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Wouter van Oortmerssen authored
Bug: 15777858 Change-Id: Iabef9b8c8044e593bb89510feebdee00d2f1840b Tested: on Linux and Windows.
d38b9af2
idl_parser.cpp 39.83 KiB
/*
* 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.
*/
#include <algorithm>
#include "flatbuffers/flatbuffers.h"
#include "flatbuffers/idl.h"
#include "flatbuffers/util.h"
namespace flatbuffers {
const char *const kTypeNames[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) IDLTYPE,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
nullptr
};
const char kTypeSizes[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
sizeof(CTYPE),
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
static void Error(const std::string &msg) {
throw msg;
}
// Ensure that integer values we parse fit inside the declared integer type.
static void CheckBitsFit(int64_t val, size_t bits) {
auto mask = (1ll << bits) - 1; // Bits we allow to be used.
if (bits < 64 &&
(val & ~mask) != 0 && // Positive or unsigned.
(val | mask) != -1) // Negative.
Error("constant does not fit in a " + NumToString(bits) + "-bit field");
}
// atot: templated version of atoi/atof: convert a string to an instance of T.
template<typename T> inline T atot(const char *s) {
auto val = StringToInt(s);
CheckBitsFit(val, sizeof(T) * 8);
return (T)val;
}
template<> inline bool atot<bool>(const char *s) {
return 0 != atoi(s);
}
template<> inline float atot<float>(const char *s) {
return static_cast<float>(strtod(s, nullptr));
}
template<> inline double atot<double>(const char *s) {
return strtod(s, nullptr);
}
template<> inline Offset<void> atot<Offset<void>>(const char *s) {
return Offset<void>(atoi(s));
}
// Declare tokens we'll use. Single character tokens are represented by their
// ascii character code (e.g. '{'), others above 256.
#define FLATBUFFERS_GEN_TOKENS(TD) \
TD(Eof, 256, "end of file") \
TD(StringConstant, 257, "string constant") \
TD(IntegerConstant, 258, "integer constant") \
TD(FloatConstant, 259, "float constant") \
TD(Identifier, 260, "identifier") \
TD(Table, 261, "table") \
TD(Struct, 262, "struct") \
TD(Enum, 263, "enum") \
TD(Union, 264, "union") \
TD(NameSpace, 265, "namespace") \
TD(RootType, 266, "root_type") \
TD(FileIdentifier, 267, "file_identifier") \
TD(FileExtension, 268, "file_extension") \
TD(Include, 269, "include")
#ifdef __GNUC__
__extension__ // Stop GCC complaining about trailing comma with -Wpendantic.
#endif
enum {
#define FLATBUFFERS_TOKEN(NAME, VALUE, STRING) kToken ## NAME = VALUE,
FLATBUFFERS_GEN_TOKENS(FLATBUFFERS_TOKEN)
#undef FLATBUFFERS_TOKEN
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
kToken ## ENUM,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
static std::string TokenToString(int t) {
static const char *tokens[] = {
#define FLATBUFFERS_TOKEN(NAME, VALUE, STRING) STRING,
FLATBUFFERS_GEN_TOKENS(FLATBUFFERS_TOKEN)
#undef FLATBUFFERS_TOKEN
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) IDLTYPE,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
if (t < 256) { // A single ascii char token.
std::string s;
s.append(1, static_cast<char>(t));
return s;
} else { // Other tokens.
return tokens[t - 256];
}
}
// Parses exactly nibbles worth of hex digits into a number, or error.
