Issue 5131 - [emscripten] Clean separation of bindings code and runtime code

compiled/bindings/generator.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#pragma once
-
-#include <cstddef>
-#include <cstdint>
+#include "generator.h"
+
 #include <cstdio>
-#include <cstdlib>
-#include <exception>
-#include <functional>
-#include <map>
-#include <string>
-#include <type_traits>
-#include <utility>
-#include <vector>
-
-#include <emscripten.h>
-
-#include "String.h"
-#include "intrusive_ptr.h"
+
+namespace
+{
+  std::vector<bindings_internal::ClassInfo> classes;
+  std::vector<bindings_internal::CustomGenerator> customGenerators;
+}
 
 namespace bindings_internal
 {
-  typedef void* TYPEID;
-
-  enum class TypeCategory
-  {
-    UNKNOWN,
-    VOID,
-    INT,
-    INT64,
-    FLOAT,
-    DOUBLE,
-    DEPENDENT_STRING,
-    OWNED_STRING,
-    STRING_REF,
-    CLASS_PTR
-  };
-
-  template<typename T>
-  struct TypeInfo
-  {
-    /*
-     * Since TypeInfo is a templated type, in practice the compiler will define
-     * a new type for each possible template parameter value. We use that fact
-     * to generate type identifiers: each of these TypeInfo types has a
-     * different s_typeIDHelper member, so we use a pointer to that static
-     * variable as a type identifier - it will be different for each template
-     * parameter.
-     */
-    static char s_typeIDHelper;
-    constexpr operator TYPEID() const
+  FunctionInfo::FunctionInfo()
+  {
+    name[0] = '\0';
+  }
+
+  FunctionInfo::FunctionInfo(TypeCategory returnType, TYPEID pointerType,
+      std::initializer_list<TypeCategory> argTypes, bool instance_function,
+      void* function)
+      : returnType(returnType), pointerType(pointerType),
+        instance_function(instance_function)
+  {
+    name[0] = '\0';
+
+    // The function parameter is a pointer to the function pointer.
+    // Emscripten's "function pointers" are actually integers indicating the
+    // position in the call table. 0 represents nullptr.
+    if (!*reinterpret_cast<int*>(function))
+      return;
+
+    std::string signature;
+
+    // Add return type to the signature. Similar logic in Emscripten:
+    // https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L46
+    switch (returnType)
     {
-      return &s_typeIDHelper;
+      case TypeCategory::DEPENDENT_STRING:
+      case TypeCategory::OWNED_STRING:
+        // Technically, objects aren't really returned with clang. The caller
+        // instead adds the reference to the resulting object as an implicit
+        // parameter.
+        signature += "vi";
+        break;
+      case TypeCategory::VOID:
+        signature += 'v';
+        break;
+      case TypeCategory::FLOAT:
+        signature += 'f';
+        break;
+      case TypeCategory::DOUBLE:
+        signature += 'd';
+        break;
+      case TypeCategory::INT:
+      case TypeCategory::INT64:
+      case TypeCategory::STRING_REF:
+      case TypeCategory::CLASS_PTR:
+        signature += 'i';
+        break;
+      default:
+        throw std::runtime_error("Unexpected function return type");
     }
 
