Use string_view inputs for conversion functions (#26031)

cbracken · web-flow · commit 5a26c1f109bb · 2021-05-08T11:17:41.000-07:00
This offers a small improvement in performance in cases where the input
is a raw char* or wchar_t* string due to not having to perform an
implicit conversion to std::string/std::wstring.

Code cleanup covered by existing tests, which already use raw C strings.
diff --git a/shell/platform/windows/string_conversion.cc b/shell/platform/windows/string_conversion.cc
@@ -8,7 +8,7 @@
 
 namespace flutter {
 
-std::string Utf8FromUtf16(const std::wstring& utf16_string) {
+std::string Utf8FromUtf16(const std::wstring_view utf16_string) {
   if (utf16_string.empty()) {
     return std::string();
   }
@@ -30,7 +30,7 @@ std::string Utf8FromUtf16(const std::wstring& utf16_string) {
   return utf8_string;
 }
 
-std::wstring Utf16FromUtf8(const std::string& utf8_string) {
+std::wstring Utf16FromUtf8(const std::string_view utf8_string) {
   if (utf8_string.empty()) {
     return std::wstring();
   }
diff --git a/shell/platform/windows/string_conversion.h b/shell/platform/windows/string_conversion.h
@@ -11,11 +11,11 @@ namespace flutter {
 
 // Converts a string from UTF-16 to UTF-8. Returns an empty string if the
 // input is not valid UTF-16.
-std::string Utf8FromUtf16(const std::wstring& utf16_string);
+std::string Utf8FromUtf16(const std::wstring_view utf16_string);
 
 // Converts a string from UTF-8 to UTF-16. Returns an empty string if the
 // input is not valid UTF-8.
-std::wstring Utf16FromUtf8(const std::string& utf8_string);
+std::wstring Utf16FromUtf8(const std::string_view utf8_string);
 
 }  // namespace flutter
 

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`
`9`	`9`	`namespace flutter {`
`10`	`10`
`11`		`-std::string Utf8FromUtf16(const std::wstring& utf16_string) {`
	`11`	`+std::string Utf8FromUtf16(const std::wstring_view utf16_string) {`
`12`	`12`	`if (utf16_string.empty()) {`
`13`	`13`	`return std::string();`
`14`	`14`	`}`
`@@ -30,7 +30,7 @@ std::string Utf8FromUtf16(const std::wstring& utf16_string) {`
`30`	`30`	`return utf8_string;`
`31`	`31`	`}`
`32`	`32`
`33`		`-std::wstring Utf16FromUtf8(const std::string& utf8_string) {`
	`33`	`+std::wstring Utf16FromUtf8(const std::string_view utf8_string) {`
`34`	`34`	`if (utf8_string.empty()) {`
`35`	`35`	`return std::wstring();`
`36`	`36`	`}`