int64_t Parser::ParseHexNum(int nibbles) {
for (int i = 0; i < nibbles; i++)
if (!isxdigit(cursor_[i]))
Error("escape code must be followed by " + NumToString(nibbles) +
" hex digits");
auto val = StringToInt(cursor_, 16);
cursor_ += nibbles;
return val;
}
void Parser::Next() {
doc_comment_.clear();
bool seen_newline = false;
for (;;) {
char c = *cursor_++;
token_ = c;
switch (c) {
case '\0': cursor_--; token_ = kTokenEof; return;
case ' ': case '\r': case '\t': break;
case '\n': line_++; seen_newline = true; break; case '{': case '}': case '(': case ')': case '[': case ']': return;
case ',': case ':': case ';': case '=': return;
case '.':
if(!isdigit(*cursor_)) return;
Error("floating point constant can\'t start with \".\"");
break;
case '\"':
attribute_ = "";
while (*cursor_ != '\"') {
if (*cursor_ < ' ' && *cursor_ >= 0)
Error("illegal character in string constant");
if (*cursor_ == '\\') {
cursor_++;
switch (*cursor_) {
case 'n': attribute_ += '\n'; cursor_++; break;
case 't': attribute_ += '\t'; cursor_++; break;
case 'r': attribute_ += '\r'; cursor_++; break;
case 'b': attribute_ += '\b'; cursor_++; break;
case 'f': attribute_ += '\f'; cursor_++; break;
case '\"': attribute_ += '\"'; cursor_++; break;
case '\\': attribute_ += '\\'; cursor_++; break;
case '/': attribute_ += '/'; cursor_++; break;
case 'x': { // Not in the JSON standard
cursor_++;
attribute_ += static_cast<char>(ParseHexNum(2));
break;
}
case 'u': {
cursor_++;
ToUTF8(static_cast<int>(ParseHexNum(4)), &attribute_);
break;
}
default: Error("unknown escape code in string constant"); break;
}
} else { // printable chars + UTF-8 bytes
attribute_ += *cursor_++;
}
}
cursor_++;
token_ = kTokenStringConstant;
return;
case '/':
if (*cursor_ == '/') {
const char *start = ++cursor_;
while (*cursor_ && *cursor_ != '\n') cursor_++;
if (*start == '/') { // documentation comment
if (!seen_newline)
Error("a documentation comment should be on a line on its own");
doc_comment_.push_back(std::string(start + 1, cursor_));
}
break;
}
// fall thru
default:
if (isalpha(static_cast<unsigned char>(c))) {
// Collect all chars of an identifier:
const char *start = cursor_ - 1;
while (isalnum(static_cast<unsigned char>(*cursor_)) ||
*cursor_ == '_')
cursor_++;
attribute_.clear();
attribute_.append(start, cursor_);
// First, see if it is a type keyword from the table of types:
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
if (attribute_ == IDLTYPE) { \
token_ = kToken ## ENUM; \
return; \
}
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD // If it's a boolean constant keyword, turn those into integers,
// which simplifies our logic downstream.
if (attribute_ == "true" || attribute_ == "false") {
attribute_ = NumToString(attribute_ == "true");
token_ = kTokenIntegerConstant;
return;
}
// Check for declaration keywords:
if (attribute_ == "table") { token_ = kTokenTable; return; }
if (attribute_ == "struct") { token_ = kTokenStruct; return; }
if (attribute_ == "enum") { token_ = kTokenEnum; return; }
if (attribute_ == "union") { token_ = kTokenUnion; return; }
if (attribute_ == "namespace") { token_ = kTokenNameSpace; return; }
if (attribute_ == "root_type") { token_ = kTokenRootType; return; }
if (attribute_ == "include") { token_ = kTokenInclude; return; }
if (attribute_ == "file_identifier") {
token_ = kTokenFileIdentifier;
return;
}
if (attribute_ == "file_extension") {
token_ = kTokenFileExtension;
return;
}
// If not, it is a user-defined identifier:
token_ = kTokenIdentifier;
return;
} else if (isdigit(static_cast<unsigned char>(c)) || c == '-') {
const char *start = cursor_ - 1;
while (isdigit(static_cast<unsigned char>(*cursor_))) cursor_++;
if (*cursor_ == '.') {
cursor_++;
while (isdigit(static_cast<unsigned char>(*cursor_))) cursor_++;
// See if this float has a scientific notation suffix. Both JSON
// and C++ (through strtod() we use) have the same format:
if (*cursor_ == 'e' || *cursor_ == 'E') {
cursor_++;
if (*cursor_ == '+' || *cursor_ == '-') cursor_++;
while (isdigit(static_cast<unsigned char>(*cursor_))) cursor_++;
}
token_ = kTokenFloatConstant;
} else {
token_ = kTokenIntegerConstant;
}
attribute_.clear();
attribute_.append(start, cursor_);
return;
}
std::string ch;
ch = c;
if (c < ' ' || c > '~') ch = "code: " + NumToString(c);
Error("illegal character: " + ch);
break;
}
}
}
// Check if a given token is next, if so, consume it as well.
bool Parser::IsNext(int t) {
bool isnext = t == token_;
if (isnext) Next();
return isnext;
}
// Expect a given token to be next, consume it, or error if not present.
void Parser::Expect(int t) {
if (t != token_) {
Error("expecting: " + TokenToString(t) + " instead got: " +
TokenToString(token_));
}
Next();}
void Parser::ParseTypeIdent(Type &type) {
auto enum_def = enums_.Lookup(attribute_);
if (enum_def) {
type = enum_def->underlying_type;
if (enum_def->is_union) type.base_type = BASE_TYPE_UNION;
} else {
type.base_type = BASE_TYPE_STRUCT;
type.struct_def = LookupCreateStruct(attribute_);
}
}
// Parse any IDL type.
void Parser::ParseType(Type &type) {
if (token_ >= kTokenBOOL && token_ <= kTokenSTRING) {
type.base_type = static_cast<BaseType>(token_ - kTokenNONE);
} else {
if (token_ == kTokenIdentifier) {
ParseTypeIdent(type);
} else if (token_ == '[') {
Next();
Type subtype;
ParseType(subtype);
if (subtype.base_type == BASE_TYPE_VECTOR) {
// We could support this, but it will complicate things, and it's
// easier to work around with a struct around the inner vector.
