/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// independent from idl_parser, since this code is not needed for most clients

#include "flatbuffers/flatbuffers.h"
#include "flatbuffers/idl.h"
#include "flatbuffers/util.h"
#include "flatbuffers/code_generators.h"

namespace flatbuffers {

struct IsAlnum {
  bool operator()(char c) {
    return !isalnum(c);
  }
};

static std::string GeneratedFileName(const std::string &path,
                                     const std::string &file_name) {
  return path + file_name + "_generated.h";
}

namespace cpp {
class CppGenerator : public BaseGenerator {
 public:
  CppGenerator(const Parser &parser, const std::string &path,
               const std::string &file_name)
      : BaseGenerator(parser, path, file_name){};
  // Iterate through all definitions we haven't generate code for (enums,
  // structs,
  // and tables) and output them to a single file.
  bool generate() {
    if (IsEverythingGenerated()) return true;

    std::string code;
    code = code + "// " + FlatBuffersGeneratedWarning();

    // Generate include guard.
    std::string include_guard_ident = file_name_;
    // Remove any non-alpha-numeric characters that may appear in a filename.
    include_guard_ident.erase(
        std::remove_if(include_guard_ident.begin(), include_guard_ident.end(),
                       IsAlnum()),
        include_guard_ident.end());
    std::string include_guard = "FLATBUFFERS_GENERATED_" + include_guard_ident;
    include_guard += "_";
    // For further uniqueness, also add the namespace.
    auto name_space = parser_.namespaces_.back();
    for (auto it = name_space->components.begin();
         it != name_space->components.end(); ++it) {
      include_guard += *it + "_";
    }
    include_guard += "H_";
    std::transform(include_guard.begin(), include_guard.end(),
                   include_guard.begin(), ::toupper);
    code += "#ifndef " + include_guard + "\n";
    code += "#define " + include_guard + "\n\n";

    code += "#include \"flatbuffers/flatbuffers.h\"\n\n";

    if (parser_.opts.include_dependence_headers) {
      int num_includes = 0;
      for (auto it = parser_.included_files_.begin();
           it != parser_.included_files_.end(); ++it) {
        auto basename =
            flatbuffers::StripPath(flatbuffers::StripExtension(it->first));
        if (basename != file_name_) {
          code += "#include \"" + basename + "_generated.h\"\n";
          num_includes++;
        }
      }
      if (num_includes) code += "\n";
    }

    assert(!cur_name_space_);

    // Generate forward declarations for all structs/tables, since they may
    // have circular references.
    for (auto it = parser_.structs_.vec.begin();
         it != parser_.structs_.vec.end(); ++it) {
      auto &struct_def = **it;
      if (!struct_def.generated) {
        SetNameSpace(struct_def.defined_namespace, &code);
        code += "struct " + struct_def.name + ";\n\n";
      }
    }

    // Generate code for all the enum declarations.
    for (auto it = parser_.enums_.vec.begin(); it != parser_.enums_.vec.end();
         ++it) {
      auto &enum_def = **it;
      if (!enum_def.generated) {
        SetNameSpace((**it).defined_namespace, &code);
        GenEnum(**it, &code);
      }
    }

    // Generate code for all structs, then all tables.
    for (auto it = parser_.structs_.vec.begin();
         it != parser_.structs_.vec.end(); ++it) {
      auto &struct_def = **it;
      if (struct_def.fixed && !struct_def.generated) {
        SetNameSpace(struct_def.defined_namespace, &code);
        GenStruct(struct_def, &code);
      }
    }
    for (auto it = parser_.structs_.vec.begin();
         it != parser_.structs_.vec.end(); ++it) {
      auto &struct_def = **it;
      if (!struct_def.fixed && !struct_def.generated) {
        SetNameSpace(struct_def.defined_namespace, &code);
        GenTable(struct_def, &code);
      }
    }

    // Generate code for union verifiers.
    for (auto it = parser_.enums_.vec.begin(); it != parser_.enums_.vec.end();
         ++it) {
      auto &enum_def = **it;
      if (enum_def.is_union && !enum_def.generated) {
        SetNameSpace(enum_def.defined_namespace, &code);
        GenEnumPost(enum_def, &code);
      }
    }

