CFX_ByteString::Reserve(), ReleaseBuffer() fixes.

Also identical fixes for CFX_WideString.

Reserve() on an empty string would not actually reserve a
buffer.  Currently unused, but there are places where this
would really help.

ReleaseBuffer() would rarely return memory to the system, since
it would short-circuit thinking it could operate in place.  Tune
the algorithm slightly so that we hold on when the savings is
small.

Bounds check release buffer args rather than just asserting.
Add tests for all of these.

Review URL: https://codereview.chromium.org/1916303004

1 files changed, 77 insertions, 0 deletions

diff --git a/core/fxcrt/fx_basic_bstring_unittest.cpp b/core/fxcrt/fx_basic_bstring_unittest.cpp
index ea7e17f1f1..087c264940 100644
--- a/core/fxcrt/fx_basic_bstring_unittest.cpp
+++ b/core/fxcrt/fx_basic_bstring_unittest.cpp
@@ -624,6 +624,83 @@ TEST(fxcrt, ByteStringTrimLeftCopies) {
   }
 }
 
+TEST(fxcrt, ByteStringReserve) {
+  {
+    CFX_ByteString str;
+    str.Reserve(6);
+    const FX_CHAR* old_buffer = str.c_str();
+    str += "ABCDEF";
+    EXPECT_EQ(old_buffer, str.c_str());
+    str += "Blah Blah Blah Blah Blah Blah";
+    EXPECT_NE(old_buffer, str.c_str());
+  }
+  {
+    CFX_ByteString str("A");
+    str.Reserve(6);
+    const FX_CHAR* old_buffer = str.c_str();
+    str += "BCDEF";
+    EXPECT_EQ(old_buffer, str.c_str());
+    str += "Blah Blah Blah Blah Blah Blah";
+    EXPECT_NE(old_buffer, str.c_str());
+  }
+}
+
+TEST(fxcrt, ByteStringGetBuffer) {
+  {
+    CFX_ByteString str;
+    FX_CHAR* buffer = str.GetBuffer(12);
+    strcpy(buffer, "clams");
+    str.ReleaseBuffer();
+    EXPECT_EQ("clams", str);
+  }
+  {
+    CFX_ByteString str("cl");
+    FX_CHAR* buffer = str.GetBuffer(12);
+    strcpy(buffer + 2, "ams");
+    str.ReleaseBuffer();
+    EXPECT_EQ("clams", str);
+  }
+}
+
+TEST(fxcrt, ByteStringReleaseBuffer) {
+  {
+    CFX_ByteString str;
+    str.Reserve(12);
+    str += "clams";
+    const FX_CHAR* old_buffer = str.c_str();
+    str.ReleaseBuffer(4);
+    EXPECT_EQ(old_buffer, str.c_str());
+    EXPECT_EQ("clam", str);
+  }
+  {
+    CFX_ByteString str("c");
+    str.Reserve(12);
+    str += "lams";
+    const FX_CHAR* old_buffer = str.c_str();
+    str.ReleaseBuffer(4);
+    EXPECT_EQ(old_buffer, str.c_str());
+    EXPECT_EQ("clam", str);
+  }
+  {
+    CFX_ByteString str;
+    str.Reserve(200);
+    str += "clams";
+    const FX_CHAR* old_buffer = str.c_str();
+    str.ReleaseBuffer(4);
+    EXPECT_NE(old_buffer, str.c_str());
+    EXPECT_EQ("clam", str);
+  }
+  {
+    CFX_ByteString str("c");
+    str.Reserve(200);
+    str += "lams";
+    const FX_CHAR* old_buffer = str.c_str();
+    str.ReleaseBuffer(4);
+    EXPECT_NE(old_buffer, str.c_str());
+    EXPECT_EQ("clam", str);
+  }
+}
+
 TEST(fxcrt, ByteStringCNotNull) {
   CFX_ByteStringC string3("abc");
   CFX_ByteStringC string6("abcdef");