audacity/libraries/lib-string-utils/UrlDecode.cpp

/*!********************************************************************

 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;
}

}