    // Generate convenient global helper functions:
    if (parser_.root_struct_def_) {
      SetNameSpace((*parser_.root_struct_def_).defined_namespace, &code);
      auto &name = parser_.root_struct_def_->name;
      std::string qualified_name =
          parser_.namespaces_.back()->GetFullyQualifiedName(name);
      std::string cpp_qualified_name = TranslateNameSpace(qualified_name);

      // The root datatype accessor:
      code += "inline const " + cpp_qualified_name + " *Get";
      code += name;
      code += "(const void *buf) { return flatbuffers::GetRoot<";
      code += cpp_qualified_name + ">(buf); }\n\n";
      if (parser_.opts.mutable_buffer) {
        code += "inline " + name + " *GetMutable";
        code += name;
        code += "(void *buf) { return flatbuffers::GetMutableRoot<";
        code += name + ">(buf); }\n\n";
      }

      // The root verifier:
      code += "inline bool Verify";
      code += name;
      code +=
          "Buffer(flatbuffers::Verifier &verifier) { "
          "return verifier.VerifyBuffer<";
      code += cpp_qualified_name + ">(); }\n\n";

      if (parser_.file_identifier_.length()) {
        // Return the identifier
        code += "inline const char *" + name;
        code += "Identifier() { return \"" + parser_.file_identifier_;
        code += "\"; }\n\n";

        // Check if a buffer has the identifier.
        code += "inline bool " + name;
        code += "BufferHasIdentifier(const void *buf) { return flatbuffers::";
        code += "BufferHasIdentifier(buf, ";
        code += name + "Identifier()); }\n\n";
      }

      if (parser_.file_extension_.length()) {
        // Return the extension
        code += "inline const char *" + name;
        code += "Extension() { return \"" + parser_.file_extension_;
        code += "\"; }\n\n";
      }

      // Finish a buffer with a given root object:
      code += "inline void Finish" + name;
      code +=
          "Buffer(flatbuffers::FlatBufferBuilder &fbb, flatbuffers::Offset<";
      code += cpp_qualified_name + "> root) { fbb.Finish(root";
      if (parser_.file_identifier_.length())
        code += ", " + name + "Identifier()";
      code += "); }\n\n";
    }

    assert(cur_name_space_);
    SetNameSpace(nullptr, &code);

    // Close the include guard.
    code += "#endif  // " + include_guard + "\n";

    return SaveFile(GeneratedFileName(path_, file_name_).c_str(), code, false);
  }

 private:
  // This tracks the current namespace so we can insert namespace declarations.
  const Namespace *cur_name_space_ = nullptr;

  // Ensure that a type is prefixed with its namespace whenever it is used
  // outside of its namespace.
  std::string WrapInNameSpace(const Namespace *ns, const std::string &name) {
    if (cur_name_space_ != ns) {
      std::string qualified_name;
      for (auto it = ns->components.begin(); it != ns->components.end(); ++it) {
        qualified_name += *it + "::";
      }
      return qualified_name + name;
    } else {
      return name;
    }
  }

  std::string WrapInNameSpace(const Definition &def) {
    return WrapInNameSpace(def.defined_namespace, def.name);
  }

  // Translates a qualified name in flatbuffer text format to the same name in
  // the equivalent C++ namespace.
  static std::string TranslateNameSpace(const std::string &qualified_name) {
    std::string cpp_qualified_name = qualified_name;
    size_t start_pos = 0;
    while ((start_pos = cpp_qualified_name.find(".", start_pos)) !=
           std::string::npos) {
      cpp_qualified_name.replace(start_pos, 1, "::");
    }
    return cpp_qualified_name;
  }

  // Return a C++ type from the table in idl.h
  std::string GenTypeBasic(const Type &type, bool user_facing_type) {
    static const char *ctypename[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE, PTYPE) #CTYPE,
        FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
    };
    if (user_facing_type) {
      if (type.enum_def) return WrapInNameSpace(*type.enum_def);
      if (type.base_type == BASE_TYPE_BOOL) return "bool";
    }
    return ctypename[type.base_type];
  }

  // Return a C++ pointer type, specialized to the actual struct/table types,
  // and vector element types.
  std::string GenTypePointer(const Type &type) {
    switch (type.base_type) {
      case BASE_TYPE_STRING:
        return "flatbuffers::String";
      case BASE_TYPE_VECTOR:
        return "flatbuffers::Vector<" +
               GenTypeWire(type.VectorType(), "", false) + ">";
      case BASE_TYPE_STRUCT: {
        return WrapInNameSpace(*type.struct_def);
      }
      case BASE_TYPE_UNION:
      // fall through
      default:
        return "void";
    }
  }

