flatbuffers/src/idl_parser.cpp
Wouter van Oortmerssen 39833d7cf0 Added namespaced way to refer to types in schemas.
Also made proper namespacing work for enums.

You can now say namespace.MyTable as the type when declaring
a field that refers to a type in a different namespace.

Previously, it would work just referring to MyTable, however
with the recent commit fixing namespaced types this now
is ambiguous.

Change-Id: Ieaa3f4ac1662b8c4dc1f16e1898ea3cdb02e10fd
Tested: on Linux.
2015-05-08 16:21:53 -07:00

1297 lines
46 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.
*/
#include <algorithm>
#include <list>
#include "flatbuffers/flatbuffers.h"
#include "flatbuffers/hash.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") \
TD(Attribute, 270, "attribute")
#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");
std::string target(cursor_, cursor_ + nibbles);
auto val = StringToInt(target.c_str(), 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_ != '\r') cursor_++;
if (*start == '/') { // documentation comment
if (cursor_ != source_ && !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_ == "attribute") { token_ = kTokenAttribute; 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::ParseNamespacing(std::string *id, std::string *last) {
while (IsNext('.')) {
*id += ".";
*id += attribute_;
if (last) *last = attribute_;
Expect(kTokenIdentifier);
}
}
EnumDef *Parser::LookupEnum(const std::string &id) {
auto ed = enums_.Lookup(GetFullyQualifiedName(id));
// id may simply not have a namespace at all, so check that too.
if (!ed) ed = enums_.Lookup(id);
return ed;
}
void Parser::ParseTypeIdent(Type &type) {
std::string id = attribute_;
Expect(kTokenIdentifier);
ParseNamespacing(&id, nullptr);
auto enum_def = LookupEnum(id);
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(id);
}
}
// Parse any IDL type.
void Parser::ParseType(Type &type) {
if (token_ >= kTokenBOOL && token_ <= kTokenSTRING) {
type.base_type = static_cast<BaseType>(token_ - kTokenNONE);
Next();
} 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(']');
} else {
Error("illegal type syntax");
}
}
}
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.file = struct_def.file;
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;
auto hash_name = field.attributes.Lookup("hash");
if (hash_name) {
switch (type.base_type) {
case BASE_TYPE_INT:
case BASE_TYPE_UINT: {
if (FindHashFunction32(hash_name->constant.c_str()) == nullptr)
Error("Unknown hashing algorithm for 32 bit types: " +
hash_name->constant);
break;
}
case BASE_TYPE_LONG:
case BASE_TYPE_ULONG: {
if (FindHashFunction64(hash_name->constant.c_str()) == nullptr)
Error("Unknown hashing algorithm for 64 bit types: " +
hash_name->constant);
break;
}
default:
Error("only int, uint, long and ulong data types support hashing.");
}
}
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'");
field.key = field.attributes.Lookup("key") != nullptr;
if (field.key) {
if (struct_def.has_key)
Error("only one field may be set as 'key'");
struct_def.has_key = true;
if (!IsScalar(field.value.type.base_type)) {
field.required = true;
if (field.value.type.base_type != BASE_TYPE_STRING)
Error("'key' field must be string or scalar type");
}
}
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;
}
case BASE_TYPE_INT:
case BASE_TYPE_UINT:
case BASE_TYPE_LONG:
case BASE_TYPE_ULONG: {
if (field && field->attributes.Lookup("hash") &&
(token_ == kTokenIdentifier || token_ == kTokenStringConstant)) {
ParseHash(val, field);
} else {
ParseSingleValue(val);
}
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;
for (;;) {
if ((!strict_json_ || !fieldn) && IsNext('}')) break;
std::string name = attribute_;
if (!IsNext(kTokenStringConstant))
Expect(strict_json_ ? kTokenStringConstant : 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;
for (;;) {
if ((!strict_json_ || !count) && IsNext(']')) break;
Value val;
val.type = type;
ParseAnyValue(val, nullptr);
field_stack_.push_back(std::make_pair(val, nullptr));
count++;
if (IsNext(']')) break;
Expect(',');
}
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);
if (known_attributes_.find(name) == known_attributes_.end())
Error("user define attributes must be declared before use: " + name);
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 = strrchr(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 = LookupEnum(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::ParseHash(Value &e, FieldDef* field) {
assert(field);
Value *hash_name = field->attributes.Lookup("hash");
switch (e.type.base_type) {
case BASE_TYPE_INT:
case BASE_TYPE_UINT: {
auto hash = FindHashFunction32(hash_name->constant.c_str());
uint32_t hashed_value = hash(attribute_.c_str());
e.constant = NumToString(hashed_value);
break;
}
case BASE_TYPE_LONG:
case BASE_TYPE_ULONG: {
auto hash = FindHashFunction64(hash_name->constant.c_str());
uint64_t hashed_value = hash(attribute_.c_str());
e.constant = NumToString(hashed_value);
break;
}
default:
assert(0);
}
Next();
}
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) {
