/*

* 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"

namespace flatbuffers {

namespace cpp {

// Return a C++ type from the table in idl.h

static std::string GenTypeBasic(const Type &type) {

static const char *ctypename[] = {

#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE) #CTYPE,

FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)

#undef FLATBUFFERS_TD

};

return ctypename[type.base_type];

}

static std::string GenTypeWire(const Parser &parser, const Type &type,

const char *postfix);

// Return a C++ pointer type, specialized to the actual struct/table types,

// and vector element types.

static std::string GenTypePointer(const Parser &parser, const Type &type) {

switch (type.base_type) {

case BASE_TYPE_STRING:

return "flatbuffers::String";

case BASE_TYPE_VECTOR:

return "flatbuffers::Vector<" +

GenTypeWire(parser, type.VectorType(), "") + ">";

case BASE_TYPE_STRUCT: {

auto ns = type.struct_def->defined_namespace;

if (parser.namespaces_.back() != ns) {

std::string qualified_name;

for (auto it = ns->components.begin();

it != ns->components.end(); ++it) {

qualified_name += *it + "::";

}

return qualified_name + type.struct_def->name;

} else {

return type.struct_def->name;

}

}

case BASE_TYPE_UNION:

// fall through

default:

return "void";

}

}

// Return a C++ type for any type (scalar/pointer) specifically for

// building a flatbuffer.

static std::string GenTypeWire(const Parser &parser, const Type &type,

const char *postfix) {

return IsScalar(type.base_type)

? GenTypeBasic(type) + postfix

: IsStruct(type)

? "const " + GenTypePointer(parser, type) + " *"

: "flatbuffers::Offset<" + GenTypePointer(parser, type) + ">" + postfix;

}

// Return a C++ type for any type (scalar/pointer) that reflects its

// serialized size.

static std::string GenTypeSize(const Parser &parser, const Type &type) {

return IsScalar(type.base_type)

? GenTypeBasic(type)

: IsStruct(type)

? GenTypePointer(parser, type)

: "flatbuffers::uoffset_t";

}

// Return a C++ type for any type (scalar/pointer) specifically for

// using a flatbuffer.

static std::string GenTypeGet(const Parser &parser, const Type &type,

const char *afterbasic, const char *beforeptr,

const char *afterptr) {

return IsScalar(type.base_type)

? GenTypeBasic(type) + afterbasic

: beforeptr + GenTypePointer(parser, type) + afterptr;

}

// Generate a documentation comment, if available.

static void GenComment(const std::string &dc,

std::string *code_ptr,

const char *prefix = "") {

std::string &code = *code_ptr;

if (dc.length()) {

code += std::string(prefix) + "///" + dc + "\n";

}

}

static std::string GenEnumVal(const EnumDef &enum_def, const EnumVal &enum_val,

const GeneratorOptions &opts) {

return opts.prefixed_enums ? enum_def.name + "_" + enum_val.name

: enum_val.name;

}

// Generate an enum declaration and an enum string lookup table.

static void GenEnum(EnumDef &enum_def, std::string *code_ptr,

std::string *code_ptr_post,

const GeneratorOptions &opts) {

if (enum_def.generated) return;

std::string &code = *code_ptr;

std::string &code_post = *code_ptr_post;

GenComment(enum_def.doc_comment, code_ptr);

code += "enum {\n";

for (auto it = enum_def.vals.vec.begin();

it != enum_def.vals.vec.end();

++it) {

auto &ev = **it;

GenComment(ev.doc_comment, code_ptr, " ");

code += " " + GenEnumVal(enum_def, ev, opts) + " = ";

code += NumToString(ev.value);

code += (it + 1) != enum_def.vals.vec.end() ? ",\n" : "\n";

}

code += "};\n\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 += "(int e) { return EnumNames" + enum_def.name + "()[e";

if (enum_def.vals.vec.front()->value)

code += " - " + GenEnumVal(enum_def, *enum_def.vals.vec.front(), opts);

code += "]; }\n\n";

}

if (enum_def.is_union) {

// 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.

auto signature = "inline bool Verify" + enum_def.name +

"(flatbuffers::Verifier &verifier, " +

"const void *union_obj, uint8_t type)";

code += signature + ";\n\n";

code_post += signature + " {\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 " + GenEnumVal(enum_def, ev, opts);

if (!ev.value) {

code_post += ": return true;\n"; // "NONE" enum value.

