Make UTF16ToASCII and UTF16TOUTF8 take a StringPiece

base/strings/utf_string_conversions.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/utf_string_conversions.h"
 
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversion_utils.h"
 
@@ skipping 55 matching lines @@
 bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
   if (IsStringASCII(StringPiece(src, src_len))) {
     output->assign(src, src + src_len);
     return true;
   } else {
     PrepareForUTF16Or32Output(src, src_len, output);
     return ConvertUnicode(src, src_len, output);
   }
 }
 
-std::wstring UTF8ToWide(const StringPiece& utf8) {
+std::wstring UTF8ToWide(StringPiece utf8) {
   if (IsStringASCII(utf8)) {
     return std::wstring(utf8.begin(), utf8.end());
   }
 
   std::wstring ret;
   PrepareForUTF16Or32Output(utf8.data(), utf8.length(), &ret);
   ConvertUnicode(utf8.data(), utf8.length(), &ret);
   return ret;
 }
 
@@ skipping 59 matching lines @@
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
   if (IsStringASCII(StringPiece(src, src_len))) {
     output->assign(src, src + src_len);
     return true;
   } else {
     PrepareForUTF16Or32Output(src, src_len, output);
     return ConvertUnicode(src, src_len, output);
   }
 }
 
-string16 UTF8ToUTF16(const StringPiece& utf8) {
+string16 UTF8ToUTF16(StringPiece utf8) {
   if (IsStringASCII(utf8)) {
     return string16(utf8.begin(), utf8.end());
   }
 
   string16 ret;
   PrepareForUTF16Or32Output(utf8.data(), utf8.length(), &ret);
   // Ignore the success flag of this call, it will do the best it can for
   // invalid input, which is what we want here.
   ConvertUnicode(utf8.data(), utf8.length(), &ret);
   return ret;
 }
 
 bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
   if (IsStringASCII(StringPiece16(src, src_len))) {
     output->assign(src, src + src_len);
     return true;
   } else {
     PrepareForUTF8Output(src, src_len, output);
     return ConvertUnicode(src, src_len, output);
   }
 }
 
-std::string UTF16ToUTF8(const string16& utf16) {
+std::string UTF16ToUTF8(StringPiece16 utf16) {
   if (IsStringASCII(utf16)) {
     return std::string(utf16.begin(), utf16.end());
   }
 
   std::string ret;
   // Ignore the success flag of this call, it will do the best it can for
   // invalid input, which is what we want here.
   UTF16ToUTF8(utf16.data(), utf16.length(), &ret);
   return ret;
 }
 
 #elif defined(WCHAR_T_IS_UTF16)
 // Easy case since we can use the "wide" versions we already wrote above.
 
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
   return UTF8ToWide(src, src_len, output);
 }
 
-string16 UTF8ToUTF16(const StringPiece& utf8) {
+string16 UTF8ToUTF16(StringPiece utf8) {
   return UTF8ToWide(utf8);
 }
 
 bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
   return WideToUTF8(src, src_len, output);
 }
 
-std::string UTF16ToUTF8(const string16& utf16) {
-  return WideToUTF8(utf16);
+std::string UTF16ToUTF8(StringPiece16 utf16) {
+  if (IsStringASCII(utf16))
+    return std::string(utf16.data(), utf16.data() + utf16.length());
+
+  std::string ret;
+  PrepareForUTF8Output(utf16.data(), utf16.length(), &ret);
+  ConvertUnicode(utf16.data(), utf16.length(), &ret);
+  return ret;
 }
 
 #endif
 
-string16 ASCIIToUTF16(const StringPiece& ascii) {
+string16 ASCIIToUTF16(StringPiece ascii) {
   DCHECK(IsStringASCII(ascii)) << ascii;
   return string16(ascii.begin(), ascii.end());
 }
 
-std::string UTF16ToASCII(const string16& utf16) {
+std::string UTF16ToASCII(StringPiece16 utf16) {
   DCHECK(IsStringASCII(utf16)) << UTF16ToUTF8(utf16);
   return std::string(utf16.begin(), utf16.end());
 }
 
 }  // namespace base