  // Return a C++ type for any type (scalar/pointer) specifically for
  // building a flatbuffer.
  std::string GenTypeWire(const Type &type,
                          const char *postfix, bool user_facing_type) {
    return IsScalar(type.base_type)
               ? GenTypeBasic(type, user_facing_type) + postfix
               : IsStruct(type)
                     ? "const " + GenTypePointer(type) + " *"
                     : "flatbuffers::Offset<" + GenTypePointer(type) +
                           ">" + postfix;
  }

  // Return a C++ type for any type (scalar/pointer) that reflects its
  // serialized size.
  std::string GenTypeSize(const Type &type) {
    return IsScalar(type.base_type)
               ? GenTypeBasic(type, false)
               : IsStruct(type) ? GenTypePointer(type)
                                : "flatbuffers::uoffset_t";
  }

  // Return a C++ type for any type (scalar/pointer) specifically for
  // using a flatbuffer.
  std::string GenTypeGet(const Type &type,
                         const char *afterbasic, const char *beforeptr,
                         const char *afterptr, bool user_facing_type) {
    return IsScalar(type.base_type)
               ? GenTypeBasic(type, user_facing_type) + afterbasic
               : beforeptr + GenTypePointer(type) + afterptr;
  }

  static std::string GenEnumDecl(const EnumDef &enum_def,
                                 const IDLOptions &opts) {
    return (opts.scoped_enums ? "enum class " : "enum ") + enum_def.name;
  }

  static std::string GenEnumVal(const EnumDef &enum_def,
                                const std::string &enum_val,
                                const IDLOptions &opts) {
    return opts.prefixed_enums ? enum_def.name + "_" + enum_val : enum_val;
  }

  static std::string GetEnumVal(const EnumDef &enum_def,
                                const EnumVal &enum_val,
                                const IDLOptions &opts) {
    if (opts.scoped_enums) {
      return enum_def.name + "::" + enum_val.name;
    } else if (opts.prefixed_enums) {
      return enum_def.name + "_" + enum_val.name;
    } else {
      return enum_val.name;
    }
  }

  std::string EnumSignature(EnumDef &enum_def) {
    return "inline bool Verify" + enum_def.name +
           "(flatbuffers::Verifier &verifier, " + "const void *union_obj, " +
           enum_def.name + " type)";
  }

  // Generate an enum declaration and an enum string lookup table.
  void GenEnum(EnumDef &enum_def, std::string *code_ptr) {
    std::string &code = *code_ptr;
    GenComment(enum_def.doc_comment, code_ptr, nullptr);
    code += GenEnumDecl(enum_def, parser_.opts);
    if (parser_.opts.scoped_enums)
      code += " : " + GenTypeBasic(enum_def.underlying_type, false);
    code += " {\n";
    int64_t anyv = 0;
    EnumVal *minv = nullptr, *maxv = nullptr;
    for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
         ++it) {
      auto &ev = **it;
      GenComment(ev.doc_comment, code_ptr, nullptr, "  ");
      code += "  " + GenEnumVal(enum_def, ev.name, parser_.opts) + " = ";
      code += NumToString(ev.value) + ",\n";
      minv = !minv || minv->value > ev.value ? &ev : minv;
      maxv = !maxv || maxv->value < ev.value ? &ev : maxv;
      anyv |= ev.value;
    }
    if (parser_.opts.scoped_enums || parser_.opts.prefixed_enums) {
      assert(minv && maxv);
      if (enum_def.attributes.Lookup("bit_flags")) {
        if (minv->value != 0)  // If the user didn't defined NONE value
          code += "  " + GenEnumVal(enum_def, "NONE", parser_.opts) + " = 0,\n";
        if (maxv->value != anyv)  // If the user didn't defined ANY value
          code += "  " + GenEnumVal(enum_def, "ANY", parser_.opts) + " = " +
                  NumToString(anyv) + "\n";
      } else {  // MIN & MAX are useless for bit_flags
        code += "  " + GenEnumVal(enum_def, "MIN", parser_.opts) + " = ";
        code += GenEnumVal(enum_def, minv->name, parser_.opts) + ",\n";
        code += "  " + GenEnumVal(enum_def, "MAX", parser_.opts) + " = ";
        code += GenEnumVal(enum_def, maxv->name, parser_.opts) + "\n";
      }
    }
    code += "};\n";
    if (parser_.opts.scoped_enums && enum_def.attributes.Lookup("bit_flags"))
      code += "DEFINE_BITMASK_OPERATORS(" + enum_def.name + ", " +
              GenTypeBasic(enum_def.underlying_type, false) + ")\n";
    code += "\n";

