Function

Summary

Matches a regular expression.

Package

lispworks

Signature

find-regexp-in-string pattern string &key start end from-end case-sensitive => pos , len

Arguments

pattern

A string or a precompiled regular expression object.

string

A string.

start , end

Bounding index designators of string .

from-end

A generalized boolean.

case-sensitive

A generalized boolean.

Values

pos

A non-negative integer or nil .

len

A non-negative integer or nil .

Description

The function find-regexp-in-string searches the string string for a match for the regular expression pattern . The index in string of the start of the first match is returned in pos , and the length of the match is len .

If from-end is nil (the default value) then the search starts at index start and ends at index end . start defaults to 0 and end defaults to nil . If from-end is true, then the search direction is reversed.

pattern should be a precompiled regular expression object or a string. If pattern is a string then find-regexp-in-string first makes a precompiled regular expression object. This operation allocates, therefore if you need to repeatedly call find-regexp-in-string with the same pattern, it is better to call precompile-regexp once and pass its result, a precompiled regular expression object, as pattern .

case-sensitive controls whether a string pattern is precompiled as a case sensitive or case insensitive search. A true value other than :default means a case sensitive search. The value nil means a case insensitive search. The default value of case-sensitive is :default which means that a string pattern is compiled with case sensitivity according to the value of the Editor variable DEFAULT-SEARCH-KIND .

The regular expression syntax used by find-regexp-in-string is similar to that used by Emacs, as described in the "Regular expression syntax" section of the LispWorks Editor User Guide .

Example

This form allocates several regular expression objects:

(loop with pos = 0 

      with len = 0 

      while pos 

      do (multiple-value-setq (pos len) 

             (find-regexp-in-string "[0,2,4,6,8]" "0123456789" 

                                    :start (+ pos len)))

      when pos 

      do (format t "~&Match at pos ~D len ~D~%" 

                 pos len))

This form does the same matching but allocates just one precompiled regular expression object:

(loop with pattern = (precompile-regexp "[0,2,4,6,8]")

      with pos = 0 

      with len = 0 

      while pos 

      do (multiple-value-setq (pos len)

             (find-regexp-in-string pattern "0123456789" 

                                    :start (+ pos len))) 

      when pos do (format t "~&Match at pos ~D len ~D~%" 

                          pos len))

See also

precompile-regexp
regexp-find-symbols