10 @@ int Lua::setvar(lua_State *L) {
 }
 
 
-std::string Lua::applyTransformations(lua_State *L, Transaction *t,
-    int idx, std::string var) {
-    std::string newVar = var;
-
+void Lua::applyTransformations(lua_State *L, const Transaction *t,
+    int idx, std::string &var) {
     if (lua_isuserdata(L, idx) || lua_isnoneornil(L, idx)) {
-        return var;
+        return;
     }
 
     if (lua_istable(L, idx)) {
@@ -429,16 +427,15 @@ std::string Lua::applyTransformations(lua_State *L, Transaction *t,
 
             /* A "none" means start over */
             if (strcmp("none", name) == 0) {
-                newVar = var;
                 continue;
             }
 
-            actions::transformations::Transformation *tfn = \
+            auto tfn = \
                 actions::transformations::Transformation::instantiate(
                     "t:" + std::string(name));
             // FIXME: transformation is not yet returning null.
             if (tfn) {
-                newVar = tfn->evaluate(newVar, t);
+                tfn->transform(var, t);
             } else {
                 ms_dbg_a(t, 1,
                     "SecRuleScript: Invalid transformation function: " \
@@ -447,32 +444,31 @@ std::string Lua::applyTransformations(lua_State *L, Transaction *t,
             delete tfn;
         }
 
-        return newVar;
+        return;
     }
 
     if (lua_isstring(L, idx)) {
         const char *name(NULL);
         name = reinterpret_cast<const char *>(luaL_checkstring(L, idx));
 
-        actions::transformations::Transformation *tfn = \
+        auto tfn = \
             actions::transformations::Transformation::instantiate(
                 "t:" + std::string(name));
 
         // FIXME: transformation is not yet returning null.
         if (tfn) {
-            newVar = tfn->evaluate(newVar, t);
+            tfn->transform(var, t);
             delete tfn;
         } else {
             ms_dbg_a(t, 1, "SecRuleScript: Invalid transformation function: " \
                 + std::string(name));
         }
-        return newVar;
+        return;
     }
     ms_dbg_a(t, 8, "SecRuleScript: Transformation parameter must be a " \
         "transformation name or array of transformation names, but found " \
         "" + std::string(lua_typename(L, idx)) + " (type " \
         + std::to_string(lua_type(L, idx)) + ")");
-    return newVar;
 }
 #endif
 
diff --git a/src/engine/lua.h b/src/engine/lua.h
index a33f28f8..452c7f49 100644
--- a/src/engine/lua.h
+++ b/src/engine/lua.h
@@ -79,8 +79,8 @@ class Lua {
     static int getvar(lua_State *L);
     static int getvars(lua_State *L);
     static int setvar(lua_State *L);
-    static std::string applyTransformations(lua_State *L, Transaction *t,
-        int idx, std::string var);
+    static void applyTransformations(lua_State *L, const Transaction *t,
+        int idx, std::string &var);
 
     LuaScriptBlob m_blob;
 #endif
diff --git a/src/modsecurity.cc b/src/modsecurity.cc
index 855facb3..93caa952 100644
--- a/src/modsecurity.cc
+++ b/src/modsecurity.cc
@@ -300,7 +300,6 @@ int ModSecurity::processContentOffset(const char *content, size_t len,
 
     while (!trans.empty()) {
         modsecurity::actions::transformations::Transformation *t;
-        std::string varValueRes;
         yajl_gen_map_open(g);
         yajl_gen_string(g,
             reinterpret_cast<const unsigned char*>("transformation"),
@@ -312,8 +311,7 @@ int ModSecurity::processContentOffset(const char *content, size_t len,
 
         t = modsecurity::actions::transformations::Transformation::instantiate(
             trans.back().str().c_str());
-        varValueRes = t->evaluate(varValue, NULL);
-        varValue.assign(varValueRes);
+        t->transform(varValue, nullptr);
         trans.pop_back();
 
         yajl_gen_string(g, reinterpret_cast<const unsigned char*>("value"),
diff --git a/src/operators/validate_utf8_encoding.cc b/src/operators/validate_utf8_encoding.cc
index 3e17686f..cd2f064c 100644
--- a/src/operators/validate_utf8_encoding.cc
+++ b/src/operators/validate_utf8_encoding.cc
@@ -19,6 +19,14 @@
 
 #include "src/operators/operator.h"
 
+
+constexpr int UNICODE_ERROR_CHARACTERS_MISSING   = -1;
+constexpr int UNICODE_ERROR_INVALID_ENCODING     = -2;
+constexpr int UNICODE_ERROR_OVERLONG_CHARACTER   = -3;
+constexpr int UNICODE_ERROR_RESTRICTED_CHARACTER = -4;
+constexpr int UNICODE_ERROR_DECODING_ERROR       = -5;
+
+
 namespace modsecurity {
 namespace operators {
 
diff --git a/src/operators/validate_utf8_encoding.h b/src/operators/validate_utf8_encoding.h
index e59eef58..2bd75dc8 100644
--- a/src/operators/validate_utf8_encoding.h
+++ b/src/operators/validate_utf8_encoding.h
@@ -22,13 +22,6 @@
 #include "src/operators/operator.h"
 