-    constexpr operator TypeCategory() const
+    // `this` pointer is an implicit parameter with clang and should be added
+    // to the signature.
+    if (instance_function)
+      signature += 'i';
+
+    // Add explicit parameters to the signature, Similar logic in Emscripten:
+    // https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L67
+    for (const auto& type : argTypes)
     {
-      if (std::is_void<T>())
-        return TypeCategory::VOID;
-
-      if (std::is_same<T, uint64_t>())
-        return TypeCategory::INT64;
-
-      if (std::is_integral<T>() || std::is_enum<T>())
-        return TypeCategory::INT;
-
-      if (std::is_same<T, float>())
-        return TypeCategory::FLOAT;
-
-      if (std::is_same<T, double>())
-        return TypeCategory::DOUBLE;
-
-      if (std::is_same<DependentString, T>() || std::is_same<const DependentString, T>())
-        return TypeCategory::DEPENDENT_STRING;
-
-      if (std::is_same<OwnedString, T>() || std::is_same<const OwnedString, T>())
-        return TypeCategory::OWNED_STRING;
-
-      if (std::is_same<String&, T>() || std::is_same<const String&, T>() ||
-        std::is_same<DependentString&, T>())
-      {
-        return TypeCategory::STRING_REF;
-      }
-
-      if (std::is_pointer<T>() && std::is_class<typename std::remove_pointer<T>::type>())
-        return TypeCategory::CLASS_PTR;
-
-      return TypeCategory::UNKNOWN;
-    }
-
-    constexpr TYPEID pointer_type() const
-    {
-      if (std::is_pointer<T>())
-        return TypeInfo<typename std::remove_pointer<T>::type>();
-      else
-        return nullptr;
-    }
-  };
-
-  template<typename T>
-  char TypeInfo<T>::s_typeIDHelper;
-
-  struct FunctionInfo
-  {
-    TypeCategory returnType;
-    TYPEID pointerType;
-    std::vector<TypeCategory> args;
-    bool instance_function;
-    int effectiveArgs;
-    TypeCategory effectiveReturnType;
-    char name[1024];
-
-    FunctionInfo()
-    {
-      name[0] = '\0';
-    }
-
-    FunctionInfo(TypeCategory returnType, TYPEID pointerType,
-        std::initializer_list<TypeCategory> argTypes, bool instance_function,
-        void* function)
-        : returnType(returnType), pointerType(pointerType),
-          instance_function(instance_function)
-    {
-      name[0] = '\0';
-
-      // The function parameter is a pointer to the function pointer.
-      // Emscripten's "function pointers" are actually integers indicating the
-      // position in the call table. 0 represents nullptr.
-      if (!*reinterpret_cast<int*>(function))
-        return;
-
-      std::string signature;
-
-      // Add return type to the signature. Similar logic in Emscripten:
-      // https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L46
-      switch (returnType)
-      {
-        case TypeCategory::DEPENDENT_STRING:
-        case TypeCategory::OWNED_STRING:
-          // Technically, objects aren't really returned with clang. The caller
-          // instead adds the reference to the resulting object as an implicit
-          // parameter.
-          signature += "vi";
-          break;
-        case TypeCategory::VOID:
-          signature += 'v';
-          break;
-        case TypeCategory::FLOAT:
-          signature += 'f';
-          break;
-        case TypeCategory::DOUBLE:
-          signature += 'd';
-          break;
+      switch (type)
+      {
         case TypeCategory::INT:
-        case TypeCategory::INT64:
         case TypeCategory::STRING_REF:
         case TypeCategory::CLASS_PTR:
           signature += 'i';
           break;
+        case TypeCategory::INT64:
+          // See https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L73,
+          // numerical types larger than 32-bit are split into multiple
+          // 32-bit parameters.
+          signature += "ii";
+          break;
+        case TypeCategory::FLOAT:
+          signature += 'f';
+          break;
+        case TypeCategory::DOUBLE:
+          signature += 'd';
+          break;
         default:
-          throw std::runtime_error("Unexpected function return type");
-      }
-
-      // `this` pointer is an implicit parameter with clang and should be added
-      // to the signature.
-      if (instance_function)
-        signature += 'i';
-
-      // Add explicit parameters to the signature, Similar logic in Emscripten:
-      // https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L67
-      for (const auto& type : argTypes)
-      {
-        switch (type)
+          throw std::runtime_error("Unexpected function argument type");
+      }
+      args.push_back(type);
+    }
+
+    get_function_name(function, signature.c_str());
+  }
+
+  bool FunctionInfo::empty() const
+  {
+    return name[0] == '\0';
+  }
+
+  void FunctionInfo::get_function_name(void* ptr, const char* signature)
+  {
+    // This is a hack, C++ won't let us get the mangled function name.
+    // JavaScript is more dynamic so we pass the pointer to our function
+    // there. With that and the function signature we can call the function -
+    // with a full stack so that we will cause it to abort. Sometimes the
+    // function we are calling will also be missing from the build. The result
+    // is the same: abort() is called which in turn calls stackTrace(). By
+    // replacing stackTrace() we get access to the call stack and search it
+    // for the name of our function.
+
+    EM_ASM_ARGS({
+      var signature = AsciiToString($2);
+      var args = [];
+      for (var i = 1; i < signature.length; i++)
+        args.push(0);
+
+      var oldPrint = Module.print;
+      var oldPrintErr = Module.printErr;
+      var oldStackTrace = stackTrace;
+      var sp = Runtime.stackSave();
+      Module.print = function(){};
