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| author | Kaz Kylheku <kaz@kylheku.com> | 2023-03-23 07:37:57 -0700 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2023-03-23 07:37:57 -0700 |
| commit | bf82e9cfa8fc2b627af6e2fcfcbc1bbfc61e63d9 (patch) | |
| tree | 1fb96bf438be30420dcc50f376b9e5d4996a8aae /stdlib | |
| parent | 5861192436b31f7377bd82cacb7acc8cc8baf4f9 (diff) | |
| download | txr-bf82e9cfa8fc2b627af6e2fcfcbc1bbfc61e63d9.tar.gz txr-bf82e9cfa8fc2b627af6e2fcfcbc1bbfc61e63d9.tar.bz2 txr-bf82e9cfa8fc2b627af6e2fcfcbc1bbfc61e63d9.zip | |
match: support @nil in predicates.
For instance @(<= 10 @nil 20) is a pattern which matches
a number between 10 and 20, without binding a variable.
* stdlib/match.tl (compile-predicate-match): Looks like
this code was already halfway expressing the intent that
the avar could be nil, because arg-var takes the value
of avar if that is non-nil, otherwise a gensym is
substituted. What was missing was that the gensym that
replaces nil must also be substituted into the predicate.
* tests/011/patmatch.tl: New tests.
* txr.1: Document that the variable embedded in a
predicate may be null.
Diffstat (limited to 'stdlib')
| -rw-r--r-- | stdlib/match.tl | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/stdlib/match.tl b/stdlib/match.tl index 3adbba27..c59179f3 100644 --- a/stdlib/match.tl +++ b/stdlib/match.tl @@ -275,21 +275,27 @@ (if (and (consp head) (eq (car head) 'sys:var)) (tree-case exp (((t rvar) (op . args)) - (let* ((avar + (let* ((arg-var (gensym "obj-")) + (avar (condlet (((vm (member-if [andf consp (op eq (car @1) 'sys:var)] args))) (let ((sym (cadar vm))) + (if (null sym) + (set sym arg-var) + (set arg-var sym)) (set args (append (ldiff args vm) (list sym) (cdr vm))) sym)) (((vm (memq 'sys:var args))) (let ((sym (cadr vm))) + (if (null sym) + (set sym arg-var) + (set arg-var sym)) (set args (append (ldiff args vm) sym)) sym)))) - (res-var (gensym "res-")) - (arg-var (if avar avar (gensym "obj-")))) + (res-var (gensym "res-"))) (unless avar (set args (append args (list arg-var)))) (let* ((guard (new match-guard |