/usr/include/fst/matcher.h is in libfst-dev 1.5.3+r3-2.
This file is owned by root:root, with mode 0o644.
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// finite-state transducer library.
//
// Classes to allow matching labels leaving FST states.
#ifndef FST_LIB_MATCHER_H_
#define FST_LIB_MATCHER_H_
#include <algorithm>
#include <set>
#include <utility>
#include <fst/mutable-fst.h> // for all internal FST accessors
namespace fst {
// MATCHERS - these can find and iterate through requested labels at
// FST states. In the simplest form, these are just some associative
// map or search keyed on labels. More generally, they may
// implement matching special labels that represent sets of labels
// such as 'sigma' (all), 'rho' (rest), or 'phi' (fail).
// The Matcher interface is:
//
// template <class F>
// class Matcher {
// public:
// typedef F FST;
// typedef F::Arc Arc;
// typedef typename Arc::StateId StateId;
// typedef typename Arc::Label Label;
// typedef typename Arc::Weight Weight;
//
// // Required constructors.
// Matcher(const F &fst, MatchType type);
// // If safe=true, the copy is thread-safe. See Fst<>::Copy()
// // for further doc.
// Matcher(const Matcher &matcher, bool safe = false);
//
// // If safe=true, the copy is thread-safe. See Fst<>::Copy()
// // for further doc.
// Matcher<F> *Copy(bool safe = false) const;
//
// // Returns the match type that can be provided (depending on
// // compatibility of the input FST). It is either
// // the requested match type, MATCH_NONE, or MATCH_UNKNOWN.
// // If 'test' is false, a costly testing is avoided, but
// // MATCH_UNKNOWN may be returned. If 'test' is true,
// // a definite answer is returned, but may involve more costly
// // computation (e.g., visiting the Fst).
// MatchType Type(bool test) const;
// // Specifies the current state.
// void SetState(StateId s);
//
// // This finds matches to a label at the current state.
// // Returns true if a match found. kNoLabel matches any
// // 'non-consuming' transitions, e.g., epsilon transitions,
// // which do not require a matching symbol.
// bool Find(Label label);
// // These iterate through any matches found:
// bool Done() const; // No more matches.
// const A& Value() const; // Current arc (when !Done)
// void Next(); // Advance to next arc (when !Done)
// // Initially and after SetState() the iterator methods
// // have undefined behavior until Find() is called.
//
// // Returns finality of state 's'.
// Weight Final(StateId s) const;
//
// // Indicates preference for being the side used for matching in
// // composition/intersection. If the value is kRequirePriority,
// // then it is manditory that it be used.
// // Calling this method when 's' is not the current state of matcher
// // invalidates the state of the matcher.
// ssize_t Priority(StateId s);
//
// // Return matcher FST.
// const F& GetFst() const;
// // This specifies the known Fst properties as viewed from this
// // matcher. It takes as argument the input Fst's known properties.
// uint64 Properties(uint64 props) const;
// };
//
// MATCHER FLAGS (see also kLookAheadFlags in lookahead-matcher.h)
//
// Matcher needs to be used as the matching side in composition for
// at least one state (has kRequirePriority).
const uint32 kRequireMatch = 0x00000001;
// Flags used for basic matchers (see also lookahead.h).
const uint32 kMatcherFlags = kRequireMatch;
// Matcher priority that is manditory.
const ssize_t kRequirePriority = -1;
// Matcher interface, templated on the Arc definition; used
// for matcher specializations that are returned by the
// InitMatcher Fst method.
template <class A>
class MatcherBase {
public:
typedef A Arc;
typedef typename A::StateId StateId;
typedef typename A::Label Label;
typedef typename A::Weight Weight;
virtual ~MatcherBase() {}
virtual MatcherBase<A> *Copy(bool safe = false) const = 0;
virtual MatchType Type(bool test) const = 0;
void SetState(StateId s) { SetState_(s); }
bool Find(Label label) { return Find_(label); }
bool Done() const { return Done_(); }
const A &Value() const { return Value_(); }
void Next() { Next_(); }
Weight Final(StateId s) const { return Final_(s); }
ssize_t Priority(StateId s) { return Priority_(s); }
virtual const Fst<A> &GetFst() const = 0;
virtual uint64 Properties(uint64 props) const = 0;
virtual uint32 Flags() const { return 0; }
private:
virtual void SetState_(StateId s) = 0;
virtual bool Find_(Label label) = 0;
virtual bool Done_() const = 0;
virtual const A &Value_() const = 0;
virtual void Next_() = 0;
virtual Weight Final_(StateId s) const { return GetFst().Final(s); }
virtual ssize_t Priority_(StateId s) { return GetFst().NumArcs(s); }
};
// A matcher that expects sorted labels on the side to be matched.
// If match_type == MATCH_INPUT, epsilons match the implicit self loop
// Arc(kNoLabel, 0, Weight::One(), current_state) as well as any
// actual epsilon transitions. If match_type == MATCH_OUTPUT, then
// Arc(0, kNoLabel, Weight::One(), current_state) is instead matched.
template <class F>
class SortedMatcher : public MatcherBase<typename F::Arc> {
public:
typedef F FST;
typedef typename F::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
// Labels >= binary_label will be searched for by binary search,
// o.w. linear search is used.