    // Generate a generate string table for enum values.
    // Problem is, if values are very sparse that could generate really big
    // tables. Ideally in that case we generate a map lookup instead, but for
    // the moment we simply don't output a table at all.
    auto range =
        enum_def.vals.vec.back()->value - enum_def.vals.vec.front()->value + 1;
    // Average distance between values above which we consider a table
    // "too sparse". Change at will.
    static const int kMaxSparseness = 5;
    if (range / static_cast<int64_t>(enum_def.vals.vec.size()) <
        kMaxSparseness) {
      code += "inline const char **EnumNames" + enum_def.name + "() {\n";
      code += "  static const char *names[] = { ";
      auto val = enum_def.vals.vec.front()->value;
      for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
           ++it) {
        while (val++ != (*it)->value) code += "\"\", ";
        code += "\"" + (*it)->name + "\", ";
      }
      code += "nullptr };\n  return names;\n}\n\n";
      code += "inline const char *EnumName" + enum_def.name;
      code += "(" + enum_def.name + " e) { return EnumNames" + enum_def.name;
      code += "()[static_cast<int>(e)";
      if (enum_def.vals.vec.front()->value) {
        code += " - static_cast<int>(";
        code +=
            GetEnumVal(enum_def, *enum_def.vals.vec.front(), parser_.opts) + ")";
      }
      code += "]; }\n\n";
    }

    if (enum_def.is_union) {
      code += EnumSignature(enum_def) + ";\n\n";
    }
  }

  void GenEnumPost(EnumDef &enum_def, std::string *code_ptr_post) {
    // Generate a verifier function for this union that can be called by the
    // table verifier functions. It uses a switch case to select a specific
    // verifier function to call, this should be safe even if the union type
    // has been corrupted, since the verifiers will simply fail when called
    // on the wrong type.
    std::string &code_post = *code_ptr_post;
    code_post += EnumSignature(enum_def) + " {\n  switch (type) {\n";
    for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
         ++it) {
      auto &ev = **it;
      code_post += "    case " + GetEnumVal(enum_def, ev, parser_.opts);
      if (!ev.value) {
        code_post += ": return true;\n";  // "NONE" enum value.
      } else {
        code_post += ": return verifier.VerifyTable(reinterpret_cast<const ";
        code_post += WrapInNameSpace(*ev.struct_def);
        code_post += " *>(union_obj));\n";
      }
    }
    code_post += "    default: return false;\n  }\n}\n\n";
  }

  // Generates a value with optionally a cast applied if the field has a
  // different underlying type from its interface type (currently only the
  // case for enums. "from" specify the direction, true meaning from the
  // underlying type to the interface type.
  std::string GenUnderlyingCast(const FieldDef &field, bool from,
                                const std::string &val) {
    if (from && field.value.type.base_type == BASE_TYPE_BOOL) {
      return val + " != 0";
    } else if ((field.value.type.enum_def &&
                IsScalar(field.value.type.base_type)) ||
               field.value.type.base_type == BASE_TYPE_BOOL) {
      return "static_cast<" + GenTypeBasic(field.value.type, from) + ">(" +
             val + ")";
    } else {
      return val;
    }
  }

  std::string GenFieldOffsetName(const FieldDef &field) {
    std::string uname = field.name;
    std::transform(uname.begin(), uname.end(), uname.begin(), ::toupper);
    return "VT_" + uname;
  }

  void GenFullyQualifiedNameGetter(const std::string &name,
                                          std::string &code) {
    if (parser_.opts.generate_name_strings) {
      code +=
          "  static FLATBUFFERS_CONSTEXPR const char *GetFullyQualifiedName() "
          "{\n";
      code += "    return \"" +
              parser_.namespaces_.back()->GetFullyQualifiedName(name) + "\";\n";
      code += "  }\n";
    }
  }

  std::string GenDefaultConstant(const FieldDef &field) {
    return field.value.type.base_type == BASE_TYPE_FLOAT
               ? field.value.constant + "f"
               : field.value.constant;
  }

