Blame view
tools/openfst-1.6.7/src/include/fst/string.h
8.3 KB
8dcb6dfcb
first commit
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 |
// See www.openfst.org for extensive documentation on this weighted
// finite-state transducer library.
//
// Utilities to convert strings into FSTs.
#ifndef FST_STRING_H_
#define FST_STRING_H_
#include <memory>
#include <sstream>
#include <string>
#include <vector>
#include <fst/flags.h>
#include <fst/log.h>
#include <fst/compact-fst.h>
#include <fst/icu.h>
#include <fst/mutable-fst.h>
#include <fst/util.h>
DECLARE_string(fst_field_separator);
namespace fst {
enum StringTokenType { SYMBOL = 1, BYTE = 2, UTF8 = 3 };
namespace internal {
template <class Label>
bool ConvertSymbolToLabel(const char *str, const SymbolTable *syms,
Label unknown_label, bool allow_negative,
Label *output) {
int64 n;
if (syms) {
n = syms->Find(str);
if ((n == -1) && (unknown_label != kNoLabel)) n = unknown_label;
if (n == -1 || (!allow_negative && n < 0)) {
VLOG(1) << "ConvertSymbolToLabel: Symbol \"" << str
<< "\" is not mapped to any integer label, symbol table = "
<< syms->Name();
return false;
}
} else {
char *p;
n = strtoll(str, &p, 10);
if (p < str + strlen(str) || (!allow_negative && n < 0)) {
VLOG(1) << "ConvertSymbolToLabel: Bad label integer "
<< "= \"" << str << "\"";
return false;
}
}
*output = n;
return true;
}
template <class Label>
bool ConvertStringToLabels(const string &str, StringTokenType token_type,
const SymbolTable *syms, Label unknown_label,
bool allow_negative, std::vector<Label> *labels) {
labels->clear();
if (token_type == StringTokenType::BYTE) {
for (const char c : str) labels->push_back(c);
} else if (token_type == StringTokenType::UTF8) {
return UTF8StringToLabels(str, labels);
} else {
std::unique_ptr<char[]> c_str(new char[str.size() + 1]);
str.copy(c_str.get(), str.size());
c_str[str.size()] = 0;
std::vector<char *> vec;
const string separator = "
" + FLAGS_fst_field_separator;
SplitString(c_str.get(), separator.c_str(), &vec, true);
for (const char *c : vec) {
Label label;
if (!ConvertSymbolToLabel(c, syms, unknown_label, allow_negative,
&label)) {
return false;
}
labels->push_back(label);
}
}
return true;
}
} // namespace internal
// Functor for compiling a string in an FST.
template <class Arc>
class StringCompiler {
public:
using Label = typename Arc::Label;
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
explicit StringCompiler(StringTokenType token_type,
const SymbolTable *syms = nullptr,
Label unknown_label = kNoLabel,
bool allow_negative = false)
: token_type_(token_type),
syms_(syms),
unknown_label_(unknown_label),
allow_negative_(allow_negative) {}
// Compiles string into an FST.
template <class FST>
bool operator()(const string &str, FST *fst) const {
std::vector<Label> labels;
if (!internal::ConvertStringToLabels(str, token_type_, syms_,
unknown_label_, allow_negative_,
&labels)) {
return false;
}
Compile(labels, fst);
return true;
}
template <class FST>
bool operator()(const string &str, FST *fst, Weight weight) const {
std::vector<Label> labels;
if (!internal::ConvertStringToLabels(str, token_type_, syms_,
unknown_label_, allow_negative_,
&labels)) {
return false;
}
Compile(labels, fst, std::move(weight));
return true;
}
private:
void Compile(const std::vector<Label> &labels, MutableFst<Arc> *fst,
Weight weight = Weight::One()) const {
fst->DeleteStates();
while (fst->NumStates() <= labels.size()) fst->AddState();
for (StateId i = 0; i < labels.size(); ++i) {
fst->AddArc(i, Arc(labels[i], labels[i], Weight::One(), i + 1));
}
fst->SetStart(0);
fst->SetFinal(labels.size(), std::move(weight));
}
template <class Unsigned>
void Compile(const std::vector<Label> &labels,
CompactStringFst<Arc, Unsigned> *fst) const {
fst->SetCompactElements(labels.begin(), labels.end());
}
template <class Unsigned>
void Compile(const std::vector<Label> &labels,
CompactWeightedStringFst<Arc, Unsigned> *fst,
const Weight &weight = Weight::One()) const {
std::vector<std::pair<Label, Weight>> compacts;
compacts.reserve(labels.size() + 1);
for (StateId i = 0; i < static_cast<StateId>(labels.size()) - 1; ++i) {
compacts.emplace_back(labels[i], Weight::One());
}
compacts.emplace_back(!labels.empty() ? labels.back() : kNoLabel, weight);
fst->SetCompactElements(compacts.begin(), compacts.end());
}
const StringTokenType token_type_;
const SymbolTable *syms_; // Symbol table (used when token type is symbol).
