diff options
| author | Kaz Kylheku <kaz@kylheku.com> | 2021-02-07 07:57:06 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2021-02-07 07:57:06 -0800 |
| commit | ab77cda50d4483da64415c13f3f398d9c28a21da (patch) | |
| tree | db2ea512372586ad7cbef6d684854f7f8ccfa5ed | |
| parent | e6e9820a2060c70b20138b8f26a35e018c029954 (diff) | |
| download | txr-ab77cda50d4483da64415c13f3f398d9c28a21da.tar.gz txr-ab77cda50d4483da64415c13f3f398d9c28a21da.tar.bz2 txr-ab77cda50d4483da64415c13f3f398d9c28a21da.zip | |
matcher: eliminate use of flags.
* share/txr/stdlib/match.tl (if-match, match-case,
lambda-match): Instead of returning the result from the
case(s), which gets stored in a result variable, and setting a
flag to t, set the result variable inside the case, and return
t. This eliminates the flag. In match-case and lambda-match,
the cases can then be combined into an or form.
| -rw-r--r-- | share/txr/stdlib/match.tl | 45 |
1 files changed, 18 insertions, 27 deletions
diff --git a/share/txr/stdlib/match.tl b/share/txr/stdlib/match.tl index a0339fab..2ed436d7 100644 --- a/share/txr/stdlib/match.tl +++ b/share/txr/stdlib/match.tl @@ -581,11 +581,12 @@ (match-p (gensym "match-p-")) (result (gensym "result-"))) ^(alet ((,cm.obj-var ,obj)) - (let* (,match-p ,*cm.(get-vars) - (,result ,cm.(wrap-guards - ^(set ,match-p t) - then))) - (if ,match-p ,result ,else))))) + (let* (,result ,*cm.(get-vars)) + (if ,cm.(wrap-guards + ^(set ,result ,then) + t) + ,result + ,else))))) (defmacro match-case (:form *match-form* :env e obj . clauses) (unless [all clauses [andf proper-listp [chain len plusp]]] @@ -599,20 +600,15 @@ clauses]) (nclauses (len clauses)) (clause-code (collect-each ((cl clauses) - (cm clause-matches) - (i 1)) + (cm clause-matches)) (mac-param-bind *match-form* (match . forms) cl - ^(unless ,(unless (eql i 1) matched-p-temp) - (let (,*cm.(get-vars)) - (set ,result-temp - ,(if (eql i nclauses) - cm.(wrap-guards . forms) - cm.(wrap-guards - ^(set ,matched-p-temp t) - . forms))))))))) + ^(let (,*cm.(get-vars)) + ,cm.(wrap-guards ^(set ,result-temp + (progn ,*forms)) + t)))))) ^(alet ((,objvar ,obj)) - (let (,matched-p-temp ,result-temp) - ,*clause-code + (let (,result-temp) + (or ,*clause-code) ,result-temp)))) (defmacro when-exprs-match (:form *match-form* :env e pats exprs . forms) @@ -666,11 +662,9 @@ (arg-temps (append fix-arg-temps opt-arg-temps)) (present-vec (vec-list (append (repeat '(t) min-args) present-p-temps))) - (matched-p-temp (gensym "matched-p")) (result-temp (gensym "result")) (nclauses (len parsed-clauses)) - (ex-clauses (collect-each ((pc parsed-clauses) - (counter 1)) + (ex-clauses (collect-each ((pc parsed-clauses)) (let* ((vp pc.variadic-pattern) (exp ^(when-exprs-match (,*pc.fixed-patterns @@ -679,9 +673,8 @@ ,*(if vp ^((list* ,*[arg-temps pc.nfixed..:] ,rest-temp)))) - ,*(unless (eql counter nclauses) - ^((set ,matched-p-temp t))) - (set ,result-temp (progn ,*pc.forms))))) + (set ,result-temp (progn ,*pc.forms)) + t))) (sys:set-macro-ancestor exp pc.orig-syntax) (when (> pc.nfixed min-args) (set exp ^(when ,[present-vec (pred pc.nfixed)] @@ -692,16 +685,14 @@ (when (and variadic (not vp) (= pc.nfixed max-args)) (set exp ^(unless ,rest-temp ,exp))) - (unless (eql 1 counter) - (set exp ^(unless ,matched-p-temp ,exp))) exp)))) ^(lambda (,*fix-arg-temps ,*(if opt-arg-temps (cons : (mapcar (ret ^(,@1 nil ,@2)) opt-arg-temps present-p-temps))) . ,rest-temp) - (let (,matched-p-temp ,result-temp) - ,*ex-clauses + (let (,result-temp) + (or ,*ex-clauses) ,result-temp)))) (defmacro lambda-match (:form *match-form* . clauses) |