source: project/wiki/eggref/5/string-utils

[[tags: egg]]

== string-utils

[[toc:]]


== Documentation

=== Memoized String

==== Usage

<enscript language=scheme>
(import memoized-string)
</enscript>

==== make-string+

<procedure>(make-string+ COUNT [FILL]) -> string</procedure>

A ''tabling'' {{make-string}}.

{{FILL}} is any valid {{char}}, including codepoints outside of the ASCII
range. As such UTF-8 strings can be memoized.

==== string+

<procedure>(string+ [CHAR...]) -> string</procedure>

A ''tabling'' {{string}}.

{{CHAR}} is any valid {{char}}, including codepoints outside of the ASCII
range. As such UTF-8 strings can be memoized.

==== global-string

<procedure>(global-string STR) -> string</procedure>

Share common string space.

==== make-string* (DEPRECATED)

<procedure>(make-string* COUNT [FILL]) -> string</procedure>

=== String Hexadecimal

==== Usage

<enscript language=scheme>
(import string-hexadecimal)
</enscript>

==== string->hex

<procedure>(string->hex STRING [START [END]]) -> string</procedure>

Returns a hexadecimal represenation of {{STRING}}. {{START}} and {{END}} are
substring limits.

{{STRING}} is treated as a string of bytes, a byte-vector.

==== hex->string

<procedure>(hex->string STRING [START [END]]) -> string</procedure>

Returns the binary representation of a hexadecimal{{STRING}}. {{START}} and
{{END}} are substring limits.

=== Hexadecimal Procedures

==== Usage

<enscript language=scheme>
(import to-hex)
</enscript>

==== str_to_hex

<procedure>(str_to_hex OUT IN OFF LEN)</procedure>

Writes the ASCII hexadecimal representation of {{IN}} to {{OUT}}.

{{IN}} is a {{nonnull-string}}.

{{OFF}} is the byte offset.

{{LEN}} is the length of the bytes at {{OFF}}.

{{OUT}} is a {{string}} of length >= {{(+ LEN 2)}}.

==== blob_to_hex

<procedure>(blob_to_hex OUT IN OFF LEN)</procedure>

Like {{str_to_hex}} except {{IN}} is a {{nonnull-blob}}.

==== u8vec_to_hex

<procedure>(u8vec_to_hex OUT IN OFF LEN)</procedure>

Like {{str_to_hex}} except {{IN}} is a {{nonnull-u8vector}}.

==== s8vec_to_hex

<procedure>(s8vec_to_hex OUT IN OFF LEN)</procedure>

Like {{str_to_hex}} except {{IN}} is a {{nonnull-s8vector}}.

==== mem_to_hex

<procedure>(mem_to_hex OUT IN OFF LEN)</procedure>

Like {{str_to_hex}} except {{IN}} is a {{nonnull-c-pointer}}.

==== hex_to_str

<procedure>(hex_to_str OUT IN OFF LEN)</procedure>

Reads the ASCII hexadecimal representation of {{IN}} to {{OUT}}.

{{IN}} is a {{nonnull-string}}.

{{OFF}} is the byte offset.

{{LEN}} is the length of the bytes at {{OFF}}.

{{OUT}} is a {{string}} of length >= {{(/ LEN 2)}}.

==== hex_to_str

<procedure>(hex_to_blob OUT IN OFF LEN)</procedure>

Like {{hex_to_str}} except {{OUT}} is a {{blob}} of size >= {{(/ LEN 2)}}.

=== Unicode Utilities

The name of this extension is misleading. Only UTF-8 is currently supported.

For a better treatment of UTF-8 see the [[utf-8]] extension.

==== Usage

<enscript language=scheme>
(import unicode-utils)
</enscript>

==== ascii-codepoint?

<procedure>(ascii-codepoint? CHAR) -> boolean</procedure>

==== unicode-char->string

<procedure>(unicode-char->string CHAR) -> string</procedure>

Returns a string formed from Unicode codepoint {{CHAR}}.

''Note'' that the {{(string-length)}} (except under [[utf-8]]) may not be equal
to {{1}}.

Generates an error should the codepoint be out-of-range.

==== unicode-string

<procedure>(unicode-string [CHAR...]) -> string</procedure>

Returns a string formed from Unicode codepoints {{CHAR...}}

''Note'' that the {{(string-length)}} (except under [[utf-8]]) may not be equal
to the length of {{CHAR...}}.

Generates an error should the codepoint be out-of-range.

==== *unicode-string

<procedure>(*unicode-string CHARS) -> string</procedure>

Returns a string formed from Unicode codepoints {{CHARS}}, a {{(list-of
char)}}.

