Expose named groups from Pattern

#125
google · Feb 18, 2021 · 2986a5d · 2986a5d
1 parent b7d3531
commit 2986a5d
Show file tree

Hide file tree

Showing 2 changed files with 35 additions and 0 deletions.
diff --git a/java/com/google/re2j/Pattern.java b/java/com/google/re2j/Pattern.java
@@ -7,6 +7,8 @@
 package com.google.re2j;
 
 import java.io.Serializable;
+import java.util.Collections;
+import java.util.Map;
 
 /**
  * A compiled representation of an RE2 regular expression, mimicking the
@@ -269,6 +271,14 @@ public int groupCount() {
     return re2.numberOfCapturingGroups();
   }
 
+  /**
+   * Return a map of the capturing groups in this matcher's pattern, where key is the name and value
+   * is the index of the group in the pattern.
+   */
+  public Map<String, Integer> namedGroups() {
+    return Collections.unmodifiableMap(re2.namedGroups);
+  }
+
   Object readResolve() {
     // The deserialized version will be missing the RE2 instance, so we need to create a new,
     // compiled version.

diff --git a/javatests/com/google/re2j/PatternTest.java b/javatests/com/google/re2j/PatternTest.java
@@ -13,12 +13,15 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
+import com.google.common.collect.ImmutableMap;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 
+import java.util.Collections;
+import java.util.Map;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -39,6 +42,16 @@ public void testCompile() {
     assertEquals(0, p.flags());
   }
 
+  @Test
+  public void testCompileExceptionWithDuplicateGroups() {
+    try {
+      Pattern.compile("(?P<any>.*)(?P<any>.*");
+      fail();
+    } catch (PatternSyntaxException e) {
+      assertEquals("error parsing regexp: duplicate capture group name: `any`", e.getMessage());
+    }
+  }
+
   @Test
   public void testToString() {
     Pattern p = Pattern.compile("abc");
@@ -152,6 +165,18 @@ public void testGroupCount() {
     ApiTestUtils.testGroupCount("(.*)(\\(a\\)b)(.*)a", 3);
   }
 
+  @Test
+  public void testNamedGroups() {
+    assertNamedGroupsEquals(Collections.<String, Integer>emptyMap(), "hello");
+    assertNamedGroupsEquals(Collections.<String, Integer>emptyMap(), "(.*)");
+    assertNamedGroupsEquals(ImmutableMap.of("any", 1), "(?P<any>.*)");
+    assertNamedGroupsEquals(ImmutableMap.of("foo", 1, "bar", 2), "(?P<foo>.*)(?P<bar>.*)");
+  }
+
+  private static void assertNamedGroupsEquals(Map<String, Integer> expected, String pattern) {
+    assertEquals(expected, Pattern.compile(pattern).namedGroups());
+  }
+
   // See https://github.com/google/re2j/issues/93.
   @Test
   public void testIssue93() {