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regexp docs: minor corrections

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Fixes inaccuracies discovered when reimplementing
regexp matching in Racket.
This commit is contained in:
Matthew Flatt 2017-06-22 12:22:16 -06:00
parent 36e2155b91
commit 0d2908f824
2 changed files with 12 additions and 2 deletions
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4
pkgs/racket-doc/scribblings/reference/regexps.scrbl
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@ -95,6 +95,10 @@ The following completes the grammar for @racket[pregexp], which uses
@px-table
In case-insensitive mode, a backreference of the form
@litchar{\}@nonterm{n} matches case-insensitively only with respect to
ASCII characters.
The Unicode categories follow.
@category-table

10
pkgs/racket-doc/scribblings/reference/rx.rkt
View File

@ -9,7 +9,7 @@
(define grammar @string-append{
Regexp ::= Pces Match Pces #co
| Regexp|Regexp Match either Regexp, try left first #co 1
Pces ::= Pce Match Pce #co
Pces ::= Match empty #co
| PcePces Match Pce followed by Pces #co
Pce ::= Repeat Match Repeat, longest possible #co 3
| Repeat? Match Repeat, shortest possible #co 6
@ -22,6 +22,7 @@
| Atom{N,} Match Atom N or more times #px 8
| Atom{,M} Match Atom between 0 and M times #px 9
| Atom{N,M} Match Atom between N and M times #px 10
| Atom{} Match Atom 0 or more times #px
Atom ::= (Regexp) Match sub-expression Regexp and report #co 11
| [Rng] Match any character in Rng #co 2
| [^Rng] Match any character not in Rng #co 12
@ -34,6 +35,7 @@
| Look Match empty if Look matches #co
| (?TstPces|Pces) Match 1st Pces if Tst, else 2nd Pces #co 36
| (?TstPces) Match Pces if Tst, empty if not Tst #co
| \`at`end`of`pattern` Match the nul character (ASCII 0) #co
Atom ::= ... ... #px
| \N Match latest reported match for N##th _(_ #px 16
| Class Match any character in Class #px
@ -64,7 +66,7 @@
| (?!Regexp) Match if Regexp doesn't match #mode 32
| (?<=Regexp) Match if Regexp matches preceding #mode 33
| (?<!Regexp) Match if Regexp doesn't match preceding #mode 34
Tst ::= (N) True if Nth _(_ has a match #mode
Tst ::= (N) True if N##th _(_ has a match #mode
| Look True if Look matches #mode 36
Lirng ::= ... ... #px
| Class Lirng contains all characters in Class #px
@ -170,6 +172,10 @@
[(#rx"^(.*?)##(.*)$" X Y)
`(,@(fixup-ids X) ,@(fixup-ids Y))]
[(#rx"^\\.\\.\\.$") (list (element #f (list s)))]
[(#rx"^([^`]*)`(.*)`$" X Y) (append (fixup-ids X)
(list
(element #f " ")
(element #f (regexp-replace* #rx"`" Y " "))))]
[(#rx"^$") null]
[else (list s)]))