Pattern matching: Difference between revisions

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{{For|the use of variable matching criteria in defining abstract patterns to match|regular expression}}

{{More citations needed|date=February 2011}}

In [[computer science]], '''pattern matching''' is the act of checking a given '''sequence''' of [[Lexical analysis#Token|tokens]] for the presence of the constituents of some [[pattern]]. In contrast to [[pattern recognition]], the match usually has to be exact: "either it will or will not be a match." The patterns generally have the form of either [[string (computer science)|sequences]] or [[tree structure]]s. Uses of pattern matching include outputting the locations (if any) of a pattern within a token sequence, to output some component of the matched pattern, and to substitute the matching pattern with some other token sequence (i.e., [[Regular expression|search and replace]]).

Sequence patterns (e.g., a text string) are often described using [[regular expression]]s and matched using techniques such as [[backtracking]].