Add function UnescapeMenuString

Turns E&dit into Edit and 'd'. Double ampersands are translated to just a single one,
hence the unescaping part of this.

Useful in the Mac port to deal with desktop UI translation strings with included
Windows hotkeys.

Common/StringUtils.cpp

@@ -342,3 +342,27 @@ std::string ReplaceAll(std::string result, const std::string& src, const std::st
 	}
 	return result;
 }
+
+std::string UnescapeMenuString(const char *input, char *shortcutChar) {
+	size_t len = strlen(input);
+	std::string output;
+	output.reserve(len);
+	bool escaping = false;
+	for (size_t i = 0; i < len; i++) {
+		if (input[i] == '&') {
+			if (escaping) {
+				output.push_back(input[i]);
+				escaping = false;
+			} else {
+				escaping = true;
+			}
+		} else {
+			output.push_back(input[i]);
+			if (escaping && shortcutChar) {
+				*shortcutChar = input[i];
+			}
+			escaping = false;
+		}
+	}
+	return output;
+}

Common/StringUtils.h

@@ -76,6 +76,10 @@ void GetQuotedStrings(const std::string& str, std::vector<std::string>& output);
 
 std::string ReplaceAll(std::string input, const std::string& src, const std::string& dest);
 
+// Takes something like R&eplace and returns Replace, plus writes 'e' to *shortcutChar
+// if not nullptr. Useful for Windows menu strings.
+std::string UnescapeMenuString(const char *input, char *shortcutChar);
+
 void SkipSpace(const char **ptr);
 
 size_t truncate_cpy(char *dest, size_t destSize, const char *src);

unittest/UnitTest.cpp

@@ -26,6 +26,11 @@
 //
 // To use, set command line parameter to one or more of the tests below, or "all".
 // Search for "availableTests".
+//
+// Example of how to run with CMake:
+//
+// ./b.sh --unittest
+// build/unittest EscapeMenuString
 
 #include "ppsspp_config.h"
 
@@ -57,6 +62,7 @@
 #include "Common/BitScan.h"
 #include "Common/CPUDetect.h"
 #include "Common/Log.h"
+#include "Common/StringUtils.h"
 #include "Core/Config.h"
 #include "Common/File/VFS/VFS.h"
 #include "Common/File/VFS/DirectoryReader.h"
@@ -890,6 +896,20 @@ bool TestInputMapping() {
 	return true;
 }
 
+bool TestEscapeMenuString() {
+	char c;
+	std::string temp = UnescapeMenuString("&File", &c);
+	EXPECT_EQ_INT((int)c, (int)'F');
+	EXPECT_EQ_STR(temp, std::string("File"));
+	temp = UnescapeMenuString("U&til", &c);
+	EXPECT_EQ_INT((int)c, (int)'t');
+	EXPECT_EQ_STR(temp, std::string("Util"));
+	temp = UnescapeMenuString("Ed&it", nullptr);
+	EXPECT_EQ_STR(temp, std::string("Edit"));
+	temp = UnescapeMenuString("Cut && Paste", nullptr);
+	EXPECT_EQ_STR(temp, std::string("Cut & Paste"));
+	return true;
+}
 
 typedef bool (*TestFunc)();
 struct TestItem {
@@ -944,6 +964,7 @@ TestItem availableTests[] = {
 	TEST_ITEM(SmallDataConvert),
 	TEST_ITEM(DepthMath),
 	TEST_ITEM(InputMapping),
+	TEST_ITEM(EscapeMenuString),
 };
 
 int main(int argc, const char *argv[]) {