1 /*
2  * Copyright (C) 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef LATINIME_EDIT_DISTANCE_H
18 #define LATINIME_EDIT_DISTANCE_H
19 
20 #include <algorithm>
21 
22 #include "defines.h"
23 #include "suggest/policyimpl/utils/edit_distance_policy.h"
24 
25 namespace latinime {
26 
27 class EditDistance {
28  public:
29     // CAVEAT: There may be performance penalty if you need the edit distance as an integer value.
getEditDistance(const EditDistancePolicy * const policy)30     AK_FORCE_INLINE static float getEditDistance(const EditDistancePolicy *const policy) {
31         const int beforeLength = policy->getString0Length();
32         const int afterLength = policy->getString1Length();
33         float dp[(beforeLength + 1) * (afterLength + 1)];
34         for (int i = 0; i <= beforeLength; ++i) {
35             dp[(afterLength + 1) * i] = i * policy->getInsertionCost(i - 1, -1);
36         }
37         for (int i = 0; i <= afterLength; ++i) {
38             dp[i] = i * policy->getDeletionCost(-1, i - 1);
39         }
40 
41         for (int i = 0; i < beforeLength; ++i) {
42             for (int j = 0; j < afterLength; ++j) {
43                 dp[(afterLength + 1) * (i + 1) + (j + 1)] = std::min(
44                         dp[(afterLength + 1) * i + (j + 1)] + policy->getInsertionCost(i, j),
45                         std::min(
46                                 dp[(afterLength + 1) * (i + 1) + j] + policy->getDeletionCost(i, j),
47                                 dp[(afterLength + 1) * i + j] + policy->getSubstitutionCost(i, j)));
48                 if (policy->allowTransposition(i, j)) {
49                     dp[(afterLength + 1) * (i + 1) + (j + 1)] = std::min(
50                             dp[(afterLength + 1) * (i + 1) + (j + 1)],
51                             dp[(afterLength + 1) * (i - 1) + (j - 1)]
52                                     + policy->getTranspositionCost(i, j));
53                 }
54             }
55         }
56         if (DEBUG_EDIT_DISTANCE) {
57             AKLOGI("IN = %d, OUT = %d", beforeLength, afterLength);
58             for (int i = 0; i < beforeLength + 1; ++i) {
59                 for (int j = 0; j < afterLength + 1; ++j) {
60                     AKLOGI("EDIT[%d][%d], %f", i, j, dp[(afterLength + 1) * i + j]);
61                 }
62             }
63         }
64         return dp[(beforeLength + 1) * (afterLength + 1) - 1];
65     }
66 
dumpEditDistance10ForDebug(const float * const editDistanceTable,const int editDistanceTableWidth,const int outputLength)67     AK_FORCE_INLINE static void dumpEditDistance10ForDebug(const float *const editDistanceTable,
68             const int editDistanceTableWidth, const int outputLength) {
69         if (DEBUG_DICT) {
70             AKLOGI("EditDistanceTable");
71             for (int i = 0; i <= 10; ++i) {
72                 float c[11];
73                 for (int j = 0; j <= 10; ++j) {
74                     if (j < editDistanceTableWidth + 1 && i < outputLength + 1) {
75                         c[j] = (editDistanceTable + i * (editDistanceTableWidth + 1))[j];
76                     } else {
77                         c[j] = -1.0f;
78                     }
79                 }
80                 AKLOGI("[ %f, %f, %f, %f, %f, %f, %f, %f, %f, %f, %f ]",
81                         c[0], c[1], c[2], c[3], c[4], c[5], c[6], c[7], c[8], c[9], c[10]);
82                 (void)c; // To suppress compiler warning
83             }
84         }
85     }
86 
87  private:
88     DISALLOW_IMPLICIT_CONSTRUCTORS(EditDistance);
89 };
90 } // namespace latinime
91 
92 #endif  // LATINIME_EDIT_DISTANCE_H
93