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// lexicographic-weight.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: rws@google.com (Richard Sproat)
//
// \file
// Lexicographic weight set and associated semiring operation definitions.
//
// A lexicographic weight is a sequence of weights, each of which must have the
// path property and Times() must be (strongly) cancellative
// (for all a,b,c != Zero(): Times(c, a) = Times(c, b) => a = b,
// Times(a, c) = Times(b, c) => a = b).
// The + operation on two weights a and b is the lexicographically
// prior of a and b.
#ifndef FST_LIB_LEXICOGRAPHIC_WEIGHT_H__
#define FST_LIB_LEXICOGRAPHIC_WEIGHT_H__
#include <string>
#include <fst/pair-weight.h>
#include <fst/weight.h>
namespace fst {
template<class W1, class W2>
class LexicographicWeight : public PairWeight<W1, W2> {
public:
using PairWeight<W1, W2>::Value1;
using PairWeight<W1, W2>::Value2;
using PairWeight<W1, W2>::SetValue1;
using PairWeight<W1, W2>::SetValue2;
using PairWeight<W1, W2>::Zero;
using PairWeight<W1, W2>::One;
using PairWeight<W1, W2>::NoWeight;
using PairWeight<W1, W2>::Quantize;
using PairWeight<W1, W2>::Reverse;
typedef LexicographicWeight<typename W1::ReverseWeight,
typename W2::ReverseWeight>
ReverseWeight;
LexicographicWeight() {}
LexicographicWeight(const PairWeight<W1, W2>& w)
: PairWeight<W1, W2>(w) {}
LexicographicWeight(W1 w1, W2 w2) : PairWeight<W1, W2>(w1, w2) {
uint64 props = kPath;
if ((W1::Properties() & props) != props) {
FSTERROR() << "LexicographicWeight must "
<< "have the path property: " << W1::Type();
SetValue1(W1::NoWeight());
}
if ((W2::Properties() & props) != props) {
FSTERROR() << "LexicographicWeight must "
<< "have the path property: " << W2::Type();
SetValue2(W2::NoWeight());
}
}
static const LexicographicWeight<W1, W2> &Zero() {
static const LexicographicWeight<W1, W2> zero(PairWeight<W1, W2>::Zero());
return zero;
}
static const LexicographicWeight<W1, W2> &One() {
static const LexicographicWeight<W1, W2> one(PairWeight<W1, W2>::One());
return one;
}
static const LexicographicWeight<W1, W2> &NoWeight() {
static const LexicographicWeight<W1, W2> no_weight(
PairWeight<W1, W2>::NoWeight());
return no_weight;
}
static const string &Type() {
static const string type = W1::Type() + "_LT_" + W2::Type();
return type;
}
bool Member() const {
if (!Value1().Member() || !Value2().Member()) return false;
// Lexicographic weights cannot mix zeroes and non-zeroes.
if (Value1() == W1::Zero() && Value2() == W2::Zero()) return true;
if (Value1() != W1::Zero() && Value2() != W2::Zero()) return true;
return false;
}
LexicographicWeight<W1, W2> Quantize(float delta = kDelta) const {
return PairWeight<W1, W2>::Quantize();
}
ReverseWeight Reverse() const {
return PairWeight<W1, W2>::Reverse();
}
static uint64 Properties() {
uint64 props1 = W1::Properties();
uint64 props2 = W2::Properties();
return props1 & props2 & (kLeftSemiring | kRightSemiring | kPath |
kIdempotent | kCommutative);
}
};
template <class W1, class W2>
inline LexicographicWeight<W1, W2> Plus(const LexicographicWeight<W1, W2> &w,
const LexicographicWeight<W1, W2> &v) {
if (!w.Member() || !v.Member())
return LexicographicWeight<W1, W2>::NoWeight();
NaturalLess<W1> less1;
NaturalLess<W2> less2;
if (less1(w.Value1(), v.Value1())) return w;
if (less1(v.Value1(), w.Value1())) return v;
if (less2(w.Value2(), v.Value2())) return w;
if (less2(v.Value2(), w.Value2())) return v;
return w;
}
template <class W1, class W2>
inline LexicographicWeight<W1, W2> Times(const LexicographicWeight<W1, W2> &w,
const LexicographicWeight<W1, W2> &v) {
return LexicographicWeight<W1, W2>(Times(w.Value1(), v.Value1()),
Times(w.Value2(), v.Value2()));
}
template <class W1, class W2>
inline LexicographicWeight<W1, W2> Divide(const LexicographicWeight<W1, W2> &w,
const LexicographicWeight<W1, W2> &v,
DivideType typ = DIVIDE_ANY) {
return LexicographicWeight<W1, W2>(Divide(w.Value1(), v.Value1(), typ),
Divide(w.Value2(), v.Value2(), typ));
}
} // namespace fst
#endif // FST_LIB_LEXICOGRAPHIC_WEIGHT_H__
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