SortedMatcher(const F &fst, MatchType match_type, Label binary_label = 1)
: fst_(fst.Copy()),
s_(kNoStateId),
aiter_(0),
match_type_(match_type),
binary_label_(binary_label),
match_label_(kNoLabel),
narcs_(0),
loop_(kNoLabel, 0, Weight::One(), kNoStateId),
error_(false),
aiter_pool_(1) {
switch (match_type_) {
case MATCH_INPUT:
case MATCH_NONE:
break;
case MATCH_OUTPUT:
std::swap(loop_.ilabel, loop_.olabel);
break;
default:
FSTERROR() << "SortedMatcher: Bad match type";
match_type_ = MATCH_NONE;
error_ = true;
}
}
SortedMatcher(const SortedMatcher<F> &matcher, bool safe = false)
: fst_(matcher.fst_->Copy(safe)),
s_(kNoStateId),
aiter_(0),
match_type_(matcher.match_type_),
binary_label_(matcher.binary_label_),
match_label_(kNoLabel),
narcs_(0),
loop_(matcher.loop_),
error_(matcher.error_),
aiter_pool_(1) {}
~SortedMatcher() override {
Destroy(aiter_, &aiter_pool_);
delete fst_;
}
SortedMatcher<F> *Copy(bool safe = false) const override {
return new SortedMatcher<F>(*this, safe);
}
MatchType Type(bool test) const override {
if (match_type_ == MATCH_NONE) return match_type_;
uint64 true_prop =
match_type_ == MATCH_INPUT ? kILabelSorted : kOLabelSorted;
uint64 false_prop =
match_type_ == MATCH_INPUT ? kNotILabelSorted : kNotOLabelSorted;
uint64 props = fst_->Properties(true_prop | false_prop, test);
if (props & true_prop)
return match_type_;
else if (props & false_prop)
return MATCH_NONE;
else
return MATCH_UNKNOWN;
}
void SetState(StateId s) {
if (s_ == s) return;
s_ = s;
if (match_type_ == MATCH_NONE) {
FSTERROR() << "SortedMatcher: Bad match type";
error_ = true;
}
Destroy(aiter_, &aiter_pool_);
aiter_ = new (&aiter_pool_) ArcIterator<F>(*fst_, s);
aiter_->SetFlags(kArcNoCache, kArcNoCache);
narcs_ = internal::NumArcs(*fst_, s);
loop_.nextstate = s;
}
bool Find(Label match_label) {
exact_match_ = true;
if (error_) {
current_loop_ = false;
match_label_ = kNoLabel;
return false;
}
current_loop_ = match_label == 0;
match_label_ = match_label == kNoLabel ? 0 : match_label;
if (Search()) {
return true;
} else {
return current_loop_;
}
}
// Positions matcher to the first position where inserting
// match_label would maintain the sort order.
void LowerBound(Label match_label) {
exact_match_ = false;
current_loop_ = false;
if (error_) {
match_label_ = kNoLabel;
return;
}
match_label_ = match_label;
Search();
}
// After Find(), returns false if no more exact matches.
// After LowerBound(), returns false if no more arcs.
bool Done() const {
if (current_loop_) return false;
if (aiter_->Done()) return true;
if (!exact_match_) return false;
aiter_->SetFlags(
match_type_ == MATCH_INPUT ? kArcILabelValue : kArcOLabelValue,
kArcValueFlags);
Label label = match_type_ == MATCH_INPUT ? aiter_->Value().ilabel
: aiter_->Value().olabel;
return label != match_label_;
}
const Arc &Value() const {
if (current_loop_) {
return loop_;
}
aiter_->SetFlags(kArcValueFlags, kArcValueFlags);
return aiter_->Value();
}
void Next() {
if (current_loop_)
current_loop_ = false;
else
aiter_->Next();
}
Weight Final(StateId s) const { return internal::Final(*fst_, s); }
ssize_t Priority(StateId s) { return internal::NumArcs(*fst_, s); }
const F &GetFst() const override { return *fst_; }
uint64 Properties(uint64 inprops) const override {
uint64 outprops = inprops;
if (error_) outprops |= kError;
return outprops;
}
size_t Position() const { return aiter_ ? aiter_->Position() : 0; }
private:
void SetState_(StateId s) override { SetState(s); }
bool Find_(Label label) override { return Find(label); }
bool Done_() const override { return Done(); }
const Arc &Value_() const override { return Value(); }
void Next_() override { Next(); }
Weight Final_(StateId s) const override { return Final(s); }
ssize_t Priority_(StateId s) override { return Priority(s); }
bool Search();
const F *fst_;
StateId s_; // Current state
ArcIterator<F> *aiter_; // Iterator for current state
MatchType match_type_; // Type of match to perform
Label binary_label_; // Least label for binary search
Label match_label_; // Current label to be matched
size_t narcs_; // Current state arc count
Arc loop_; // For non-consuming symbols
bool current_loop_; // Current arc is the implicit loop
bool exact_match_; // Exact match or lower bound?
bool error_; // Error encountered
MemoryPool<ArcIterator<F>> aiter_pool_; // Pool of arc iterators
void operator=(const SortedMatcher<F> &); // Disallow
};
// Returns true iff match to match_label_. Positions arc iterator at
// lower bound regardless.
template <class F>
inline bool SortedMatcher<F>::Search() {
aiter_->SetFlags(
match_type_ == MATCH_INPUT ? kArcILabelValue : kArcOLabelValue,
kArcValueFlags);
if (match_label_ >= binary_label_) {
// Binary search for match.