const Label unknown_label_; // Label for token missing from symbol table.
const bool allow_negative_; // Negative labels allowed?
StringCompiler(const StringCompiler &) = delete;
StringCompiler &operator=(const StringCompiler &) = delete;
};
// Functor for printing a string FST as a string.
template <class Arc>
class StringPrinter {
public:
using Label = typename Arc::Label;
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
explicit StringPrinter(StringTokenType token_type,
const SymbolTable *syms = nullptr)
: token_type_(token_type), syms_(syms) {}
// Converts the FST into a string.
bool operator()(const Fst<Arc> &fst, string *result) {
if (!FstToLabels(fst)) {
VLOG(1) << "StringPrinter::operator(): FST is not a string";
return false;
}
result->clear();
if (token_type_ == StringTokenType::SYMBOL) {
std::stringstream sstrm;
for (size_t i = 0; i < labels_.size(); ++i) {
if (i) sstrm << *(FLAGS_fst_field_separator.rbegin());
if (!PrintLabel(labels_[i], sstrm)) return false;
}
*result = sstrm.str();
} else if (token_type_ == StringTokenType::BYTE) {
result->reserve(labels_.size());
for (size_t i = 0; i < labels_.size(); ++i) result->push_back(labels_[i]);
} else if (token_type_ == StringTokenType::UTF8) {
return LabelsToUTF8String(labels_, result);
} else {
VLOG(1) << "StringPrinter::operator(): Unknown token type: "
<< token_type_;
return false;
}
return true;
}
private:
bool FstToLabels(const Fst<Arc> &fst) {
labels_.clear();
auto s = fst.Start();
if (s == kNoStateId) {
VLOG(2) << "StringPrinter::FstToLabels: Invalid starting state for "
<< "string FST";
return false;
}
while (fst.Final(s) == Weight::Zero()) {
ArcIterator<Fst<Arc>> aiter(fst, s);
if (aiter.Done()) {
VLOG(2) << "StringPrinter::FstToLabels: String FST traversal does "
<< "not reach final state";
return false;
}
const auto &arc = aiter.Value();
labels_.push_back(arc.olabel);
s = arc.nextstate;
if (s == kNoStateId) {
VLOG(2) << "StringPrinter::FstToLabels: Transition to invalid state";
return false;
}
aiter.Next();
if (!aiter.Done()) {
VLOG(2) << "StringPrinter::FstToLabels: State with multiple "
<< "outgoing arcs found";
return false;
}
}
return true;
}
bool PrintLabel(Label label, std::ostream &ostrm) {
if (syms_) {
const auto symbol = syms_->Find(label);
if (symbol == "") {
VLOG(2) << "StringPrinter::PrintLabel: Integer " << label << " is not "
<< "mapped to any textual symbol, symbol table = "
<< syms_->Name();
return false;
}
ostrm << symbol;
} else {
ostrm << label;
}
return true;
}
const StringTokenType token_type_;
const SymbolTable *syms_; // Symbol table (used when token type is symbol).
std::vector<Label> labels_; // Input FST labels.
StringPrinter(const StringPrinter &) = delete;
StringPrinter &operator=(const StringPrinter &) = delete;
};
} // namespace fst
#endif // FST_STRING_H_
|