} else {

code_post += ": return verifier.VerifyTable(reinterpret_cast<const ";

code_post += ev.struct_def->name + " *>(union_obj));\n";

}

}

code_post += " default: return false;\n }\n}\n\n";

}

}

// Generate an accessor struct, builder structs & function for a table.

static void GenTable(const Parser &parser, StructDef &struct_def,

std::string *code_ptr) {

if (struct_def.generated) return;

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);

code += "struct " + struct_def.name + " : private flatbuffers::Table";

code += " {\n";

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.

GenComment(field.doc_comment, code_ptr, " ");

code += " " + GenTypeGet(parser, field.value.type, " ", "const ", " *");

code += field.name + "() const { return ";

// Call a different accessor for pointers, that indirects.

code += IsScalar(field.value.type.base_type)

? "GetField<"

: (IsStruct(field.value.type) ? "GetStruct<" : "GetPointer<");

code += GenTypeGet(parser, field.value.type, "", "const ", " *") + ">(";

code += NumToString(field.value.offset);

// Default value as second arg for non-pointer types.

if (IsScalar(field.value.type.base_type))

code += ", " + field.value.constant;

code += "); }\n";

auto nested = field.attributes.Lookup("nested_flatbuffer");

if (nested) {

auto nested_root = parser.structs_.Lookup(nested->constant);

assert(nested_root); // Guaranteed to exist by parser.

code += " const " + nested_root->name + " *" + field.name;

code += "_nested_root() { return flatbuffers::GetRoot<";

code += nested_root->name + ">(" + field.name + "()->Data()); }\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<" + GenTypeSize(parser, field.value.type);

code += ">(verifier, " + NumToString(field.value.offset);

code += " /* " + field.name + " */)";

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(parser, field.value.type, " ") + field.name;

code += ") { fbb_.Add";

if (IsScalar(field.value.type.base_type))

code += "Element<" + GenTypeWire(parser, field.value.type, "") + ">";

else if (IsStruct(field.value.type))

code += "Struct";

else

code += "Offset";

code += "(" + NumToString(field.value.offset) + ", " + field.name;

if (IsScalar(field.value.type.base_type))

code += ", " + field.value.constant;

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() { return flatbuffers::Offset<" + struct_def.name;

code += ">(fbb_.EndTable(start_, ";

code += NumToString(struct_def.fields.vec.size()) + ")); }\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(parser, field.value.type, " ");

code += field.name + " = " + field.value.constant;

}

}

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, const std::function<void (int bits)> &f) {

if (field.padding) {

for (int i = 0; i < 4; i++)

if (static_cast<int>(field.padding) & (1 << i))

f((1 << i) * 8);

assert(!(field.padding & ~0xF));

}

}

// Generate an accessor struct with constructor for a flatbuffers struct.

static void GenStruct(const Parser &parser, 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);

code += "MANUALLY_ALIGNED_STRUCT(" + NumToString(struct_def.minalign) + ") ";

code += struct_def.name + " {\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(parser, field.value.type, " ", "", " ");

code += field.name + "_;\n";

GenPadding(field, [&code, &padding_id](int bits) {

code += " int" + NumToString(bits) +

"_t __padding" + NumToString(padding_id++) + ";\n";

});

}

// Generate a constructor that takes all fields as arguments.

code += "\n public:\n " + 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(parser, field.value.type, " ", "const ", " &");

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(" + field.name + "))";

else

code += field.name + ")";

GenPadding(field, [&code, &padding_id](int bits) {

(void)bits;

code += ", __padding" + NumToString(padding_id++) + "(0)";

});

}

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](int bits) {

(void)bits;

code += " (void)__padding" + NumToString(padding_id++) + ";";

});

}

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, " ");

code += " " + GenTypeGet(parser, field.value.type, " ", "const ", " &");

code += field.name + "() const { return ";

if (IsScalar(field.value.type.base_type))

code += "flatbuffers::EndianScalar(" + field.name + "_)";

else

code += field.name + "_";

code += "; }\n";

}

code += "};\nSTRUCT_END(" + struct_def.name + ", ";

code += NumToString(struct_def.bytesize) + ");\n\n";

}

void GenerateNestedNameSpaces(Namespace *ns, std::string *code_ptr) {

for (auto it = ns->components.begin(); it != ns->components.end(); ++it) {

*code_ptr += "namespace " + *it + " {\n";

}

}

void CloseNestedNameSpaces(Namespace *ns, std::string *code_ptr) {

for (auto it = ns->components.rbegin(); it != ns->components.rend(); ++it) {

*code_ptr += "} // namespace " + *it + "\n";

}

}

} // namespace cpp

// Iterate through all definitions we haven't generate code for (enums, structs,

// and tables) and output them to a single file.

