/usr/include/fst/extensions/pdt/compose.h is in libfst-dev 1.6.3-2.
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// finite-state transducer library.
//
// Composes a PDT and an FST.
#ifndef FST_EXTENSIONS_PDT_COMPOSE_H_
#define FST_EXTENSIONS_PDT_COMPOSE_H_
#include <list>
#include <fst/extensions/pdt/pdt.h>
#include <fst/compose.h>
namespace fst {
// Returns paren arcs for Find(kNoLabel).
constexpr uint32 kParenList = 0x00000001;
// Returns a kNolabel loop for Find(paren).
constexpr uint32 kParenLoop = 0x00000002;
// This class is a matcher that treats parens as multi-epsilon labels.
// It is most efficient if the parens are in a range non-overlapping with
// the non-paren labels.
template <class F>
class ParenMatcher {
public:
using FST = F;
using M = SortedMatcher<FST>;
using Arc = typename FST::Arc;
using Label = typename Arc::Label;
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
ParenMatcher(const FST &fst, MatchType match_type,
uint32 flags = (kParenLoop | kParenList))
: matcher_(fst, match_type), match_type_(match_type), flags_(flags) {
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;
}
ParenMatcher(const ParenMatcher<FST> &matcher, bool safe = false)
: matcher_(matcher.matcher_, safe),
match_type_(matcher.match_type_),
flags_(matcher.flags_),
open_parens_(matcher.open_parens_),
close_parens_(matcher.close_parens_),
loop_(matcher.loop_) {
loop_.nextstate = kNoStateId;
}
ParenMatcher<FST> *Copy(bool safe = false) const {
return new ParenMatcher<FST>(*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 paren_loop_ ? loop_ : matcher_.Value(); }
void Next();
Weight Final(StateId s) { return matcher_.Final(s); }
ssize_t Priority(StateId s) { return matcher_.Priority(s); }
const FST &GetFst() const { return matcher_.GetFst(); }
uint64 Properties(uint64 props) const { return matcher_.Properties(props); }
uint32 Flags() const { return matcher_.Flags(); }
void AddOpenParen(Label label) {
if (label == 0) {
FSTERROR() << "ParenMatcher: Bad open paren label: 0";
} else {
open_parens_.Insert(label);
}
}
void AddCloseParen(Label label) {
if (label == 0) {
FSTERROR() << "ParenMatcher: Bad close paren label: 0";
} else {
close_parens_.Insert(label);
}
}
void RemoveOpenParen(Label label) {
if (label == 0) {
FSTERROR() << "ParenMatcher: Bad open paren label: 0";
} else {
open_parens_.Erase(label);
}
}
void RemoveCloseParen(Label label) {
if (label == 0) {
FSTERROR() << "ParenMatcher: Bad close paren label: 0";
} else {
close_parens_.Erase(label);
}
}
void ClearOpenParens() { open_parens_.Clear(); }
void ClearCloseParens() { close_parens_.Clear(); }
bool IsOpenParen(Label label) const { return open_parens_.Member(label); }
bool IsCloseParen(Label label) const { return close_parens_.Member(label); }
private:
// Advances matcher to next open paren, returning true if it exists.
bool NextOpenParen();
// Advances matcher to next close paren, returning true if it exists.
bool NextCloseParen();
M matcher_;
MatchType match_type_; // Type of match to perform.
uint32 flags_;
// Open paren label set.
CompactSet<Label, kNoLabel> open_parens_;
// Close paren label set.
CompactSet<Label, kNoLabel> close_parens_;
bool open_paren_list_; // Matching open paren list?
bool close_paren_list_; // Matching close paren list?
bool paren_loop_; // Current arc is the implicit paren loop?
mutable Arc loop_; // For non-consuming symbols.
bool done_; // Matching done?