  // Generate an accessor struct, builder structs & function for a table.
  void GenTable(StructDef &struct_def, std::string *code_ptr) {
    std::string &code = *code_ptr;
    // Generate an accessor struct, with methods of the form:
    // type name() const { return GetField<type>(offset, defaultval); }
    GenComment(struct_def.doc_comment, code_ptr, nullptr);
    code += "struct " + struct_def.name;
    code += " FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table";
    code += " {\n";
    // Generate GetFullyQualifiedName
    GenFullyQualifiedNameGetter(struct_def.name, code);
    // Generate field id constants.
    if (struct_def.fields.vec.size() > 0) {
      code += "  enum {\n";
      bool is_first_field =
          true;  // track the first field that's not deprecated
      for (auto it = struct_def.fields.vec.begin();
           it != struct_def.fields.vec.end(); ++it) {
        auto &field = **it;
        if (!field.deprecated) {  // Deprecated fields won't be accessible.
          if (!is_first_field) {
            // Add trailing comma and newline to previous element. Don't add
            // trailing comma to
            // last element since older versions of gcc complain about this.
            code += ",\n";
          } else {
            is_first_field = false;
          }
          code += "    " + GenFieldOffsetName(field) + " = ";
          code += NumToString(field.value.offset);
        }
      }
      code += "\n  };\n";
    }
    // Generate the accessors.
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (!field.deprecated) {  // Deprecated fields won't be accessible.
        auto is_scalar = IsScalar(field.value.type.base_type);
        GenComment(field.doc_comment, code_ptr, nullptr, "  ");
        code += "  " +
                GenTypeGet(field.value.type, " ", "const ", " *", true);
        code += field.name + "() const { return ";
        // Call a different accessor for pointers, that indirects.
        auto accessor =
            is_scalar
                ? "GetField<"
                : (IsStruct(field.value.type) ? "GetStruct<" : "GetPointer<");
        auto offsetstr = GenFieldOffsetName(field);
        auto call = accessor + GenTypeGet(field.value.type, "",
                                          "const ", " *", false) +
                    ">(" + offsetstr;
        // Default value as second arg for non-pointer types.
        if (IsScalar(field.value.type.base_type))
          call += ", " + GenDefaultConstant(field);
        call += ")";
        code += GenUnderlyingCast(field, true, call);
        code += "; }\n";
        if (parser_.opts.mutable_buffer) {
          if (is_scalar) {
            code += "  bool mutate_" + field.name + "(";
            code += GenTypeBasic(field.value.type, true);
            code +=
                " _" + field.name + ") { return SetField(" + offsetstr + ", ";
            code += GenUnderlyingCast(field, false, "_" + field.name);
            code += "); }\n";
          } else {
            auto type =
                GenTypeGet(field.value.type, " ", "", " *", true);
            code += "  " + type + "mutable_" + field.name + "() { return ";
            code += GenUnderlyingCast(field, true,
                                      accessor + type + ">(" + offsetstr + ")");
            code += "; }\n";
          }
        }
        auto nested = field.attributes.Lookup("nested_flatbuffer");
        if (nested) {
          std::string qualified_name =
              parser_.namespaces_.back()->GetFullyQualifiedName(
                  nested->constant);
          auto nested_root = parser_.structs_.Lookup(qualified_name);
          assert(nested_root);  // Guaranteed to exist by parser.
          (void)nested_root;
          std::string cpp_qualified_name = TranslateNameSpace(qualified_name);

