Add optimized OUString += literal overload

Change-Id: Ib34196185f90204a71598f2c659c3fddce7a0e4d

3 files changed, 33 insertions, 0 deletions

diff --git a/sal/qa/rtl/strings/test_oustring_concat.cxx b/sal/qa/rtl/strings/test_oustring_concat.cxx
index f02bde560451..977229691702 100644
--- a/sal/qa/rtl/strings/test_oustring_concat.cxx
+++ b/sal/qa/rtl/strings/test_oustring_concat.cxx
@@ -40,12 +40,14 @@ class StringConcat : public CppUnit::TestFixture
 {
 private:
     void checkConcat();
+    void checkConcatAsciiL();
     void checkEnsureCapacity();
     void checkAppend();
     void checkInvalid();
 
 CPPUNIT_TEST_SUITE(StringConcat);
 CPPUNIT_TEST(checkConcat);
+CPPUNIT_TEST(checkConcatAsciiL);
 CPPUNIT_TEST(checkEnsureCapacity);
 CPPUNIT_TEST(checkAppend);
 CPPUNIT_TEST(checkInvalid);
@@ -71,6 +73,12 @@ void test::oustring::StringConcat::checkConcat()
     CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUStringBuffer, OUString > )), typeid( OUStringBuffer( "foo" ) + OUString( "bar" )));
 }
 
+void test::oustring::StringConcat::checkConcatAsciiL()
+{
+    CPPUNIT_ASSERT_EQUAL(OUString("foo"), OUString("foo") += "");
+    CPPUNIT_ASSERT_EQUAL(OUString("foobar"), OUString("foo") += "bar");
+}
+
 void test::oustring::StringConcat::checkEnsureCapacity()
 {
     rtl_uString* str = NULL;
diff --git a/sal/rtl/ustring.cxx b/sal/rtl/ustring.cxx
index de733e86be0d..b31bc2fcddeb 100644
--- a/sal/rtl/ustring.cxx
+++ b/sal/rtl/ustring.cxx
@@ -25,6 +25,8 @@
 
 #include <cassert>
 #include <cstdlib>
+#include <limits>
+#include <stdexcept>
 
 #include <osl/diagnose.h>
 #include <osl/interlck.h>
@@ -595,6 +597,28 @@ void SAL_CALL rtl_uString_newFromCodePoints(
     RTL_LOG_STRING_NEW( *newString );
 }
 
+void rtl_uString_newConcatAsciiL(
+    rtl_uString ** newString, rtl_uString * left, char const * right,
+    sal_Int32 rightLength)
+{
+    assert(newString != nullptr);
+    assert(left != nullptr);
+    assert(right != nullptr);
+    assert(rightLength >= 0);
+    if (left->length > std::numeric_limits<sal_Int32>::max() - rightLength) {
+        throw std::length_error("rtl_uString_newConcatAsciiL");
+    }
+    sal_Int32 n = left->length + rightLength;
+    rtl_uString_assign(newString, left);
+    rtl_uString_ensureCapacity(newString, n);
+    sal_Unicode * p = (*newString)->buffer + (*newString)->length;
+    for (sal_Int32 i = 0; i != rightLength; ++i) {
+        p[i] = static_cast<unsigned char>(right[i]);
+    }
+    (*newString)->buffer[n] = 0;
+    (*newString)->length = n;
+}
+
 /* ======================================================================= */
 
 static int rtl_ImplGetFastUTF8UnicodeLen( const sal_Char* pStr, sal_Int32 nLen, bool * ascii )
diff --git a/sal/util/sal.map b/sal/util/sal.map
index c41ee41ebc7e..e3f920c7e33c 100644
--- a/sal/util/sal.map
+++ b/sal/util/sal.map
@@ -685,6 +685,7 @@ LIBO_UDK_5.0 { # symbols available in >= LibO 5.0
 
 LIBO_UDK_5.1 { # symbols available in >= LibO 5.1
     global:
+        rtl_uString_newConcatAsciiL;
         rtl_uString_newReplaceAllToAsciiL;
         rtl_uString_newReplaceFirstToAsciiL;
 } LIBO_UDK_5.0;