/usr/include/fst/const-fst.h is in libfst-dev 1.5.3+r3-2.
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// finite-state transducer library.
//
// Simple concrete immutable FST whose states and arcs are each stored in
// single arrays.
#ifndef FST_LIB_CONST_FST_H_
#define FST_LIB_CONST_FST_H_
#include <string>
#include <vector>
#include <fst/expanded-fst.h>
#include <fst/fst-decl.h> // For optional argument declarations
#include <fst/mapped-file.h>
#include <fst/test-properties.h>
#include <fst/util.h>
namespace fst {
template <class A, class U>
class ConstFst;
template <class F, class G>
void Cast(const F &, G *);
// States and arcs each implemented by single arrays, templated on the
// Arc definition. The unsigned type U is used to represent indices into
// the arc array.
template <class A, class U>
class ConstFstImpl : public FstImpl<A> {
public:
using FstImpl<A>::SetInputSymbols;
using FstImpl<A>::SetOutputSymbols;
using FstImpl<A>::SetType;
using FstImpl<A>::SetProperties;
using FstImpl<A>::Properties;
typedef A Arc;
typedef typename A::Weight Weight;
typedef typename A::StateId StateId;
typedef U Unsigned;
ConstFstImpl()
: states_region_(0),
arcs_region_(0),
states_(0),
arcs_(0),
nstates_(0),
narcs_(0),
start_(kNoStateId) {
string type = "const";
if (sizeof(U) != sizeof(uint32)) {
string size;
Int64ToStr(8 * sizeof(U), &size);
type += size;
}
SetType(type);
SetProperties(kNullProperties | kStaticProperties);
}
explicit ConstFstImpl(const Fst<A> &fst);
~ConstFstImpl() override {
delete arcs_region_;
delete states_region_;
}
StateId Start() const { return start_; }
Weight Final(StateId s) const { return states_[s].final; }
StateId NumStates() const { return nstates_; }
size_t NumArcs(StateId s) const { return states_[s].narcs; }
size_t NumInputEpsilons(StateId s) const { return states_[s].niepsilons; }
size_t NumOutputEpsilons(StateId s) const { return states_[s].noepsilons; }
static ConstFstImpl<A, U> *Read(std::istream &strm,
const FstReadOptions &opts);
const A *Arcs(StateId s) const { return arcs_ + states_[s].pos; }
// Provide information needed for generic state iterator
void InitStateIterator(StateIteratorData<A> *data) const {
data->base = 0;
data->nstates = nstates_;
}
// Provide information needed for the generic arc iterator
void InitArcIterator(StateId s, ArcIteratorData<A> *data) const {
data->base = 0;
data->arcs = arcs_ + states_[s].pos;
data->narcs = states_[s].narcs;
data->ref_count = 0;
}
private:
friend class ConstFst<A, U>; // Allow finding narcs_, nstates_ during Write
// States implemented by array *states_ below, arcs by (single) *arcs_.
struct State {
Weight final; // Final weight
Unsigned pos; // Start of state's arcs in *arcs_
Unsigned narcs; // Number of arcs (per state)
Unsigned niepsilons; // # of input epsilons
Unsigned noepsilons; // # of output epsilons
State() : final(Weight::Zero()), niepsilons(0), noepsilons(0) {}
};
// Properties always true of this Fst class
static const uint64 kStaticProperties = kExpanded;
// Current unaligned file format version. The unaligned version was added and
// made the default since the aligned version does not work on pipes.
static const int kFileVersion = 2;
// Current aligned file format version
static const int kAlignedFileVersion = 1;
// Minimum file format version supported
static const int kMinFileVersion = 1;
MappedFile *states_region_; // Mapped file for states
MappedFile *arcs_region_; // Mapped file for arcs
State *states_; // States represenation
A *arcs_; // Arcs representation
StateId nstates_; // Number of states
size_t narcs_; // Number of arcs (per FST)
StateId start_; // Initial state
DISALLOW_COPY_AND_ASSIGN(ConstFstImpl);
};
template <class A, class U>
const uint64 ConstFstImpl<A, U>::kStaticProperties;
template <class A, class U>
const int ConstFstImpl<A, U>::kFileVersion;
template <class A, class U>
const int ConstFstImpl<A, U>::kAlignedFileVersion;
template <class A, class U>
const int ConstFstImpl<A, U>::kMinFileVersion;
template <class A, class U>
ConstFstImpl<A, U>::ConstFstImpl(const Fst<A> &fst) : nstates_(0), narcs_(0) {
string type = "const";
if (sizeof(U) != sizeof(uint32)) {
string size;
Int64ToStr(sizeof(U) * 8, &size);
type += size;
}
SetType(type);
SetInputSymbols(fst.InputSymbols());
SetOutputSymbols(fst.OutputSymbols());
start_ = fst.Start();
// Count # of states and arcs.
