blob: 179dc2cea845891aa127dd917381942b2551b88e (
plain) (
tree)
|
|
// arcfilter.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.
//
// Copyright 2005-2010 Google, Inc.
// Author: riley@google.com (Michael Riley)
//
// \file
// Function objects to restrict which arcs are traversed in an FST.
#ifndef FST_LIB_ARCFILTER_H__
#define FST_LIB_ARCFILTER_H__
#include <fst/fst.h>
#include <fst/util.h>
namespace fst {
// True for all arcs.
template <class A>
class AnyArcFilter {
public:
bool operator()(const A &arc) const { return true; }
};
// True for (input/output) epsilon arcs.
template <class A>
class EpsilonArcFilter {
public:
bool operator()(const A &arc) const {
return arc.ilabel == 0 && arc.olabel == 0;
}
};
// True for input epsilon arcs.
template <class A>
class InputEpsilonArcFilter {
public:
bool operator()(const A &arc) const {
return arc.ilabel == 0;
}
};
// True for output epsilon arcs.
template <class A>
class OutputEpsilonArcFilter {
public:
bool operator()(const A &arc) const {
return arc.olabel == 0;
}
};
// True if specified labels match (don't match) when keep_match is
// true (false).
template <class A>
class MultiLabelArcFilter {
public:
typedef typename A::Label Label;
MultiLabelArcFilter(bool match_input = true, bool keep_match = true)
: match_input_(match_input),
keep_match_(keep_match) {}
bool operator()(const A &arc) const {
Label label = match_input_ ? arc.ilabel : arc.olabel;
bool match = labels_.Find(label) != labels_.End();
return keep_match_ ? match : !match;
}
void AddLabel(Label label) {
labels_.Insert(label);
}
private:
CompactSet<Label, kNoLabel> labels_;
bool match_input_;
bool keep_match_;
};
} // namespace fst
#endif // FST_LIB_ARCFILTER_H__
|