flatbuffers/src/idl_gen_text.cpp

389 lines
15 KiB
C++

/*
* 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/flexbuffers.h"
#include "flatbuffers/idl.h"
#include "flatbuffers/util.h"
namespace flatbuffers {
static bool GenStruct(const StructDef &struct_def, const Table *table,
int indent, const IDLOptions &opts, std::string *_text);
// If indentation is less than 0, that indicates we don't want any newlines
// either.
const char *NewLine(const IDLOptions &opts) {
return opts.indent_step >= 0 ? "\n" : "";
}
int Indent(const IDLOptions &opts) { return std::max(opts.indent_step, 0); }
// Output an identifier with or without quotes depending on strictness.
void OutputIdentifier(const std::string &name, const IDLOptions &opts,
std::string *_text) {
std::string &text = *_text;
if (opts.strict_json) text += "\"";
text += name;
if (opts.strict_json) text += "\"";
}
// Print (and its template specialization below for pointers) generate text
// for a single FlatBuffer value into JSON format.
// The general case for scalars:
template<typename T>
bool Print(T val, Type type, int /*indent*/, const uint8_t * /*prev_val*/,
soffset_t /*vector_index*/, const IDLOptions &opts,
std::string *_text) {
std::string &text = *_text;
if (type.enum_def && opts.output_enum_identifiers) {
std::vector<EnumVal const *> enum_values;
if (auto ev = type.enum_def->ReverseLookup(static_cast<int64_t>(val))) {
enum_values.push_back(ev);
} else if (val && type.enum_def->attributes.Lookup("bit_flags")) {
for (auto it = type.enum_def->Vals().begin(),
e = type.enum_def->Vals().end();
it != e; ++it) {
if ((*it)->GetAsUInt64() & static_cast<uint64_t>(val))
enum_values.push_back(*it);
}
}
if (!enum_values.empty()) {
text += '\"';
for (auto it = enum_values.begin(), e = enum_values.end(); it != e; ++it)
text += (*it)->name + ' ';
text[text.length() - 1] = '\"';
return true;
}
}
if (type.base_type == BASE_TYPE_BOOL) {
text += val != 0 ? "true" : "false";
} else {
text += NumToString(val);
}
return true;
}
// Print a vector or an array of JSON values, comma seperated, wrapped in "[]".
template<typename T, typename Container>
bool PrintContainer(const Container &c, size_t size, Type type, int indent,
const uint8_t *prev_val, const IDLOptions &opts,
std::string *_text) {
std::string &text = *_text;
text += "[";
text += NewLine(opts);
for (uoffset_t i = 0; i < size; i++) {
if (i) {
if (!opts.protobuf_ascii_alike) text += ",";
text += NewLine(opts);
}
text.append(indent + Indent(opts), ' ');
if (IsStruct(type)) {
if (!Print(reinterpret_cast<const void *>(c.Data() +
i * type.struct_def->bytesize),
type, indent + Indent(opts), nullptr, -1, opts, _text)) {
return false;
}
} else {
if (!Print(c[i], type, indent + Indent(opts), prev_val,
static_cast<soffset_t>(i), opts, _text)) {
return false;
}
}
}
text += NewLine(opts);
text.append(indent, ' ');
text += "]";
return true;
}
template<typename T>
bool PrintVector(const Vector<T> &v, Type type, int indent,
const uint8_t *prev_val, const IDLOptions &opts,
std::string *_text) {
return PrintContainer<T, Vector<T>>(v, v.size(), type, indent, prev_val, opts,
_text);
}
// Print an array a sequence of JSON values, comma separated, wrapped in "[]".
template<typename T>
bool PrintArray(const Array<T, 0xFFFF> &a, size_t size, Type type, int indent,
const IDLOptions &opts, std::string *_text) {
return PrintContainer<T, Array<T, 0xFFFF>>(a, size, type, indent, nullptr,
opts, _text);
}
// Specialization of Print above for pointer types.
template<>
bool Print<const void *>(const void *val, Type type, int indent,
const uint8_t *prev_val, soffset_t vector_index,
const IDLOptions &opts, std::string *_text) {
switch (type.base_type) {
case BASE_TYPE_UNION: {
// If this assert hits, you have an corrupt buffer, a union type field
// was not present or was out of range.