size_t low = 0;
size_t high = narcs_;
while (low < high) {
size_t mid = (low + high) / 2;
aiter_->Seek(mid);
Label label = match_type_ == MATCH_INPUT ? aiter_->Value().ilabel
: aiter_->Value().olabel;
if (label > match_label_) {
high = mid;
} else if (label < match_label_) {
low = mid + 1;
} else {
// find first matching label (when non-determinism)
for (size_t i = mid; i > low; --i) {
aiter_->Seek(i - 1);
label = match_type_ == MATCH_INPUT ? aiter_->Value().ilabel
: aiter_->Value().olabel;
if (label != match_label_) {
aiter_->Seek(i);
return true;
}
}
return true;
}
}
aiter_->Seek(low);
return false;
} else {
// Linear search for match.
for (aiter_->Reset(); !aiter_->Done(); aiter_->Next()) {
Label label = match_type_ == MATCH_INPUT ? aiter_->Value().ilabel
: aiter_->Value().olabel;
if (label == match_label_) {
return true;
}
if (label > match_label_) break;
}
return false;
}
}
// Specifies whether during matching we rewrite both the input and output sides.
enum MatcherRewriteMode {
MATCHER_REWRITE_AUTO = 0, // Rewrites both sides iff acceptor.
MATCHER_REWRITE_ALWAYS,
MATCHER_REWRITE_NEVER
};
// For any requested label that doesn't match at a state, this matcher
// considers all transitions that match the label 'rho_label' (rho =
// 'rest'). Each such rho transition found is returned with the
// rho_label rewritten as the requested label (both sides if an
// acceptor, or if 'rewrite_both' is true and both input and output
// labels of the found transition are 'rho_label'). If 'rho_label' is
// kNoLabel, this special matching is not done. RhoMatcher is
// templated itself on a matcher, which is used to perform the
// underlying matching. By default, the underlying matcher is
// constructed by RhoMatcher. The user can instead pass in this
// object; in that case, RhoMatcher takes its ownership.
template <class M>
class RhoMatcher : public MatcherBase<typename M::Arc> {
public:
typedef typename M::FST FST;
typedef typename M::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
RhoMatcher(const FST &fst, MatchType match_type, Label rho_label = kNoLabel,
MatcherRewriteMode rewrite_mode = MATCHER_REWRITE_AUTO,
M *matcher = 0)
: matcher_(matcher ? matcher : new M(fst, match_type)),
match_type_(match_type),
rho_label_(rho_label),
error_(false),
s_(kNoStateId) {
if (match_type == MATCH_BOTH) {
FSTERROR() << "RhoMatcher: Bad match type";
match_type_ = MATCH_NONE;
error_ = true;
}
if (rho_label == 0) {
FSTERROR() << "RhoMatcher: 0 cannot be used as rho_label";
rho_label_ = kNoLabel;
error_ = true;
}
if (rewrite_mode == MATCHER_REWRITE_AUTO)
rewrite_both_ = fst.Properties(kAcceptor, true);
else if (rewrite_mode == MATCHER_REWRITE_ALWAYS)
rewrite_both_ = true;
else
rewrite_both_ = false;
}
RhoMatcher(const RhoMatcher<M> &matcher, bool safe = false)
: matcher_(new M(*matcher.matcher_, safe)),
match_type_(matcher.match_type_),
rho_label_(matcher.rho_label_),
rewrite_both_(matcher.rewrite_both_),
error_(matcher.error_),
s_(kNoStateId) {}
~RhoMatcher() override { delete matcher_; }
RhoMatcher<M> *Copy(bool safe = false) const override {
return new RhoMatcher<M>(*this, safe);
}
MatchType Type(bool test) const override { return matcher_->Type(test); }
void SetState(StateId s) {
if (s_ == s) return;
s_ = s;
matcher_->SetState(s);
has_rho_ = rho_label_ != kNoLabel;
}
bool Find(Label match_label) {
if (match_label == rho_label_ && rho_label_ != kNoLabel) {
FSTERROR() << "RhoMatcher::Find: bad label (rho)";
error_ = true;
return false;
}
if (matcher_->Find(match_label)) {
rho_match_ = kNoLabel;
return true;
} else if (has_rho_ && match_label != 0 && match_label != kNoLabel &&
(has_rho_ = matcher_->Find(rho_label_))) {
rho_match_ = match_label;
return true;
} else {
return false;
}
}
bool Done() const { return matcher_->Done(); }
const Arc &Value() const {
if (rho_match_ == kNoLabel) {
return matcher_->Value();
} else {
rho_arc_ = matcher_->Value();
if (rewrite_both_) {
if (rho_arc_.ilabel == rho_label_) rho_arc_.ilabel = rho_match_;
if (rho_arc_.olabel == rho_label_) rho_arc_.olabel = rho_match_;
} else if (match_type_ == MATCH_INPUT) {
rho_arc_.ilabel = rho_match_;
} else {
rho_arc_.olabel = rho_match_;
}
return rho_arc_;
}
}
void Next() { matcher_->Next(); }
Weight Final(StateId s) const { return matcher_->Final(s); }
ssize_t Priority(StateId s) {
s_ = s;
matcher_->SetState(s);
has_rho_ = matcher_->Find(rho_label_);
if (has_rho_) {
return kRequirePriority;
} else {
return matcher_->Priority(s);
}
}
const FST &GetFst() const override { return matcher_->GetFst(); }
uint64 Properties(uint64 props) const override;
uint32 Flags() const override {
if (rho_label_ == kNoLabel || match_type_ == MATCH_NONE) {
return matcher_->Flags();
}
return matcher_->Flags() | kRequireMatch;
}
private:
void SetState_(StateId s) override { SetState(s); }
bool Find_(Label label) override { return Find(label); }
bool Done_() const override { return Done(); }
const Arc &Value_() const override { return Value(); }
void Next_() override { Next(); }
Weight Final_(StateId s) const override { return Final(s); }
ssize_t Priority_(StateId s) override { return Priority(s); }
M *matcher_;
MatchType match_type_; // Type of match requested
Label rho_label_; // Label that represents the rho transition
bool rewrite_both_; // Rewrite both sides when both are 'rho_label_'
bool has_rho_; // Are there possibly rhos at the current state?
