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srfi.152
- String library (reduced)This is an improved version of srfi.13
. The spec is actually smaller
than SRFI-13 (hence ’reduced’ in the title) by removing bells and whistles.
The consistency with R7RS and recent srfis are also considered.
The following are built-in. See Strings, for the details.
string? make-string string string-length string->vector string->list vector->string list->string string-ref string-set! substring string-copy string=? string<? string<=? string>? string>=? string-append string-join string-split string-map string-for-each read-string write-string string-fill!
The following procedures are defined to use Unicode string case folding,
and gauche.unicode
module provides them.
See Full string case conversion, for the details.
Note that Gauche’s
built-in versions uses character-wise case folding, which differs
from string case folding on some characters (German eszett, for example).
string-ci=? string-ci<? string-ci<=? string-ci>? string-ci>=?
The following procedures are defined in SRFI-13. See srfi.13
- String library,
for the details. Note: Some of those procedures in SRFI-13 that require
predicate allows a char-set or a character to be passed instead
(e.g. string-filter
). In SRFI-152, only predicate is allowed.
Our SRFI-152 implementation shares the same procedure with SRFI-13, so
they accept the same arguments as SRFI-13’s, but such code won’t be
portable as SRFI-152.
string-null? string-any string-every string-tabulate string-unfold string-unfold-right reverse-list->string string-take string-drop string-take-right string-drop-right string-pad string-pad-right string-trim string-trim-right string-trim-both string-replace string-prefix-length string-suffix-length string-prefix? string-suffix? string-index string-index-right string-skip string-skip-right string-contains string-concatenate string-concatenate-reverse string-fold string-fold-right string-count string-filter string-copy!
We describe procedures unique to this module below.
[SRFI.152]{srfi.152}
Returns a substring of string between start and end,
except characters that satisfy pred. In other words,
it is (string-filter (complement pred) string start end)
.
This is called string-delete in srfi.13
. Being changed
to take only a predicate (but not a character), it is renamed for
the consistency of other srfi (e.g. filter
, remove
and
delete
in SRFI-1.)
(string-remove char-whitespace? "Quick fox jumps over the lazy dog" 3 22) ⇒ "ckfoxjumpsovert"
[SRFI-152]{srfi.152}
Extended substring. It is called xsubstring
in SRFI-13, but
renamed for the consistency.
Extract a substring of string between start and end,
and conceptually create a bidirectional infinite string by repeating
the substring to both direction. For example, suppose string
is "abcde"
, start is 1, and end is 4. So we repeat
the substring "bcd"
, with one b
falling on the index zero:
... b c d b c d b c d b c d b ... -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
Then we extract a substring between from and to out of this infinite string.
(string-replicate "abcde" 2 10 1 4) ⇒ "dbcdbcdb" (string-replicate "abcde" -5 -3 1 4) ⇒ "cdbcdbcd"
[SRFI-152]{srfi.152} Splits string by every k characters and returns a list of those strings. The last string may be shorter than k.
(string-segment "abcdefghijklmn" 3) ⇒ ("abc" "def" "ghi" "jkl" "mn")
We have a similar procedure on lists, slices
(see List accessors and modifiers).
[SRFI-152]{srfi.152}
Like string-contains
, looks for a needle string2 from
a haystack string1, but if it is found, returns the start index
of the last match, instead of the first match. The returned index
is in string1. The optional arguments limit the range of a needle
and a haystack. If a needle isn’t found, #f
is returned.
An edge case: If a needle is empty (e.g. string2 is empty, or start2 = end2), it always matches right after the haystack, so end1 is returned.
(string-contains-right "Little Lisper" "Li") ⇒ 7
[SRFI-152]{srfi.152} Returns the longest prefix or suffix of string in which all characters satisfy pred.
Note: The order of pred and the source object is different from
other take-while
-style procedures, such as take-while
(scheme.list
- R7RS lists), ideque-take-while
(scheme.ideque
- R7RS immutable deques),
and lseq-take-while
(scheme.lseq
- R7RS lazy sequences).
[SRFI-152]{srfi.152} Returns the longest prefix or suffix of string in which all characters does not satisfy pred.
Note: The order of pred and the source object is different from
other drop-while
-style procedures, such as drop-while
(scheme.list
- R7RS lists), ideque-drop-while
(scheme.ideque
- R7RS immutable deques),
and lseq-drop-while
(scheme.lseq
- R7RS lazy sequences).
[SRFI-152]{srfi.152} Find the longest prefix of string between start and end in which all characters satisy / do not satisfy pred, and returns the prefix and the rest of substring as two values.
(string-break "foo@example.com" (cut eqv? <> #\@)) ⇒ "foo" and "@example.com" (string-break "foo@example.com" (cut eqv? <> #\@) 1 10) ⇒ "oo" "@exampl" ;; This is Gauche specific - a char-set can work as a predicate: (string-span "VAR_1 = $VAR_2" #[\w]) ⇒ "VAR_1" and " = $VAR_2"
Note: The order of pred and the source object is different from
span
and break
in scheme.list
(see scheme.list
- R7RS lists).
Next: srfi.154
- First-class dynamic extents, Previous: srfi.130
- Cursor-based string library, Up: Library modules - SRFIs [Contents][Index]