com.github.gumtreediff.utils.SequenceAlgorithms Maven / Gradle / Ivy
The newest version!
/*
* This file is part of GumTree.
*
* GumTree is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GumTree is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with GumTree. If not, see
* Copyright 2011-2015 Floréal Morandat
*/
package com.github.gumtreediff.utils;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.github.gumtreediff.tree.Tree;
public final class SequenceAlgorithms {
private SequenceAlgorithms() {}
/**
* Returns the longest common subsequence between two strings.
*
* @return a list of size 2 int arrays that corresponds
* to match of index in sequence 1 to index in sequence 2.
*/
public static List longestCommonSubsequence(String s0, String s1) {
int[][] lengths = new int[s0.length() + 1][s1.length() + 1];
for (int i = 0; i < s0.length(); i++)
for (int j = 0; j < s1.length(); j++)
if (s0.charAt(i) == (s1.charAt(j)))
lengths[i + 1][j + 1] = lengths[i][j] + 1;
else
lengths[i + 1][j + 1] = Math.max(lengths[i + 1][j], lengths[i][j + 1]);
return extractIndexes(lengths, s0.length(), s1.length());
}
/**
* Returns the hunks of the longest common subsequence between s1 and s2.
* @return the hunks as a list of int arrays of size 4 with start index and end index of sequence 1
* and corresponding start index and end index in sequence 2.
*/
public static List hunks(String s0, String s1) {
List lcs = longestCommonSubsequence(s0 ,s1);
List hunks = new ArrayList();
int inf0 = -1;
int inf1 = -1;
int last0 = -1;
int last1 = -1;
for (int i = 0; i < lcs.size(); i++) {
int[] match = lcs.get(i);
if (inf0 == -1 || inf1 == -1) {
inf0 = match[0];
inf1 = match[1];
} else if (last0 + 1 != match[0] || last1 + 1 != match[1]) {
hunks.add(new int[] {inf0, last0 + 1, inf1, last1 + 1});
inf0 = match[0];
inf1 = match[1];
} else if (i == lcs.size() - 1) {
hunks.add(new int[] {inf0, match[0] + 1, inf1, match[1] + 1});
break;
}
last0 = match[0];
last1 = match[1];
}
return hunks;
}
/**
* Returns the longest common sequence between two strings as a string.
*/
public static String longestCommonSequence(String s1, String s2) {
int start = 0;
int max = 0;
for (int i = 0; i < s1.length(); i++) {
for (int j = 0; j < s2.length(); j++) {
int x = 0;
while (s1.charAt(i + x) == s2.charAt(j + x)) {
x++;
if (((i + x) >= s1.length()) || ((j + x) >= s2.length())) break;
}
if (x > max) {
max = x;
start = i;
}
}
}
return s1.substring(start, (start + max));
}
/**
* Returns the longest common subsequence between the two list of nodes. This version use
* type and label to ensure equality.
*
* @see Tree#hasSameTypeAndLabel(Tree)
* @return a list of size 2 int arrays that corresponds
* to match of index in sequence 1 to index in sequence 2.
*/
public static List longestCommonSubsequenceWithTypeAndLabel(List s0, List s1) {
int[][] lengths = new int[s0.size() + 1][s1.size() + 1];
for (int i = 0; i < s0.size(); i++)
for (int j = 0; j < s1.size(); j++)
if (s0.get(i).hasSameTypeAndLabel(s1.get(j)))
lengths[i + 1][j + 1] = lengths[i][j] + 1;
else
lengths[i + 1][j + 1] = Math.max(lengths[i + 1][j], lengths[i][j + 1]);
return extractIndexes(lengths, s0.size(), s1.size());
}
/**
* Returns the longest common subsequence between the two list of nodes. This version use
* type to ensure equality.
*
* @see Tree#hasSameType(Tree)
* @return a list of size 2 int arrays that corresponds
* to match of index in sequence 1 to index in sequence 2.
*/
public static List longestCommonSubsequenceWithType(List s0, List s1) {
int[][] lengths = new int[s0.size() + 1][s1.size() + 1];
for (int i = 0; i < s0.size(); i++)
for (int j = 0; j < s1.size(); j++)
if (s0.get(i).hasSameType(s1.get(j)))
lengths[i + 1][j + 1] = lengths[i][j] + 1;
else
lengths[i + 1][j + 1] = Math.max(lengths[i + 1][j], lengths[i][j + 1]);
return extractIndexes(lengths, s0.size(), s1.size());
}
/**
* Returns the longest common subsequence between the two list of nodes. This version use
* isomorphism to ensure equality.
*
* @see Tree#isIsomorphicTo(Tree)
* @return a list of size 2 int arrays that corresponds
* to match of index in sequence 1 to index in sequence 2.
*/
public static List longestCommonSubsequenceWithIsomorphism(List s0, List s1) {
int[][] lengths = new int[s0.size() + 1][s1.size() + 1];
for (int i = 0; i < s0.size(); i++)
for (int j = 0; j < s1.size(); j++)
if (s0.get(i).isIsomorphicTo(s1.get(j)))
lengths[i + 1][j + 1] = lengths[i][j] + 1;
else
lengths[i + 1][j + 1] = Math.max(lengths[i + 1][j], lengths[i][j + 1]);
return extractIndexes(lengths, s0.size(), s1.size());
}
/**
* Returns the longest common subsequence between the two list of nodes. This version use
* isomorphism to ensure equality.
*
* @see Tree#isIsoStructuralTo(Tree)
* @return a list of size 2 int arrays that corresponds
* to match of index in sequence 1 to index in sequence 2.
*/
public static List longestCommonSubsequenceWithIsostructure(List s0, List s1) {
int[][] lengths = new int[s0.size() + 1][s1.size() + 1];
for (int i = 0; i < s0.size(); i++)
for (int j = 0; j < s1.size(); j++)
if (s0.get(i).isIsoStructuralTo(s1.get(j)))
lengths[i + 1][j + 1] = lengths[i][j] + 1;
else
lengths[i + 1][j + 1] = Math.max(lengths[i + 1][j], lengths[i][j + 1]);
return extractIndexes(lengths, s0.size(), s1.size());
}
private static List extractIndexes(int[][] lengths, int length1, int length2) {
List indexes = new ArrayList<>();
for (int x = length1, y = length2; x != 0 && y != 0; ) {
if (lengths[x][y] == lengths[x - 1][y]) x--;
else if (lengths[x][y] == lengths[x][y - 1]) y--;
else {
indexes.add(new int[] {x - 1, y - 1});
x--;
y--;
}
}
Collections.reverse(indexes);
return indexes;
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy