Re: [Python-ideas] FInd first tuple argument for str.find and str.index
Guido> On 9/4/07, Ron Adam <rrr@ronadam.com> wrote:
Could we add the ability of str.index and str.find to accept a tuple as the first argument and return the index of the first item found in it.
I should have added a few more comments. If you're going to implement the original desired functionality and make it run quickly, you're probably going to dream up something along the lines of what Aho & Corasick did so beautifully. It's tricky to get it right. As you walk the text string, several patterns may be currently matching. But the next char you consider might cause one or more of the current matches to fail, or a currently non-matching pattern to begin to match. The A&C algorithm builds a trie with failure arcs, so the matching is linear (both linear time to build the trie and the failure arcs, and then linear to walk the trie with the text). It has accepting states, so you know as soon as something matches, and can quit early. If this is going to be implemented you may as well do it right the first time. You could also return a dict in which (pattern) keys are absent if they didn't match at all. Then it would be fast to tell which, if any, patterns matched - no need to step through all passed patterns, just use result.keys() to get them. Terry
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Terry Jones