ASCII <-> UTF16 conversion functions. These are just copies of WideToASCII and

ASCIIToWide but they work with string16 instead of wstring.

R=brettw

Review URL: http://codereview.chromium.org/28189

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10493 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 29 insertions, 8 deletions

diff --git a/base/string_util.cc b/base/string_util.cc
index 4ba8c4b..d84fadb 100644
--- a/base/string_util.cc
+++ b/base/string_util.cc
@@ -450,6 +450,16 @@ std::wstring ASCIIToWide(const std::string& ascii) {
   return std::wstring(ascii.begin(), ascii.end());
 }
 
+std::string UTF16ToASCII(const string16& utf16) {
+  DCHECK(IsStringASCII(utf16));
+  return std::string(utf16.begin(), utf16.end());
+}
+
+string16 ASCIIToUTF16(const std::string& ascii) {
+  DCHECK(IsStringASCII(ascii));
+  return string16(ascii.begin(), ascii.end());
+}
+
 // Latin1 is just the low range of Unicode, so we can copy directly to convert.
 bool WideToLatin1(const std::wstring& wide, std::string* latin1) {
   std::string output;
@@ -472,20 +482,28 @@ bool IsString8Bit(const std::wstring& str) {
   return true;
 }
 
-bool IsStringASCII(const std::wstring& str) {
+template<class STR>
+static bool DoIsStringASCII(const STR& str) {
   for (size_t i = 0; i < str.length(); i++) {
-    if (str[i] > 0x7F)
+    typename ToUnsigned<typename STR::value_type>::Unsigned c = str[i];
+    if (c > 0x7F)
       return false;
   }
   return true;
 }
 
+bool IsStringASCII(const std::wstring& str) {
+  return DoIsStringASCII(str);
+}
+
+#if !defined(WCHAR_T_IS_UTF16)
+bool IsStringASCII(const string16& str) {
+  return DoIsStringASCII(str);
+}
+#endif
+
 bool IsStringASCII(const std::string& str) {
-  for (size_t i = 0; i < str.length(); i++) {
-    if (static_cast<unsigned char>(str[i]) > 0x7F)
-      return false;
-  }
-  return true;
+  return DoIsStringASCII(str);
 }
 
 // Helper functions that determine whether the given character begins a
diff --git a/base/string_util.h b/base/string_util.h
index 500a114..93b4898 100644
--- a/base/string_util.h
+++ b/base/string_util.h
@@ -156,9 +156,11 @@ TrimPositions TrimWhitespace(const std::string& input,
 std::wstring CollapseWhitespace(const std::wstring& text,
                                 bool trim_sequences_with_line_breaks);
 
-// These convert between ASCII (7-bit) and UTF16 strings.
+// These convert between ASCII (7-bit) and Wide/UTF16 strings.
 std::string WideToASCII(const std::wstring& wide);
 std::wstring ASCIIToWide(const std::string& ascii);
+std::string UTF16ToASCII(const string16& utf16);
+string16 ASCIIToUTF16(const std::string& ascii);
 
 // These convert between UTF-8, -16, and -32 strings. They are potentially slow,
 // so avoid unnecessary conversions. The low-level versions return a boolean
@@ -235,6 +237,7 @@ bool IsStringUTF8(const std::string& str);
 bool IsStringWideUTF8(const std::wstring& str);
 bool IsStringASCII(const std::wstring& str);
 bool IsStringASCII(const std::string& str);
+bool IsStringASCII(const string16& str);
 
 // ASCII-specific tolower.  The standard library's tolower is locale sensitive,
 // so we don't want to use it here.