ParenMatcher &operator=(const ParenMatcher &) = delete;
};
template <class FST>
inline bool ParenMatcher<FST>::Find(Label match_label) {
open_paren_list_ = false;
close_paren_list_ = false;
paren_loop_ = false;
done_ = false;
// Returns all parenthesis arcs.
if (match_label == kNoLabel && (flags_ & kParenList)) {
if (open_parens_.LowerBound() != kNoLabel) {
matcher_.LowerBound(open_parens_.LowerBound());
open_paren_list_ = NextOpenParen();
if (open_paren_list_) return true;
}
if (close_parens_.LowerBound() != kNoLabel) {
matcher_.LowerBound(close_parens_.LowerBound());
close_paren_list_ = NextCloseParen();
if (close_paren_list_) return true;
}
}
// Returns the implicit paren loop.
if (match_label > 0 && (flags_ & kParenLoop) &&
(IsOpenParen(match_label) || IsCloseParen(match_label))) {
paren_loop_ = true;
return true;
}
// Returns all other labels.
if (matcher_.Find(match_label)) return true;
done_ = true;
return false;
}
template <class FST>
inline void ParenMatcher<FST>::Next() {
if (paren_loop_) {
paren_loop_ = false;
done_ = true;
} else if (open_paren_list_) {
matcher_.Next();
open_paren_list_ = NextOpenParen();
if (open_paren_list_) return;
if (close_parens_.LowerBound() != kNoLabel) {
matcher_.LowerBound(close_parens_.LowerBound());
close_paren_list_ = NextCloseParen();
if (close_paren_list_) return;
}
done_ = !matcher_.Find(kNoLabel);
} else if (close_paren_list_) {
matcher_.Next();
close_paren_list_ = NextCloseParen();
if (close_paren_list_) return;
done_ = !matcher_.Find(kNoLabel);
} else {
matcher_.Next();
done_ = matcher_.Done();
}
}
// Advances matcher to next open paren, returning true if it exists.
template <class FST>
inline bool ParenMatcher<FST>::NextOpenParen() {
for (; !matcher_.Done(); matcher_.Next()) {
Label label = match_type_ == MATCH_INPUT ? matcher_.Value().ilabel
: matcher_.Value().olabel;
if (label > open_parens_.UpperBound()) return false;
if (IsOpenParen(label)) return true;
}
return false;
}
// Advances matcher to next close paren, returning true if it exists.
template <class FST>
inline bool ParenMatcher<FST>::NextCloseParen() {
for (; !matcher_.Done(); matcher_.Next()) {
Label label = match_type_ == MATCH_INPUT ? matcher_.Value().ilabel
: matcher_.Value().olabel;
if (label > close_parens_.UpperBound()) return false;
if (IsCloseParen(label)) return true;
}
return false;
}
template <class Filter>
class ParenFilter {
public:
using FST1 = typename Filter::FST1;
using FST2 = typename Filter::FST2;
using Arc = typename Filter::Arc;
using Label = typename Arc::Label;
using StateId = typename Arc::StateId;
using Weight = typename Arc::Weight;
using Matcher1 = typename Filter::Matcher1;
using Matcher2 = typename Filter::Matcher2;
using StackId = StateId;
using ParenStack = PdtStack<StackId, Label>;
using FilterState1 = typename Filter::FilterState;
using FilterState2 = IntegerFilterState<StackId>;
using FilterState = PairFilterState<FilterState1, FilterState2>;
ParenFilter(const FST1 &fst1, const FST2 &fst2, Matcher1 *matcher1 = nullptr,
Matcher2 *matcher2 = nullptr,
const std::vector<std::pair<Label, Label>> *parens = nullptr,
bool expand = false, bool keep_parens = true)
: filter_(fst1, fst2, matcher1, matcher2),
parens_(parens ? *parens : std::vector<std::pair<Label, Label>>()),
expand_(expand),
keep_parens_(keep_parens),
fs_(FilterState::NoState()),
stack_(parens_),
paren_id_(-1) {
if (parens) {
for (const auto &pair : *parens) {
parens_.push_back(pair);
GetMatcher1()->AddOpenParen(pair.first);
GetMatcher2()->AddOpenParen(pair.first);
if (!expand_) {
GetMatcher1()->AddCloseParen(pair.second);
GetMatcher2()->AddCloseParen(pair.second);
}
}
}
}