Error("nested vector types not supported (wrap in table first).");
}
if (subtype.base_type == BASE_TYPE_UNION) {
// We could support this if we stored a struct of 2 elements per
// union element.
Error("vector of union types not supported (wrap in table first).");
}
type = Type(BASE_TYPE_VECTOR, subtype.struct_def, subtype.enum_def);
type.element = subtype.base_type;
Expect(']');
return;
} else {
Error("illegal type syntax");
}
}
Next();
}
FieldDef &Parser::AddField(StructDef &struct_def,
const std::string &name,
const Type &type) {
auto &field = *new FieldDef();
field.value.offset =
FieldIndexToOffset(static_cast<voffset_t>(struct_def.fields.vec.size()));
field.name = name;
field.value.type = type;
if (struct_def.fixed) { // statically compute the field offset
auto size = InlineSize(type);
auto alignment = InlineAlignment(type);
// structs_ need to have a predictable format, so we need to align to
// the largest scalar
struct_def.minalign = std::max(struct_def.minalign, alignment);
struct_def.PadLastField(alignment);
field.value.offset = static_cast<voffset_t>(struct_def.bytesize);
struct_def.bytesize += size;
}
if (struct_def.fields.Add(name, &field))
Error("field already exists: " + name);
return field;
}
void Parser::ParseField(StructDef &struct_def) {
std::string name = attribute_; std::vector<std::string> dc = doc_comment_;
Expect(kTokenIdentifier);
Expect(':');
Type type;
ParseType(type);
if (struct_def.fixed && !IsScalar(type.base_type) && !IsStruct(type))
Error("structs_ may contain only scalar or struct fields");
FieldDef *typefield = nullptr;
if (type.base_type == BASE_TYPE_UNION) {
// For union fields, add a second auto-generated field to hold the type,
// with _type appended as the name.
typefield = &AddField(struct_def, name + "_type",
type.enum_def->underlying_type);
}
auto &field = AddField(struct_def, name, type);
if (token_ == '=') {
Next();
if (!IsScalar(type.base_type))
Error("default values currently only supported for scalars");
ParseSingleValue(field.value);
}
if (type.enum_def &&
IsScalar(type.base_type) &&
!struct_def.fixed &&
!type.enum_def->attributes.Lookup("bit_flags") &&
!type.enum_def->ReverseLookup(static_cast<int>(
StringToInt(field.value.constant.c_str()))))
Error("enum " + type.enum_def->name +
" does not have a declaration for this field\'s default of " +
field.value.constant);
field.doc_comment = dc;
ParseMetaData(field);
field.deprecated = field.attributes.Lookup("deprecated") != nullptr;
if (field.deprecated && struct_def.fixed)
Error("can't deprecate fields in a struct");
field.required = field.attributes.Lookup("required") != nullptr;
if (field.required && (struct_def.fixed ||
IsScalar(field.value.type.base_type)))
Error("only non-scalar fields in tables may be 'required'");
auto nested = field.attributes.Lookup("nested_flatbuffer");
if (nested) {
if (nested->type.base_type != BASE_TYPE_STRING)
Error("nested_flatbuffer attribute must be a string (the root type)");
if (field.value.type.base_type != BASE_TYPE_VECTOR ||
field.value.type.element != BASE_TYPE_UCHAR)
Error("nested_flatbuffer attribute may only apply to a vector of ubyte");
// This will cause an error if the root type of the nested flatbuffer
// wasn't defined elsewhere.
LookupCreateStruct(nested->constant);
}
if (typefield) {
// If this field is a union, and it has a manually assigned id,
// the automatically added type field should have an id as well (of N - 1).
