symbol-table.cc
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// sherpa-onnx/csrc/symbol-table.cc
//
// Copyright (c) 2022-2023 Xiaomi Corporation
#include "sherpa-onnx/csrc/symbol-table.h"
#include <cassert>
#include <fstream>
#include <sstream>
#if __ANDROID_API__ >= 9
#include <strstream>
#include "android/asset_manager.h"
#include "android/asset_manager_jni.h"
#endif
#include "sherpa-onnx/csrc/base64-decode.h"
#include "sherpa-onnx/csrc/onnx-utils.h"
namespace sherpa_onnx {
SymbolTable::SymbolTable(const std::string &filename) {
std::ifstream is(filename);
Init(is);
}
#if __ANDROID_API__ >= 9
SymbolTable::SymbolTable(AAssetManager *mgr, const std::string &filename) {
auto buf = ReadFile(mgr, filename);
std::istrstream is(buf.data(), buf.size());
Init(is);
}
#endif
void SymbolTable::Init(std::istream &is) {
std::string sym;
int32_t id;
while (is >> sym >> id) {
#if 0
// we disable the test here since for some multi-lingual BPE models
// from NeMo, the same symbol can appear multiple times with different IDs.
if (sym != " ") {
assert(sym2id_.count(sym) == 0);
}
#endif
assert(id2sym_.count(id) == 0);
sym2id_.insert({sym, id});
id2sym_.insert({id, sym});
}
assert(is.eof());
}
std::string SymbolTable::ToString() const {
std::ostringstream os;
char sep = ' ';
for (const auto &p : sym2id_) {
os << p.first << sep << p.second << "\n";
}
return os.str();
}
const std::string SymbolTable::operator[](int32_t id) const {
std::string sym = id2sym_.at(id);
if (sym.size() >= 3) {
// For BPE-based models, we replace ▁ with a space
// Unicode 9601, hex 0x2581, utf8 0xe29681
const uint8_t *p = reinterpret_cast<const uint8_t *>(sym.c_str());
if (p[0] == 0xe2 && p[1] == 0x96 && p[2] == 0x81) {
sym = sym.replace(0, 3, " ");
}
}
// for byte-level BPE
// id 0 is blank, id 1 is sos/eos, id 2 is unk
if (id >= 3 && id <= 258 && sym.size() == 6 && sym[0] == '<' &&
sym[1] == '0' && sym[2] == 'x' && sym[5] == '>') {
std::ostringstream os;
os << std::hex << std::uppercase << (id - 3);
if (std::string(sym.data() + 3, sym.data() + 5) == os.str()) {
uint8_t i = id - 3;
sym = std::string(&i, &i + 1);
}
}
return sym;
}
int32_t SymbolTable::operator[](const std::string &sym) const {
return sym2id_.at(sym);
}
bool SymbolTable::Contains(int32_t id) const { return id2sym_.count(id) != 0; }
bool SymbolTable::Contains(const std::string &sym) const {
return sym2id_.count(sym) != 0;
}
std::ostream &operator<<(std::ostream &os, const SymbolTable &symbol_table) {
return os << symbol_table.ToString();
}
void SymbolTable::ApplyBase64Decode() {
sym2id_.clear();
for (auto &p : id2sym_) {
p.second = Base64Decode(p.second);
sym2id_[p.second] = p.first;
}
}
} // namespace sherpa_onnx