 
-#define UNICODE_ERROR_CHARACTERS_MISSING    -1
-#define UNICODE_ERROR_INVALID_ENCODING      -2
-#define UNICODE_ERROR_OVERLONG_CHARACTER    -3
-#define UNICODE_ERROR_RESTRICTED_CHARACTER  -4
-#define UNICODE_ERROR_DECODING_ERROR        -5
-
-
 namespace modsecurity {
 namespace operators {
 
diff --git a/src/rule_with_actions.cc b/src/rule_with_actions.cc
index e5d8183f..1b76005c 100644
--- a/src/rule_with_actions.cc
+++ b/src/rule_with_actions.cc
@@ -25,6 +25,7 @@
 #include <list>
 #include <utility>
 #include <memory>
+#include <cassert>
 
 #include "modsecurity/rules_set.h"
 #include "src/operators/operator.h"
@@ -323,49 +324,42 @@ void RuleWithActions::executeAction(Transaction *trans,
 
 
 inline void RuleWithActions::executeTransformation(
-    actions::transformations::Transformation *a,
-    std::shared_ptr<std::string> *value,
-    Transaction *trans,
+    const actions::transformations::Transformation &a,
+    std::string &value,
+    const Transaction *trans,
     TransformationResults *ret,
     std::string *path,
     int *nth) const {
 
-    std::string *oldValue = (*value).get();
-    std::string newValue = a->evaluate(*oldValue, trans);
-
-    if (newValue != *oldValue) {
-        auto u = std::make_shared<std::string>(newValue);
-        if (m_containsMultiMatchAction) {
-            ret->push_back(std::make_pair(u, a->m_name));
-            (*nth)++;
-        }
-        *value = u;
+    if (a.transform(value, trans) &&
+        m_containsMultiMatchAction) {
+        ret.emplace_back(value, a.m_name);
+        (*nth)++;
     }
 
     if (path->empty()) {
-        path->append(*a->m_name.get());
+        path->append(*a.m_name.get());
     } else {
-        path->append("," + *a->m_name.get());
+        path->append("," + *a.m_name.get());
     }
 
     ms_dbg_a(trans, 9, " T (" + \
         std::to_string(*nth) + ") " + \
-        *a->m_name.get() + ": \"" + \
-        utils::string::limitTo(80, newValue) +"\"");
+        *a.m_name.get() + ": \"" + \
+        utils::string::limitTo(80, value) +"\"");
 }
 
 void RuleWithActions::executeTransformations(
-    Transaction *trans, const std::string &in, TransformationResults &ret) {
+    const Transaction *trans, const std::string &in, TransformationResults &ret) {
     int none = 0;
     int transformations = 0;
     std::string path("");
-    auto value = std::make_shared<std::string>(in);
+    auto value = in;
 
     if (m_containsMultiMatchAction == true) {
         /* keep the original value */
-        ret.push_back(std::make_pair(
-            std::make_shared<std::string>(*value),
-            std::make_shared<std::string>(path)));
+        ret.emplace_back(value,
+                       std::make_shared<std::string>(path));
     }
 
     for (Action *a : m_transformations) {
@@ -385,15 +379,17 @@ void RuleWithActions::executeTransformations(
             }
 
             // FIXME: here the object needs to be a transformation already.
-            Transformation *t = dynamic_cast<Transformation *>(a.get());
-            executeTransformation(t, &value, trans, &ret, &path,
+            auto t = dynamic_cast<const Transformation*>(a.get());
+            assert(t != nullptr);
+            executeTransformation(*t, value, trans, &ret, &path,
                 &transformations);
         }
     }
 
-    for (Transformation *a : m_transformations) {
+    for (const Transformation *a : m_transformations) {
+        assert(a != nullptr);
         if (none == 0) {
-            executeTransformation(a, &value, trans, &ret, &path,
+            executeTransformation(*a, value, trans, &ret, &path,
                 &transformations);
         }
         if (a->m_isNone) {
@@ -408,7 +404,8 @@ void RuleWithActions::executeTransformations(
         if (m_ruleId != b.first) {
             continue;
         }
-        Transformation *a = dynamic_cast<Transformation*>(b.second.get());
+        auto a = dynamic_cast<const Transformation*>(b.second.get());
+        assert(a != nullptr);
         if (a->m_isNone) {
             none++;
         }
@@ -419,9 +416,10 @@ void RuleWithActions::executeTransformations(
         if (m_ruleId != b.first) {
             continue;
         }
-        Transformation *a = dynamic_cast<Transformation*>(b.second.get());
+        auto a = dynamic_cast<const Transformation*>(b.second.get());
+        assert(a != nullptr);
         if (none == 0) {
-            executeTransformation(a, &value, trans, &ret, &path,
+            executeTransformation(*a, value, trans, &ret, &path,
                 &transformations);
         }
         if (a->m_isNone) {
@@ -436,9 +434,8 @@ void RuleWithActions::executeTransformations(
     }
 