FLATBUFFERS_ASSERT(prev_val);
auto union_type_byte = *prev_val; // Always a uint8_t.
if (vector_index >= 0) {
auto type_vec = reinterpret_cast<const Vector<uint8_t> *>(
prev_val + ReadScalar<uoffset_t>(prev_val));
union_type_byte = type_vec->Get(static_cast<uoffset_t>(vector_index));
}
auto enum_val = type.enum_def->ReverseLookup(union_type_byte, true);
if (enum_val) {
return Print<const void *>(val, enum_val->union_type, indent, nullptr,
-1, opts, _text);
} else {
return false;
}
}
case BASE_TYPE_STRUCT:
return GenStruct(*type.struct_def, reinterpret_cast<const Table *>(val),
indent, opts, _text);
case BASE_TYPE_STRING: {
auto s = reinterpret_cast<const String *>(val);
return EscapeString(s->c_str(), s->size(), _text, opts.allow_non_utf8,
opts.natural_utf8);
}
case BASE_TYPE_VECTOR: {
const auto vec_type = type.VectorType();
// Call PrintVector above specifically for each element type:
// clang-format off
switch (vec_type.base_type) {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, ...) \
case BASE_TYPE_ ## ENUM: \
if (!PrintVector<CTYPE>( \
*reinterpret_cast<const Vector<CTYPE> *>(val), \
vec_type, indent, prev_val, opts, _text)) { \
return false; \
} \
break;
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
}
// clang-format on
return true;
}
case BASE_TYPE_ARRAY: {
const auto vec_type = type.VectorType();
// Call PrintArray above specifically for each element type:
// clang-format off
switch (vec_type.base_type) {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, ...) \
case BASE_TYPE_ ## ENUM: \
if (!PrintArray<CTYPE>( \
*reinterpret_cast<const Array<CTYPE, 0xFFFF> *>(val), \
type.fixed_length, \
vec_type, indent, opts, _text)) { \
return false; \
} \
break;
FLATBUFFERS_GEN_TYPES_SCALAR(FLATBUFFERS_TD)
// Arrays of scalars or structs are only possible.
FLATBUFFERS_GEN_TYPES_POINTER(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
case BASE_TYPE_ARRAY: FLATBUFFERS_ASSERT(0);
}
// clang-format on
return true;
}
default: FLATBUFFERS_ASSERT(0); return false;
}
}
template<typename T> static T GetFieldDefault(const FieldDef &fd) {
T val;
auto check = StringToNumber(fd.value.constant.c_str(), &val);
(void)check;
FLATBUFFERS_ASSERT(check);
return val;
}
// Generate text for a scalar field.
template<typename T>
static bool GenField(const FieldDef &fd, const Table *table, bool fixed,
const IDLOptions &opts, int indent, std::string *_text) {
return Print(
fixed ? reinterpret_cast<const Struct *>(table)->GetField<T>(
fd.value.offset)
: table->GetField<T>(fd.value.offset, GetFieldDefault<T>(fd)),
fd.value.type, indent, nullptr, -1, opts, _text);
}
static bool GenStruct(const StructDef &struct_def, const Table *table,
int indent, const IDLOptions &opts, std::string *_text);
// Generate text for non-scalar field.
static bool GenFieldOffset(const FieldDef &fd, const Table *table, bool fixed,
int indent, const uint8_t *prev_val,
const IDLOptions &opts, std::string *_text) {
const void *val = nullptr;
if (fixed) {
// The only non-scalar fields in structs are structs or arrays.