Label rho_match_; // Current label that matches rho transition
mutable Arc rho_arc_; // Arc to return when rho match
bool error_; // Error encountered
StateId s_; // Current state
void operator=(const RhoMatcher<M> &); // Disallow
};
template <class M>
inline uint64 RhoMatcher<M>::Properties(uint64 inprops) const {
uint64 outprops = matcher_->Properties(inprops);
if (error_) outprops |= kError;
if (match_type_ == MATCH_NONE) {
return outprops;
} else if (match_type_ == MATCH_INPUT) {
if (rewrite_both_) {
return outprops &
~(kODeterministic | kNonODeterministic | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
} else {
return outprops &
~(kODeterministic | kAcceptor | kString | kILabelSorted |
kNotILabelSorted);
}
} else if (match_type_ == MATCH_OUTPUT) {
if (rewrite_both_) {
return outprops &
~(kIDeterministic | kNonIDeterministic | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
} else {
return outprops &
~(kIDeterministic | kAcceptor | kString | kOLabelSorted |
kNotOLabelSorted);
}
} else {
// Shouldn't ever get here.
FSTERROR() << "RhoMatcher: Bad match type: " << match_type_;
return 0;
}
}
// For any requested label, this matcher considers all transitions
// that match the label 'sigma_label' (sigma = "any"), and this in
// additions to transitions with the requested label. Each such sigma
// transition found is returned with the sigma_label rewritten as the
// requested label (both sides if an acceptor, or if 'rewrite_both' is
// true and both input and output labels of the found transition are
// 'sigma_label'). If 'sigma_label' is kNoLabel, this special
// matching is not done. SigmaMatcher is templated itself on a
// matcher, which is used to perform the underlying matching. By
// default, the underlying matcher is constructed by SigmaMatcher.
// The user can instead pass in this object; in that case,
// SigmaMatcher takes its ownership.
template <class M>
class SigmaMatcher : public MatcherBase<typename M::Arc> {
public:
typedef typename M::FST FST;
typedef typename M::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
SigmaMatcher(const FST &fst, MatchType match_type,
Label sigma_label = kNoLabel,
MatcherRewriteMode rewrite_mode = MATCHER_REWRITE_AUTO,
M *matcher = 0)
: matcher_(matcher ? matcher : new M(fst, match_type)),
match_type_(match_type),
sigma_label_(sigma_label),
error_(false),
s_(kNoStateId) {
if (match_type == MATCH_BOTH) {
FSTERROR() << "SigmaMatcher: Bad match type";
match_type_ = MATCH_NONE;
error_ = true;
}
if (sigma_label == 0) {
FSTERROR() << "SigmaMatcher: 0 cannot be used as sigma_label";
sigma_label_ = kNoLabel;
error_ = true;
}
if (rewrite_mode == MATCHER_REWRITE_AUTO)
rewrite_both_ = fst.Properties(kAcceptor, true);
else if (rewrite_mode == MATCHER_REWRITE_ALWAYS)
rewrite_both_ = true;
else
rewrite_both_ = false;
}
SigmaMatcher(const SigmaMatcher<M> &matcher, bool safe = false)
: matcher_(new M(*matcher.matcher_, safe)),
match_type_(matcher.match_type_),
sigma_label_(matcher.sigma_label_),
rewrite_both_(matcher.rewrite_both_),
error_(matcher.error_),
s_(kNoStateId) {}
~SigmaMatcher() override { delete matcher_; }
SigmaMatcher<M> *Copy(bool safe = false) const override {
return new SigmaMatcher<M>(*this, safe);
}
MatchType Type(bool test) const override { return matcher_->Type(test); }
void SetState(StateId s) {
if (s == s_) return;
s_ = s;
matcher_->SetState(s);
has_sigma_ =
sigma_label_ != kNoLabel ? matcher_->Find(sigma_label_) : false;
}
bool Find(Label match_label) {
match_label_ = match_label;
if (match_label == sigma_label_ && sigma_label_ != kNoLabel) {
FSTERROR() << "SigmaMatcher::Find: bad label (sigma)";
error_ = true;
return false;
}
if (matcher_->Find(match_label)) {
sigma_match_ = kNoLabel;
return true;
} else if (has_sigma_ && match_label != 0 && match_label != kNoLabel &&
matcher_->Find(sigma_label_)) {
sigma_match_ = match_label;
return true;
} else {
return false;
}
}
bool Done() const { return matcher_->Done(); }
const Arc &Value() const {
if (sigma_match_ == kNoLabel) {
return matcher_->Value();
} else {
sigma_arc_ = matcher_->Value();
if (rewrite_both_) {
if (sigma_arc_.ilabel == sigma_label_) sigma_arc_.ilabel = sigma_match_;
if (sigma_arc_.olabel == sigma_label_) sigma_arc_.olabel = sigma_match_;
} else if (match_type_ == MATCH_INPUT) {
sigma_arc_.ilabel = sigma_match_;
} else {
sigma_arc_.olabel = sigma_match_;
}
return sigma_arc_;
}
}
void Next() {
matcher_->Next();
if (matcher_->Done() && has_sigma_ && (sigma_match_ == kNoLabel) &&
(match_label_ > 0)) {
matcher_->Find(sigma_label_);
sigma_match_ = match_label_;
}
}
Weight Final(StateId s) const { return matcher_->Final(s); }
ssize_t Priority(StateId s) {
if (sigma_label_ != kNoLabel) {
SetState(s);
return has_sigma_ ? kRequirePriority : matcher_->Priority(s);
} else {
return matcher_->Priority(s);
}
}
const FST &GetFst() const override { return matcher_->GetFst(); }
uint64 Properties(uint64 props) const override;
uint32 Flags() const override {
if (sigma_label_ == kNoLabel || match_type_ == MATCH_NONE)
return matcher_->Flags();
return matcher_->Flags() | kRequireMatch;
}
private:
void SetState_(StateId s) override { SetState(s); }
bool Find_(Label label) override { return Find(label); }
bool Done_() const override { return Done(); }
const Arc &Value_() const override { return Value(); }
void Next_() override { Next(); }
Weight Final_(StateId s) const override { return Final(s); }
ssize_t Priority_(StateId s) override { return Priority(s); }
M *matcher_;
MatchType match_type_; // Type of match requested
Label sigma_label_; // Label that represents the sigma transition
bool rewrite_both_; // Rewrite both sides when both are 'sigma_label_'
bool has_sigma_; // Are there sigmas at the current state?
