using std::tr1::regex_iterator to search and replace occurences in a string.

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Is it possible to use std::tr1::regex_iterator to search and replace in a string ?

I know I can use std::tr1::regex_replace to replace all occurrences (or only one), but I need to replace each "pattern" that I find with something different, so I need to iterate my input string and replace on the fly.

std::string expression; // valid input string.
std::tr1::regex variableRegExpression; // valid regular expression.

std::tr1::sregex_iterator m1(
	expression.begin(), 
	expression.end(), 
	variableRegExpression);

std::tr1::sregex_iterator m2;
std::vector<std::string> tokens;
for (; m1 != m2; ++m1)
{
	std::string token = m1->str();
	// here, I want to replace token in the input string expression, but that will probably break the iterator.
}

The above code will iterate all occurrences of what I'm searching for in the string expression.

What I'd like to do would be to replace each occurrence with something else.

I was able to do that with some loops with std::tr1::regex_search and std::regex_replace, but it does not look "clean" :

std::string expression; // valid input string.
std::tr1::regex variableRegExpression; // valid regular expression.

// substitute variables.
bool found = true;
while (found)
{
	std::tr1::smatch matchResult;

	found = std::tr1::regex_search(
                expression, matchResult, variableRegExpression  );
        if ( found )
        {
                std::string newValue("Cloud1");
                // replace only first instance.
                // will change the input string.
                expression = std::tr1::regex_replace(
                        expression, variableRegExpression, newValue, 
                        std::tr1::regex_constants::format_first_only);

        }
        else
        {
                found = false;
        }
}

Question :
Is it possible to do a simple search and replace with the regex_iterator ?

Thanks

Max.