+      Module.printErr = function(){};
+      stackTrace = function()
+      {
+        var stack = [];
+        for (var f = arguments.callee.caller; f; f = f.caller)
         {
-          case TypeCategory::INT:
-          case TypeCategory::STRING_REF:
-          case TypeCategory::CLASS_PTR:
-            signature += 'i';
-            break;
-          case TypeCategory::INT64:
-            // See https://github.com/kripken/emscripten/blob/1.37.3/src/modules.js#L73,
-            // numerical types larger than 32-bit are split into multiple
-            // 32-bit parameters.
-            signature += "ii";
-            break;
-          case TypeCategory::FLOAT:
-            signature += 'f';
-            break;
-          case TypeCategory::DOUBLE:
-            signature += 'd';
-            break;
-          default:
-            throw std::runtime_error("Unexpected function argument type");
+          if (f.name)
+          {
+            if (f.name.indexOf("dynCall") == 0)
+              break;
+            else
+              stack.push(f.name);
+          }
         }
-        args.push_back(type);
-      }
-
-      get_function_name(function, signature.c_str());
-    }
-
-    template<typename ReturnType, typename... Args>
-    FunctionInfo(ReturnType (*function)(Args...))
-        : FunctionInfo(TypeInfo<ReturnType>(),
-          TypeInfo<ReturnType>().pointer_type(), { TypeInfo<Args>()... }, false,
-          &function)
-    {
-    }
-
-    template<typename ClassType, typename ReturnType, typename... Args>
-    FunctionInfo(ReturnType (ClassType::*function)(Args...))
-        : FunctionInfo(TypeInfo<ReturnType>(),
-          TypeInfo<ReturnType>().pointer_type(), { TypeInfo<Args>()... }, true,
-          &function)
-    {
-    }
-
-    template<typename ClassType, typename ReturnType, typename... Args>
-    FunctionInfo(ReturnType (ClassType::*function)(Args...) const)
-        : FunctionInfo(TypeInfo<ReturnType>(),
-          TypeInfo<ReturnType>().pointer_type(), { TypeInfo<Args>()... }, true,
-          &function)
-    {
-    }
-
-    bool empty() const
-    {
-      return name[0] == '\0';
-    }
-
-    void get_function_name(void* ptr, const char* signature)
-    {
-      // This is a hack, C++ won't let us get the mangled function name.
-      // JavaScript is more dynamic so we pass the pointer to our function
-      // there. With that and the function signature we can call the function -
-      // with a full stack so that we will cause it to abort. Sometimes the
-      // function we are calling will also be missing from the build. The result
-      // is the same: abort() is called which in turn calls stackTrace(). By
-      // replacing stackTrace() we get access to the call stack and search it
-      // for the name of our function.
-
-      EM_ASM_ARGS({
-        var signature = AsciiToString($2);
-        var args = [];
-        for (var i = 1; i < signature.length; i++)
-          args.push(0);
-
-        var oldPrint = Module.print;
-        var oldPrintErr = Module.printErr;
-        var oldStackTrace = stackTrace;
-        var sp = Runtime.stackSave();
-        Module.print = function(){};
-        Module.printErr = function(){};
-        stackTrace = function()
-        {
-          var stack = [];
-          for (var f = arguments.callee.caller; f; f = f.caller)
-          {
-            if (f.name)
-            {
-              if (f.name.indexOf("dynCall") == 0)
-                break;
-              else
-                stack.push(f.name);
-            }
-          }
-
-          result = stack[stack.length - 1];
-          if (result && result.indexOf("__wrapper") >= 0)
-            result = stack[stack.length - 2];
-          throw result;
-        };
-
-        Runtime.stackRestore(STACK_MAX);
-
-        try
-        {
-          Runtime.dynCall(signature, HEAP32[$1 >> 2], args);
-        }
-        catch(e)
-        {
-          Module.stringToAscii(e, $0);
-        }
-        finally
-        {
-          Runtime.stackRestore(sp);
-          Module.print = oldPrint;
-          Module.printErr = oldPrintErr;
-          stackTrace = oldStackTrace;
-        }
-      }, name, ptr, signature);
-    }
-  };
-
-  class NoBaseClass
-  {
-  };
-
-  struct PropertyInfo
-  {
-    std::string name;
-    FunctionInfo getter;
-    FunctionInfo setter;
-    std::string jsValue;
-  };
-
-  struct MethodInfo
-  {
-    std::string name;
-    FunctionInfo call;
-  };
-
-  struct DifferentiatorInfo
-  {
-    size_t offset;
-    std::vector<std::pair<int, std::string>> mapping;
-  };
-
-  struct ClassInfo
-  {
-    ClassInfo* baseClass;
-    std::string name;
-    std::vector<PropertyInfo> properties;
-    std::vector<MethodInfo> methods;
-    DifferentiatorInfo subclass_differentiator;
-    ptrdiff_t ref_counted_offset;
-  };
-
-  typedef std::function<void()>  CustomGenerator;
-
-  std::map<TYPEID, ClassInfo> classes;
-  std::vector<CustomGenerator> customGenerators;
+
+        result = stack[stack.length - 1];
+        if (result && result.indexOf("__wrapper") >= 0)
+          result = stack[stack.length - 2];
+        throw result;
+      };
+
+      Runtime.stackRestore(STACK_MAX);
+
+      try
+      {
+        Runtime.dynCall(signature, HEAP32[$1 >> 2], args);
+      }
+      catch(e)
+      {
+        Module.stringToAscii(e, $0);
+      }
+      finally
+      {
+        Runtime.stackRestore(sp);
+        Module.print = oldPrint;
+        Module.printErr = oldPrintErr;
+        stackTrace = oldStackTrace;
+      }
+    }, name, ptr, signature);
+  }
+
+  ClassInfo* find_class(TYPEID classID)
+  {
+    for (auto& classInfo : classes)
+      if (classInfo.id == classID)
+        return &classInfo;
+    return nullptr;
+  }
 