for (StateIterator<Fst<A>> siter(fst); !siter.Done(); siter.Next()) {
++nstates_;
StateId s = siter.Value();
for (ArcIterator<Fst<A>> aiter(fst, s); !aiter.Done(); aiter.Next())
++narcs_;
}
states_region_ = MappedFile::Allocate(nstates_ * sizeof(*states_));
arcs_region_ = MappedFile::Allocate(narcs_ * sizeof(*arcs_));
states_ = reinterpret_cast<State *>(states_region_->mutable_data());
arcs_ = reinterpret_cast<A *>(arcs_region_->mutable_data());
size_t pos = 0;
for (StateId s = 0; s < nstates_; ++s) {
states_[s].final = fst.Final(s);
states_[s].pos = pos;
states_[s].narcs = 0;
states_[s].niepsilons = 0;
states_[s].noepsilons = 0;
for (ArcIterator<Fst<A>> aiter(fst, s); !aiter.Done(); aiter.Next()) {
const A &arc = aiter.Value();
++states_[s].narcs;
if (arc.ilabel == 0) ++states_[s].niepsilons;
if (arc.olabel == 0) ++states_[s].noepsilons;
arcs_[pos++] = arc;
}
}
uint64 props = fst.Properties(kMutable, false) ?
fst.Properties(kCopyProperties, true) :
CheckProperties(fst,
kCopyProperties & ~kWeightedCycles & ~kUnweightedCycles,
kCopyProperties);
SetProperties(props | kStaticProperties);
}
template <class A, class U>
ConstFstImpl<A, U> *ConstFstImpl<A, U>::Read(std::istream &strm,
const FstReadOptions &opts) {
ConstFstImpl<A, U> *impl = new ConstFstImpl<A, U>;
FstHeader hdr;
if (!impl->ReadHeader(strm, opts, kMinFileVersion, &hdr)) {
delete impl;
return 0;
}
impl->start_ = hdr.Start();
impl->nstates_ = hdr.NumStates();
impl->narcs_ = hdr.NumArcs();
// Ensures compatibility
if (hdr.Version() == kAlignedFileVersion)
hdr.SetFlags(hdr.GetFlags() | FstHeader::IS_ALIGNED);
if ((hdr.GetFlags() & FstHeader::IS_ALIGNED) && !AlignInput(strm)) {
LOG(ERROR) << "ConstFst::Read: Alignment failed: " << opts.source;
delete impl;
return 0;
}
size_t b = impl->nstates_ * sizeof(typename ConstFstImpl<A, U>::State);
impl->states_region_ =
MappedFile::Map(&strm, opts.mode == FstReadOptions::MAP, opts.source, b);
if (!strm || impl->states_region_ == nullptr) {
LOG(ERROR) << "ConstFst::Read: Read failed: " << opts.source;
delete impl;
return 0;
}
impl->states_ =
reinterpret_cast<State *>(impl->states_region_->mutable_data());
if ((hdr.GetFlags() & FstHeader::IS_ALIGNED) && !AlignInput(strm)) {
LOG(ERROR) << "ConstFst::Read: Alignment failed: " << opts.source;
delete impl;
return 0;
}
b = impl->narcs_ * sizeof(A);
impl->arcs_region_ =
MappedFile::Map(&strm, opts.mode == FstReadOptions::MAP, opts.source, b);
if (!strm || impl->arcs_region_ == nullptr) {
LOG(ERROR) << "ConstFst::Read: Read failed: " << opts.source;
delete impl;
return 0;
}
impl->arcs_ = reinterpret_cast<A *>(impl->arcs_region_->mutable_data());
return impl;
}
// Simple concrete immutable FST. This class attaches interface to
// implementation and handles reference counting, delegating most
// methods to ImplToExpandedFst. The unsigned type U is used to
// represent indices into the arc array (default declared
// in fst-decl.h).
