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#ifndef LLMR_UTIL_PBF
#define LLMR_UTIL_PBF
/*
* Some parts are from upb - a minimalist implementation of protocol buffers.
*
* Copyright (c) 2008-2011 Google Inc. See LICENSE for details.
* Author: Josh Haberman <jhaberman@gmail.com>
*/
#include <string>
#include <cstring>
namespace llmr {
struct pbf {
struct exception : std::exception {};
struct unterminated_varint_exception : exception {};
struct varint_too_long_exception : exception {};
struct unknown_field_type_exception : exception {};
struct end_of_buffer_exception : exception {};
inline pbf(const unsigned char *data, size_t length);
inline pbf();
inline operator bool() const;
inline bool next();
inline bool next(uint32_t tag);
template <typename T = uint32_t> inline T varint();
template <typename T = uint32_t> inline T svarint();
template <typename T = uint32_t, int bytes = 4> inline T fixed();
inline float float32();
inline double float64();
inline std::string string();
inline bool boolean();
inline pbf message();
inline void skip();
inline void skipValue(uint32_t val);
inline void skipBytes(uint32_t bytes);
const uint8_t *data = nullptr;
const uint8_t *end = nullptr;
uint32_t value = 0;
uint32_t tag = 0;
};
pbf::pbf(const unsigned char *data, size_t length)
: data(data),
end(data + length),
value(0),
tag(0) {
}
pbf::pbf()
: data(nullptr),
end(nullptr),
value(0),
tag(0) {
}
pbf::operator bool() const {
return data < end;
}
bool pbf::next() {
if (data < end) {
value = static_cast<uint32_t>(varint());
tag = value >> 3;
return true;
}
return false;
}
bool pbf::next(uint32_t requested_tag) {
while (next()) {
if (tag == requested_tag) {
return true;
} else {
skip();
}
}
return false;
}
template <typename T>
T pbf::varint() {
uint8_t byte = 0x80;
T result = 0;
int bitpos;
for (bitpos = 0; bitpos < 70 && (byte & 0x80); bitpos += 7) {
if (data >= end) {
throw unterminated_varint_exception();
}
result |= ((T)(byte = *data) & 0x7F) << bitpos;
data++;
}
if (bitpos == 70 && (byte & 0x80)) {
throw varint_too_long_exception();
}
return result;
}
template <typename T>
T pbf::svarint() {
T n = varint<T>();
return (n >> 1) ^ -(T)(n & 1);
}
template <typename T, int bytes>
T pbf::fixed() {
skipBytes(bytes);
T result;
memcpy(&result, data - bytes, bytes);
return result;
}
float pbf::float32() {
return fixed<float, 4>();
}
double pbf::float64() {
return fixed<double, 8>();
}
std::string pbf::string() {
uint32_t bytes = static_cast<uint32_t>(varint());
const char *string = reinterpret_cast<const char*>(data);
skipBytes(bytes);
return std::string(string, bytes);
}
bool pbf::boolean() {
skipBytes(1);
return *(bool *)(data - 1);
}
pbf pbf::message() {
uint32_t bytes = static_cast<uint32_t>(varint());
const uint8_t *pos = data;
skipBytes(bytes);
return pbf(pos, bytes);
}
void pbf::skip() {
skipValue(value);
}
void pbf::skipValue(uint32_t val) {
switch (val & 0x7) {
case 0: // varint
varint();
break;
case 1: // 64 bit
skipBytes(8);
break;
case 2: // string/message
skipBytes(static_cast<uint32_t>(varint()));
break;
case 5: // 32 bit
skipBytes(4);
break;
default:
throw unknown_field_type_exception();
}
}
void pbf::skipBytes(uint32_t bytes) {
if (data + bytes > end) {
throw end_of_buffer_exception();
}
data += bytes;
}
} // end namespace llmr
#endif
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