   void register_class(const char* name, TYPEID classID, TYPEID baseClassID,
                       ptrdiff_t ref_counted_offset)
   {
-    auto it = classes.find(classID);
-    if (it != classes.end())
+    if (find_class(classID))
       throw std::runtime_error(std::string("Duplicate definition for class ") + name);
 
-    ClassInfo* baseClass = nullptr;
-    if (baseClassID != TypeInfo<NoBaseClass>())
-    {
-      it = classes.find(baseClassID);
-      if (it == classes.end())
-        throw std::runtime_error(std::string("Unknown base class defined for class ") + name);
-      baseClass = &(it->second);
-    }
+    if (baseClassID != TypeInfo<NoBaseClass>() && !find_class(baseClassID))
+      throw std::runtime_error(std::string("Unknown base class defined for class ") + name);
 
     ClassInfo classInfo;
-    classInfo.baseClass = baseClass;
+    classInfo.id = classID;
+    classInfo.baseClass = baseClassID;
     classInfo.name = name;
     classInfo.subclass_differentiator.offset = SIZE_MAX;
     classInfo.ref_counted_offset = ref_counted_offset;
-    classes[classID] = classInfo;
+    classes.push_back(classInfo);
   }
 
   void register_property(TYPEID classID, const char* name,
       const FunctionInfo& getter, const FunctionInfo& setter,
-      const char* jsValue = "")
-  {
-    auto it = classes.find(classID);
-    if (it == classes.end())
+      const char* jsValue)
+  {
+    ClassInfo* classInfo = find_class(classID);
+    if (!classInfo)
       throw std::runtime_error(std::string("Property defined on unknown class: ") + name);
 
     PropertyInfo propertyInfo;
     propertyInfo.name = name;
     propertyInfo.getter = getter;
     propertyInfo.setter = setter;
     propertyInfo.jsValue = jsValue;
-    it->second.properties.push_back(propertyInfo);
+    classInfo->properties.push_back(propertyInfo);
   }
 
   void register_method(TYPEID classID, const char* name,
       const FunctionInfo& call)
   {
-    auto it = classes.find(classID);
-    if (it == classes.end())
+    ClassInfo* classInfo = find_class(classID);
+    if (!classInfo)
       throw std::runtime_error(std::string("Method defined on unknown class: ") + name);
 
     MethodInfo methodInfo;
     methodInfo.name = name;
     methodInfo.call = call;
-    it->second.methods.push_back(methodInfo);
+    classInfo->methods.push_back(methodInfo);
   }
 
   void register_differentiator(TYPEID classID, size_t offset,
       std::vector<std::pair<int, std::string>>& mapping)
   {
-    auto it = classes.find(classID);
-    if (it == classes.end())
+    ClassInfo* classInfo = find_class(classID);
+    if (!classInfo)
       throw std::runtime_error("Subclass differentiator defined on unknown class");
 
-    if (it->second.subclass_differentiator.offset != SIZE_MAX)
-      throw std::runtime_error("More than one subclass differentiator defined for class " + it->second.name);
+    if (classInfo->subclass_differentiator.offset != SIZE_MAX)
+      throw std::runtime_error("More than one subclass differentiator defined for class " + classInfo->name);
 