Label sigma_match_; // Current label that matches sigma transition
mutable Arc sigma_arc_; // Arc to return when sigma match
Label match_label_; // Label being matched
bool error_; // Error encountered
StateId s_; // Current state
void operator=(const SigmaMatcher<M> &); // disallow
};
template <class M>
inline uint64 SigmaMatcher<M>::Properties(uint64 inprops) const {
uint64 outprops = matcher_->Properties(inprops);
if (error_) outprops |= kError;
if (match_type_ == MATCH_NONE) {
return outprops;
} else if (rewrite_both_) {
return outprops &
~(kIDeterministic | kNonIDeterministic | kODeterministic |
kNonODeterministic | kILabelSorted | kNotILabelSorted |
kOLabelSorted | kNotOLabelSorted | kString);
} else if (match_type_ == MATCH_INPUT) {
return outprops &
~(kIDeterministic | kNonIDeterministic | kODeterministic |
kNonODeterministic | kILabelSorted | kNotILabelSorted | kString |
kAcceptor);
} else if (match_type_ == MATCH_OUTPUT) {
return outprops &
~(kIDeterministic | kNonIDeterministic | kODeterministic |
kNonODeterministic | kOLabelSorted | kNotOLabelSorted | kString |
kAcceptor);
} else {
// Shouldn't ever get here.
FSTERROR() << "SigmaMatcher: Bad match type: " << match_type_;
return 0;
}
}
// For any requested label that doesn't match at a state, this matcher
// considers the *unique* transition that matches the label 'phi_label'
// (phi = 'fail'), and recursively looks for a match at its
// destination. When 'phi_loop' is true, if no match is found but a
// phi self-loop is found, then the phi transition found is returned
// with the phi_label rewritten as the requested label (both sides if
// an acceptor, or if 'rewrite_both' is true and both input and output
// labels of the found transition are 'phi_label'). If 'phi_label' is
// kNoLabel, this special matching is not done. PhiMatcher is
// templated itself on a matcher, which is used to perform the
// underlying matching. By default, the underlying matcher is
// constructed by PhiMatcher. The user can instead pass in this
// object; in that case, PhiMatcher takes its ownership.
// Warning: phi non-determinism not supported (for simplicity).
template <class M>
class PhiMatcher : public MatcherBase<typename M::Arc> {
public:
typedef typename M::FST FST;
typedef typename M::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
PhiMatcher(const FST &fst, MatchType match_type, Label phi_label = kNoLabel,
bool phi_loop = true,
MatcherRewriteMode rewrite_mode = MATCHER_REWRITE_AUTO,
M *matcher = 0)
: matcher_(matcher ? matcher : new M(fst, match_type)),
match_type_(match_type),
phi_label_(phi_label),
state_(kNoStateId),
phi_loop_(phi_loop),
error_(false) {
if (match_type == MATCH_BOTH) {
FSTERROR() << "PhiMatcher: Bad match type";
match_type_ = MATCH_NONE;
error_ = true;
}
if (rewrite_mode == MATCHER_REWRITE_AUTO)
rewrite_both_ = fst.Properties(kAcceptor, true);
else if (rewrite_mode == MATCHER_REWRITE_ALWAYS)
rewrite_both_ = true;
else
rewrite_both_ = false;
}
PhiMatcher(const PhiMatcher<M> &matcher, bool safe = false)
: matcher_(new M(*matcher.matcher_, safe)),
match_type_(matcher.match_type_),
phi_label_(matcher.phi_label_),
rewrite_both_(matcher.rewrite_both_),
state_(kNoStateId),
phi_loop_(matcher.phi_loop_),
error_(matcher.error_) {}
~PhiMatcher() override { delete matcher_; }
PhiMatcher<M> *Copy(bool safe = false) const override {
return new PhiMatcher<M>(*this, safe);
}
MatchType Type(bool test) const override { return matcher_->Type(test); }
void SetState(StateId s) {
if (state_ == s) return;
matcher_->SetState(s);
state_ = s;
has_phi_ = phi_label_ != kNoLabel;
}
bool Find(Label match_label);
bool Done() const { return matcher_->Done(); }
const Arc &Value() const {
if ((phi_match_ == kNoLabel) && (phi_weight_ == Weight::One())) {
return matcher_->Value();
} else if (phi_match_ == 0) { // Virtual epsilon loop
phi_arc_ = Arc(kNoLabel, 0, Weight::One(), state_);
if (match_type_ == MATCH_OUTPUT)
std::swap(phi_arc_.ilabel, phi_arc_.olabel);
return phi_arc_;
} else {
phi_arc_ = matcher_->Value();
phi_arc_.weight = Times(phi_weight_, phi_arc_.weight);
if (phi_match_ != kNoLabel) { // Phi loop match
if (rewrite_both_) {
if (phi_arc_.ilabel == phi_label_) phi_arc_.ilabel = phi_match_;
if (phi_arc_.olabel == phi_label_) phi_arc_.olabel = phi_match_;
} else if (match_type_ == MATCH_INPUT) {
phi_arc_.ilabel = phi_match_;
} else {
phi_arc_.olabel = phi_match_;
}
}
return phi_arc_;
}
}
void Next() { matcher_->Next(); }
Weight Final(StateId s) const {
Weight final = matcher_->Final(s);
