40 lines
1.4 KiB
Text
40 lines
1.4 KiB
Text
Rebol [
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Title: "Regular Expression Matching"
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URL: http://rosettacode.org/wiki/Regular_expression_matching
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]
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string: "This is a string."
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; Rebol doesn't use a conventional Perl-compatible regular expression
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; syntax. Instead, it uses a variant Parsing Expression Grammar with
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; the 'parse' function. It's also not limited to just strings. You can
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; define complex grammars that actually parse and execute program
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; files.
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; Here, I provide a rule to 'parse' that specifies searching through
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; the string until "string." is found, then the end of the string. If
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; the subject string satisfies the rule, the expression will be true.
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if parse string [thru "string." end] [
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print "Subject ends with 'string.'"]
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; For replacement, I take advantage of the ability to call arbitrary
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; code when a pattern is matched -- everything in the parens will be
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; executed when 'to " a "' is satisfied. This marks the current string
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; location, then removes the offending word and inserts the replacement.
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parse string [
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to " a " ; Jump to target.
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mark: (
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remove/part mark 3 ; Remove target.
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mark: insert mark " another " ; Insert replacement.
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)
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:mark ; Pick up where I left off.
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]
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print [crlf "Parse replacement:" string]
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; For what it's worth, the above operation is more conveniently done
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; with the 'replace' function:
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replace string " another " " a " ; Change string back.
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print [crlf "Replacement:" string]
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