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

Disallow greedy quantifiers from having empty operands in order to stave off

Browse Source 
infinite loops.

original commit: d9c96724bdb2425e802a3360ceaa7ba4f02ab679
This commit is contained in:
Dorai Sitaram 2005-04-25 15:52:34 +00:00
parent 4836b4c50e
commit 372146cde9
1 changed files with 17 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
collects/mzlib/pregexp.ss
View File

@ -520,10 +520,20 @@
(let* ((maximal? (not (cadr re)))
(p (caddr re))
(q (cadddr re))
(could-loop-infinitely? (and maximal? (not q)))
(re (car (cddddr re))))
(let loup-p ((k 0) (i i))
(if (< k p)
(sub re i (lambda (i1) (loup-p (+ k 1) i1)) fk)
(sub
re
i
(lambda (i1)
(if (and could-loop-infinitely? (= i1 i))
(error
'pregexp-match-positions-aux
'greedy-quantifier-operand-could-be-empty))
(loup-p (+ k 1) i1))
fk)
(let ((q (and q (- q p))))
(let loup-q ((k 0) (i i))
(let ((fk (lambda () (sk i))))
@ -533,7 +543,12 @@
(sub
re
i
(lambda (i1) (or (loup-q (+ k 1) i1) (fk)))
(lambda (i1)
(if (and could-loop-infinitely? (= i1 i))
(error
'pregexp-match-positions-aux
'greedy-quantifier-operand-could-be-empty))
(or (loup-q (+ k 1) i1) (fk)))
fk)
(or (fk)
(sub