Re: "Inverse" Pattern Matching

How long are the pattern chunks, and could you scan the string piece by piece?

For example, if you simplify your operation into searching for '123456' in a loop, then you could do a reverse regex and search for the string in the pattern (while changing 'x' to '..?')

Comment on Re: "Inverse" Pattern Matching

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Re^2: "Inverse" Pattern Matching by hdb (Monsignor) on Jul 04, 2013 at 20:59 UTC
The length of the pattern can be hundreds. The main source of inefficiency when looping is IMHO that every 'x' constitutes a branch in the pattern. If there is only one 'x' it could stand for one character and one has to pick n-1 other characters to create a pattern of the same length as my short string. However, if 'x' stands for two characters one has to pick only n-2 characters. And if every 'x' stands for two choices, the one has 2**k variants if there are k 'x's.	[reply] [d/l]

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Re^2: "Inverse" Pattern Matching
by hdb (Monsignor) on Jul 04, 2013 at 20:59 UTC

The length of the pattern can be hundreds. The main source of inefficiency when looping is IMHO that every 'x' constitutes a branch in the pattern. If there is only one 'x' it could stand for one character and one has to pick n-1 other characters to create a pattern of the same length as my short string. However, if 'x' stands for two characters one has to pick only n-2 characters. And if every 'x' stands for two choices, the one has 2**k variants if there are k 'x's.

[reply]
[d/l]