Added new flag Pattern.LONGEST_MATCH to allow changing hard-coded "lo…

…ngest=false" in Pattern.compile()
google · Dec 5, 2019 · 1c00a62 · 1c00a62
1 parent 2953c0d
commit 1c00a62
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Showing 2 changed files with 26 additions and 3 deletions.
diff --git a/java/com/google/re2j/Pattern.java b/java/com/google/re2j/Pattern.java
@@ -37,6 +37,11 @@ public final class Pattern implements Serializable {
    */
   public static final int DISABLE_UNICODE_GROUPS = 8;
 
+  /**
+   * Flag: matches longest possible string.
+   */
+  public static final int LONGEST_MATCH = 16;
+
   // The pattern string at construction time.
   private final String pattern;
 
@@ -117,10 +122,11 @@ public static Pattern compile(String regex, int flags) {
     if ((flags & MULTILINE) != 0) {
       flregex = "(?m)" + flregex;
     }
-    if ((flags & ~(MULTILINE | DOTALL | CASE_INSENSITIVE | DISABLE_UNICODE_GROUPS)) != 0) {
+    if ((flags & ~(MULTILINE | DOTALL | CASE_INSENSITIVE | DISABLE_UNICODE_GROUPS | LONGEST_MATCH))
+        != 0) {
       throw new IllegalArgumentException(
           "Flags should only be a combination "
-              + "of MULTILINE, DOTALL, CASE_INSENSITIVE, DISABLE_UNICODE_GROUPS");
+              + "of MULTILINE, DOTALL, CASE_INSENSITIVE, DISABLE_UNICODE_GROUPS, LONGEST_MATCH");
     }
     return compile(flregex, regex, flags);
   }
@@ -133,7 +139,8 @@ private static Pattern compile(String flregex, String regex, int flags) {
     if ((flags & DISABLE_UNICODE_GROUPS) != 0) {
       re2Flags &= ~RE2.UNICODE_GROUPS;
     }
-    return new Pattern(regex, flags, RE2.compileImpl(flregex, re2Flags, /*longest=*/ false));
+    return new Pattern(
+        regex, flags, RE2.compileImpl(flregex, re2Flags, (flags & LONGEST_MATCH) != 0));
   }
 
   /**

diff --git a/javatests/com/google/re2j/MatcherTest.java b/javatests/com/google/re2j/MatcherTest.java
@@ -468,4 +468,20 @@ private String appendReplacement(Matcher m, String replacement) {
     m.appendReplacement(b, replacement);
     return b.toString();
   }
+
+  @Test
+  public void testPatternLongestMatch() {
+    final String pattern = "(?:a+)|(?:a+ b+)";
+    final String text = "xxx aaa bbb yyy";
+    {
+      final Matcher matcher = Pattern.compile(pattern).matcher(text);
+      assertEquals(true, matcher.find());
+      assertEquals("aaa", text.substring(matcher.start(), matcher.end()));
+    }
+    {
+      final Matcher matcher = Pattern.compile(pattern, Pattern.LONGEST_MATCH).matcher(text);
+      assertEquals(true, matcher.find());
+      assertEquals("aaa bbb", text.substring(matcher.start(), matcher.end()));
+    }
+  }
 }