if (phi_label_ == kNoLabel || final != Weight::Zero()) {
return final;
} else {
final = Weight::One();
StateId state = s;
matcher_->SetState(state);
while (matcher_->Final(state) == Weight::Zero()) {
if (!matcher_->Find(phi_label_ == 0 ? -1 : phi_label_)) break;
final = Times(final, matcher_->Value().weight);
if (state == matcher_->Value().nextstate)
return Weight::Zero(); // Do not follow phi self loops.
state = matcher_->Value().nextstate;
matcher_->SetState(state);
}
final = Times(final, matcher_->Final(state));
return final;
}
}
ssize_t Priority(StateId s) {
if (phi_label_ != kNoLabel) {
matcher_->SetState(s);
const bool has_phi = matcher_->Find(phi_label_ == 0 ? -1 : phi_label_);
return has_phi ? kRequirePriority : matcher_->Priority(s);
} else {
return matcher_->Priority(s);
}
}
const FST &GetFst() const override { return matcher_->GetFst(); }
uint64 Properties(uint64 props) const override;
uint32 Flags() const override {
if (phi_label_ == kNoLabel || match_type_ == MATCH_NONE)
return matcher_->Flags();
return matcher_->Flags() | kRequireMatch;
}
private:
void SetState_(StateId s) override { SetState(s); }
bool Find_(Label label) override { return Find(label); }
bool Done_() const override { return Done(); }
const Arc &Value_() const override { return Value(); }
void Next_() override { Next(); }
Weight Final_(StateId s) const override { return Final(s); }
ssize_t Priority_(StateId s) override { return Priority(s); }
mutable M *matcher_;
MatchType match_type_; // Type of match requested
Label phi_label_; // Label that represents the phi transition
bool rewrite_both_; // Rewrite both sides when both are 'phi_label_'
bool has_phi_; // Are there possibly phis at the current state?
Label phi_match_; // Current label that matches phi loop
mutable Arc phi_arc_; // Arc to return
StateId state_; // State where looking for matches
Weight phi_weight_; // Product of the weights of phi transitions taken
bool phi_loop_; // When true, phi self-loop are allowed and treated
// as rho (required for Aho-Corasick)
bool error_; // Error encountered
void operator=(const PhiMatcher<M> &); // disallow
};
template <class M>
inline bool PhiMatcher<M>::Find(Label match_label) {
if (match_label == phi_label_ && phi_label_ != kNoLabel && phi_label_ != 0) {
FSTERROR() << "PhiMatcher::Find: bad label (phi): " << phi_label_;
error_ = true;
return false;
}
matcher_->SetState(state_);
phi_match_ = kNoLabel;
phi_weight_ = Weight::One();
if (phi_label_ == 0) { // When 'phi_label_ == 0',
if (match_label == kNoLabel) // there are no more true epsilon arcs,
return false;
if (match_label == 0) { // but virtual eps loop need to be returned
if (!matcher_->Find(kNoLabel)) {
return matcher_->Find(0);
} else {
phi_match_ = 0;
return true;
}
}
}
if (!has_phi_ || match_label == 0 || match_label == kNoLabel)
return matcher_->Find(match_label);
StateId state = state_;
while (!matcher_->Find(match_label)) {
// Look for phi transition (if phi_label_ == 0, we need to look
// for -1 to avoid getting the virtual self-loop)
if (!matcher_->Find(phi_label_ == 0 ? -1 : phi_label_)) return false;
if (phi_loop_ && matcher_->Value().nextstate == state) {
phi_match_ = match_label;
return true;
}
phi_weight_ = Times(phi_weight_, matcher_->Value().weight);
state = matcher_->Value().nextstate;
matcher_->Next();
if (!matcher_->Done()) {
FSTERROR() << "PhiMatcher: Phi non-determinism not supported";
error_ = true;
}
matcher_->SetState(state);
}
return true;
}
template <class M>
inline uint64 PhiMatcher<M>::Properties(uint64 inprops) const {
uint64 outprops = matcher_->Properties(inprops);
if (error_) outprops |= kError;
if (match_type_ == MATCH_NONE) {
return outprops;
} else if (match_type_ == MATCH_INPUT) {
if (phi_label_ == 0) {
outprops &= ~kEpsilons | ~kIEpsilons | ~kOEpsilons;
outprops |= kNoEpsilons | kNoIEpsilons;
}
if (rewrite_both_) {
return outprops &
~(kODeterministic | kNonODeterministic | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
} else {
return outprops &
~(kODeterministic | kAcceptor | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
}
} else if (match_type_ == MATCH_OUTPUT) {
if (phi_label_ == 0) {
outprops &= ~kEpsilons | ~kIEpsilons | ~kOEpsilons;
outprops |= kNoEpsilons | kNoOEpsilons;
}
if (rewrite_both_) {
return outprops &
~(kIDeterministic | kNonIDeterministic | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
} else {
return outprops &
~(kIDeterministic | kAcceptor | kString | kILabelSorted |
kNotILabelSorted | kOLabelSorted | kNotOLabelSorted);
}
} else {
// Shouldn't ever get here.