FLATBUFFERS_ASSERT(IsStruct(fd.value.type) || IsArray(fd.value.type));
val = reinterpret_cast<const Struct *>(table)->GetStruct<const void *>(
fd.value.offset);
} else if (fd.flexbuffer) {
auto vec = table->GetPointer<const Vector<uint8_t> *>(fd.value.offset);
auto root = flexbuffers::GetRoot(vec->data(), vec->size());
root.ToString(true, opts.strict_json, *_text);
return true;
} else if (fd.nested_flatbuffer) {
auto vec = table->GetPointer<const Vector<uint8_t> *>(fd.value.offset);
auto root = GetRoot<Table>(vec->data());
return GenStruct(*fd.nested_flatbuffer, root, indent, opts, _text);
} else {
val = IsStruct(fd.value.type)
? table->GetStruct<const void *>(fd.value.offset)
: table->GetPointer<const void *>(fd.value.offset);
}
return Print(val, fd.value.type, indent, prev_val, -1, opts, _text);
}
// Generate text for a struct or table, values separated by commas, indented,
// and bracketed by "{}"
static bool GenStruct(const StructDef &struct_def, const Table *table,
int indent, const IDLOptions &opts, std::string *_text) {
std::string &text = *_text;
text += "{";
int fieldout = 0;
const uint8_t *prev_val = nullptr;
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
FieldDef &fd = **it;
auto is_present = struct_def.fixed || table->CheckField(fd.value.offset);
auto output_anyway = opts.output_default_scalars_in_json &&
IsScalar(fd.value.type.base_type) && !fd.deprecated;
if (is_present || output_anyway) {
if (fieldout++) {
if (!opts.protobuf_ascii_alike) text += ",";
}
text += NewLine(opts);
text.append(indent + Indent(opts), ' ');
OutputIdentifier(fd.name, opts, _text);
if (!opts.protobuf_ascii_alike ||
(fd.value.type.base_type != BASE_TYPE_STRUCT &&
fd.value.type.base_type != BASE_TYPE_VECTOR))
text += ":";
text += " ";
switch (fd.value.type.base_type) {
// clang-format off
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, ...) \
case BASE_TYPE_ ## ENUM: \
if (!GenField<CTYPE>(fd, table, struct_def.fixed, \
opts, indent + Indent(opts), _text)) { \
return false; \
} \
break;
FLATBUFFERS_GEN_TYPES_SCALAR(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
// Generate drop-thru case statements for all pointer types:
#define FLATBUFFERS_TD(ENUM, ...) \
case BASE_TYPE_ ## ENUM:
FLATBUFFERS_GEN_TYPES_POINTER(FLATBUFFERS_TD)
FLATBUFFERS_GEN_TYPE_ARRAY(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
if (!GenFieldOffset(fd, table, struct_def.fixed, indent + Indent(opts),
prev_val, opts, _text)) {
return false;
}
break;
// clang-format on
}
// Track prev val for use with union types.
if (struct_def.fixed) {
prev_val = reinterpret_cast<const uint8_t *>(table) + fd.value.offset;
} else {
prev_val = table->GetAddressOf(fd.value.offset);
}
}
}
text += NewLine(opts);
text.append(indent, ' ');
text += "}";
return true;
}
// Generate a text representation of a flatbuffer in JSON format.
bool GenerateTextFromTable(const Parser &parser, const void *table,
const std::string &table_name, std::string *_text) {
auto struct_def = parser.LookupStruct(table_name);
if (struct_def == nullptr) { return false; }
auto &text = *_text;
text.reserve(1024); // Reduce amount of inevitable reallocs.
auto root = static_cast<const Table *>(table);
if (!GenStruct(*struct_def, root, 0, parser.opts, &text)) { return false; }
text += NewLine(parser.opts);
return true;
}
// Generate a text representation of a flatbuffer in JSON format.
bool GenerateText(const Parser &parser, const void *flatbuffer,
std::string *_text) {
std::string &text = *_text;
FLATBUFFERS_ASSERT(parser.root_struct_def_); // call SetRootType()
text.reserve(1024); // Reduce amount of inevitable reallocs.
auto root = parser.opts.size_prefixed ? GetSizePrefixedRoot<Table>(flatbuffer)
: GetRoot<Table>(flatbuffer);
if (!GenStruct(*parser.root_struct_def_, root, 0, parser.opts, _text)) {
return false;
}
text += NewLine(parser.opts);
return true;
}
std::string TextFileName(const std::string &path,
const std::string &file_name) {
return path + file_name + ".json";
}
bool GenerateTextFile(const Parser &parser, const std::string &path,
const std::string &file_name) {
if (parser.opts.use_flexbuffers) {
std::string json;
parser.flex_root_.ToString(true, parser.opts.strict_json, json);
return flatbuffers::SaveFile(TextFileName(path, file_name).c_str(),
json.c_str(), json.size(), true);
}
if (!parser.builder_.GetSize() || !parser.root_struct_def_) return true;
std::string text;
if (!GenerateText(parser, parser.builder_.GetBufferPointer(), &text)) {
return false;
}
return flatbuffers::SaveFile(TextFileName(path, file_name).c_str(), text,
false);
}
std::string TextMakeRule(const Parser &parser, const std::string &path,
const std::string &file_name) {
if (!parser.builder_.GetSize() || !parser.root_struct_def_) return "";
std::string filebase =
flatbuffers::StripPath(flatbuffers::StripExtension(file_name));
std::string make_rule = TextFileName(path, filebase) + ": " + file_name;
auto included_files =
parser.GetIncludedFilesRecursive(parser.root_struct_def_->file);
for (auto it = included_files.begin(); it != included_files.end(); ++it) {
make_rule += " " + *it;
}
return make_rule;
}
} // namespace flatbuffers