==== unicode-make-string

<procedure>(unicode-make-string COUNT [FILL]) -> string</procedure>

Returns a string formed from {{COUNT}} occurrences of the Unicode codepoint
{{FILL}}. The {{FILL}} default is {{#\space}}.

''Note'' that the {{(string-length)}} (except under [[utf-8]]) may not be equal
to {{COUNT}}.

Generates an error should the codepoint be out-of-range.

==== unicode-surrogate?

<procedure>(unicode-surrogate? NUM) -> boolean</procedure>

==== unicode-surrogates->codepoint

<procedure>(unicode-surrogates->codepoint HIGH LOW) -> (or boolean fixnum)</procedure>

Returns the codepoint for the valid surrogate pair {{HIGH}} and {{LOW}}.
Otherwise returns {{#f}}.

=== String Utilities

==== Usage

<enscript language=scheme>
(import string-utils)
</enscript>

==== string-fixed-length

<procedure>(string-fixed-length S N [pad-char: #\space] [trailing: "..."]) -> string</procedure>

Returns the string {{S}} with the {{string-length}} fixed to {{N}}.

A shorter string is padded. A longer string is truncated, & suffixed with the
{{trailing}}.

=== String Interpolation

==== Usage

<enscript language=scheme>
(import string-interpolation-syntax)
</enscript>

==== set-sharp-string-interpolation-syntax

<procedure>(set-sharp-string-interpolation-syntax PROC)</procedure>

Extends the read-syntax with #"..." where the {{"..."}} is evaluated using
{{(PROC "...")}}. When {{PROC}} is {{#f}} the read-syntax is cleared. When
{{PROC}} is {{#t}} then {{PROC}} is {{identity}}.

<enscript language=scheme>
(use string-interpolation-syntax utf8-string-interpolation)

(set-sharp-string-interpolation-syntax string-interpolate)
#"foo #(+ 1 2)bar #{(and 1 2)} baz"
;=> "foo 3bar 2 baz"
</enscript>

See [[http://wiki.call-cc.org/man/5/Extensions%20to%20the%20standard#multiline-string-constant-with-embedded-expressions|Multiline String Constant with Embedded Expressions]].

==== Usage

<enscript language=scheme>
(import string-interpolation) ;or (import utf8-string-interpolation)
</enscript>

==== string-interpolate

<procedure>(string-interpolate STR [eval-tag: EVAL-TAG]) -> list</procedure>

Performs substitution of embedded Scheme expressions, prefixed with
{{EVAL-TAG}} and optionally enclosed in curly brackets. Two consecutive
{{EVAL-TAG}}s are translated to a single {{EVAL-TAG}}.

Similar to the {{#<#}} multi-line string.

{{STR}} is a {{string}}.

{{EVAL-TAG}} is a {{character}}, default {{#\#}}.

Automatically invokes {{(set-sharp-string-interpolation-syntax
string-interpolate)}} on load.


== Requirements

[[check-errors]]
[[miscmacros]]
[[srfi-1]]
[[srfi-13]]
[[srfi-69]]
[[utf8]]

[[test]]


== Author

[[/users/kon-lovett|Kon Lovett]]


== Version history

; 2.2.0 : Fix {{string-interpolation}}.
; 2.1.0 : Add {{utf8-string-interpolation}}.
; 2.0.0 : C5 release.
; 1.6.0 : Add {{string-utils-extensions}}.
; 1.5.6 : Add types.
; 1.5.5 :
; 1.5.4 :
; 1.5.3 : {{memorize-string}} -> {{global-string}}.
; 1.5.2 : Fix {{string+}} & {{memorize-string}}.
; 1.5.1 : Fix {{string+}} unicode support.
; 1.5.0 : Deprecate {{make-string*}} for {{make-string+}}, add {{memorize-string}} & {{string+}}.
; 1.4.0 : Add string-interpolation modules.
; 1.3.1 : Fix {{hex_to_str}}, {{hex_to_blob}}.
; 1.3.0 : Add {{hex->string}}, {{hex_to_str}}, {{hex_to_blob}}.
; 1.2.5 : Remove [[lookup-table]].
; 1.2.2 : Unicode string construction a little faster. Removed {{blob->hex}}.
; 1.2.1 : Added {{blob->hex}}.
; 1.2.0 : Added "generic" bytes to hexadecimal string.
; 1.1.0 : Split into separate modules. Added some UTF-8 support.
; 1.0.0 : Hello


== License

Copyright (C) 2010-2017 Kon Lovett.  All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the Software),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.