This package provides charseq structure which represents an efficient character sequence. charseq is a wrapper of common-lisp standard string and it has following features:
- Creating substring is very efficient.
- When creating a substring, charseq shares the source string instance and maintains start and end position of new string. Hence it is a constant time (and size) operation.
- It is ensured that charseq instance always holds a (simple-array character *) string as internal representation.
- (simple-array character *) is one of the most efficient type that represents strings.
0.1.9
chraseq has no implementation-depended code, but it is highly optimized for SBCL(later 1.0.37) only.
Use asdf-install.
* (require :asdf)
* (require :asdf-install)
* (asdf-install:install :charseq)A charseq instance.
The range of available string index.
(integer 0 #.array-total-size-limit)
Indicates the specified index is negative or exceeding target string size.
Indicates the specified indices (start and end position) are not within range of target string.
Creates new charseq instance from string.
| name | type | default value | description |
|---|---|---|---|
| string | string | Input source string. If this type is (simple-array character *), new charseq instance shares it. Otherwise charseq coerce input string to that's type and new instance holds it. |
|
| start | charseq:index | 0 | Start position of charseq |
| end | charseq:index | (length string) | End position of charseq |
| charseq | charseq:charseq | Created charseq instance |
Example:
* (charseq:make "common lisp")
#S(CHARSEQ:CHARSEQ :STR "common lisp" :BEG 0 :END 11)
* (charseq:make "common lisp" :start 1 :end 6)
#S(CHARSEQ:CHARSEQ :STR "common lisp" :BEG 1 :END 6)
* (charseq:to-string *)
"ommon"
* (charseq:= (charseq:make "common lisp" :start 1 :end 6)
(charseq:make (subseq "common lisp" 1 6)))
TAccesses the character of charseq specified by index.
| name | type | description |
|---|---|---|
| charseq | charseq:charseq | Charseq instance |
| index | charseq:index | An index for the charseq |
| character | character | Referred character |
Example:
* (charseq:ref (charseq:make "common lisp") 2)
#\m
* (charseq:ref (charseq:make "common lisp" :start 6) 2)
#\iReturns the length of charseq.
| name | type | description |
|---|---|---|
| charseq | charseq:charseq | Charseq instance |
| length | integer | the length of charseq |
Example:
* (charseq:length (charseq:make "common lisp" :start 2 :end 5))
3
* (charseq:to-string (charseq:make "common lisp" :start 2 :end 5))
"mmo"Creates a charseq instance that is a subpart of charseq bounded by start and end. Internal string data is shared between charseq and sub-charseq.
| name | type | default value | description |
|---|---|---|---|
| charseq | charseq:charseq | Source charseq instance | |
| start | charseq:index | Start position of sub-charseq | |
| end | charseq:index | (length charseq) | End position of sub-charseq |
| sub-charseq | charseq:charseq | Created charseq instance |
Example:
* (defparameter *c0* (charseq:make "common-lisp"))
*C0*
* (defparameter *c1* (charseq:sub *c0* 1 10))
*C1*
* *c1*
#S(CHARSEQ:CHARSEQ :STR "common-lisp" :BEG 1 :END 10)
* (charseq:to-string *c1*)
"ommon-lis"
* (defparameter *c2* (charseq:sub *c1* 2 5))
*C2*
* *c2*
#S(CHARSEQ:CHARSEQ :STR "common-lisp" :BEG 3 :END 6)
* (charseq:to-string *c2*)
"mon"Creates a string that is a copy of the subpart of charseq bounded by start and end.
| name | type | default value | description |
|---|---|---|---|
| charseq | charseq:charseq | Source charseq instance | |
| start | charseq:index | 0 | Start position of string |
| end | charseq:index | (length charseq) | End position of string |
| string | (simple-array character *) | Created string |
Example:
* (charseq:to-string (charseq:make "common-lisp"))
"common-lisp"
* (charseq:to-string (charseq:make "common-lisp") 3)
"mon-lisp"
* (charseq:to-string (charseq:make "common-lisp") 3 6)
"mon"These functions perform lexicographical order comparison of charseq1 and charseq2.
This macro iterates over the character of charseq.
| name | type | default value | description |
|---|---|---|---|
| char-var | symbol(variable) | In each iteration, the focused character is bound to this variable | |
| charseq | charseq:charseq | Input charseq instance | |
| result-form | T | nil | After the iteration, this form is evaluated as the result |
| body | T* | The body is executed once for each character in the charseq |
Example:
* (defparameter *c* (charseq:make "common-lisp" :start 3 :end 8))
*C*
* (charseq:each (char *c* 'done)
(print (list :char char)))
(:CHAR #\m)
(:CHAR #\o)
(:CHAR #\n)
(:CHAR #\-)
(:CHAR #\l)
DONEThis macro binds the internal state of charseq to string-var, start-var, and end-var, then executes body.
| name | type | description |
|---|---|---|
| string-var | symbol(variable) | The internal string data of charseq is bound to this variable |
| start-var | symbol(variable) | The start position of charseq is bound to this variable |
| end-var | symbol(variable) | The end position of charseq is bound to this variable |
| charseq | charseq:charseq | Input charseq instance |
| body | T* | Any expressions. the scope of bound variables is limited in this body. |
| result | T | Executed result of body |
Example:
* (defparameter *c* (charseq:make "common-lisp" :start 3 :end 8))
*C*
* (charseq:as-string (str start end) *c*
(print (list str start end))
'done)
("common-lisp" 3 8)
DONEThe semantics of this macro is almost equivalent to the following expression:
(let ((charseq-var (charseq:make :start start :end end)))
(declare (dynamic-extent charseq-var))
,@body)On SBCL, the value of charseq-var will be allocated on the stack instead of the heap. In that case, the cost of creating charseq instance (from (simple-array character *) string) will be almost negligible.