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      1 // product-weight.h
      2 
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //     http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 //
     15 // Copyright 2005-2010 Google, Inc.
     16 // Author: riley (at) google.com (Michael Riley)
     17 //
     18 // \file
     19 // Product weight set and associated semiring operation definitions.
     20 
     21 #ifndef FST_LIB_PRODUCT_WEIGHT_H__
     22 #define FST_LIB_PRODUCT_WEIGHT_H__
     23 
     24 #include <stack>
     25 #include <string>
     26 
     27 #include <fst/pair-weight.h>
     28 #include <fst/weight.h>
     29 
     30 
     31 namespace fst {
     32 
     33 // Product semiring: W1 * W2
     34 template<class W1, class W2>
     35 class ProductWeight : public PairWeight<W1, W2> {
     36  public:
     37   using PairWeight<W1, W2>::Zero;
     38   using PairWeight<W1, W2>::One;
     39   using PairWeight<W1, W2>::NoWeight;
     40   using PairWeight<W1, W2>::Quantize;
     41   using PairWeight<W1, W2>::Reverse;
     42 
     43   typedef ProductWeight<typename W1::ReverseWeight, typename W2::ReverseWeight>
     44   ReverseWeight;
     45 
     46   ProductWeight() {}
     47 
     48   ProductWeight(const PairWeight<W1, W2>& w) : PairWeight<W1, W2>(w) {}
     49 
     50   ProductWeight(W1 w1, W2 w2) : PairWeight<W1, W2>(w1, w2) {}
     51 
     52   static const ProductWeight<W1, W2> &Zero() {
     53     static const ProductWeight<W1, W2> zero(PairWeight<W1, W2>::Zero());
     54     return zero;
     55   }
     56 
     57   static const ProductWeight<W1, W2> &One() {
     58     static const ProductWeight<W1, W2> one(PairWeight<W1, W2>::One());
     59     return one;
     60   }
     61 
     62   static const ProductWeight<W1, W2> &NoWeight() {
     63     static const ProductWeight<W1, W2> no_weight(
     64         PairWeight<W1, W2>::NoWeight());
     65     return no_weight;
     66   }
     67 
     68   static const string &Type() {
     69     static const string type = W1::Type() + "_X_" + W2::Type();
     70     return type;
     71   }
     72 
     73   static uint64 Properties() {
     74     uint64 props1 = W1::Properties();
     75     uint64 props2 = W2::Properties();
     76     return props1 & props2 & (kLeftSemiring | kRightSemiring |
     77                               kCommutative | kIdempotent);
     78   }
     79 
     80   ProductWeight<W1, W2> Quantize(float delta = kDelta) const {
     81     return PairWeight<W1, W2>::Quantize(delta);
     82   }
     83 
     84   ReverseWeight Reverse() const {
     85     return PairWeight<W1, W2>::Reverse();
     86   }
     87 
     88 
     89 };
     90 
     91 template <class W1, class W2>
     92 inline ProductWeight<W1, W2> Plus(const ProductWeight<W1, W2> &w,
     93                                   const ProductWeight<W1, W2> &v) {
     94   return ProductWeight<W1, W2>(Plus(w.Value1(), v.Value1()),
     95                                Plus(w.Value2(), v.Value2()));
     96 }
     97 
     98 template <class W1, class W2>
     99 inline ProductWeight<W1, W2> Times(const ProductWeight<W1, W2> &w,
    100                                    const ProductWeight<W1, W2> &v) {
    101   return ProductWeight<W1, W2>(Times(w.Value1(), v.Value1()),
    102                                Times(w.Value2(), v.Value2()));
    103 }
    104 
    105 template <class W1, class W2>
    106 inline ProductWeight<W1, W2> Divide(const ProductWeight<W1, W2> &w,
    107                                     const ProductWeight<W1, W2> &v,
    108                                     DivideType typ = DIVIDE_ANY) {
    109   return ProductWeight<W1, W2>(Divide(w.Value1(), v.Value1(), typ),
    110                                Divide(w.Value2(), v.Value2(), typ));
    111 }
    112 
    113 }  // namespace fst
    114 
    115 #endif  // FST_LIB_PRODUCT_WEIGHT_H__
    116