@iftex
@finalout
@end iftex
-@comment $Id: scheme.texinfo,v 1.68 1999/04/29 22:21:30 cph Exp $
+@comment $Id: scheme.texinfo,v 1.69 1999/05/08 02:57:38 cph Exp $
@comment %**start of header (This is for running Texinfo on a region.)
@setfilename scheme
@settitle MIT Scheme Reference
@titlepage
@title{MIT Scheme Reference Manual}
-@subtitle Edition 1.68
+@subtitle Edition 1.69
@subtitle for Scheme Release 7.5
-@subtitle 29 April 1999
+@subtitle 7 May 1999
@author by Chris Hanson
@author the MIT Scheme Team
@author and a cast of thousands
@cindex character, searching string for
@cindex substring, searching string for
+The first few procedures in this section perform @dfn{string search}, in
+which a given string (the @dfn{text}) is searched to see if it contains
+another given string (the @dfn{pattern}) as a proper substring. At
+present these procedures are implemented using a hybrid strategy. For
+short patterns of less than 4 characters, the naive string-search
+algorithm is used. For longer patterns, the Boyer-Moore string-search
+algorithm is used.
+
+@deffn {procedure+} string-search-forward string pattern
+@deffnx {procedure+} substring-search-forward string start end pattern
+@var{Pattern} must be a string. Searches @var{string} to see if it
+contains @var{pattern} as a substring. The search is performed from
+left to right; if successful, returns the index of the first character
+of the match. Otherwise, returns @code{#f}.
+
+@code{substring-search-forward} limits its search to the specified
+substring of @var{string}; @code{string-search-forward} searches all of
+@var{string}.
+
+@example
+@group
+(string-search-forward "pirate" "rat")
+ @result{} 2
+(string-search-forward "pirate rating" "rat")
+ @result{} 2
+(substring-search-forward "pirate rating" 4 13 "rat")
+ @result{} 7
+(substring-search-forward "pirate rating" 9 13 "rat")
+ @result{} #f
+@end group
+@end example
+@end deffn
+
+@deffn {procedure+} string-search-backward string pattern
+@deffnx {procedure+} substring-search-backward string start end pattern
+@var{Pattern} must be a string. Searches @var{string} to see if it
+contains @var{pattern} as a substring. The search is performed from
+right to left; if successful, returns the index after the last character
+of the match. Otherwise, returns @code{#f}.
+
+@code{substring-search-backward} limits its search to the specified
+substring of @var{string}; @code{string-search-backward} searches all of
+@var{string}.
+
+@example
+@group
+(string-search-backward "pirate" "rat")
+ @result{} 5
+(string-search-backward "pirate rating" "rat")
+ @result{} 10
+(substring-search-backward "pirate rating" 1 8 "rat")
+ @result{} 5
+(substring-search-backward "pirate rating" 9 13 "rat")
+ @result{} #f
+@end group
+@end example
+@end deffn
+
+@deffn {procedure+} string-search-all string pattern
+@deffnx {procedure+} substring-search-all string start end pattern
+@var{Pattern} must be a string. Searches @var{string} to find all
+occurrences of @var{pattern}. Returns a list of the occurrences; each
+element of the list is an index pointing to the first character of an
+occurrence.
+
+@code{substring-search-all} limits its search to the specified substring
+of @var{string}; @code{string-search-all} searches all of @var{string}.
+
+@example
+@group
+(string-search-all "pirate" "rat")
+ @result{} (2)
+(string-search-all "pirate rating" "rat")
+ @result{} (2 7)
+(substring-search-all "pirate rating" 4 13 "rat")
+ @result{} (7)
+(substring-search-all "pirate rating" 9 13 "rat")
+ @result{} ()
+@end group
+@end example
+@end deffn
+
@deffn {procedure+} substring? pattern string
-Searches @var{string} to see if it contains the substring @var{pattern}.
-Returns the index of the first substring of @var{string} that is equal
-to @var{pattern}; or @code{#f} if @var{string} does not contain @var{pattern}.
+@var{Pattern} must be a string. Searches @var{string} to see if it
+contains @var{pattern} as a substring. Returns @code{#t} if
+@var{pattern} is a substring of @var{string}, otherwise returns
+@code{#f}.
@example
@group
-(substring? "rat" "pirate") @result{} 2
+(substring? "rat" "pirate") @result{} #t
(substring? "rat" "outrage") @result{} #f
-(substring? "" any-string) @result{} 0
+(substring? "" any-string) @result{} #t
(if (substring? "moon" text)
(process-lunar text)
'no-moon)
@example
@group
(string-find-next-char-in-set my-string char-set:alphabetic)
- @result{} @r{start position of the first word in} my-string
+ @result{} @r{start position of the first word in} my-string
@r{; Can be used as a predicate:}
(if (string-find-next-char-in-set my-string
(char-set #\( #\) ))
@end example
@end deffn
+@deffn {procedure+} reverse-string string
+@deffnx {procedure+} reverse-substring string start end
+@deffnx {procedure+} reverse-string! string
+@deffnx {procedure+} reverse-substring! string start end
+Reverses the order of the characters in the given string or substring.
+@code{reverse-string} and @code{reverse-substring} return newly
+allocated strings; @code{reverse-string!} and @code{reverse-substring!}
+modify their argument strings and return an unspecified value.
+
+@example
+@group
+(reverse-string "foo bar baz") @result{} "zab rab oof"
+(reverse-substring "foo bar baz" 4 7) @result{} "rab"
+(let ((foo "foo bar baz"))
+ (reverse-string! foo)
+ foo) @result{} "zab rab oof"
+(let ((foo "foo bar baz"))
+ (reverse-substring! foo 4 7)
+ foo) @result{} "foo rab baz"
+@end group
+@end example
+@end deffn
+
@node Variable-Length Strings, Byte Vectors, Modification of Strings, Strings
@section Variable-Length Strings
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