std::string qualified_name = GetFullyQualifiedName(name);
auto struct_def = structs_.Lookup(qualified_name);
// Unqualified names may simply have no namespace at all, so try that too.
if (!struct_def) 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(qualified_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> enum_comment = doc_comment_;
Next();
std::string enum_name = attribute_;
Expect(kTokenIdentifier);
auto &enum_def = *new EnumDef();
enum_def.name = enum_name;
if (!files_being_parsed_.empty()) enum_def.file = files_being_parsed_.top();
enum_def.doc_comment = enum_comment;
enum_def.is_union = is_union;
enum_def.defined_namespace = namespaces_.back();
if (enums_.Add(GetFullyQualifiedName(enum_name), &enum_def))
Error("enum already exists: " + enum_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 {
auto value_name = attribute_;
auto full_name = value_name;
std::vector<std::string> value_comment = doc_comment_;
Expect(kTokenIdentifier);
if (is_union) ParseNamespacing(&full_name, &value_name);
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(value_name, value);
if (enum_def.vals.Add(value_name, &ev))
Error("enum value already exists: " + value_name);
ev.doc_comment = value_comment;
if (is_union) {
ev.struct_def = LookupCreateStruct(full_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;
if (!files_being_parsed_.empty()) struct_def.file = files_being_parsed_.top();
// 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(GetFullyQualifiedName(name));
return root_struct_def != nullptr;
}
std::string Parser::GetFullyQualifiedName(const std::string &name) const {
Namespace *ns = namespaces_.back();
// Early exit if we don't have a defined namespace, or if the name is already
// partially qualified
if (ns->components.size() == 0 || name.find(".") != std::string::npos) {
return name;
}
std::stringstream stream;
for (size_t i = 0; i != ns->components.size(); ++i) {
if (i != 0) {
stream << ".";
}
stream << ns->components[i];
}
stream << "." << name;
return stream.str();
}
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") {
std::vector<std::string> struct_comment = doc_comment_;
Next();
auto &struct_def = StartStruct();
struct_def.doc_comment = struct_comment;
Expect('{');
while (token_ != '}') {
std::vector<std::string> field_comment = doc_comment_;
// 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.doc_comment = field_comment;
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);
return type;
}
bool Parser::Parse(const char *source, const char **include_paths,
const char *source_filename) {
if (source_filename &&
included_files_.find(source_filename) == included_files_.end()) {
included_files_[source_filename] = true;
files_included_per_file_[source_filename] = std::set<std::string>();
files_being_parsed_.push(source_filename);
}
if (!include_paths) {
const char *current_directory[] = { "", nullptr };
include_paths = current_directory;
}
source_ = cursor_ = source;
line_ = 1;
error_.clear();
builder_.Clear();
try {
Next();
// Includes must come first:
while (IsNext(kTokenInclude)) {
auto name = attribute_;
Expect(kTokenStringConstant);
// Look for the file in include_paths.
std::string filepath;
for (auto paths = include_paths; paths && *paths; paths++) {
filepath = flatbuffers::ConCatPathFileName(*paths, name);
if(FileExists(filepath.c_str())) break;
}
if (filepath.empty())
Error("unable to locate include file: " + name);
if (source_filename)
files_included_per_file_[source_filename].insert(filepath);
if (included_files_.find(filepath) == included_files_.end()) {
// We found an include file that we have not parsed yet.
// Load it and parse it.
std::string contents;
if (!LoadFile(filepath.c_str(), true, &contents))
Error("unable to load include file: " + name);
if (!Parse(contents.c_str(), include_paths, filepath.c_str())) {
// 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 if(token_ == kTokenAttribute) {
Next();
auto name = attribute_;
Expect(kTokenStringConstant);
Expect(';');
known_attributes_.insert(name);
} 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 val_it = enum_def.vals.vec.begin();
val_it != enum_def.vals.vec.end();
++val_it) {
auto &val = **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;
if (source_filename) files_being_parsed_.pop();
return false;
}
if (source_filename) files_being_parsed_.pop();
assert(!struct_stack_.size());
return true;
}
std::set<std::string> Parser::GetIncludedFilesRecursive(
const std::string &file_name) const {
std::set<std::string> included_files;
std::list<std::string> to_process;
if (file_name.empty()) return included_files;
to_process.push_back(file_name);
while (!to_process.empty()) {
std::string current = to_process.front();
to_process.pop_front();
included_files.insert(current);
auto new_files = files_included_per_file_.at(current);
for (auto it = new_files.begin(); it != new_files.end(); ++it) {
if (included_files.find(*it) == included_files.end())
to_process.push_back(*it);
}
}
return included_files;
}
} // namespace flatbuffers