auto attr = field.attributes.Lookup("id");
if (attr) {
auto id = atoi(attr->constant.c_str());
auto val = new Value();
val->type = attr->type;
val->constant = NumToString(id - 1);
typefield->attributes.Add("id", val);
}
}
Expect(';');
}
void Parser::ParseAnyValue(Value &val, FieldDef *field) {
switch (val.type.base_type) {
case BASE_TYPE_UNION: {
assert(field);
if (!field_stack_.size() ||
field_stack_.back().second->value.type.base_type != BASE_TYPE_UTYPE)
Error("missing type field before this union value: " + field->name);
auto enum_idx = atot<unsigned char>(
field_stack_.back().first.constant.c_str());
auto enum_val = val.type.enum_def->ReverseLookup(enum_idx);
if (!enum_val) Error("illegal type id for: " + field->name);
val.constant = NumToString(ParseTable(*enum_val->struct_def));
break;
}
case BASE_TYPE_STRUCT:
val.constant = NumToString(ParseTable(*val.type.struct_def));
break;
case BASE_TYPE_STRING: {
auto s = attribute_;
Expect(kTokenStringConstant);
val.constant = NumToString(builder_.CreateString(s).o);
break;
}
case BASE_TYPE_VECTOR: {
Expect('[');
val.constant = NumToString(ParseVector(val.type.VectorType()));
break;
}
default:
ParseSingleValue(val);
break;
}
}
void Parser::SerializeStruct(const StructDef &struct_def, const Value &val) {
auto off = atot<uoffset_t>(val.constant.c_str());
assert(struct_stack_.size() - off == struct_def.bytesize);
builder_.Align(struct_def.minalign);
builder_.PushBytes(&struct_stack_[off], struct_def.bytesize);
struct_stack_.resize(struct_stack_.size() - struct_def.bytesize);
builder_.AddStructOffset(val.offset, builder_.GetSize());
}
uoffset_t Parser::ParseTable(const StructDef &struct_def) {
Expect('{');
size_t fieldn = 0;
if (!IsNext('}')) for (;;) {
std::string name = attribute_;
if (!IsNext(kTokenStringConstant)) Expect(kTokenIdentifier);
auto field = struct_def.fields.Lookup(name);
if (!field) Error("unknown field: " + name);
if (struct_def.fixed && (fieldn >= struct_def.fields.vec.size()
|| struct_def.fields.vec[fieldn] != field)) {
Error("struct field appearing out of order: " + name);
}
Expect(':');
Value val = field->value;
ParseAnyValue(val, field);
field_stack_.push_back(std::make_pair(val, field));
fieldn++;
if (IsNext('}')) break;
Expect(',');
}
for (auto it = field_stack_.rbegin();
it != field_stack_.rbegin() + fieldn; ++it) {
if (it->second->used)
Error("field set more than once: " + it->second->name); it->second->used = true;
}
for (auto it = field_stack_.rbegin();
it != field_stack_.rbegin() + fieldn; ++it) {
it->second->used = false;
}
if (struct_def.fixed && fieldn != struct_def.fields.vec.size())
Error("incomplete struct initialization: " + struct_def.name);
auto start = struct_def.fixed
? builder_.StartStruct(struct_def.minalign)
: builder_.StartTable();
for (size_t size = struct_def.sortbysize ? sizeof(largest_scalar_t) : 1;
size;
size /= 2) {
// Go through elements in reverse, since we're building the data backwards.
for (auto it = field_stack_.rbegin();
it != field_stack_.rbegin() + fieldn; ++it) {
auto &value = it->first;
auto field = it->second;
if (!struct_def.sortbysize || size == SizeOf(value.type.base_type)) {
switch (value.type.base_type) {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
case BASE_TYPE_ ## ENUM: \
builder_.Pad(field->padding); \
if (struct_def.fixed) { \
builder_.PushElement(atot<CTYPE>(value.constant.c_str())); \
} else { \
builder_.AddElement(value.offset, \
atot<CTYPE>( value.constant.c_str()), \
atot<CTYPE>(field->value.constant.c_str())); \
} \
break;
FLATBUFFERS_GEN_TYPES_SCALAR(FLATBUFFERS_TD);
#undef FLATBUFFERS_TD
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
case BASE_TYPE_ ## ENUM: \
builder_.Pad(field->padding); \
if (IsStruct(field->value.type)) { \
SerializeStruct(*field->value.type.struct_def, value); \
} else { \
builder_.AddOffset(value.offset, \
atot<CTYPE>(value.constant.c_str())); \
} \
break;
FLATBUFFERS_GEN_TYPES_POINTER(FLATBUFFERS_TD);
#undef FLATBUFFERS_TD
}
}
}
}
for (size_t i = 0; i < fieldn; i++) field_stack_.pop_back();
if (struct_def.fixed) {
builder_.ClearOffsets();
builder_.EndStruct();
// Temporarily store this struct in a side buffer, since this data has to
// be stored in-line later in the parent object.
auto off = struct_stack_.size();
struct_stack_.insert(struct_stack_.end(),
builder_.GetBufferPointer(),
builder_.GetBufferPointer() + struct_def.bytesize);
builder_.PopBytes(struct_def.bytesize);
return static_cast<uoffset_t>(off);
} else {
return builder_.EndTable(
start,
static_cast<voffset_t>(struct_def.fields.vec.size()));
}
}
uoffset_t Parser::ParseVector(const Type &type) {
int count = 0;
if (token_ != ']') for (;;) {
Value val;
val.type = type;
ParseAnyValue(val, NULL);
field_stack_.push_back(std::make_pair(val, nullptr));
count++;
if (token_ == ']') break;
Expect(',');
}
Next();
builder_.StartVector(count * InlineSize(type) / InlineAlignment(type),
InlineAlignment(type));
for (int i = 0; i < count; i++) {
// start at the back, since we're building the data backwards.
