[Bug-kawa] [bug #37633] char-set-union with same char-sets

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?37633>

                 Summary: char-set-union with same char-sets
                 Project: Kawa
            Submitted by: None
            Submitted on: Fri 26 Oct 2012 12:04:24 AM UTC
                Category: Scheme library
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

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Details:

char-set-union from the srfi-14 lib goes in an infinite loop when applying it
to the same charsets. For example, this fails with a stack overflow:

(import (srfi :14)) (char-set-union char-set:ascii char-set:ascii)

it is fixed by defining %boundary-pairs-union as follows, with one additional
and clause:

(define (%boundary-pairs-union (l1 ::list) (l2 ::list)) ::list
  (display l1) (display " -- ") 
  (display l2) (newline)
  (cond ((null? l1) l2)
        ((null? l2) l1)
        ((or (> (cdar l2) (cdar l1))        ; swap arguments if
             (and (= (cdar l2) (cdar l1))   ; necessary to ensure
                  (< (caar l2) (cdar l1))   ; (cdar l1) is highest
                  (> (caar l2) (caar l1)))) 
         (%boundary-pairs-union l2 l1))
        (else
....





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