[parenscript-devel] Patch: destructuring-bind now supports dotted lists and nested lists
A couple of examples, followed by patch: (ps (destructuring-bind (a . rest) list (blah a rest))) => "var a = list[0]; var rest = list.length > 1 ? list.slice(1) : null; blah(a, rest);" (ps (destructuring-bind ((a (b c)) (d e)) list)) => "var _js42 = list[0]; var a = _js42[0]; var _js43 = _js42[1]; var b = _js43[0]; var c = _js43[1]; var _js44 = list[1]; var d = _js44[0]; var e = _js44[1];"
From 74d29fe528d40795071e61df4fb1e4b56b28f049 Mon Sep 17 00:00:00 2001 From: Daniel Gackle <danielgackle@gmail.com> Date: Fri, 10 Jul 2009 16:31:55 -0600 Subject: [PATCH 1/2] DESTRUCTURING-BIND can now handle dotted and nested binding lists.
--- src/lib/ps-macro-lib.lisp | 31 +++++++++++++++++++++---------- 1 files changed, 21 insertions(+), 10 deletions(-) diff --git a/src/lib/ps-macro-lib.lisp b/src/lib/ps-macro-lib.lisp index 1013939..d70561c 100644 --- a/src/lib/ps-macro-lib.lisp +++ b/src/lib/ps-macro-lib.lisp @@ -144,14 +144,25 @@ (first args)))) `((@ ,fn :apply) this ,arglist))) -(defpsmacro destructuring-bind (vars expr &body body) - ;; a simple implementation that for now only supports flat lists, - ;; but does allow NIL bindings to indicate ignore (a la LOOP) +(defun destructuring-wrap (arr n bindings body) + (cond ((null bindings) + body) + ((atom bindings) + ;; dotted destructuring list + `(let ((,bindings (when (> (length ,arr) ,n) + ((@ ,arr :slice) ,n)))) + ,body)) + (t (let ((var (car bindings)) + (inner-body (destructuring-wrap arr (1+ n) (cdr bindings) body))) + (cond ((null var) inner-body) + ((atom var) `(let ((,var (aref ,arr ,n))) + ,inner-body)) + (t `(destructuring-bind ,var (aref ,arr ,n) + ,inner-body))))))) + +(defpsmacro destructuring-bind (bindings expr &body body) (let* ((arr (if (complex-js-expr? expr) (ps-gensym) expr)) - (n -1) - (bindings - (append (unless (equal arr expr) `((,arr ,expr))) - (mapcan (lambda (var) - (incf n) - (when var `((,var (aref ,arr ,n))))) vars)))) - `(let* ,bindings ,@body))) + (bound (destructuring-wrap arr 0 bindings (cons 'progn body)))) + (if (eq arr expr) + bound + `(let ((,arr ,expr)) ,bound)))) -- 1.6.1
Just pushed this. Thanks for the patch! On Fri, Jul 10, 2009 at 8:26 PM, Daniel Gackle<danielgackle@gmail.com> wrote:
A couple of examples, followed by patch:
(ps (destructuring-bind (a . rest) list (blah a rest))) => "var a = list[0]; var rest = list.length > 1 ? list.slice(1) : null; blah(a, rest);"
(ps (destructuring-bind ((a (b c)) (d e)) list)) => "var _js42 = list[0]; var a = _js42[0]; var _js43 = _js42[1]; var b = _js43[0]; var c = _js43[1]; var _js44 = list[1]; var d = _js44[0]; var e = _js44[1];"
From 74d29fe528d40795071e61df4fb1e4b56b28f049 Mon Sep 17 00:00:00 2001 From: Daniel Gackle <danielgackle@gmail.com> Date: Fri, 10 Jul 2009 16:31:55 -0600 Subject: [PATCH 1/2] DESTRUCTURING-BIND can now handle dotted and nested binding lists.
--- src/lib/ps-macro-lib.lisp | 31 +++++++++++++++++++++---------- 1 files changed, 21 insertions(+), 10 deletions(-)
diff --git a/src/lib/ps-macro-lib.lisp b/src/lib/ps-macro-lib.lisp index 1013939..d70561c 100644 --- a/src/lib/ps-macro-lib.lisp +++ b/src/lib/ps-macro-lib.lisp @@ -144,14 +144,25 @@ (first args)))) `((@ ,fn :apply) this ,arglist)))
-(defpsmacro destructuring-bind (vars expr &body body) - ;; a simple implementation that for now only supports flat lists, - ;; but does allow NIL bindings to indicate ignore (a la LOOP) +(defun destructuring-wrap (arr n bindings body) + (cond ((null bindings) + body) + ((atom bindings) + ;; dotted destructuring list + `(let ((,bindings (when (> (length ,arr) ,n) + ((@ ,arr :slice) ,n)))) + ,body)) + (t (let ((var (car bindings)) + (inner-body (destructuring-wrap arr (1+ n) (cdr bindings) body))) + (cond ((null var) inner-body) + ((atom var) `(let ((,var (aref ,arr ,n))) + ,inner-body)) + (t `(destructuring-bind ,var (aref ,arr ,n) + ,inner-body))))))) + +(defpsmacro destructuring-bind (bindings expr &body body) (let* ((arr (if (complex-js-expr? expr) (ps-gensym) expr)) - (n -1) - (bindings - (append (unless (equal arr expr) `((,arr ,expr))) - (mapcan (lambda (var) - (incf n) - (when var `((,var (aref ,arr ,n))))) vars)))) - `(let* ,bindings ,@body))) + (bound (destructuring-wrap arr 0 bindings (cons 'progn body)))) + (if (eq arr expr) + bound + `(let ((,arr ,expr)) ,bound)))) -- 1.6.1
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