template <class A, class U /* = uint32 */>
class ConstFst : public ImplToExpandedFst<ConstFstImpl<A, U>> {
public:
friend class StateIterator<ConstFst<A, U>>;
friend class ArcIterator<ConstFst<A, U>>;
template <class F, class G>
void friend Cast(const F &, G *);
typedef A Arc;
typedef typename A::StateId StateId;
typedef ConstFstImpl<A, U> Impl;
typedef U Unsigned;
ConstFst() : ImplToExpandedFst<Impl>(std::make_shared<Impl>()) {}
explicit ConstFst(const Fst<A> &fst)
: ImplToExpandedFst<Impl>(std::make_shared<Impl>(fst)) {}
ConstFst(const ConstFst<A, U> &fst, bool safe = false)
: ImplToExpandedFst<Impl>(fst) {}
// Get a copy of this ConstFst. See Fst<>::Copy() for further doc.
ConstFst<A, U> *Copy(bool safe = false) const override {
return new ConstFst<A, U>(*this, safe);
}
// Read a ConstFst from an input stream; return nullptr on error
static ConstFst<A, U> *Read(std::istream &strm, const FstReadOptions &opts) {
Impl *impl = Impl::Read(strm, opts);
return impl ? new ConstFst<A, U>(std::shared_ptr<Impl>(impl)) : nullptr;
}
// Read a ConstFst from a file; return nullptr on error
// Empty filename reads from standard input
static ConstFst<A, U> *Read(const string &filename) {
Impl *impl = ImplToExpandedFst<Impl>::Read(filename);
return impl ? new ConstFst<A, U>(std::shared_ptr<Impl>(impl)) : nullptr;
}
bool Write(std::ostream &strm, const FstWriteOptions &opts) const override {
return WriteFst(*this, strm, opts);
}
bool Write(const string &filename) const override {
return Fst<A>::WriteFile(filename);
}
template <class F>
static bool WriteFst(const F &fst, std::ostream &strm,
const FstWriteOptions &opts);
void InitStateIterator(StateIteratorData<Arc> *data) const override {
GetImpl()->InitStateIterator(data);
}
void InitArcIterator(StateId s, ArcIteratorData<Arc> *data) const override {
GetImpl()->InitArcIterator(s, data);
}
private:
explicit ConstFst(std::shared_ptr<Impl> impl)
: ImplToExpandedFst<Impl>(impl) {}
using ImplToFst<Impl, ExpandedFst<A>>::GetImpl;
// Use overloading to extract the type of the argument.
static const Impl *GetImplIfConstFst(const ConstFst &const_fst) {
return const_fst.GetImpl();
}
// Note that this does not give privileged treatment to subtypes of ConstFst.
template <typename NonConstFst>
static Impl *GetImplIfConstFst(const NonConstFst &fst) {
return nullptr;
}
void operator=(const ConstFst<A, U> &fst); // disallow
};
// Writes Fst in Const format, potentially with a pass over the machine
// before writing to compute number of states and arcs.
//
template <class A, class U>
template <class F>
bool ConstFst<A, U>::WriteFst(const F &fst, std::ostream &strm,
const FstWriteOptions &opts) {
int file_version = opts.align ? ConstFstImpl<A, U>::kAlignedFileVersion
: ConstFstImpl<A, U>::kFileVersion;
size_t num_arcs = -1, num_states = -1;
size_t start_offset = 0;
bool update_header = true;
if (const Impl *impl = GetImplIfConstFst(fst)) {
num_arcs = impl->narcs_;
num_states = impl->nstates_;
update_header = false;
} else if (opts.stream_write || (start_offset = strm.tellp()) == -1) {
// precompute values needed for header when we cannot seek to rewrite it.