auto &val = field_stack_.back().first;
switch (val.type.base_type) {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) \
case BASE_TYPE_ ## ENUM: \
if (IsStruct(val.type)) SerializeStruct(*val.type.struct_def, val); \
else builder_.PushElement(atot<CTYPE>(val.constant.c_str())); \
break;
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
}
field_stack_.pop_back();
}
builder_.ClearOffsets();
return builder_.EndVector(count);
}
void Parser::ParseMetaData(Definition &def) {
if (IsNext('(')) {
for (;;) {
auto name = attribute_;
Expect(kTokenIdentifier);
auto e = new Value();
def.attributes.Add(name, e);
if (IsNext(':')) {
ParseSingleValue(*e);
}
if (IsNext(')')) break;
Expect(',');
}
}
}
bool Parser::TryTypedValue(int dtoken,
bool check,
Value &e,
BaseType req) {
bool match = dtoken == token_;
if (match) {
e.constant = attribute_;
if (!check) {
if (e.type.base_type == BASE_TYPE_NONE) {
e.type.base_type = req;
} else {
Error(std::string("type mismatch: expecting: ") +
kTypeNames[e.type.base_type] +
", found: " +
kTypeNames[req]);
}
}
Next();
} return match;
}
int64_t Parser::ParseIntegerFromString(Type &type) {
int64_t result = 0;
// Parse one or more enum identifiers, separated by spaces.
const char *next = attribute_.c_str();
do {
const char *divider = strchr(next, ' ');
std::string word;
if (divider) {
word = std::string(next, divider);
next = divider + strspn(divider, " ");
} else {
word = next;
next += word.length();
}
if (type.enum_def) { // The field has an enum type
auto enum_val = type.enum_def->vals.Lookup(word);
if (!enum_val)
Error("unknown enum value: " + word +
", for enum: " + type.enum_def->name);
result |= enum_val->value;
} else { // No enum type, probably integral field.
if (!IsInteger(type.base_type))
Error("not a valid value for this field: " + word);
// TODO: could check if its a valid number constant here.
const char *dot = strchr(word.c_str(), '.');
if (!dot) Error("enum values need to be qualified by an enum type");
std::string enum_def_str(word.c_str(), dot);
std::string enum_val_str(dot + 1, word.c_str() + word.length());
auto enum_def = enums_.Lookup(enum_def_str);
if (!enum_def) Error("unknown enum: " + enum_def_str);
auto enum_val = enum_def->vals.Lookup(enum_val_str);
if (!enum_val) Error("unknown enum value: " + enum_val_str);
result |= enum_val->value;
}
} while(*next);
return result;
}
void Parser::ParseSingleValue(Value &e) {
// First check if this could be a string/identifier enum value:
if (e.type.base_type != BASE_TYPE_STRING &&
e.type.base_type != BASE_TYPE_NONE &&
(token_ == kTokenIdentifier || token_ == kTokenStringConstant)) {
e.constant = NumToString(ParseIntegerFromString(e.type));
Next();
} else if (TryTypedValue(kTokenIntegerConstant,
IsScalar(e.type.base_type),
e,
BASE_TYPE_INT) ||
TryTypedValue(kTokenFloatConstant,
IsFloat(e.type.base_type),
e,
BASE_TYPE_FLOAT) ||
TryTypedValue(kTokenStringConstant,
e.type.base_type == BASE_TYPE_STRING,
e,
BASE_TYPE_STRING)) {
} else {
Error("cannot parse value starting with: " + TokenToString(token_));
}
}
StructDef *Parser::LookupCreateStruct(const std::string &name) {
auto struct_def = structs_.Lookup(name);
if (!struct_def) {
// Rather than failing, we create a "pre declared" StructDef, due to
// circular references, and check for errors at the end of parsing. struct_def = new StructDef();
structs_.Add(name, struct_def);
struct_def->name = name;
struct_def->predecl = true;
struct_def->defined_namespace = namespaces_.back();
}
return struct_def;
}
void Parser::ParseEnum(bool is_union) {
std::vector<std::string> dc = doc_comment_;
Next();
std::string name = attribute_;
Expect(kTokenIdentifier);
auto &enum_def = *new EnumDef();
enum_def.name = name;
enum_def.doc_comment = dc;
enum_def.is_union = is_union;
enum_def.defined_namespace = namespaces_.back();
if (enums_.Add(name, &enum_def)) Error("enum already exists: " + name);
if (is_union) {
enum_def.underlying_type.base_type = BASE_TYPE_UTYPE;
enum_def.underlying_type.enum_def = &enum_def;
} else {
if (proto_mode_) {
enum_def.underlying_type.base_type = BASE_TYPE_SHORT;
} else {
// Give specialized error message, since this type spec used to
// be optional in the first FlatBuffers release.
if (!IsNext(':')) Error("must specify the underlying integer type for this"
" enum (e.g. \': short\', which was the default).");
// Specify the integer type underlying this enum.
