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syntax:pattern [2021/08/23 17:12] fgrose [Patterns and pattern matching] not to be confused with reqular expressions |
syntax:pattern [2021/10/21 00:52] fgrose links to POSIX character classes & collation symbols |
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| The pattern description language is relatively easy. Any character that's not mentioned below matches itself. | The pattern description language is relatively easy. Any character that's not mentioned below matches itself. | ||
| - | The ''NUL'' character may not occur in a pattern. If special characters are quoted, they're matched literally, i.e. without their special meaning. | + | The ''NUL'' character may not occur in a pattern. If special characters are quoted, they're matched literally, i.e., without their special meaning. |
| Do **not** confuse patterns with **//regular expressions//**, because they share some symbols and do similar matching work. | Do **not** confuse patterns with **//regular expressions//**, because they share some symbols and do similar matching work. | ||
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| |''[XYZ]''|The "normal" bracket expression, matching either ''X'', ''Y'' or ''Z''| | |''[XYZ]''|The "normal" bracket expression, matching either ''X'', ''Y'' or ''Z''| | ||
| |''[X-Z]''|A range expression: Matching all the characters from ''X'' to ''Y'' (your current **locale**, defines how the characters are **sorted**!)| | |''[X-Z]''|A range expression: Matching all the characters from ''X'' to ''Y'' (your current **locale**, defines how the characters are **sorted**!)| | ||
| - | |''<nowiki>[[:class:]]</nowiki>''|Matches all the characters defined by a POSIX(r) character class: ''alnum'', ''alpha'', ''ascii'', ''blank'', ''cntrl'', ''digit'', ''graph'', ''lower'', ''print'', ''punct'', ''space'', ''upper'', ''word'' and ''xdigit''| | + | |''<nowiki>[[:class:]]</nowiki>''|Matches all the characters defined by a [[https://pubs.opengroup.org/onlinepubs/009696899/basedefs/xbd_chap07.html#tag_07_03_01|POSIX(r) character class]]: ''alnum'', ''alpha'', ''ascii'', ''blank'', ''cntrl'', ''digit'', ''graph'', ''lower'', ''print'', ''punct'', ''space'', ''upper'', ''word'' and ''xdigit''| |
| |''[^...]''|A negating expression: It matches all the characters that are **not** in the bracket expression| | |''[^...]''|A negating expression: It matches all the characters that are **not** in the bracket expression| | ||
| |''[!...]''|Equivalent to ''[^...]''| | |''[!...]''|Equivalent to ''[^...]''| | ||
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| * => ''Hello world+'' | * => ''Hello world+'' | ||
| * => ''Hello world?'' | * => ''Hello world?'' | ||
| - | * Pattern ''<nowiki>[[.backslash.]]Hello[[.vertical-line.]]world[[.exclamation-mark.]]</nowiki>'' matches (using collation sybols) | + | * Pattern ''<nowiki>[[.backslash.]]Hello[[.vertical-line.]]world[[.exclamation-mark.]]</nowiki>'' matches (using [[https://pubs.opengroup.org/onlinepubs/009696899/basedefs/xbd_chap07.html#tag_07_03_02_04|collation symbols]]) |
| * => ''\Hello|world!'' | * => ''\Hello|world!'' | ||