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// sparse-power-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: krr@google.com (Kasturi Rangan Raghavan)
// Inspiration: allauzen@google.com (Cyril Allauzen)
//
// \file
// Cartesian power weight semiring operation definitions.
// Uses SparseTupleWeight as underlying representation.
#ifndef FST_LIB_SPARSE_POWER_WEIGHT_H__
#define FST_LIB_SPARSE_POWER_WEIGHT_H__
#include<string>
#include <fst/sparse-tuple-weight.h>
#include <fst/weight.h>
namespace fst {
// Below SparseTupleWeight*Mapper are used in conjunction with
// SparseTupleWeightMap to compute the respective semiring operations
template<class W, class K>
struct SparseTupleWeightPlusMapper {
W Map(const K& k, const W& v1, const W& v2) const {
return Plus(v1, v2);
}
};
template<class W, class K>
struct SparseTupleWeightTimesMapper {
W Map(const K& k, const W& v1, const W& v2) const {
return Times(v1, v2);
}
};
template<class W, class K>
struct SparseTupleWeightDivideMapper {
SparseTupleWeightDivideMapper(DivideType divide_type) {
divide_type_ = divide_type;
}
W Map(const K& k, const W& v1, const W& v2) const {
return Divide(v1, v2, divide_type_);
}
DivideType divide_type_;
};
template<class W, class K>
struct SparseTupleWeightApproxMapper {
SparseTupleWeightApproxMapper(float delta) { delta_ = delta; }
W Map(const K& k, const W& v1, const W& v2) const {
return ApproxEqual(v1, v2, delta_) ? W::One() : W::Zero();
}
float delta_;
};
// Sparse cartesian power semiring: W ^ n
// Forms:
// - a left semimodule when W is a left semiring,
// - a right semimodule when W is a right semiring,
// - a bisemimodule when W is a semiring,
// the free semimodule of rank n over W
// The Times operation is overloaded to provide the
// left and right scalar products.
// K is the key value type. kNoKey(-1) is reserved for internal use
template <class W, class K = int>
class SparsePowerWeight : public SparseTupleWeight<W, K> {
public:
using SparseTupleWeight<W, K>::Zero;
using SparseTupleWeight<W, K>::One;
using SparseTupleWeight<W, K>::NoWeight;
using SparseTupleWeight<W, K>::Quantize;
using SparseTupleWeight<W, K>::Reverse;
typedef SparsePowerWeight<typename W::ReverseWeight, K> ReverseWeight;
SparsePowerWeight() {}
SparsePowerWeight(const SparseTupleWeight<W, K> &w) :
SparseTupleWeight<W, K>(w) { }
template <class Iterator>
SparsePowerWeight(Iterator begin, Iterator end) :
SparseTupleWeight<W, K>(begin, end) { }
SparsePowerWeight(const K &key, const W &w) :
SparseTupleWeight<W, K>(key, w) { }
static const SparsePowerWeight<W, K> &Zero() {
static const SparsePowerWeight<W, K> zero(SparseTupleWeight<W, K>::Zero());
return zero;
}
static const SparsePowerWeight<W, K> &One() {
static const SparsePowerWeight<W, K> one(SparseTupleWeight<W, K>::One());
return one;
}
static const SparsePowerWeight<W, K> &NoWeight() {
static const SparsePowerWeight<W, K> no_weight(
SparseTupleWeight<W, K>::NoWeight());
return no_weight;
}
// Overide this: Overwrite the Type method to reflect the key type
// if using non-default key type.
static const string &Type() {
static string type;
if(type.empty()) {
type = W::Type() + "_^n";
if(sizeof(K) != sizeof(uint32)) {
string size;
Int64ToStr(8 * sizeof(K), &size);
type += "_" + size;
}
}
return type;
}
static uint64 Properties() {
uint64 props = W::Properties();
return props & (kLeftSemiring | kRightSemiring |
kCommutative | kIdempotent);
}
SparsePowerWeight<W, K> Quantize(float delta = kDelta) const {
return SparseTupleWeight<W, K>::Quantize(delta);
}
ReverseWeight Reverse() const {
return SparseTupleWeight<W, K>::Reverse();
}
};
// Semimodule plus operation
template <class W, class K>
inline SparsePowerWeight<W, K> Plus(const SparsePowerWeight<W, K> &w1,
const SparsePowerWeight<W, K> &w2) {
SparsePowerWeight<W, K> ret;
SparseTupleWeightPlusMapper<W, K> operator_mapper;
SparseTupleWeightMap(&ret, w1, w2, operator_mapper);
return ret;
}
// Semimodule times operation
template <class W, class K>
inline SparsePowerWeight<W, K> Times(const SparsePowerWeight<W, K> &w1,
const SparsePowerWeight<W, K> &w2) {
SparsePowerWeight<W, K> ret;
SparseTupleWeightTimesMapper<W, K> operator_mapper;
SparseTupleWeightMap(&ret, w1, w2, operator_mapper);
return ret;
}
// Semimodule divide operation
template <class W, class K>
inline SparsePowerWeight<W, K> Divide(const SparsePowerWeight<W, K> &w1,
const SparsePowerWeight<W, K> &w2,
DivideType type = DIVIDE_ANY) {
SparsePowerWeight<W, K> ret;
SparseTupleWeightDivideMapper<W, K> operator_mapper(type);
SparseTupleWeightMap(&ret, w1, w2, operator_mapper);
return ret;
}
// Semimodule dot product
template <class W, class K>
inline const W& DotProduct(const SparsePowerWeight<W, K> &w1,
const SparsePowerWeight<W, K> &w2) {
const SparsePowerWeight<W, K>& product = Times(w1, w2);
W ret(W::Zero());
for (SparseTupleWeightIterator<W, K> it(product); !it.Done(); it.Next()) {
ret = Plus(ret, it.Value().second);
}
return ret;
}
template <class W, class K>
inline bool ApproxEqual(const SparsePowerWeight<W, K> &w1,
const SparsePowerWeight<W, K> &w2,
float delta = kDelta) {
SparseTupleWeight<W, K> ret;
SparseTupleWeightApproxMapper<W, K> operator_mapper(kDelta);
SparseTupleWeightMap(&ret, w1, w2, operator_mapper);
return ret == SparsePowerWeight<W, K>::One();
}
template <class W, class K>
inline SparsePowerWeight<W, K> Times(const W &k,
const SparsePowerWeight<W, K> &w2) {
SparsePowerWeight<W, K> w1(k);
return Times(w1, w2);
}
template <class W, class K>
inline SparsePowerWeight<W, K> Times(const SparsePowerWeight<W, K> &w1,
const W &k) {
SparsePowerWeight<W, K> w2(k);
return Times(w1, w2);
}
template <class W, class K>
inline SparsePowerWeight<W, K> Divide(const SparsePowerWeight<W, K> &w1,
const W &k,
DivideType divide_type = DIVIDE_ANY) {
SparsePowerWeight<W, K> w2(k);
return Divide(w1, w2, divide_type);
}
} // namespace fst
#endif // FST_LIB_SPARSE_POWER_WEIGHT_H__
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