ParseType(enum_def.underlying_type);
if (!IsInteger(enum_def.underlying_type.base_type))
Error("underlying enum type must be integral");
}
// Make this type refer back to the enum it was derived from.
enum_def.underlying_type.enum_def = &enum_def;
}
ParseMetaData(enum_def);
Expect('{');
if (is_union) enum_def.vals.Add("NONE", new EnumVal("NONE", 0));
do {
std::string name = attribute_;
std::vector<std::string> dc = doc_comment_;
Expect(kTokenIdentifier);
auto prevsize = enum_def.vals.vec.size();
auto value = enum_def.vals.vec.size()
? enum_def.vals.vec.back()->value + 1
: 0;
auto &ev = *new EnumVal(name, value);
if (enum_def.vals.Add(name, &ev))
Error("enum value already exists: " + name);
ev.doc_comment = dc;
if (is_union) {
ev.struct_def = LookupCreateStruct(name);
}
if (IsNext('=')) {
ev.value = atoi(attribute_.c_str());
Expect(kTokenIntegerConstant);
if (prevsize && enum_def.vals.vec[prevsize - 1]->value >= ev.value)
Error("enum values must be specified in ascending order");
}
} while (IsNext(proto_mode_ ? ';' : ',') && token_ != '}');
Expect('}');
if (enum_def.attributes.Lookup("bit_flags")) {
for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
++it) {
if (static_cast<size_t>((*it)->value) >=
SizeOf(enum_def.underlying_type.base_type) * 8) Error("bit flag out of range of underlying integral type");
(*it)->value = 1LL << (*it)->value;
}
}
}
StructDef &Parser::StartStruct() {
std::string name = attribute_;
Expect(kTokenIdentifier);
auto &struct_def = *LookupCreateStruct(name);
if (!struct_def.predecl) Error("datatype already exists: " + name);
struct_def.predecl = false;
struct_def.name = name;
// Move this struct to the back of the vector just in case it was predeclared,
// to preserve declaration order.
remove(structs_.vec.begin(), structs_.vec.end(), &struct_def);
structs_.vec.back() = &struct_def;
return struct_def;
}
void Parser::ParseDecl() {
std::vector<std::string> dc = doc_comment_;
bool fixed = IsNext(kTokenStruct);
if (!fixed) Expect(kTokenTable);
auto &struct_def = StartStruct();
struct_def.doc_comment = dc;
struct_def.fixed = fixed;
ParseMetaData(struct_def);
struct_def.sortbysize =
struct_def.attributes.Lookup("original_order") == nullptr && !fixed;
Expect('{');
while (token_ != '}') ParseField(struct_def);
auto force_align = struct_def.attributes.Lookup("force_align");
if (fixed && force_align) {
auto align = static_cast<size_t>(atoi(force_align->constant.c_str()));
if (force_align->type.base_type != BASE_TYPE_INT ||
align < struct_def.minalign ||
align > 256 ||
align & (align - 1))
Error("force_align must be a power of two integer ranging from the"
"struct\'s natural alignment to 256");
struct_def.minalign = align;
}
struct_def.PadLastField(struct_def.minalign);
// Check if this is a table that has manual id assignments
auto &fields = struct_def.fields.vec;
if (!struct_def.fixed && fields.size()) {
size_t num_id_fields = 0;
for (auto it = fields.begin(); it != fields.end(); ++it) {
if ((*it)->attributes.Lookup("id")) num_id_fields++;
}
// If any fields have ids..
if (num_id_fields) {
// Then all fields must have them.
if (num_id_fields != fields.size())
Error("either all fields or no fields must have an 'id' attribute");
// Simply sort by id, then the fields are the same as if no ids had
// been specified.
std::sort(fields.begin(), fields.end(),
[](const FieldDef *a, const FieldDef *b) -> bool {
auto a_id = atoi(a->attributes.Lookup("id")->constant.c_str());
auto b_id = atoi(b->attributes.Lookup("id")->constant.c_str());
return a_id < b_id;
});
// Verify we have a contiguous set, and reassign vtable offsets.
for (int i = 0; i < static_cast<int>(fields.size()); i++) {
if (i != atoi(fields[i]->attributes.Lookup("id")->constant.c_str()))
Error("field id\'s must be consecutive from 0, id " +
NumToString(i) + " missing or set twice");
fields[i]->value.offset = FieldIndexToOffset(static_cast<voffset_t>(i)); }
}
}
// Check that no identifiers clash with auto generated fields.