num_arcs = 0;
num_states = 0;
for (StateIterator<F> siter(fst); !siter.Done(); siter.Next()) {
num_arcs += fst.NumArcs(siter.Value());
++num_states;
}
update_header = false;
}
FstHeader hdr;
hdr.SetStart(fst.Start());
hdr.SetNumStates(num_states);
hdr.SetNumArcs(num_arcs);
string type = "const";
if (sizeof(U) != sizeof(uint32)) {
string size;
Int64ToStr(8 * sizeof(U), &size);
type += size;
}
uint64 properties = fst.Properties(kCopyProperties, true) |
ConstFstImpl<A, U>::kStaticProperties;
FstImpl<A>::WriteFstHeader(fst, strm, opts, file_version, type, properties,
&hdr);
if (opts.align && !AlignOutput(strm)) {
LOG(ERROR) << "Could not align file during write after header";
return false;
}
size_t pos = 0, states = 0;
typename ConstFstImpl<A, U>::State state;
for (StateIterator<F> siter(fst); !siter.Done(); siter.Next()) {
state.final = fst.Final(siter.Value());
state.pos = pos;
state.narcs = fst.NumArcs(siter.Value());
state.niepsilons = fst.NumInputEpsilons(siter.Value());
state.noepsilons = fst.NumOutputEpsilons(siter.Value());
strm.write(reinterpret_cast<const char *>(&state), sizeof(state));
pos += state.narcs;
++states;
}
hdr.SetNumStates(states);
hdr.SetNumArcs(pos);
if (opts.align && !AlignOutput(strm)) {
LOG(ERROR) << "Could not align file during write after writing states";
}
for (StateIterator<F> siter(fst); !siter.Done(); siter.Next()) {
StateId s = siter.Value();
for (ArcIterator<F> aiter(fst, s); !aiter.Done(); aiter.Next()) {
const A &arc = aiter.Value();
strm.write(reinterpret_cast<const char *>(&arc), sizeof(arc));
}
}
strm.flush();
if (!strm) {
LOG(ERROR) << "ConstFst::WriteFst: write failed: " << opts.source;
return false;
}
if (update_header) {
return FstImpl<A>::UpdateFstHeader(fst, strm, opts, file_version, type,
properties, &hdr, start_offset);
} else {
if (hdr.NumStates() != num_states) {
LOG(ERROR) << "Inconsistent number of states observed during write";
return false;
}
if (hdr.NumArcs() != num_arcs) {
LOG(ERROR) << "Inconsistent number of arcs observed during write";
return false;
}
}
return true;
}
// Specialization for ConstFst; see generic version in fst.h
// for sample usage (but use the ConstFst type!). This version
// should inline.
template <class A, class U>
class StateIterator<ConstFst<A, U>> {
public:
typedef typename A::StateId StateId;
explicit StateIterator(const ConstFst<A, U> &fst)
: nstates_(fst.GetImpl()->NumStates()), s_(0) {}
bool Done() const { return s_ >= nstates_; }
StateId Value() const { return s_; }
void Next() { ++s_; }
void Reset() { s_ = 0; }
private:
StateId nstates_;
StateId s_;
DISALLOW_COPY_AND_ASSIGN(StateIterator);
};
// Specialization for ConstFst; see generic version in fst.h
// for sample usage (but use the ConstFst type!). This version
// should inline.
template <class A, class U>
class ArcIterator<ConstFst<A, U>> {
public:
typedef typename A::StateId StateId;
ArcIterator(const ConstFst<A, U> &fst, StateId s)
: arcs_(fst.GetImpl()->Arcs(s)),
narcs_(fst.GetImpl()->NumArcs(s)),
i_(0) {}
bool Done() const { return i_ >= narcs_; }
const A &Value() const { return arcs_[i_]; }
void Next() { ++i_; }
size_t Position() const { return i_; }
void Reset() { i_ = 0; }
void Seek(size_t a) { i_ = a; }
uint32 Flags() const { return kArcValueFlags; }
void SetFlags(uint32 f, uint32 m) {}
private:
const A *arcs_;
size_t narcs_;
size_t i_;
DISALLOW_COPY_AND_ASSIGN(ArcIterator);
};
// A useful alias when using StdArc.
typedef ConstFst<StdArc> StdConstFst;
} // namespace fst
#endif // FST_LIB_CONST_FST_H_
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