     if (!m_containsMultiMatchAction) {
-        ret.push_back(std::make_pair(
-            std::make_shared<std::string>(*value),
-            std::make_shared<std::string>(path)));
+        ret.emplace_back(value,
+                       std::make_shared<std::string>(path));
     }
 }
 
diff --git a/src/rule_with_operator.cc b/src/rule_with_operator.cc
index f54ffb5c..b043af5c 100644
--- a/src/rule_with_operator.cc
+++ b/src/rule_with_operator.cc
@@ -296,10 +296,9 @@ bool RuleWithOperator::evaluate(Transaction *trans,
             executeTransformations(trans, value, values);
 
             for (const auto &valueTemp : values) {
-                bool ret;
-                std::string valueAfterTrans = std::move(*valueTemp.first);
+                const auto &valueAfterTrans = valueTemp.first;
 
-                ret = executeOperatorAt(trans, key, valueAfterTrans, ruleMessage);
+                const bool ret = executeOperatorAt(trans, key, valueAfterTrans, ruleMessage);
 
                 if (ret == true) {
                     ruleMessage->m_match = m_operator->resolveMatchMessage(trans,
diff --git a/src/utils/string.h b/src/utils/string.h
index b0c3c17d..dbfb9b47 100644
--- a/src/utils/string.h
+++ b/src/utils/string.h
@@ -235,18 +235,18 @@ inline unsigned char *c2x(unsigned what, unsigned char *where) {
 }
 
 
-inline std::string string_to_hex(const std::string& input) {
-    static const char* const lut = "0123456789ABCDEF";
-    size_t len = input.length();
+inline std::string string_to_hex(std::string_view input) {
+    static const char* const lut = "0123456789abcdef";
 
-    std::string output;
-    output.reserve(2 * len);
-    for (size_t i = 0; i < len; ++i) {
-        const unsigned char c = input[i];
-        output.push_back(lut[c >> 4]);
-        output.push_back(lut[c & 15]);
+    std::string a(input.size()*2, 0);
+    char *d = a.data();
+
+    for (const unsigned char c : input) {
+        *d++ = lut[c >> 4];
+        *d++ = lut[c & 15];
     }
-    return output;
+
+    return a;
 }
 
 
diff --git a/test/coding_style_suppressions.txt b/test/coding_style_suppressions.txt
index c2b1ea52..bba5a62c 100644
--- a/test/coding_style_suppressions.txt
+++ b/test/coding_style_suppressions.txt
@@ -13,7 +13,6 @@
 ./src/utils/acmp.cc
 ./src/utils/acmp.h
 ./src/utils/mbedtls/
-./src/utils/md5.cc
 ./src/utils/md5.h
 ./src/utils/msc_tree.cc
 ./src/utils/msc_tree.h
diff --git a/test/unit/unit.cc b/test/unit/unit.cc
index 75fec137..5ebc9d3f 100644
--- a/test/unit/unit.cc
+++ b/test/unit/unit.cc
@@ -89,8 +89,10 @@ struct TransformationTest {
         return tfn;
     }
 
-    static UnitTestResult eval(ItemType &tfn, const UnitTest &t) {
-        return {1, tfn.evaluate(t.input, nullptr)};
+    static UnitTestResult eval(const ItemType &tfn, const UnitTest &t) {
+        std::string ret = t.input;
+        tfn.transform(ret, nullptr);
+        return {1, ret};
     }
 
     static bool check(const UnitTestResult &result, const UnitTest &t) {
diff --git a/test/unit/unit_test.cc b/test/unit/unit_test.cc
index dee4f1ae..b0060732 100644
--- a/test/unit/unit_test.cc
+++ b/test/unit/unit_test.cc
@@ -30,20 +30,6 @@
 namespace modsecurity_test {
 
 
-std::string string_to_hex(const std::string& input) {
-    static const char* const lut = "0123456789ABCDEF";
-    size_t len = input.length();
-
-    std::string output;
-    output.reserve(2 * len);
-    for (size_t i = 0; i < len; ++i) {
-        const unsigned char c = input[i];
-        output.push_back(lut[c >> 4]);
-        output.push_back(lut[c & 15]);
-    }
-    return output;
-}
-
 void replaceAll(std::string *s, const std::string &search,
     const char replace) {
     for (size_t pos = 0; ; pos += 0) {