          code += "  const " + cpp_qualified_name + " *" + field.name;
          code += "_nested_root() const { return flatbuffers::GetRoot<";
          code += cpp_qualified_name + ">(" + field.name + "()->Data()); }\n";
        }
        // Generate a comparison function for this field if it is a key.
        if (field.key) {
          code += "  bool KeyCompareLessThan(const " + struct_def.name;
          code += " *o) const { return ";
          if (field.value.type.base_type == BASE_TYPE_STRING) code += "*";
          code += field.name + "() < ";
          if (field.value.type.base_type == BASE_TYPE_STRING) code += "*";
          code += "o->" + field.name + "(); }\n";
          code += "  int KeyCompareWithValue(";
          if (field.value.type.base_type == BASE_TYPE_STRING) {
            code += "const char *val) const { return strcmp(" + field.name;
            code += "()->c_str(), val); }\n";
          } else {
            if (parser_.opts.scoped_enums && field.value.type.enum_def &&
                IsScalar(field.value.type.base_type)) {
              code += GenTypeGet(field.value.type, " ", "const ", " *", true);
            } else {
              code += GenTypeBasic(field.value.type, false);
            }
            code += " val) const { return " + field.name + "() < val ? -1 : ";
            code += field.name + "() > val; }\n";
          }
        }
      }
    }
    // Generate a verifier function that can check a buffer from an untrusted
    // source will never cause reads outside the buffer.
    code += "  bool Verify(flatbuffers::Verifier &verifier) const {\n";
    code += "    return VerifyTableStart(verifier)";
    std::string prefix = " &&\n           ";
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (!field.deprecated) {
        code += prefix + "VerifyField";
        if (field.required) code += "Required";
        code += "<" + GenTypeSize(field.value.type);
        code += ">(verifier, " + GenFieldOffsetName(field) + ")";
        switch (field.value.type.base_type) {
          case BASE_TYPE_UNION:
            code += prefix + "Verify" + field.value.type.enum_def->name;
            code +=
                "(verifier, " + field.name + "(), " + field.name + "_type())";
            break;
          case BASE_TYPE_STRUCT:
            if (!field.value.type.struct_def->fixed) {
              code += prefix + "verifier.VerifyTable(" + field.name;
              code += "())";
            }
            break;
          case BASE_TYPE_STRING:
            code += prefix + "verifier.Verify(" + field.name + "())";
            break;
          case BASE_TYPE_VECTOR:
            code += prefix + "verifier.Verify(" + field.name + "())";
            switch (field.value.type.element) {
              case BASE_TYPE_STRING: {
                code += prefix + "verifier.VerifyVectorOfStrings(" + field.name;
                code += "())";
                break;
              }
              case BASE_TYPE_STRUCT: {
                if (!field.value.type.struct_def->fixed) {
                  code +=
                      prefix + "verifier.VerifyVectorOfTables(" + field.name;
                  code += "())";
                }
                break;
              }
              default:
                break;
            }
            break;
          default:
            break;
        }
      }
    }
    code += prefix + "verifier.EndTable()";
    code += ";\n  }\n";
    code += "};\n\n";

    // Generate a builder struct, with methods of the form:
    // void add_name(type name) { fbb_.AddElement<type>(offset, name, default);
    // }
    code += "struct " + struct_def.name;
    code += "Builder {\n  flatbuffers::FlatBufferBuilder &fbb_;\n";
    code += "  flatbuffers::uoffset_t start_;\n";
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (!field.deprecated) {
        code += "  void add_" + field.name + "(";
        code += GenTypeWire(field.value.type, " ", true) + field.name;
        code += ") { fbb_.Add";
        if (IsScalar(field.value.type.base_type)) {
          code += "Element<" + GenTypeWire(field.value.type, "", false);
          code += ">";
        } else if (IsStruct(field.value.type)) {
          code += "Struct";
        } else {
          code += "Offset";
        }
        code += "(" + struct_def.name + "::" + GenFieldOffsetName(field) + ", ";
        code += GenUnderlyingCast(field, false, field.name);
        if (IsScalar(field.value.type.base_type))
          code += ", " + GenDefaultConstant(field);
        code += "); }\n";
      }
    }
    code += "  " + struct_def.name;
    code += "Builder(flatbuffers::FlatBufferBuilder &_fbb) : fbb_(_fbb) ";
    code += "{ start_ = fbb_.StartTable(); }\n";
    code += "  " + struct_def.name + "Builder &operator=(const ";
    code += struct_def.name + "Builder &);\n";
    code += "  flatbuffers::Offset<" + struct_def.name;
    code += "> Finish() {\n    auto o = flatbuffers::Offset<" + struct_def.name;
    code += ">(fbb_.EndTable(start_, ";
    code += NumToString(struct_def.fields.vec.size()) + "));\n";
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (!field.deprecated && field.required) {
        code += "    fbb_.Required(o, ";
        code += struct_def.name + "::" + GenFieldOffsetName(field);
        code += ");  // " + field.name + "\n";
      }
    }
    code += "    return o;\n  }\n};\n\n";