// This is not an ideal situation, but should occur very infrequently,
// and allows us to keep using very readable names for type & length fields
// without inducing compile errors.
auto CheckClash = [&fields, &struct_def](const char *suffix,
BaseType basetype) {
auto len = strlen(suffix);
for (auto it = fields.begin(); it != fields.end(); ++it) {
auto &name = (*it)->name;
if (name.length() > len &&
name.compare(name.length() - len, len, suffix) == 0 &&
(*it)->value.type.base_type != BASE_TYPE_UTYPE) {
auto field = struct_def.fields.Lookup(
name.substr(0, name.length() - len));
if (field && field->value.type.base_type == basetype)
Error("Field " + name +
" would clash with generated functions for field " +
field->name);
}
}
};
CheckClash("_type", BASE_TYPE_UNION);
CheckClash("Type", BASE_TYPE_UNION);
CheckClash("_length", BASE_TYPE_VECTOR);
CheckClash("Length", BASE_TYPE_VECTOR);
Expect('}');
}
bool Parser::SetRootType(const char *name) {
root_struct_def = structs_.Lookup(name);
return root_struct_def != nullptr;
}
void Parser::MarkGenerated() {
// Since the Parser object retains definitions across files, we must
// ensure we only output code for definitions once, in the file they are first
// declared. This function marks all existing definitions as having already
// been generated.
for (auto it = enums_.vec.begin();
it != enums_.vec.end(); ++it) {
(*it)->generated = true;
}
for (auto it = structs_.vec.begin();
it != structs_.vec.end(); ++it) {
(*it)->generated = true;
}
}
void Parser::ParseNamespace() {
Next();
auto ns = new Namespace();
namespaces_.push_back(ns);
for (;;) {
ns->components.push_back(attribute_);
Expect(kTokenIdentifier);
if (!IsNext('.')) break;
}
Expect(';');
}
// Best effort parsing of .proto declarations, with the aim to turn them
// in the closest corresponding FlatBuffer equivalent.
// We parse everything as identifiers instead of keywords, since we don't
// want protobuf keywords to become invalid identifiers in FlatBuffers.
void Parser::ParseProtoDecl() {
if (attribute_ == "package") {
// These are identical in syntax to FlatBuffer's namespace decl. ParseNamespace();
} else if (attribute_ == "message") {
Next();
auto &struct_def = StartStruct();
Expect('{');
while (token_ != '}') {
// Parse the qualifier.
bool required = false;
bool repeated = false;
if (attribute_ == "optional") {
// This is the default.
} else if (attribute_ == "required") {
required = true;
} else if (attribute_ == "repeated") {
repeated = true;
} else {
Error("expecting optional/required/repeated, got: " + attribute_);
}
Type type = ParseTypeFromProtoType();
// Repeated elements get mapped to a vector.
if (repeated) {
type.element = type.base_type;
type.base_type = BASE_TYPE_VECTOR;
}
std::string name = attribute_;
Expect(kTokenIdentifier);
// Parse the field id. Since we're just translating schemas, not
// any kind of binary compatibility, we can safely ignore these, and
// assign our own.
Expect('=');
Expect(kTokenIntegerConstant);
auto &field = AddField(struct_def, name, type);
field.required = required;
// See if there's a default specified.
if (IsNext('[')) {
if (attribute_ != "default") Error("\'default\' expected");
Next();
Expect('=');
field.value.constant = attribute_;
Next();
Expect(']');
}
Expect(';');
}
Next();
} else if (attribute_ == "enum") {
// These are almost the same, just with different terminator:
ParseEnum(false);
} else if (attribute_ == "import") {
Next();
included_files_[attribute_] = true;
Expect(kTokenStringConstant);
Expect(';');
} else if (attribute_ == "option") { // Skip these.
Next();
Expect(kTokenIdentifier);
Expect('=');
Next(); // Any single token.
Expect(';');
} else {
Error("don\'t know how to parse .proto declaration starting with " +
attribute_);
}
}
// Parse a protobuf type, and map it to the corresponding FlatBuffer one.
