Add Regexp.hashCode and tests. (#79)

Fixes warning about equals() being implemented without hashCode().
google · Oct 23, 2018 · 205f0d2 · 205f0d2
1 parent a7ce289
commit 205f0d2
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diff --git a/java/com/google/re2j/Regexp.java b/java/com/google/re2j/Regexp.java
@@ -278,6 +278,36 @@ int maxCap() {
     return m;
   }
 
+  @Override
+  public int hashCode() {
+    int hashcode = op.hashCode();
+    switch (op) {
+      case END_TEXT:
+        hashcode += 31 * (flags & RE2.WAS_DOLLAR);
+        break;
+      case LITERAL:
+      case CHAR_CLASS:
+        hashcode += 31 * Arrays.hashCode(runes);
+        break;
+      case ALTERNATE:
+      case CONCAT:
+        hashcode += 31 * Arrays.deepHashCode(subs);
+        break;
+      case STAR:
+      case PLUS:
+      case QUEST:
+        hashcode += 31 * (flags & RE2.NON_GREEDY) + 31 * subs[0].hashCode();
+        break;
+      case REPEAT:
+        hashcode += 31 * min + 31 * max + 31 * subs[0].hashCode();
+        break;
+      case CAPTURE:
+        hashcode += 31 * cap + 31 * (name != null ? name.hashCode() : 0) + 31 * subs[0].hashCode();
+        break;
+    }
+    return hashcode;
+  }
+
   // equals() returns true if this and that have identical structure.
   @Override
   public boolean equals(Object that) {

diff --git a/javatests/com/google/re2j/RegexpHashcodeEqualsTest.java b/javatests/com/google/re2j/RegexpHashcodeEqualsTest.java
@@ -0,0 +1,52 @@
+package com.google.re2j;
+
+import com.google.common.truth.Truth;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.Arrays;
+
+@RunWith(Parameterized.class)
+public class RegexpHashcodeEqualsTest {
+  @Parameterized.Parameters
+  public static Iterable<Object[]> testCases() {
+    return Arrays.asList(
+        new Object[][] {
+          {"abc", "abc", true, RE2.POSIX},
+          {"abc", "def", false, RE2.POSIX},
+          {"(abc)", "(a)(b)(c)", false, RE2.POSIX},
+          {"a|$", "a|$", true, RE2.POSIX},
+          {"abc|def", "def|abc", false, RE2.POSIX},
+          {"a?", "b?", false, RE2.POSIX},
+          {"a?", "a?", true, RE2.POSIX},
+          {"a{1,3}", "a{1,3}", true, RE2.POSIX},
+          {"a{2,3}", "a{1,3}", false, RE2.POSIX},
+          {"^((?P<foo>what)a)$", "^((?P<foo>what)a)$", true, RE2.PERL},
+          {"^((?P<foo>what)a)$", "^((?P<bar>what)a)$", false, RE2.PERL},
+        });
+  }
+
+  @Parameterized.Parameter public String a;
+
+  @Parameterized.Parameter(1)
+  public String b;
+
+  @Parameterized.Parameter(2)
+  public boolean areEqual;
+
+  @Parameterized.Parameter(3)
+  public int mode;
+
+  @Test
+  public void testEquals() {
+    Regexp ra = Parser.parse(a, mode);
+    Regexp rb = Parser.parse(b, mode);
+    if (areEqual) {
+      Truth.assertThat(ra).isEqualTo(rb);
+      Truth.assertThat(ra.hashCode()).isEqualTo(rb.hashCode());
+    } else {
+      Truth.assertThat(ra).isNotEqualTo(rb);
+    }
+  }
+}