FSTERROR() << "PhiMatcher: Bad match type: " << match_type_;
return 0;
}
}
//
// MULTI-EPS MATCHER FLAGS
//
// Return multi-epsilon arcs for Find(kNoLabel).
const uint32 kMultiEpsList = 0x00000001;
// Return a kNolabel loop for Find(multi_eps).
const uint32 kMultiEpsLoop = 0x00000002;
// MultiEpsMatcher: allows treating multiple non-0 labels as
// non-consuming labels in addition to 0 that is always
// non-consuming. Precise behavior controlled by 'flags' argument. By
// default, the underlying matcher is constructed by
// MultiEpsMatcher. The user can instead pass in this object; in that
// case, MultiEpsMatcher takes its ownership iff 'own_matcher' is
// true.
template <class M>
class MultiEpsMatcher {
public:
typedef typename M::FST FST;
typedef typename M::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
MultiEpsMatcher(const FST &fst, MatchType match_type,
uint32 flags = (kMultiEpsLoop | kMultiEpsList),
M *matcher = 0, bool own_matcher = true)
: matcher_(matcher ? matcher : new M(fst, match_type)),
flags_(flags),
own_matcher_(matcher ? own_matcher : true) {
if (match_type == MATCH_INPUT) {
loop_.ilabel = kNoLabel;
loop_.olabel = 0;
} else {
loop_.ilabel = 0;
loop_.olabel = kNoLabel;
}
loop_.weight = Weight::One();
loop_.nextstate = kNoStateId;
}
MultiEpsMatcher(const MultiEpsMatcher<M> &matcher, bool safe = false)
: matcher_(new M(*matcher.matcher_, safe)),
flags_(matcher.flags_),
own_matcher_(true),
multi_eps_labels_(matcher.multi_eps_labels_),
loop_(matcher.loop_) {
loop_.nextstate = kNoStateId;
}
~MultiEpsMatcher() {
if (own_matcher_) delete matcher_;
}
MultiEpsMatcher<M> *Copy(bool safe = false) const {
return new MultiEpsMatcher<M>(*this, safe);
}
MatchType Type(bool test) const { return matcher_->Type(test); }
void SetState(StateId s) {
matcher_->SetState(s);
loop_.nextstate = s;
}
bool Find(Label match_label);
bool Done() const { return done_; }
const Arc &Value() const { return current_loop_ ? loop_ : matcher_->Value(); }
void Next() {
if (!current_loop_) {
matcher_->Next();
done_ = matcher_->Done();
if (done_ && multi_eps_iter_ != multi_eps_labels_.End()) {
++multi_eps_iter_;
while ((multi_eps_iter_ != multi_eps_labels_.End()) &&
!matcher_->Find(*multi_eps_iter_))
++multi_eps_iter_;
if (multi_eps_iter_ != multi_eps_labels_.End())
done_ = false;
else
done_ = !matcher_->Find(kNoLabel);
}
} else {
done_ = true;
}
}
Weight Final(StateId s) const { return matcher_->Final(s); }
ssize_t Priority(StateId s) { return matcher_->Priority(s); }
const FST &GetFst() const { return matcher_->GetFst(); }
const M *GetMatcher() const { return matcher_; }
uint64 Properties(uint64 props) const { return matcher_->Properties(props); }
uint32 Flags() const { return matcher_->Flags(); }
void AddMultiEpsLabel(Label label) {
if (label == 0) {
FSTERROR() << "MultiEpsMatcher: Bad multi-eps label: 0";
} else {
multi_eps_labels_.Insert(label);
}
}
void RemoveMultiEpsLabel(Label label) {
if (label == 0) {
FSTERROR() << "MultiEpsMatcher: Bad multi-eps label: 0";
} else {
multi_eps_labels_.Erase(label);
}
}
void ClearMultiEpsLabels() { multi_eps_labels_.Clear(); }
private:
M *matcher_;
uint32 flags_;
bool own_matcher_; // Does this class delete the matcher?
