diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 35 |
1 files changed, 32 insertions, 3 deletions
@@ -24836,9 +24836,9 @@ stream. .desc The .code regex-parse -function parses a character string which contains a regular expression -(without any surrounding / characters) and turns it into a Lisp data structure -(the abstract syntax tree representation of the regular expression). +function parses a character string which contains a regular expression and +turns it into a Lisp data structure (the abstract syntax tree representation of +the regular expression). The regular expression syntax .code #/RE/ @@ -24871,6 +24871,35 @@ value, that structure is then something which is suitable as input to .codn regex-compile . +There is a small difference in the syntax accepted by +.code regex-parse +and the syntax of regular expression literals. Any +.code / +(slash) characters occurring in any position within +.meta string +are treated as ordinary characters, not as regular expression delimiters. +The call +.code (regex-parse "/a/") +matches three characters: a slash, followed by the letter "a", followed +by another slash. Note that the slashes are not escaped. + +Note: if a +.code regex-parse +call is written using a string literal as the +.meta string +argument, then note that any backslashes which are to be processed +by the regular expression must be doubled up, otherwise they belong +to the string literal: + +.cblk + (regex-parse "\e*") ;; error, invalid string literal escape + (regex-parse "\e\e*") ;; correct: the \e* literal match for * +.cble + +The double backslash in the string literal produces a single backslash +in the resulting string object that is processed by +.codn regex-parse . + .SS* Hashing Library .coNP Functions @, make-hash and @ hash .synb |