Checking key edit distance of candidate words for gesture scoring.

bug: 8616704
Change-Id: I98c3248877b1e3e722a6c00a2851e543e5fcbe11

native/jni/src/correction.cpp

@@ -23,6 +23,8 @@
 #include "defines.h"
 #include "proximity_info_state.h"
 #include "suggest_utils.h"
+#include "suggest/policyimpl/utils/edit_distance.h"
+#include "suggest/policyimpl/utils/damerau_levenshtein_edit_distance_policy.h"
 
 namespace latinime {
 
@@ -906,50 +908,11 @@ inline static bool isUpperCase(unsigned short c) {
     return totalFreq;
 }
 
-/* Damerau-Levenshtein distance */
-inline static int editDistanceInternal(int *editDistanceTable, const int *before,
-        const int beforeLength, const int *after, const int afterLength) {
-    // dp[li][lo] dp[a][b] = dp[ a * lo + b]
-    int *dp = editDistanceTable;
-    const int li = beforeLength + 1;
-    const int lo = afterLength + 1;
-    for (int i = 0; i < li; ++i) {
-        dp[lo * i] = i;
-    }
-    for (int i = 0; i < lo; ++i) {
-        dp[i] = i;
-    }
-
-    for (int i = 0; i < li - 1; ++i) {
-        for (int j = 0; j < lo - 1; ++j) {
-            const int ci = toBaseLowerCase(before[i]);
-            const int co = toBaseLowerCase(after[j]);
-            const int cost = (ci == co) ? 0 : 1;
-            dp[(i + 1) * lo + (j + 1)] = min(dp[i * lo + (j + 1)] + 1,
-                    min(dp[(i + 1) * lo + j] + 1, dp[i * lo + j] + cost));
-            if (i > 0 && j > 0 && ci == toBaseLowerCase(after[j - 1])
-                    && co == toBaseLowerCase(before[i - 1])) {
-                dp[(i + 1) * lo + (j + 1)] = min(
-                        dp[(i + 1) * lo + (j + 1)], dp[(i - 1) * lo + (j - 1)] + cost);
-            }
-        }
-    }
-
-    if (DEBUG_EDIT_DISTANCE) {
-        AKLOGI("IN = %d, OUT = %d", beforeLength, afterLength);
-        for (int i = 0; i < li; ++i) {
-            for (int j = 0; j < lo; ++j) {
-                AKLOGI("EDIT[%d][%d], %d", i, j, dp[i * lo + j]);
-            }
-        }
-    }
-    return dp[li * lo - 1];
-}
-
 /* static */ int Correction::RankingAlgorithm::editDistance(const int *before,
         const int beforeLength, const int *after, const int afterLength) {
-    int table[(beforeLength + 1) * (afterLength + 1)];
+    const DamerauLevenshteinEditDistancePolicy daemaruLevenshtein(
-    return editDistanceInternal(table, before, beforeLength, after, afterLength);
+            before, beforeLength, after, afterLength);
+    return static_cast<int>(EditDistance::getEditDistance(&daemaruLevenshtein));
 }
 
 

native/jni/src/suggest/policyimpl/utils/damerau_levenshtein_edit_distance_policy.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef LATINIME_DAEMARU_LEVENSHTEIN_EDIT_DISTANCE_POLICY_H
+#define LATINIME_DAEMARU_LEVENSHTEIN_EDIT_DISTANCE_POLICY_H
+
+#include "char_utils.h"
+#include "suggest/policyimpl/utils/edit_distance_policy.h"
+
+namespace latinime {
+
+class DamerauLevenshteinEditDistancePolicy : public EditDistancePolicy {
+ public:
+    DamerauLevenshteinEditDistancePolicy(const int *const string0, const int length0,
+            const int *const string1, const int length1)
+            : mString0(string0), mString0Length(length0), mString1(string1),
+              mString1Length(length1) {}
+    ~DamerauLevenshteinEditDistancePolicy() {}
+
+    AK_FORCE_INLINE float getSubstitutionCost(const int index0, const int index1) const {
+        const int c0 = toBaseLowerCase(mString0[index0]);
+        const int c1 = toBaseLowerCase(mString1[index1]);
+        return (c0 == c1) ? 0.0f : 1.0f;
+    }
+
+    AK_FORCE_INLINE float getDeletionCost(const int index0, const int index1) const {
+        return 1.0f;
+    }
+
+    AK_FORCE_INLINE float getInsertionCost(const int index0, const int index1) const {
+        return 1.0f;
+    }
+
+    AK_FORCE_INLINE bool allowTransposition(const int index0, const int index1) const {
+        const int c0 = toBaseLowerCase(mString0[index0]);
+        const int c1 = toBaseLowerCase(mString1[index1]);
+        if (index0 > 0 && index1 > 0 && c0 == toBaseLowerCase(mString1[index1 - 1])
+                && c1 == toBaseLowerCase(mString0[index0 - 1])) {
+            return true;
+        }
+        return false;
+    }
+
+    AK_FORCE_INLINE float getTranspositionCost(const int index0, const int index1) const {
+        return getSubstitutionCost(index0, index1);
+    }
+
+    AK_FORCE_INLINE int getString0Length() const {
+        return mString0Length;
+    }
+
+    AK_FORCE_INLINE int getString1Length() const {
+        return mString1Length;
+    }
+
+ private:
+    DISALLOW_COPY_AND_ASSIGN (DamerauLevenshteinEditDistancePolicy);
+
+    const int *const mString0;
+    const int mString0Length;
+    const int *const mString1;
+    const int mString1Length;
+};
+} // namespace latinime
+
+#endif  // LATINIME_DAEMARU_LEVENSHTEIN_EDIT_DISTANCE_POLICY_H

