Adds lib-string-utils

libraries/lib-string-utils/UrlDecode.cpp

@@ -0,0 +1,51 @@
+/*!********************************************************************
+
+ Audacity: A Digital Audio Editor
+
+ @file UrlDecode.cpp
+ @brief Define a function to decode an URL encode string.
+
+ Dmitry Vedenko
+ **********************************************************************/
+
+#include "UrlDecode.h"
+
+#include "HexHelpers.h"
+
+namespace audacity
+{
+
+std::string UrlDecode (const std::string& url)
+{
+    std::string result;
+
+    const size_t length = url.length ();
+
+    for (auto it = url.begin (), end = url.end (); it != end; ++it)
+    {
+        const char c = *it; 
+
+        if (c != '%')
+        {
+            result.push_back (c);
+        }
+        else
+        {
+            if (++it == url.end ())
+                break; // Malformed input string
+
+            const char c1 = *it; 
+            
+            if (++it == url.end ())
+                break; // Malformed input string
+
+            const char c2 = *it;
+
+            result.push_back (HexCharToNum (c1) << 4 | HexCharToNum (c2));
+        }
+    }
+
+    return result;
+}
+
+}