From d545762e334f7589e5c1c77d174589c60ce0af39 Mon Sep 17 00:00:00 2001
From: Ben Yu <yujige@gmail.com>
Date: Wed, 6 Dec 2023 18:59:01 -0800
Subject: [PATCH] Substring.Match.contentEquals() as cheaper
 toString().equals()

---
 .../main/java/com/google/mu/util/Substring.java   | 10 ++++++++++
 .../java/com/google/mu/util/SubstringTest.java    | 15 +++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/mug/src/main/java/com/google/mu/util/Substring.java b/mug/src/main/java/com/google/mu/util/Substring.java
index 04c3ba07f4..bd2809c198 100644
--- a/mug/src/main/java/com/google/mu/util/Substring.java
+++ b/mug/src/main/java/com/google/mu/util/Substring.java
@@ -2511,6 +2511,16 @@ public int index() {
       return startIndex;
     }
 
+    /**
+     * Equivalent to {@code toString().equals(str)} but without copying the characters into a
+     * temporary string.
+     *
+     * @since 7.1
+     */
+    public boolean contentEquals(String str) {
+      return str.length() == length() && context.startsWith(str, startIndex);
+    }
+
     /**
      * Returns true if this match starts with the given {@code prefix}.
      *
diff --git a/mug/src/test/java/com/google/mu/util/SubstringTest.java b/mug/src/test/java/com/google/mu/util/SubstringTest.java
index 4b6529a691..8e9b31c83a 100644
--- a/mug/src/test/java/com/google/mu/util/SubstringTest.java
+++ b/mug/src/test/java/com/google/mu/util/SubstringTest.java
@@ -3802,6 +3802,21 @@ public void splitAfterDelimiter() {
         .isEmpty();
   }
 
+  @Test
+  public void match_contentEquals_false() {
+    Substring.Match match = first("bar").in("foobarbaz").get();
+    assertThat(match.contentEquals("barb")).isFalse();
+    assertThat(match.contentEquals("obar")).isFalse();
+    assertThat(match.contentEquals("ba")).isFalse();
+    assertThat(match.contentEquals("ar")).isFalse();
+  }
+
+  @Test
+  public void match_contentEquals_true() {
+    Substring.Match match = first("bar").in("foobarbaz").get();
+    assertThat(match.contentEquals("bar")).isTrue();
+  }
+
   @Test
   public void match_startsWith_false() {
     Substring.Match match = first("bar").in("foobarbaz").get();