// Multi-eps label set
CompactSet<Label, kNoLabel> multi_eps_labels_;
typename CompactSet<Label, kNoLabel>::const_iterator multi_eps_iter_;
bool current_loop_; // Current arc is the implicit loop
mutable Arc loop_; // For non-consuming symbols
bool done_; // Matching done
void operator=(const MultiEpsMatcher<M> &); // Disallow
};
template <class M>
inline bool MultiEpsMatcher<M>::Find(Label match_label) {
multi_eps_iter_ = multi_eps_labels_.End();
current_loop_ = false;
bool ret;
if (match_label == 0) {
ret = matcher_->Find(0);
} else if (match_label == kNoLabel) {
if (flags_ & kMultiEpsList) {
// return all non-consuming arcs (incl. epsilon)
multi_eps_iter_ = multi_eps_labels_.Begin();
while ((multi_eps_iter_ != multi_eps_labels_.End()) &&
!matcher_->Find(*multi_eps_iter_))
++multi_eps_iter_;
if (multi_eps_iter_ != multi_eps_labels_.End())
ret = true;
else
ret = matcher_->Find(kNoLabel);
} else {
// return all epsilon arcs
ret = matcher_->Find(kNoLabel);
}
} else if ((flags_ & kMultiEpsLoop) &&
multi_eps_labels_.Find(match_label) != multi_eps_labels_.End()) {
// return 'implicit' loop
current_loop_ = true;
ret = true;
} else {
ret = matcher_->Find(match_label);
}
done_ = !ret;
return ret;
}
// This class discards any implicit matches (e.g. the implicit epsilon
// self-loops in the SortedMatcher). Matchers are most often used in
// composition/intersection where the implicit matches are needed
// e.g. for epsilon processing. However, if a matcher is simply being
// used to look-up explicit label matches, this class saves the user
// from having to check for and discard the unwanted implicit matches
// themselves.
template <class M>
class ExplicitMatcher : public MatcherBase<typename M::Arc> {
public:
typedef typename M::FST FST;
typedef typename M::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
ExplicitMatcher(const FST &fst, MatchType match_type, M *matcher = 0)
: matcher_(matcher ? matcher : new M(fst, match_type)),
match_type_(match_type),
error_(false) {}
ExplicitMatcher(const ExplicitMatcher<M> &matcher, bool safe = false)
: matcher_(new M(*matcher.matcher_, safe)),
match_type_(matcher.match_type_),
error_(matcher.error_) {}
~ExplicitMatcher() override { delete matcher_; }
ExplicitMatcher<M> *Copy(bool safe = false) const override {
return new ExplicitMatcher<M>(*this, safe);
}
MatchType Type(bool test) const override { return matcher_->Type(test); }
void SetState(StateId s) { matcher_->SetState(s); }
bool Find(Label match_label) {
matcher_->Find(match_label);
CheckArc();
return !Done();
}
bool Done() const { return matcher_->Done(); }
const Arc &Value() const { return matcher_->Value(); }
void Next() {
matcher_->Next();
CheckArc();
}
Weight Final(StateId s) const { return matcher_->Final(s); }
ssize_t Priority(StateId s) { return matcher_->Priority(s); }
const FST &GetFst() const override { return matcher_->GetFst(); }
const M *GetMatcher() const { return matcher_; }
uint64 Properties(uint64 inprops) const override {
return matcher_->Properties(inprops);
}
uint32 Flags() const override { return matcher_->Flags(); }
private:
// Checks current arc if available and explicit.
// If not available, stops. If not explicit, checks next ones.
void CheckArc() {
for (; !matcher_->Done(); matcher_->Next()) {
Label label = match_type_ == MATCH_INPUT ? matcher_->Value().ilabel
: matcher_->Value().olabel;
if (label != kNoLabel) return;
}
}
void SetState_(StateId s) override { SetState(s); }
bool Find_(Label label) override { return Find(label); }
bool Done_() const override { return Done(); }
const Arc &Value_() const override { return Value(); }
void Next_() override { Next(); }
Weight Final_(StateId s) const override { return Final(s); }
ssize_t Priority_(StateId s) override { return Priority(s); }
M *matcher_;
MatchType match_type_; // Type of match requested
bool error_; // Error encountered
void operator=(const ExplicitMatcher<M> &); // disallow
};
// Generic matcher, templated on the FST definition
// - a wrapper around pointer to specific one.
// Here is a typical use: \code
// Matcher<StdFst> matcher(fst, MATCH_INPUT);
// matcher.SetState(state);
// if (matcher.Find(label))
// for (; !matcher.Done(); matcher.Next()) {
// StdArc &arc = matcher.Value();
// ...
// } \endcode
template <class F>
class Matcher {
public:
typedef F FST;
typedef typename F::Arc Arc;
typedef typename Arc::StateId StateId;
typedef typename Arc::Label Label;
typedef typename Arc::Weight Weight;
Matcher(const F &fst, MatchType match_type) {
base_ = fst.InitMatcher(match_type);
if (!base_) base_ = new SortedMatcher<F>(fst, match_type);
}
Matcher(const Matcher<F> &matcher, bool safe = false) {
base_ = matcher.base_->Copy(safe);
}
// Takes ownership of the provided matcher
Matcher(MatcherBase<Arc> *base_matcher) { base_ = base_matcher; }
~Matcher() { delete base_; }
Matcher<F> *Copy(bool safe = false) const {
return new Matcher<F>(*this, safe);
}
MatchType Type(bool test) const { return base_->Type(test); }
void SetState(StateId s) { base_->SetState(s); }
bool Find(Label label) { return base_->Find(label); }
bool Done() const { return base_->Done(); }
const Arc &Value() const { return base_->Value(); }
void Next() { base_->Next(); }
Weight Final(StateId s) const { return base_->Final(s); }
ssize_t Priority(StateId s) { return base_->Priority(s); }
const F &GetFst() const { return static_cast<const F &>(base_->GetFst()); }
uint64 Properties(uint64 props) const { return base_->Properties(props); }
uint32 Flags() const { return base_->Flags() & kMatcherFlags; }
private:
MatcherBase<Arc> *base_;
void operator=(const Matcher<Arc> &); // disallow
};
} // namespace fst
#endif // FST_LIB_MATCHER_H_
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