ParenFilter(const ParenFilter &filter, bool safe = false)
: filter_(filter.filter_, safe),
parens_(filter.parens_),
expand_(filter.expand_),
keep_parens_(filter.keep_parens_),
fs_(FilterState::NoState()),
stack_(filter.parens_),
paren_id_(-1) {}
FilterState Start() const {
return FilterState(filter_.Start(), FilterState2(0));
}
void SetState(StateId s1, StateId s2, const FilterState &fs) {
fs_ = fs;
filter_.SetState(s1, s2, fs_.GetState1());
if (!expand_) return;
ssize_t paren_id = stack_.Top(fs.GetState2().GetState());
if (paren_id != paren_id_) {
if (paren_id_ != -1) {
GetMatcher1()->RemoveCloseParen(parens_[paren_id_].second);
GetMatcher2()->RemoveCloseParen(parens_[paren_id_].second);
}
paren_id_ = paren_id;
if (paren_id_ != -1) {
GetMatcher1()->AddCloseParen(parens_[paren_id_].second);
GetMatcher2()->AddCloseParen(parens_[paren_id_].second);
}
}
}
FilterState FilterArc(Arc *arc1, Arc *arc2) const {
const auto fs1 = filter_.FilterArc(arc1, arc2);
const auto &fs2 = fs_.GetState2();
if (fs1 == FilterState1::NoState()) return FilterState::NoState();
if (arc1->olabel == kNoLabel && arc2->ilabel) { // arc2 parentheses.
if (keep_parens_) {
arc1->ilabel = arc2->ilabel;
} else if (arc2->ilabel) {
arc2->olabel = arc1->ilabel;
}
return FilterParen(arc2->ilabel, fs1, fs2);
} else if (arc2->ilabel == kNoLabel && arc1->olabel) { // arc1 parentheses.
if (keep_parens_) {
arc2->olabel = arc1->olabel;
} else {
arc1->ilabel = arc2->olabel;
}
return FilterParen(arc1->olabel, fs1, fs2);
} else {
return FilterState(fs1, fs2);
}
}
void FilterFinal(Weight *w1, Weight *w2) const {
if (fs_.GetState2().GetState() != 0) *w1 = Weight::Zero();
filter_.FilterFinal(w1, w2);
}
// Returns respective matchers; ownership stays with filter.
Matcher1 *GetMatcher1() { return filter_.GetMatcher1(); }
Matcher2 *GetMatcher2() { return filter_.GetMatcher2(); }
uint64 Properties(uint64 iprops) const {
return filter_.Properties(iprops) & kILabelInvariantProperties &
kOLabelInvariantProperties;
}
private:
const FilterState FilterParen(Label label, const FilterState1 &fs1,
const FilterState2 &fs2) const {
if (!expand_) return FilterState(fs1, fs2);
const auto stack_id = stack_.Find(fs2.GetState(), label);
if (stack_id < 0) {
return FilterState::NoState();
} else {
return FilterState(fs1, FilterState2(stack_id));
}
}
Filter filter_;
std::vector<std::pair<Label, Label>> parens_;
bool expand_; // Expands to FST?
bool keep_parens_; // Retains parentheses in output?
FilterState fs_; // Current filter state.
mutable ParenStack stack_;
ssize_t paren_id_;
};
// Class to setup composition options for PDT composition. Default is to take
// the PDT as the first composition argument.
template <class Arc, bool left_pdt = true>
class PdtComposeFstOptions
: public ComposeFstOptions<
Arc, ParenMatcher<Fst<Arc>>,
ParenFilter<AltSequenceComposeFilter<ParenMatcher<Fst<Arc>>>>> {
public:
using Label = typename Arc::Label;
using PdtMatcher = ParenMatcher<Fst<Arc>>;
using PdtFilter = ParenFilter<AltSequenceComposeFilter<PdtMatcher>>;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::matcher1;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::matcher2;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::filter;
PdtComposeFstOptions(const Fst<Arc> &ifst1,
const std::vector<std::pair<Label, Label>> &parens,
const Fst<Arc> &ifst2, bool expand = false,
bool keep_parens = true) {
matcher1 = new PdtMatcher(ifst1, MATCH_OUTPUT, kParenList);
matcher2 = new PdtMatcher(ifst2, MATCH_INPUT, kParenLoop);
filter = new PdtFilter(ifst1, ifst2, matcher1, matcher2, &parens, expand,
keep_parens);
}
};
// Class to setup composition options for PDT with FST composition.