    // Generate a convenient CreateX function that uses the above builder
    // to create a table in one go.
    code += "inline flatbuffers::Offset<" + struct_def.name + "> Create";
    code += struct_def.name;
    code += "(flatbuffers::FlatBufferBuilder &_fbb";
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (!field.deprecated) {
        code += ",\n   " + GenTypeWire(field.value.type, " ", true);
        code += field.name + " = ";
        if (field.value.type.enum_def && IsScalar(field.value.type.base_type)) {
          auto ev = field.value.type.enum_def->ReverseLookup(
              static_cast<int>(StringToInt(field.value.constant.c_str())),
              false);
          if (ev) {
            code += WrapInNameSpace(
                field.value.type.enum_def->defined_namespace,
                GetEnumVal(*field.value.type.enum_def, *ev, parser_.opts));
          } else {
            code += GenUnderlyingCast(field, true, field.value.constant);
          }
        } else if (field.value.type.base_type == BASE_TYPE_BOOL) {
          code += field.value.constant == "0" ? "false" : "true";
        } else {
          code += GenDefaultConstant(field);
        }
      }
    }
    code += ") {\n  " + struct_def.name + "Builder builder_(_fbb);\n";
    for (size_t size = struct_def.sortbysize ? sizeof(largest_scalar_t) : 1;
         size; size /= 2) {
      for (auto it = struct_def.fields.vec.rbegin();
           it != struct_def.fields.vec.rend(); ++it) {
        auto &field = **it;
        if (!field.deprecated && (!struct_def.sortbysize ||
                                  size == SizeOf(field.value.type.base_type))) {
          code += "  builder_.add_" + field.name + "(" + field.name + ");\n";
        }
      }
    }
    code += "  return builder_.Finish();\n}\n\n";
  }

  static void GenPadding(const FieldDef &field, std::string &code,
                         int &padding_id,
                         const std::function<void(int bits, std::string &code,
                                                  int &padding_id)> &f) {
    if (field.padding) {
      for (int i = 0; i < 4; i++)
        if (static_cast<int>(field.padding) & (1 << i))
          f((1 << i) * 8, code, padding_id);
      assert(!(field.padding & ~0xF));
    }
  }

  static void PaddingDefinition(int bits, std::string &code, int &padding_id) {
    code += "  int" + NumToString(bits) + "_t __padding" +
            NumToString(padding_id++) + ";\n";
  }

  static void PaddingDeclaration(int bits, std::string &code, int &padding_id) {
    (void)bits;
    code += " (void)__padding" + NumToString(padding_id++) + ";";
  }

  static void PaddingInitializer(int bits, std::string &code, int &padding_id) {
    (void)bits;
    code += ", __padding" + NumToString(padding_id++) + "(0)";
  }

  // Generate an accessor struct with constructor for a flatbuffers struct.
  void GenStruct(StructDef &struct_def, std::string *code_ptr) {
    if (struct_def.generated) return;
    std::string &code = *code_ptr;

    // Generate an accessor struct, with private variables of the form:
    // type name_;
    // Generates manual padding and alignment.
    // Variables are private because they contain little endian data on all
    // platforms.
    GenComment(struct_def.doc_comment, code_ptr, nullptr);
    code +=
        "MANUALLY_ALIGNED_STRUCT(" + NumToString(struct_def.minalign) + ") ";
    code += struct_def.name + " FLATBUFFERS_FINAL_CLASS {\n private:\n";
    int padding_id = 0;
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      code += "  " + GenTypeGet(field.value.type, " ", "", " ", false);
      code += field.name + "_;\n";
      GenPadding(field, code, padding_id, PaddingDefinition);
    }

    // Generate GetFullyQualifiedName
    code += "\n public:\n";
    GenFullyQualifiedNameGetter(struct_def.name, code);

    // Generate a constructor that takes all fields as arguments.
    code += "  " + struct_def.name + "(";
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (it != struct_def.fields.vec.begin()) code += ", ";
      code += GenTypeGet(field.value.type, " ", "const ", " &", true);
      code += "_" + field.name;
    }
    code += ")\n    : ";
    padding_id = 0;
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      if (it != struct_def.fields.vec.begin()) code += ", ";
      code += field.name + "_(";
      if (IsScalar(field.value.type.base_type)) {
        code += "flatbuffers::EndianScalar(";
        code += GenUnderlyingCast(field, false, "_" + field.name);
        code += "))";
      } else {
        code += "_" + field.name + ")";
      }
      GenPadding(field, code, padding_id, PaddingInitializer);
    }

    code += " {";
    padding_id = 0;
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      GenPadding(field, code, padding_id, PaddingDeclaration);
    }
    code += " }\n\n";

