From 184b82553000a41fd0c90be56fa2f1c1503e2e9e Mon Sep 17 00:00:00 2001
From: tsepez <tsepez@chromium.org>
Date: Mon, 11 Apr 2016 10:56:00 -0700
Subject: Avoid copying in TrimRight() and TrimLeft() if possible.

Make Byte and Wide code identical while at it.

Review URL: https://codereview.chromium.org/1877553002
---
 core/fxcrt/fx_basic_bstring_unittest.cpp | 62 ++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

(limited to 'core/fxcrt/fx_basic_bstring_unittest.cpp')

diff --git a/core/fxcrt/fx_basic_bstring_unittest.cpp b/core/fxcrt/fx_basic_bstring_unittest.cpp
index 73235ddf5f..8c72b2a054 100644
--- a/core/fxcrt/fx_basic_bstring_unittest.cpp
+++ b/core/fxcrt/fx_basic_bstring_unittest.cpp
@@ -505,6 +505,37 @@ TEST(fxcrt, ByteStringTrimRight) {
   EXPECT_EQ("", empty);
 }
 
+TEST(fxcrt, ByteStringTrimRightCopies) {
+  {
+    // With a single reference, no copy takes place.
+    CFX_ByteString fred("  FRED  ");
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimRight();
+    EXPECT_EQ("  FRED", fred);
+    EXPECT_EQ(old_buffer, fred.c_str());
+  }
+  {
+    // With multiple references, we must copy.
+    CFX_ByteString fred("  FRED  ");
+    CFX_ByteString other_fred = fred;
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimRight();
+    EXPECT_EQ("  FRED", fred);
+    EXPECT_EQ("  FRED  ", other_fred);
+    EXPECT_NE(old_buffer, fred.c_str());
+  }
+  {
+    // With multiple references, but no modifications, no copy.
+    CFX_ByteString fred("FRED");
+    CFX_ByteString other_fred = fred;
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimRight();
+    EXPECT_EQ("FRED", fred);
+    EXPECT_EQ("FRED", other_fred);
+    EXPECT_EQ(old_buffer, fred.c_str());
+  }
+}
+
 TEST(fxcrt, ByteStringTrimLeft) {
   CFX_ByteString fred("  FRED  ");
   fred.TrimLeft();
@@ -533,6 +564,37 @@ TEST(fxcrt, ByteStringTrimLeft) {
   EXPECT_EQ("", empty);
 }
 
+TEST(fxcrt, ByteStringTrimLeftCopies) {
+  {
+    // With a single reference, no copy takes place.
+    CFX_ByteString fred("  FRED  ");
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimLeft();
+    EXPECT_EQ("FRED  ", fred);
+    EXPECT_EQ(old_buffer, fred.c_str());
+  }
+  {
+    // With multiple references, we must copy.
+    CFX_ByteString fred("  FRED  ");
+    CFX_ByteString other_fred = fred;
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimLeft();
+    EXPECT_EQ("FRED  ", fred);
+    EXPECT_EQ("  FRED  ", other_fred);
+    EXPECT_NE(old_buffer, fred.c_str());
+  }
+  {
+    // With multiple references, but no modifications, no copy.
+    CFX_ByteString fred("FRED");
+    CFX_ByteString other_fred = fred;
+    const FX_CHAR* old_buffer = fred.c_str();
+    fred.TrimLeft();
+    EXPECT_EQ("FRED", fred);
+    EXPECT_EQ("FRED", other_fred);
+    EXPECT_EQ(old_buffer, fred.c_str());
+  }
+}
+
 TEST(fxcrt, ByteStringCNotNull) {
   CFX_ByteStringC string3("abc");
   CFX_ByteStringC string6("abcdef");
-- 
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