// Specialization is for the FST as the first composition argument.
template <class Arc>
class PdtComposeFstOptions<Arc, false>
: public ComposeFstOptions<
Arc, ParenMatcher<Fst<Arc>>,
ParenFilter<SequenceComposeFilter<ParenMatcher<Fst<Arc>>>>> {
public:
using Label = typename Arc::Label;
using PdtMatcher = ParenMatcher<Fst<Arc>>;
using PdtFilter = ParenFilter<SequenceComposeFilter<PdtMatcher>>;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::matcher1;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::matcher2;
using ComposeFstOptions<Arc, PdtMatcher, PdtFilter>::filter;
PdtComposeFstOptions(const Fst<Arc> &ifst1, const Fst<Arc> &ifst2,
const std::vector<std::pair<Label, Label>> &parens,
bool expand = false, bool keep_parens = true) {
matcher1 = new PdtMatcher(ifst1, MATCH_OUTPUT, kParenLoop);
matcher2 = new PdtMatcher(ifst2, MATCH_INPUT, kParenList);
filter = new PdtFilter(ifst1, ifst2, matcher1, matcher2, &parens, expand,
keep_parens);
}
};
enum PdtComposeFilter {
PAREN_FILTER, // Bar-Hillel construction; keeps parentheses.
EXPAND_FILTER, // Bar-Hillel + expansion; removes parentheses.
EXPAND_PAREN_FILTER, // Bar-Hillel + expansion; keeps parentheses.
};
struct PdtComposeOptions {
bool connect; // Connect output?
PdtComposeFilter filter_type; // Pre-defined filter to use.
explicit PdtComposeOptions(bool connect = true,
PdtComposeFilter filter_type = PAREN_FILTER)
: connect(connect), filter_type(filter_type) {}
};
// Composes pushdown transducer (PDT) encoded as an FST (1st arg) and an FST
// (2nd arg) with the result also a PDT encoded as an FST (3rd arg). In the
// PDTs, some transitions are labeled with open or close parentheses. To be
// interpreted as a PDT, the parens must balance on a path (see PdtExpand()).
// The open-close parenthesis label pairs are passed using the parens argument.
template <class Arc>
void Compose(const Fst<Arc> &ifst1,
const std::vector<
std::pair<typename Arc::Label, typename Arc::Label>> &parens,
const Fst<Arc> &ifst2, MutableFst<Arc> *ofst,
const PdtComposeOptions &opts = PdtComposeOptions()) {
bool expand = opts.filter_type != PAREN_FILTER;
bool keep_parens = opts.filter_type != EXPAND_FILTER;
PdtComposeFstOptions<Arc, true> copts(ifst1, parens, ifst2, expand,
keep_parens);
copts.gc_limit = 0;
*ofst = ComposeFst<Arc>(ifst1, ifst2, copts);
if (opts.connect) Connect(ofst);
}
// Composes an FST (1st arg) and pushdown transducer (PDT) encoded as an FST
// (2nd arg) with the result also a PDT encoded as an FST (3rd arg). In the
// PDTs, some transitions are labeled with open or close parentheses. To be
// interpreted as a PDT, the parens must balance on a path (see ExpandFst()).
// The open-close parenthesis label pairs are passed using the parens argument.
template <class Arc>
void Compose(const Fst<Arc> &ifst1, const Fst<Arc> &ifst2,
const std::vector<
std::pair<typename Arc::Label, typename Arc::Label>> &parens,
MutableFst<Arc> *ofst,
const PdtComposeOptions &opts = PdtComposeOptions()) {
bool expand = opts.filter_type != PAREN_FILTER;
bool keep_parens = opts.filter_type != EXPAND_FILTER;
PdtComposeFstOptions<Arc, false> copts(ifst1, ifst2, parens, expand,
keep_parens);
copts.gc_limit = 0;
*ofst = ComposeFst<Arc>(ifst1, ifst2, copts);
if (opts.connect) Connect(ofst);
}
} // namespace fst
#endif // FST_EXTENSIONS_PDT_COMPOSE_H_
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