    // Generate accessor methods of the form:
    // type name() const { return flatbuffers::EndianScalar(name_); }
    for (auto it = struct_def.fields.vec.begin();
         it != struct_def.fields.vec.end(); ++it) {
      auto &field = **it;
      GenComment(field.doc_comment, code_ptr, nullptr, "  ");
      auto is_scalar = IsScalar(field.value.type.base_type);
      code += "  " +
              GenTypeGet(field.value.type, " ", "const ", " &", true);
      code += field.name + "() const { return ";
      code += GenUnderlyingCast(
          field, true, is_scalar
                           ? "flatbuffers::EndianScalar(" + field.name + "_)"
                           : field.name + "_");
      code += "; }\n";
      if (parser_.opts.mutable_buffer) {
        if (is_scalar) {
          code += "  void mutate_" + field.name + "(";
          code += GenTypeBasic(field.value.type, true);
          code += " _" + field.name + ") { flatbuffers::WriteScalar(&";
          code += field.name + "_, ";
          code += GenUnderlyingCast(field, false, "_" + field.name);
          code += "); }\n";
        } else {
          code += "  ";
          code += GenTypeGet(field.value.type, "", "", " &", true);
          code += "mutable_" + field.name + "() { return " + field.name;
          code += "_; }\n";
        }
      }
    }
    code += "};\nSTRUCT_END(" + struct_def.name + ", ";
    code += NumToString(struct_def.bytesize) + ");\n\n";
  }

  // Set up the correct namespace. Only open a namespace if
  // the existing one is different (closing/opening only what is necessary) :
  //
  // the file must start and end with an empty (or null) namespace
  // so that namespaces are properly opened and closed
  void SetNameSpace(const Namespace *ns, std::string *code_ptr) {
    if (cur_name_space_ == ns) return;
    // compute the size of the longest common namespace prefix.  
    // if cur_name_space is A::B::C::D and ns is A::B::E::F::G, 
    // the common prefix is A::B:: and we have old_size = 4, new_size = 5
    // and common_prefix_size = 2
    auto old_size =
        cur_name_space_ == nullptr ? 0 : cur_name_space_->components.size();
    auto new_size = ns == nullptr ? 0 : ns->components.size();
    std::vector<std::string>::size_type common_prefix_size = 0;
    while (common_prefix_size < old_size && common_prefix_size < new_size &&
           ns->components[common_prefix_size] ==
               cur_name_space_->components[common_prefix_size])
      common_prefix_size++;
    // close cur_name_space in reverse order to reach the common prefix
    // in the previous example, D then C are closed  
    for (auto j = old_size; j > common_prefix_size; --j)
      *code_ptr +=
          "}  // namespace " + cur_name_space_->components[j - 1] + "\n";
    if (old_size != common_prefix_size) *code_ptr += "\n";
    // open namespace parts to reach the ns namespace
    // in the previous example, E, then F, then G are opened  
    for (auto j = common_prefix_size; j != new_size; ++j)
      *code_ptr += "namespace " + ns->components[j] + " {\n";
    if (new_size != common_prefix_size) *code_ptr += "\n";
    cur_name_space_ = ns;
  }
};
}  // namespace cpp

bool GenerateCPP(const Parser &parser, const std::string &path,
                 const std::string &file_name) {
  cpp::CppGenerator generator(parser, path, file_name);
  return generator.generate();
}

std::string CPPMakeRule(const Parser &parser,
                        const std::string &path,
                        const std::string &file_name) {
  std::string filebase = flatbuffers::StripPath(
      flatbuffers::StripExtension(file_name));
  std::string make_rule = GeneratedFileName(path, filebase) + ": ";
  auto included_files = parser.GetIncludedFilesRecursive(file_name);
  for (auto it = included_files.begin();
       it != included_files.end(); ++it) {
    make_rule += " " + *it;
  }
  return make_rule;
}

}  // namespace flatbuffers