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1   /***
2    * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
3    */
4   package net.sourceforge.pmd.cpd;
5   
6   import java.util.ArrayList;
7   import java.util.Collections;
8   import java.util.HashMap;
9   import java.util.HashSet;
10  import java.util.Iterator;
11  import java.util.List;
12  import java.util.Map;
13  import java.util.Set;
14  
15  public class MatchCollector {
16  
17      private MatchAlgorithm ma;
18      private Map startMap = new HashMap();
19      private Map fileMap = new HashMap();
20  
21      public MatchCollector(MatchAlgorithm ma) {
22          this.ma = ma;
23      }
24  
25      public void collect(List marks) {
26          //first get a pairwise collection of all maximal matches
27          for (int i = 0; i < marks.size() - 1; i++) {
28              TokenEntry mark1 = (TokenEntry) marks.get(i);
29              for (int j = i + 1; j < marks.size(); j++) {
30                  TokenEntry mark2 = (TokenEntry) marks.get(j);
31                  int diff = mark1.getIndex() - mark2.getIndex();
32                  if (-diff < ma.getMinimumTileSize()) {
33                      continue;
34                  }
35                  if (hasPreviousDupe(mark1, mark2)) {
36                      continue;
37                  }
38  
39                  // "match too small" check
40                  int dupes = countDuplicateTokens(mark1, mark2);
41                  if (dupes < ma.getMinimumTileSize()) {
42                      continue;
43                  }
44                  // is it still too close together
45                  if (diff + dupes >= 1) {
46                      continue;
47                  }
48                  determineMatch(mark1, mark2, dupes);
49              }
50          }
51      }
52  
53      public List getMatches() {
54          List matchList = new ArrayList(startMap.values());
55          Collections.sort(matchList);
56          Set matchSet = new HashSet();
57          Match.MatchCode matchCode = new Match.MatchCode();
58          for (int i = matchList.size(); i > 1; i--) {
59              Match match1 = (Match) matchList.get(i - 1);
60              TokenEntry mark1 = (TokenEntry) match1.getMarkSet().iterator().next();
61              matchSet.clear();
62              matchSet.add(match1.getMatchCode());
63              for (int j = i - 1; j > 0; j--) {
64                  Match match2 = (Match) matchList.get(j - 1);
65                  if (match1.getTokenCount() != match2.getTokenCount()) {
66                      break;
67                  }
68                  TokenEntry mark2 = null;
69                  for (Iterator iter = match2.getMarkSet().iterator(); iter.hasNext();) {
70                      mark2 = (TokenEntry) iter.next();
71                      if (mark2 != mark1) {
72                          break;
73                      }
74                  }
75                  int dupes = countDuplicateTokens(mark1, mark2);
76                  if (dupes < match1.getTokenCount()) {
77                      break;
78                  }
79                  matchSet.add(match2.getMatchCode());
80                  match1.getMarkSet().addAll(match2.getMarkSet());
81                  matchList.remove(i - 2);
82                  i--;
83              }
84              if (matchSet.size() == 1) {
85                  continue;
86              }
87              //prune the mark set
88              Set pruned = match1.getMarkSet();
89              boolean done = false;
90              ArrayList a1 = new ArrayList(match1.getMarkSet());
91              Collections.sort(a1);
92              for (int outer = 0; outer < a1.size() - 1 && !done; outer++) {
93                  TokenEntry cmark1 = (TokenEntry) a1.get(outer);
94                  for (int inner = outer + 1; inner < a1.size() && !done; inner++) {
95                      TokenEntry cmark2 = (TokenEntry) a1.get(inner);
96                      matchCode.setFirst(cmark1.getIndex());
97                      matchCode.setSecond(cmark2.getIndex());
98                      if (!matchSet.contains(matchCode)) {
99                          if (pruned.size() > 2) {
100                             pruned.remove(cmark2);
101                         }
102                         if (pruned.size() == 2) {
103                             done = true;
104                         }
105                     }
106                 }
107             }
108         }
109         return matchList;
110     }
111 
112     /***
113      * A greedy algorithm for determining non-overlapping matches
114      */
115     private void determineMatch(TokenEntry mark1, TokenEntry mark2, int dupes) {
116         Match match = new Match(dupes, mark1, mark2);
117         String fileKey = mark1.getTokenSrcID() + mark2.getTokenSrcID();
118         List pairMatches = (ArrayList) fileMap.get(fileKey);
119         if (pairMatches == null) {
120             pairMatches = new ArrayList();
121             fileMap.put(fileKey, pairMatches);
122         }
123         boolean add = true;
124         for (int i = 0; i < pairMatches.size(); i++) {
125             Match other = (Match) pairMatches.get(i);
126             if (other.getFirstMark().getIndex() + other.getTokenCount() - mark1.getIndex()
127                     > 0) {
128                 boolean ordered = other.getSecondMark().getIndex() - mark2.getIndex() < 0;
129                 if ((ordered && (other.getEndIndex() - mark2.getIndex() > 0))
130                         || (!ordered && (match.getEndIndex() - other.getSecondMark().getIndex()) > 0)) {
131                     if (other.getTokenCount() >= match.getTokenCount()) {
132                         add = false;
133                         break;
134                     } else {
135                         pairMatches.remove(i);
136                         startMap.remove(other.getMatchCode());
137                     }
138                 }
139             }
140         }
141         if (add) {
142             pairMatches.add(match);
143             startMap.put(match.getMatchCode(), match);
144         }
145     }
146 
147     private boolean hasPreviousDupe(TokenEntry mark1, TokenEntry mark2) {
148         if (mark1.getIndex() == 0) {
149             return false;
150         }
151         return !matchEnded(ma.tokenAt(-1, mark1), ma.tokenAt(-1, mark2));
152     }
153 
154     private int countDuplicateTokens(TokenEntry mark1, TokenEntry mark2) {
155         int index = 0;
156         while (!matchEnded(ma.tokenAt(index, mark1), ma.tokenAt(index, mark2))) {
157             index++;
158         }
159         return index;
160     }
161 
162     private boolean matchEnded(TokenEntry token1, TokenEntry token2) {
163         return token1.getIdentifier() != token2.getIdentifier() || token1 == TokenEntry.EOF || token2 == TokenEntry.EOF;
164     }
165 }