Replacing with "" / null is missing.
I first looked at the function and modified it. Quickly noticed that a few unit tests were missing:

	assert(replace("foo", "foo", "") == "");
	assert(replace("foo", "foo", null) == "");

On 10.08.2010 00:29, simendsjo wrote:
> Replacing with "" / null is missing.
> I first looked at the function and modified it. Quickly noticed that a
> few unit tests were missing:
>
> assert(replace("foo", "foo", "") == "");
> assert(replace("foo", "foo", null) == "");

I refactored replace to understand what was going on (related to my post "is this more readable").
I've seen a couple of functions using Appender, and it's documentation says it's faster than ~=. I tried to change char[] result to Appender, but dmd crashed...


string replace(string s, string from, string to)
{
    if (from.length == 0) // Nothing to replace
        return s;

    char[] result;
    for (size_t searchIndex; searchIndex < s.length; )
    {
        auto rest = s[searchIndex .. s.length];
        auto fromIndex = indexOf(rest, from);

        bool nothingToReplace = (fromIndex == -1);
        if (nothingToReplace)
        {
            bool firstSearch = (searchIndex == 0);
            if (firstSearch)
            {
                // Never found, so just return s
                return s;
            }

            result ~= rest;
            break;
        }

        auto beforeFrom = s[searchIndex .. searchIndex + fromIndex];
        result ~= beforeFrom;
        result ~= to;

        searchIndex += fromIndex + from.length;
    }

    return assumeUnique(result);
}