std::string GenerateCPP(const Parser &parser,

const std::string &file_name,

const GeneratorOptions &opts) {

using namespace cpp;

// Generate code for all the enum declarations.

std::string enum_code, enum_code_post;

for (auto it = parser.enums_.vec.begin();

it != parser.enums_.vec.end(); ++it) {

GenEnum(**it, &enum_code, &enum_code_post, opts);

}

// Generate forward declarations for all structs/tables, since they may

// have circular references.

std::string forward_decl_code_same_namespace;

std::string forward_decl_code_other_namespace;

Namespace *cur_name_space = nullptr;

for (auto it = parser.structs_.vec.begin();

it != parser.structs_.vec.end(); ++it) {

auto &struct_def = **it;

auto decl = "struct " + struct_def.name + ";\n";

if (struct_def.defined_namespace == parser.namespaces_.back()) {

forward_decl_code_same_namespace += decl;

} else {

// Wrap this decl in the correct namespace. Only open a namespace if

// the adjacent one is different.

// TODO: this could be done more intelligently, by sorting to

// namespace path and only opening/closing what is necessary, but that's

// quite a bit more complexity.

if (cur_name_space != struct_def.defined_namespace) {

if (cur_name_space) {

CloseNestedNameSpaces(cur_name_space,

&forward_decl_code_other_namespace);

}

GenerateNestedNameSpaces(struct_def.defined_namespace,

&forward_decl_code_other_namespace);

cur_name_space = struct_def.defined_namespace;

}

forward_decl_code_other_namespace += decl;

}

}

if (cur_name_space) {

CloseNestedNameSpaces(cur_name_space,

&forward_decl_code_other_namespace);

}

// Generate code for all structs, then all tables.

std::string decl_code;

for (auto it = parser.structs_.vec.begin();

it != parser.structs_.vec.end(); ++it) {

if ((**it).fixed) GenStruct(parser, **it, &decl_code);

}

for (auto it = parser.structs_.vec.begin();

it != parser.structs_.vec.end(); ++it) {

if (!(**it).fixed) GenTable(parser, **it, &decl_code);

}

// Only output file-level code if there were any declarations.

if (enum_code.length() || decl_code.length()) {

std::string code;

code = "// automatically generated by the FlatBuffers compiler,"

" do not modify\n\n";

// 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(),

[](char c) { return !isalnum(c); }),

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";

code += forward_decl_code_other_namespace;

code += "\n";

GenerateNestedNameSpaces(name_space, &code);

code += "\n";

code += forward_decl_code_same_namespace;

code += "\n";

// Output the main declaration code from above.

code += enum_code;

code += decl_code;

code += enum_code_post;

// Generate convenient global helper functions:

if (parser.root_struct_def) {

// The root datatype accessor:

code += "inline const " + parser.root_struct_def->name + " *Get";

code += parser.root_struct_def->name;

code += "(const void *buf) { return flatbuffers::GetRoot<";

code += parser.root_struct_def->name + ">(buf); }\n\n";

// The root verifier:

code += "inline bool Verify";

code += parser.root_struct_def->name;

code += "Buffer(flatbuffers::Verifier &verifier) { "

"return verifier.VerifyBuffer<";

code += parser.root_struct_def->name + ">(); }\n\n";

// Finish a buffer with a given root object:

code += "inline void Finish" + parser.root_struct_def->name;

code += "Buffer(flatbuffers::FlatBufferBuilder &fbb, flatbuffers::Offset<";

code += parser.root_struct_def->name + "> root) { fbb.Finish(root";

if (parser.file_identifier_.length())

code += ", \"" + parser.file_identifier_ + "\"";

code += "); }\n\n";

if (parser.file_identifier_.length()) {

// Check if a buffer has the identifier.

code += "inline bool " + parser.root_struct_def->name;

code += "BufferHasIdentifier(const void *buf) { return flatbuffers::";

code += "BufferHasIdentifier(buf, \"" + parser.file_identifier_;

code += "\"); }\n\n";

}

}

CloseNestedNameSpaces(name_space, &code);

// Close the include guard.

code += "\n#endif // " + include_guard + "\n";

return code;

}

return std::string();

}

bool GenerateCPP(const Parser &parser,

const std::string &path,

const std::string &file_name,

const GeneratorOptions &opts) {

auto code = GenerateCPP(parser, file_name, opts);

return !code.length() ||

SaveFile((path + file_name + "_generated.h").c_str(), code, false);

}

} // namespace flatbuffers