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* lisp/emacs-lisp/pcase.el (pcase--u1): Understand non-linear patterns.

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Stefan Monnier 2011-02-17 23:58:21 -05:00
parent 5da16a8641
commit f9d554dd46
2 changed files with 12 additions and 1 deletions
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4
lisp/ChangeLog
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@ -1,3 +1,7 @@
2011-02-18 Stefan Monnier <monnier@iro.umontreal.ca>
* emacs-lisp/pcase.el (pcase--u1): Understand non-linear patterns.
2011-02-18 Christian Ohler <ohler@gnu.org>
* emacs-lisp/ert.el (ert--setup-results-buffer)

9
lisp/emacs-lisp/pcase.el
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@ -61,6 +61,8 @@ UPatterns can take the following forms:
`QPAT matches if the QPattern QPAT matches.
(pred PRED) matches if PRED applied to the object returns non-nil.
(guard BOOLEXP) matches if BOOLEXP evaluates to non-nil.
If a SYMBOL is used twice in the same pattern (i.e. the pattern is
\"non-linear\"), then the second occurrence is turned into an `eq'uality test.
QPatterns can take the following forms:
(QPAT1 . QPAT2) matches if QPAT1 matches the car and QPAT2 the cdr.
@ -457,7 +459,12 @@ and otherwise defers to REST which is a list of branches of the form
(pcase--u1 matches code vars then-rest)
(pcase--u else-rest))))
((symbolp upat)
(pcase--u1 matches code (cons (cons upat sym) vars) rest))
(if (not (assq upat vars))
(pcase--u1 matches code (cons (cons upat sym) vars) rest)
;; Non-linear pattern. Turn it into an `eq' test.
(pcase--u1 (cons `(match ,sym . (pred (eq ,(cdr (assq upat vars)))))
matches)
code vars rest)))
((eq (car-safe upat) '\`)
(pcase--q1 sym (cadr upat) matches code vars rest))
((eq (car-safe upat) 'or)