     DifferentiatorInfo differentiatorInfo;
     differentiatorInfo.offset = offset;
     differentiatorInfo.mapping = mapping;
-    it->second.subclass_differentiator = differentiatorInfo;
+    classInfo->subclass_differentiator = differentiatorInfo;
   }
 
   const std::string generateCall(const FunctionInfo& call,
       std::vector<std::string>& params)
   {
     if (call.returnType == TypeCategory::DEPENDENT_STRING ||
         call.returnType == TypeCategory::OWNED_STRING)
     {
       params.insert(params.begin(), "string");
     }
@@ skipping 33 matching lines @@
       }
       case TypeCategory::STRING_REF:
         return "  var result = readString(" + call_str + ");\n";
       case TypeCategory::CLASS_PTR:
       {
         std::string result;
         result += "  var result = " + call_str + ";\n";
         result += "  if (result)\n";
         result += "  {\n";
 
-        auto it = classes.find(call.pointerType);
-        if (it == classes.end())
+        const ClassInfo* cls = find_class(call.pointerType);
+        if (!cls)
           throw std::runtime_error("Function " + std::string(call.name) + " returns pointer to unknown class");
 
-        const ClassInfo& cls = it->second;
-        auto offset = cls.subclass_differentiator.offset;
+        auto offset = cls->subclass_differentiator.offset;
         if (offset == SIZE_MAX)
-          result += "    result = exports." + cls.name + "(result);\n";
+          result += "    result = exports." + cls->name + "(result);\n";
         else
-          result += "    result = exports." + cls.name + ".fromPointer(result);\n";
+          result += "    result = exports." + cls->name + ".fromPointer(result);\n";
 
         result += "  }\n";
         result += "  else\n";
         result += "    result = null;\n";
         return result;
       }
       default:
         throw std::runtime_error("Unexpected return type for " + std::string(call.name));
     }
   }
@@ skipping 103 matching lines @@
         {
           Module._ReleaseRef(this._pointer + ref_counted_offset);
         };
         return result;
       }
     )");
   }
 
   void printClass(const ClassInfo& cls)
   {
+    ClassInfo* baseClass = find_class(cls.baseClass);
     printf("exports.%s = createClass(%s, %i);\n", cls.name.c_str(),
-        (cls.baseClass ? ("exports." + cls.baseClass->name).c_str() : "null"),
+        (baseClass ? ("exports." + baseClass->name).c_str() : "null"),
         cls.ref_counted_offset);
 
     DifferentiatorInfo differentiator = cls.subclass_differentiator;
     if (differentiator.offset != SIZE_MAX)
     {
       printf("var %s_mapping = \n", cls.name.c_str());
       puts("{");
       for (const auto& item : differentiator.mapping)
         printf("  %i: '%s',\n", item.first, item.second.c_str());
       puts("};");
@@ skipping 23 matching lines @@
 
     for (const auto& item : cls.methods)
     {
       std::string obj("exports." + cls.name);
       if (item.call.instance_function)
         obj += ".prototype";
       printf("%s.%s = %s;\n", obj.c_str(), item.name.c_str(),
           wrapCall(item.call).c_str());
     }
   }
-
-  void printBindings()
-  {
-    printHelpers();
-
-    for (const auto& item : classes)
-      printClass(item.second);
-
-    for (const auto& item : customGenerators)
-      item();
-  }
 }
 