native/jni/src/suggest/policyimpl/utils/edit_distance.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef LATINIME_EDIT_DISTANCE_H
+#define LATINIME_EDIT_DISTANCE_H
+
+#include "defines.h"
+#include "suggest/policyimpl/utils/edit_distance_policy.h"
+
+namespace latinime {
+
+class EditDistance {
+ public:
+    // CAVEAT: There may be performance penalty if you need the edit distance as an integer value.
+    AK_FORCE_INLINE static float getEditDistance(const EditDistancePolicy *const policy) {
+        const int beforeLength = policy->getString0Length();
+        const int afterLength = policy->getString1Length();
+        float dp[(beforeLength + 1) * (afterLength + 1)];
+        for (int i = 0; i <= beforeLength; ++i) {
+            dp[(afterLength + 1) * i] = i * policy->getInsertionCost(i - 1, -1);
+        }
+        for (int i = 0; i <= afterLength; ++i) {
+            dp[i] = i * policy->getDeletionCost(-1, i - 1);
+        }
+
+        for (int i = 0; i < beforeLength; ++i) {
+            for (int j = 0; j < afterLength; ++j) {
+                dp[(afterLength + 1) * (i + 1) + (j + 1)] = min(
+                        dp[(afterLength + 1) * i + (j + 1)] + policy->getInsertionCost(i, j),
+                        min(dp[(afterLength + 1) * (i + 1) + j] + policy->getDeletionCost(i, j),
+                                dp[(afterLength + 1) * i + j]
+                                        + policy->getSubstitutionCost(i, j)));
+                if (policy->allowTransposition(i, j)) {
+                    dp[(afterLength + 1) * (i + 1) + (j + 1)] = min(
+                            dp[(afterLength + 1) * (i + 1) + (j + 1)],
+                            dp[(afterLength + 1) * (i - 1) + (j - 1)]
+                                    + policy->getTranspositionCost(i, j));
+                }
+            }
+        }
+        if (DEBUG_EDIT_DISTANCE) {
+            AKLOGI("IN = %d, OUT = %d", beforeLength, afterLength);
+            for (int i = 0; i < beforeLength + 1; ++i) {
+                for (int j = 0; j < afterLength + 1; ++j) {
+                    AKLOGI("EDIT[%d][%d], %f", i, j, dp[(afterLength + 1) * i + j]);
+                }
+            }
+        }
+        return dp[(beforeLength + 1) * (afterLength + 1) - 1];
+    }
+
+ private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(EditDistance);
+};
+} // namespace latinime
+
+#endif  // LATINIME_EDIT_DISTANCE_H

native/jni/src/suggest/policyimpl/utils/edit_distance_policy.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef LATINIME_EDIT_DISTANCE_POLICY_H
+#define LATINIME_EDIT_DISTANCE_POLICY_H
+
+#include "defines.h"
+
+namespace latinime {
+
+class EditDistancePolicy {
+ public:
+    virtual float getSubstitutionCost(const int index0, const int index1) const = 0;
+    virtual float getDeletionCost(const int index0, const int index1) const = 0;
+    virtual float getInsertionCost(const int index0, const int index1) const = 0;
+    virtual bool allowTransposition(const int index0, const int index1) const = 0;
+    virtual float getTranspositionCost(const int index0, const int index1) const = 0;
+    virtual int getString0Length() const = 0;
+    virtual int getString1Length() const = 0;
+
+ protected:
+    EditDistancePolicy() {}
+    virtual ~EditDistancePolicy() {}
+
+ private:
+    DISALLOW_COPY_AND_ASSIGN(EditDistancePolicy);
+};
+} // namespace latinime
+
+#endif  // LATINIME_EDIT_DISTANCE_POLICY_H