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// mutable-fst.h
//
// 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.
//
//
// \file
// Expanded FST augmented with mutators - interface class definition
// and mutable arc iterator interface.
#ifndef FST_LIB_MUTABLE_FST_H__
#define FST_LIB_MUTABLE_FST_H__
#include <vector>
#include "fst/lib/expanded-fst.h"
namespace fst {
template <class A> class MutableArcIteratorData;
// An expanded FST plus mutators (use MutableArcIterator to modify arcs).
template <class A>
class MutableFst : public ExpandedFst<A> {
public:
typedef A Arc;
typedef typename A::Weight Weight;
typedef typename A::StateId StateId;
virtual MutableFst<A> &operator=(const Fst<A> &fst) = 0;
virtual void SetStart(StateId) = 0; // Set the initial state
virtual void SetFinal(StateId, Weight) = 0; // Set a state's final weight
virtual void SetProperties(uint64 props,
uint64 mask) = 0; // Set property bits wrt mask
virtual StateId AddState() = 0; // Add a state, return its ID
virtual void AddArc(StateId, const A &arc) = 0; // Add an arc to state
virtual void DeleteStates(const vector<StateId>&) = 0; // Delete some states
virtual void DeleteStates() = 0; // Delete all states
virtual void DeleteArcs(StateId, size_t n) = 0; // Delete some arcs at state
virtual void DeleteArcs(StateId) = 0; // Delete all arcs at state
// Return input label symbol table; return NULL if not specified
virtual const SymbolTable* InputSymbols() const = 0;
// Return output label symbol table; return NULL if not specified
virtual const SymbolTable* OutputSymbols() const = 0;
// Return input label symbol table; return NULL if not specified
virtual SymbolTable* InputSymbols() = 0;
// Return output label symbol table; return NULL if not specified
virtual SymbolTable* OutputSymbols() = 0;
// Set input label symbol table; NULL signifies not unspecified
virtual void SetInputSymbols(const SymbolTable* isyms) = 0;
// Set output label symbol table; NULL signifies not unspecified
virtual void SetOutputSymbols(const SymbolTable* osyms) = 0;
// Get a copy of this MutableFst.
virtual MutableFst<A> *Copy() const = 0;
// Read an MutableFst from an input stream; return NULL on error.
static MutableFst<A> *Read(istream &strm, const FstReadOptions &opts) {
FstReadOptions ropts(opts);
FstHeader hdr;
if (ropts.header)
hdr = *opts.header;
else {
if (!hdr.Read(strm, opts.source))
return 0;
ropts.header = &hdr;
}
if (!(hdr.Properties() & kMutable)) {
LOG(ERROR) << "MutableFst::Read: Not an MutableFst: " << ropts.source;
return 0;
}
FstRegister<A> *registr = FstRegister<A>::GetRegister();
const typename FstRegister<A>::Reader reader =
registr->GetReader(hdr.FstType());
if (!reader) {
LOG(ERROR) << "MutableFst::Read: Unknown FST type \"" << hdr.FstType()
<< "\" (arc type = \"" << A::Type()
<< "\"): " << ropts.source;
return 0;
}
Fst<A> *fst = reader(strm, ropts);
if (!fst) return 0;
return down_cast<MutableFst<A> *>(fst);
}
// Read an MutableFst from a file; returns NULL on error.
static MutableFst<A> *Read(const string &filename) {
ifstream strm(filename.c_str());
if (!strm) {
LOG(ERROR) << "MutableFst::Read: Can't open file: " << filename;
return 0;
}
return Read(strm, FstReadOptions(filename));
}
// For generic mutuble arc iterator construction; not normally called
// directly by users.
virtual void InitMutableArcIterator(StateId s,
MutableArcIteratorData<A> *) = 0;
};
// Mutable arc iterator interface, templated on the Arc definition.
template <class A>
class MutableArcIteratorBase : public ArcIteratorBase<A> {
public:
typedef A Arc;
virtual void SetValue(const A &arc) = 0; // Set current arc's contents
};
template <class A>
struct MutableArcIteratorData {
MutableArcIteratorBase<A> *base; // Specific iterator
};
// Generic mutable arc iterator, templated on the FST definition
// - a wrapper around pointer to specific one.
// Here is a typical use: \code
// for (MutableArcIterator<StdFst> aiter(&fst, s));
// !aiter.Done();
// aiter.Next()) {
// StdArc arc = aiter.Value();
// arc.ilabel = 7;
// aiter.SetValue(arc);
// ...
// } \endcode
// This version requires function calls.
template <class F>
class MutableArcIterator : public MutableArcIteratorBase<typename F::Arc> {
public:
typedef typename F::Arc Arc;
typedef typename Arc::StateId StateId;
MutableArcIterator(F *fst, StateId s) {
fst->InitMutableArcIterator(s, &data_);
}
~MutableArcIterator() { delete data_.base; }
bool Done() const { return data_.base->Done(); }
const Arc& Value() const { return data_.base->Value(); }
void Next() { data_.base->Next(); }
void Reset() { data_.base->Reset(); }
void Seek(size_t a) { data_.base->Seek(a); }
void SetValue(const Arc &a) { data_.base->SetValue(a); }
private:
MutableArcIteratorData<Arc> data_;
DISALLOW_EVIL_CONSTRUCTORS(MutableArcIterator);
};
// A useful alias when using StdArc.
typedef MutableFst<StdArc> StdMutableFst;
} // namespace fst;
#endif // FST_LIB_MUTABLE_FST_H__
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