-#if defined(PRINT_BINDINGS)
-  // Bindings generation step: collect bindings information and print
-  // corresponding JS code.
-  #define EMSCRIPTEN_BINDINGS \
-      void InitializeBindings();\
-      int main()\
-      {\
-        try\
-        {\
-          InitializeBindings();\
-          bindings_internal::printBindings();\
-        }\
-        catch (const std::exception& e)\
-        {\
-          EM_ASM_ARGS(\
-            console.error("Error occurred generating JavaScript bindings: " +\
-                Module.AsciiToString($0)), e.what()\
-          );\
-          abort();\
-        }\
-        return 0;\
-      }\
-      void InitializeBindings()
-#else
-  // Actual compilation step: ignore bindings information but define some
-  // exported helper functions necessary for the bindings.
-  #define EMSCRIPTEN_BINDINGS \
-      extern "C"\
-      {\
-        void EMSCRIPTEN_KEEPALIVE InitString(DependentString* str,\
-            String::value_type* data, String::size_type len)\
-        {\
-          /* String is already allocated on stack, we merely need to call*/\
-          /* constructor.*/\
-          new (str) DependentString(data, len);\
-        }\
-        void EMSCRIPTEN_KEEPALIVE DestroyString(OwnedString* str)\
-        {\
-          /* Stack memory will be freed automatically, we need to call*/\
-          /* destructor explicitly however.*/\
-          str->~OwnedString();\
-        }\
-        String::size_type EMSCRIPTEN_KEEPALIVE GetStringLength(\
-            const String& str)\
-        {\
-          return str.length();\
-        }\
-        const String::value_type* EMSCRIPTEN_KEEPALIVE GetStringData(\
-            const String& str)\
-        {\
-          return str.data();\
-        }\
-        void EMSCRIPTEN_KEEPALIVE ReleaseRef(ref_counted* ptr)\
-        {\
-          ptr->ReleaseRef();\
-        }\
-      }\
-      void BindingsInitializer_dummy()
-#endif
+void printBindings()
+{
+  bindings_internal::printHelpers();
 
-template<typename ClassType,
-    typename BaseClass = bindings_internal::NoBaseClass,
-    typename std::enable_if<std::is_base_of<ref_counted, ClassType>::value>::type* = nullptr>
-class class_
-{
-public:
-  class_(const char* name)
-  {
-    ClassType* ptr = reinterpret_cast<ClassType*>(0x10000000);
-    ptrdiff_t ref_counted_offset =
-        reinterpret_cast<char*>(static_cast<ref_counted*>(ptr)) -
-        reinterpret_cast<char*>(ptr);
-    bindings_internal::register_class(name,
-        bindings_internal::TypeInfo<ClassType>(),
-        bindings_internal::TypeInfo<BaseClass>(),
-        ref_counted_offset
-      );
-  }
+  for (const auto& item : classes)
+    bindings_internal::printClass(item);
 
-  template<typename FieldType>
-  const class_& property(const char* name,
-      FieldType (ClassType::*getter)() const,
-      void (ClassType::*setter)(FieldType) = nullptr) const
-  {
-    bindings_internal::register_property(
-        bindings_internal::TypeInfo<ClassType>(), name, getter, setter);
-    return *this;
-  }
-
-  const class_& class_property(const char* name,
-      const char* jsValue) const
-  {
-    bindings_internal::register_property(
-        bindings_internal::TypeInfo<ClassType>(), name,
-        bindings_internal::FunctionInfo(), bindings_internal::FunctionInfo(),
-        jsValue);
-    return *this;
-  }
-
-  template<typename ReturnType, typename... Args>
-  const class_& function(const char* name, ReturnType (ClassType::*method)(Args...)) const
-  {
-    bindings_internal::register_method(
-        bindings_internal::TypeInfo<ClassType>(), name, method);
-    return *this;
-  }
-
-  template<typename ReturnType, typename... Args>
-  const class_& function(const char* name, ReturnType (ClassType::*method)(Args...) const) const
-  {
-    bindings_internal::register_method(
-        bindings_internal::TypeInfo<ClassType>(), name, method);
-    return *this;
-  }
-
-  template<typename ReturnType, typename... Args>
-  const class_& class_function(const char* name, ReturnType (*method)(Args...)) const
-  {
-    bindings_internal::register_method(
-        bindings_internal::TypeInfo<ClassType>(), name, method);
-    return *this;
-  }
-
-  template<typename ReturnType,
-      typename std::enable_if<std::is_convertible<ReturnType, int32_t>::value>::type* = nullptr>
-  const class_& subclass_differentiator(ReturnType ClassType::* member,
-      std::initializer_list<std::pair<ReturnType, const char*>> list) const
-  {
-    ClassType* instance = nullptr;
-    size_t offset = (char*)&(instance->*member) - (char*)instance;
-
-    std::vector<std::pair<int, std::string>> mapping;
-    for (const auto& item : list)
-      mapping.emplace_back(item.first, item.second);
-
-    bindings_internal::register_differentiator(
-        bindings_internal::TypeInfo<ClassType>(), offset, mapping);
-    return *this;
-  }
-};
+  for (const auto& item : customGenerators)
+    item();
+}
 
 void custom_generator(bindings_internal::CustomGenerator generator)
 {
-  bindings_internal::customGenerators.push_back(generator);
+  customGenerators.push_back(generator);
 }