Type Parser::ParseTypeFromProtoType() {
Expect(kTokenIdentifier);
struct type_lookup { const char *proto_type; BaseType fb_type; };
static type_lookup lookup[] = { { "float", BASE_TYPE_FLOAT }, { "double", BASE_TYPE_DOUBLE },
{ "int32", BASE_TYPE_INT }, { "int64", BASE_TYPE_LONG },
{ "uint32", BASE_TYPE_UINT }, { "uint64", BASE_TYPE_ULONG },
{ "sint32", BASE_TYPE_INT }, { "sint64", BASE_TYPE_LONG },
{ "fixed32", BASE_TYPE_UINT }, { "fixed64", BASE_TYPE_ULONG },
{ "sfixed32", BASE_TYPE_INT }, { "sfixed64", BASE_TYPE_LONG },
{ "bool", BASE_TYPE_BOOL },
{ "string", BASE_TYPE_STRING },
{ "bytes", BASE_TYPE_STRING },
{ nullptr, BASE_TYPE_NONE }
};
Type type;
for (auto tl = lookup; tl->proto_type; tl++) {
if (attribute_ == tl->proto_type) {
type.base_type = tl->fb_type;
Next();
return type;
}
}
ParseTypeIdent(type);
Expect(kTokenIdentifier);
return type;
}
bool Parser::Parse(const char *source, const char **include_paths,
const char *source_filename) {
if (source_filename) included_files_[source_filename] = true;
source_ = cursor_ = source;
line_ = 1;
error_.clear();
builder_.Clear();
try {
Next();
// Includes must come first:
while (IsNext(kTokenInclude)) {
auto name = attribute_;
Expect(kTokenStringConstant);
if (included_files_.find(name) == included_files_.end()) {
// We found an include file that we have not parsed yet.
// Load it and parse it.
std::string contents;
if (!include_paths) {
const char *current_directory[] = { "", nullptr };
include_paths = current_directory;
}
for (auto paths = include_paths; paths && *paths; paths++) {
auto filepath = flatbuffers::ConCatPathFileName(*paths, name);
if(LoadFile(filepath.c_str(), true, &contents)) break;
}
if (contents.empty())
Error("unable to load include file: " + name);
included_files_[name] = true;
if (!Parse(contents.c_str(), include_paths)) {
// Any errors, we're done.
return false;
}
// We do not want to output code for any included files:
MarkGenerated();
// This is the easiest way to continue this file after an include:
// instead of saving and restoring all the state, we simply start the
// file anew. This will cause it to encounter the same include statement
// again, but this time it will skip it, because it was entered into
// included_files_.
// This is recursive, but only go as deep as the number of include
// statements.
return Parse(source, include_paths, source_filename);
}
Expect(';');
}
// Now parse all other kinds of declarations: while (token_ != kTokenEof) {
if (proto_mode_) {
ParseProtoDecl();
} else if (token_ == kTokenNameSpace) {
ParseNamespace();
} else if (token_ == '{') {
if (!root_struct_def) Error("no root type set to parse json with");
if (builder_.GetSize()) {
Error("cannot have more than one json object in a file");
}
builder_.Finish(Offset<Table>(ParseTable(*root_struct_def)),
file_identifier_.length() ? file_identifier_.c_str() : nullptr);
} else if (token_ == kTokenEnum) {
ParseEnum(false);
} else if (token_ == kTokenUnion) {
ParseEnum(true);
} else if (token_ == kTokenRootType) {
Next();
auto root_type = attribute_;
Expect(kTokenIdentifier);
if (!SetRootType(root_type.c_str()))
Error("unknown root type: " + root_type);
if (root_struct_def->fixed)
Error("root type must be a table");
Expect(';');
} else if (token_ == kTokenFileIdentifier) {
Next();
file_identifier_ = attribute_;
Expect(kTokenStringConstant);
if (file_identifier_.length() !=
FlatBufferBuilder::kFileIdentifierLength)
Error("file_identifier must be exactly " +
NumToString(FlatBufferBuilder::kFileIdentifierLength) +
" characters");
Expect(';');
} else if (token_ == kTokenFileExtension) {
Next();
file_extension_ = attribute_;
Expect(kTokenStringConstant);
Expect(';');
} else if(token_ == kTokenInclude) {
Error("includes must come before declarations");
} else {
ParseDecl();
}
}
for (auto it = structs_.vec.begin(); it != structs_.vec.end(); ++it) {
if ((*it)->predecl)
Error("type referenced but not defined: " + (*it)->name);
}
for (auto it = enums_.vec.begin(); it != enums_.vec.end(); ++it) {
auto &enum_def = **it;
if (enum_def.is_union) {
for (auto it = enum_def.vals.vec.begin();
it != enum_def.vals.vec.end();
++it) {
auto &val = **it;
if (val.struct_def && val.struct_def->fixed)
Error("only tables can be union elements: " + val.name);
}
}
}
} catch (const std::string &msg) {
error_ = source_filename ? AbsolutePath(source_filename) : "";
#ifdef _WIN32
error_ += "(" + NumToString(line_) + ")"; // MSVC alike
#else
if (source_filename) error_ += ":";
error_ += NumToString(line_) + ":0"; // gcc alike
#endif error_ += ": error: " + msg;
return false;
}
assert(!struct_stack_.size());
return true;
}
} // namespace flatbuffers