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guile/module/language/tree-il/canonicalize.scm
Andy Wingo 19113f1ca7 allow case-lambda expressions with no clauses
* module/ice-9/psyntax-pp.scm:
* module/ice-9/psyntax.scm (case-lambda, case-lambda*): Allow 0
  clauses.

* module/language/scheme/decompile-tree-il.scm (do-decompile):
  (choose-output-names):
* module/language/tree-il.scm (unparse-tree-il):
  (tree-il-fold, post-order!, pre-order!):
* module/language/tree-il/effects.scm (make-effects-analyzer):
* module/language/tree-il/cse.scm (cse):
* module/language/tree-il/debug.scm (verify-tree-il):
* module/language/tree-il/peval.scm (peval): Allow for lambda-body to be
  #f.

* libguile/memoize.c (memoize):
* module/language/tree-il/canonicalize.scm (canonicalize!): Give a body
  to empty case-lambda before evaluating it or compiling it,
  respectively.

* test-suite/tests/optargs.test ("case-lambda", "case-lambda*"): Add
  tests.
2013-03-09 11:16:31 +01:00

101 lines
3.6 KiB
Scheme

;;; Tree-il canonicalizer
;; Copyright (C) 2011, 2012, 2013 Free Software Foundation, Inc.
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;; Code:
(define-module (language tree-il canonicalize)
#:use-module (language tree-il)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:export (canonicalize!))
(define (tree-il-any proc exp)
(tree-il-fold (lambda (exp res)
(or res (proc exp)))
(lambda (exp res)
(or res (proc exp)))
(lambda (exp res) res)
#f exp))
(define (canonicalize! x)
(post-order!
(lambda (x)
(match x
(($ <sequence> src (tail))
tail)
(($ <sequence> src exps)
(and (any sequence? exps)
(make-sequence src
(append-map (lambda (x)
(if (sequence? x)
(sequence-exps x)
(list x)))
exps))))
(($ <let> src () () () body)
body)
(($ <letrec> src _ () () () body)
body)
(($ <fix> src () () () body)
body)
(($ <dynlet> src () () body)
body)
(($ <lambda> src meta #f)
;; Give a body to case-lambda with no clauses.
(make-lambda
src meta
(make-lambda-case
#f '() #f #f #f '() '()
(make-application
#f
(make-primitive-ref #f 'throw)
(list (make-const #f 'wrong-number-of-args)
(make-const #f #f)
(make-const #f "Wrong number of arguments")
(make-const #f '())
(make-const #f #f)))
#f)))
(($ <prompt> src tag body handler)
(define (escape-only? handler)
(match handler
(($ <lambda-case> _ (_ . _) _ _ _ _ (cont . _) body #f)
(not (tree-il-any (lambda (x)
(and (lexical-ref? x)
(eq? (lexical-ref-gensym x) cont)))
body)))
(else #f)))
(define (thunk-application? x)
(match x
(($ <application> _
($ <lambda> _ _ ($ <lambda-case> _ () #f #f #f))
()) #t)
(_ #f)))
(define (make-thunk-application body)
(define thunk
(make-lambda #f '()
(make-lambda-case #f '() #f #f #f '() '() body #f)))
(make-application #f thunk '()))
;; This code has a nasty job to do: to ensure that either the
;; handler is escape-only, or the body is the application of a
;; thunk. Sad but true.
(if (or (escape-only? handler)
(thunk-application? body))
#f
(make-prompt src tag (make-thunk-application body) handler)))
(_ #f)))
x))