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Source for wiki StringSlicesCowan version 4

author

cowan

comment

ipnr

127.11.51.1

name

StringSlicesCowan

readonly

0

text

== String slice library ==

This is a library for manipulating textual content based on ''string slices'', which are references to part of a Scheme string, and ''string cursors'', which are pointers into strings.  It is not defined whether the string slice type is disjoint from strings, or whether string cursors are a disjoint type at all.  String slices are immutable, and it is an error to mutate the underlying string.

In addition, string cursors may or may not be the same as character-based indexes into strings.  For example, in an implementation whose internal representation of strings is UTF-8, string cursors may be pointers to individual bytes in the string.  However, the operations provided here (with the exception of those in the Compatibility section) are entirely independent of the character repertoire supported by the implementation.

This proposal contains a useful subset of SRFI 13, which manipulates strings directly with some allowances for shared substrings (which are both then and now provided only on Guile).  The string operations are defined in terms of the string slice operations.  Unlike SRFI 13, it does not provide ''start'' and ''end'' arguments, as their functionality is subsumed by slices.  In addition, the low-level procedures are not provided, nor are any mutation operations.

Procedures marked [R7RS-small] are available in the small language, and are not exported by implementations of this proposal.  They are included only for completeness.

All predicates passed to procedures defined in this proposal may be called in any order and any number of times, except as otherwise noted.

== Issues ==

Allow negative indices in constructors?

Is `string-slice-string` a bad idea?

Titlecase doesn't really fit; keep it?

Functional update worthwhile?

String tree worthwhile?


== String constructors ==

In addition to the R7RS-small constructors `make-string` and `string`, the following constructors for strings are provided:

`(string-tabulate `''proc len''`)`

`(string-unfold `''stop? mapper successor'' [ ''seed'' ]`)`

`(string-unfold-right `''stop? mapper successor'' [ ''seed'' ]`)`

`(char->string `''char''`)`

== String slice constructors ==

`(string-slice-whole `''string''`)`

`(string-slice `''string start end''`)`

`(string-subslice `''slice start end''`)`

`(string-slice/cursors `''string start-cursor end-cursor''`)`

`(string-subslice/cursors `''string start-cursor end-cursor''`)`

`(string-slice-transform `''proc slice arg'' ...`)`

`(char->string-slice `''char''`)`

== Predicates ==

`(string-slice? `''obj''`)`

`(string? `''obj''`)`  [R7RS-small]

`(string-slice-null? `''slice''`)`

`(string-null? `''string''`)`  [R7RS-small]

`(string-slice-every `''pred slice''`)`

`(string-every `''pred string''`)`

`(string-slice-any `''pred slice''`)`

`(string-any `''pred string''`)`

`(string-slice-whole? `''slice''`)`

`(is-char? `''char''`)`

`(in-char-set? `''char-set''`)`

== Selection ==

{{{
string-slice-ref                     string-ref [R7RS-small]
string-slice-take                    string-take
string-slice-take-right              string-take-right
string-slice-drop                    string-drop
string-slice-drop-right              string-drop-right
string-slice-pad                     string-pad
string-slice-pad-right               string-pad-right
string-slice-trim                    string-trim
string-slice-trim-right              string-trim-right
string-slice-replicate               string-replicate
}}}

== Prefixes and suffixes ==

{{{
string-slice-prefix                  string-common-prefix
string-slice-suffix                  string-common-suffix
string-slice-prefix-length           string-prefix-length
string-slice-suffix-length           string-suffix-length
string-slice-prefix?                 string-prefix?
string-slice-suffix?                 string-suffix?
}}}

== Searching ==

{{{
string-slice-index                   string-index
string-slice-index-right             string-index-right
string-slice-skip                    string-skip
string-slice-skip-right              string-skip-right
string-slice-count                   string-count
string-slice-contains                string-contains
string-slice-take-while              string-take-while
string-slice-drop-while              string-drop-while
string-slice-break                   string-break
string-slice-span                    string-span
}}}

== The whole string slice ==

{{{
string-slice-length                  string-length [R7RS-small]
string-slice-copy                    string-copy [R7RS-small]
string-slice-reverse                 string-reverse [R7RS-small]
string-slice-append                  string-append [R7RS-small]
string-slice-concatenate             string-concatenate
string-slice-concatenate-reverse     string-concatenate-reverse
string-slice-compress                string-compress
}}}

== Folding and mapping ==

{{{
string-slice-map                     string-map [R7RS-small]
string-slice-fold                    string-fold
string-slice-fold-right              string-fold-right
string-slice-for-each                string-for-each
string-slice-for-each-index          string-for-each-index
}}}

== Parsing ==

{{{
string-slice-tokenize                string-tokenize
string-slice-split                   string-split
}}}

== Filtering and partitioning ==

{{{
string-slice-filter                  string-filter
string-slice-remove                  string-remove
string-slice-partition               string-partition
}}}

== Functional update ==

{{{
string-slice-set                     string-set
string-slice-fill                    string-fill
}}}

== String trees ==

{{{
string-tree->string                  write-string-tree

== Compatibility ==

{{{
string-slice-upcase     string-slice-downcase   string-slice-foldcase
string-slice=?          string-slice<?          string-slice>?
string-slice<=?         string-slice>=?

string-slice-titlecase  string-titlecase
}}}

== Low-level operations ==

{{{
string-slice-start
string-slice-end
string-slice-string
}}}

== String cursors ==

{{{
string-cursor-start                  string-cursor-end
string-cursor-ref
string-cursor-next                   string-cursor-previous
string-cursor-forward                string-cursor-backward
string-cursor-forward-until          string-cursor-backward-until
string-cursor=?
string-cursor<?                      string-cursor>?
string-cursor<=?                     string-cursor>=?
string-cursors->string               string-cursors-length
}}}

time

2014-11-08 01:25:35

version

4