string_replace()

//#define UNITTEST
 
#include <string>
 
using std::string;
 
string string_replace( string src, string const& target, string const& repl)
{
    // handle error situations/trivial cases
 
    if (target.length() == 0) {
        // searching for a match to the empty string will result in 
        //  an infinite loop
        //  it might make sense to throw an exception for this case
        return src;
    }
 
    if (src.length() == 0) {
        return src;  // nothing to match against
    }
 
    for (size_t idx = src.find( target); idx != string::npos; idx = src.find( target, idx)) {
        src.replace( idx, target.length(), repl);
        idx += repl.length();
    }
 
    return src;
}
 
#ifdef UNITTEST
 
#include <iostream>
using std::cout;
using std::endl;
 
void test( string s, string const& t, string const& r, string const& expected)
{
    string result = string_replace( s, t, r);
 
    if (result != expected) {
        cout << "ERROR: string_replace( \"" << s << "\", \"" << t << "\", \"" << r << "\") == \"" << result << "\", expected: \"" << expected << "\"" << endl;
    }
}
 
 
int main() 
{
    test( "", "", "", "");
    test( "a", "a", "b", "b");
    test( "cabcab", "cab", "xyz", "xyzxyz");
    test( "", "x", "y", "");
    test( "ababababa", "ba", "", "a");
    test( "cabcabcab", "cab", "cabcab", "cabcabcabcabcabcab");
}
#endif