suzanne.soy/trivial
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[let-regexp] docs

Browse Source
This commit is contained in:
ben 2016-02-25 12:21:19 -05:00
parent d768e59ca2
commit c5c5aba477
1 changed files with 27 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
scribblings/trivial.scrbl
View File

@ -84,7 +84,7 @@ In other words, the result is one string for the matched substring and an unknow
(U #f (List String String))) (U #f (List String String)))
] ]
Regular expression patterns are expensive to compile, so we offer a definition form that remembers the number of groups in a pattern for later calls to @racket[regexp-match:]. Large regular expression patterns are expensive to compile, so we offer a definition form that remembers the number of groups in a pattern for later calls to @racket[regexp-match:].
@defform*[((define-regexp: id pattern) @defform*[((define-regexp: id pattern)
(define-pregexp: id pattern) (define-pregexp: id pattern)
@ -110,6 +110,32 @@ Regular expression patterns are expensive to compile, so we offer a definition f
(U #f (List Bytes)))) (U #f (List Bytes))))
] ]
Similarly, @racket[let-regexp:] and friends are expression-binding forms.
For both the @racket[define-] and @racket[let-] forms, the @racket[pattern] may be any expression.
The only difference is that regular expression metadata is checked and preserved if present.
@defform*[((let-regexp: ([id expr] ...) expr ...)
(let-pregexp: ([id expr] ...) expr ...)
(let-byte-regexp: ([id expr] ...) expr ...)
(let-byte-pregexp: ([id expr] ...) expr ...))]{}
@examples[#:eval trivial-eval
(let-regexp: ([hamburger (regexp: "^{{.*beef.*}}$")])
(ann (regexp-match: hamburger "{{ lettuce tomato cheese }}")
(U #f (List String))))
(let-pregexp: ([bigmac (pregexp: "(bun).*(bun).*(bun)")])
(ann (regexp-match: bigmac "bun tomato bun meat bun")
(U #f (List String String String String))))
(let-byte-regexp: ([low-carb (byte-regexp: #"^([^bun]*)meat([^bun]*)$")])
(ann (regexp-match: low-carb "meat meat meat")
(U #f (List Bytes Bytes Bytes))))
(let-byte-pregexp: ([double-diet (byte-pregexp: #" {2}")])
(ann (regexp-match: double-diet " ")
(U #f (List Bytes))))
]
The following expression forms also cache the number of pattern groups. The following expression forms also cache the number of pattern groups.
Use these instead of the standard defaults. Use these instead of the standard defaults.