ice-9/syncase.scm

   1 ;;;;    Copyright (C) 1997, 2000, 2001 Free Software Foundation, Inc.
   2 ;;;;
   3 ;;;; This program is free software; you can redistribute it and/or modify
   4 ;;;; it under the terms of the GNU General Public License as published by
   5 ;;;; the Free Software Foundation; either version 2, or (at your option)
   6 ;;;; any later version.
   7 ;;;;
   8 ;;;; This program is distributed in the hope that it will be useful,
   9 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 ;;;; GNU General Public License for more details.
  12 ;;;;
  13 ;;;; You should have received a copy of the GNU General Public License
  14 ;;;; along with this software; see the file COPYING.  If not, write to
  15 ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16 ;;;; Boston, MA 02111-1307 USA
  17 ;;;;
  18 ;;;; As a special exception, the Free Software Foundation gives permission
  19 ;;;; for additional uses of the text contained in its release of GUILE.
  20 ;;;;
  21 ;;;; The exception is that, if you link the GUILE library with other files
  22 ;;;; to produce an executable, this does not by itself cause the
  23 ;;;; resulting executable to be covered by the GNU General Public License.
  24 ;;;; Your use of that executable is in no way restricted on account of
  25 ;;;; linking the GUILE library code into it.
  26 ;;;;
  27 ;;;; This exception does not however invalidate any other reasons why
  28 ;;;; the executable file might be covered by the GNU General Public License.
  29 ;;;;
  30 ;;;; This exception applies only to the code released by the
  31 ;;;; Free Software Foundation under the name GUILE.  If you copy
  32 ;;;; code from other Free Software Foundation releases into a copy of
  33 ;;;; GUILE, as the General Public License permits, the exception does
  34 ;;;; not apply to the code that you add in this way.  To avoid misleading
  35 ;;;; anyone as to the status of such modified files, you must delete
  36 ;;;; this exception notice from them.
  37 ;;;;
  38 ;;;; If you write modifications of your own for GUILE, it is your choice
  39 ;;;; whether to permit this exception to apply to your modifications.
  40 ;;;; If you do not wish that, delete this exception notice.
  41 ;;;;
  42 \f
  43
  44 (define-module (ice-9 syncase)
  45   :use-module (ice-9 debug)
  46   :export-syntax (sc-macro define-syntax eval-when fluid-let-syntax
  47                   identifier-syntax let-syntax
  48                   letrec-syntax syntax syntax-case  syntax-rules
  49                   with-syntax
  50                   include)
  51   :export (sc-expand sc-expand3 install-global-transformer
  52            syntax-dispatch syntax-error bound-identifier=?
  53            datum->syntax-object free-identifier=?
  54            generate-temporaries identifier? syntax-object->datum
  55            void eval syncase))
  56
  57 \f
  58
  59 (define sc-macro
  60   (procedure->memoizing-macro
  61     (lambda (exp env)
  62       (sc-expand exp))))
  63
  64 ;;; Exported variables
  65
  66 (define sc-expand #f)
  67 (define sc-expand3 #f)
  68 (define install-global-transformer #f)
  69 (define syntax-dispatch #f)
  70 (define syntax-error #f)
  71
  72 (define bound-identifier=? #f)
  73 (define datum->syntax-object #f)
  74 (define define-syntax sc-macro)
  75 (define eval-when sc-macro)
  76 (define fluid-let-syntax sc-macro)
  77 (define free-identifier=? #f)
  78 (define generate-temporaries #f)
  79 (define identifier? #f)
  80 (define identifier-syntax sc-macro)
  81 (define let-syntax sc-macro)
  82 (define letrec-syntax sc-macro)
  83 (define syntax sc-macro)
  84 (define syntax-case sc-macro)
  85 (define syntax-object->datum #f)
  86 (define syntax-rules sc-macro)
  87 (define with-syntax sc-macro)
  88 (define include sc-macro)
  89
  90 (define primitive-syntax '(quote lambda letrec if set! begin define or
  91                               and let let* cond do quasiquote unquote
  92                               unquote-splicing case))
  93
  94 (for-each (lambda (symbol)
  95             (set-symbol-property! symbol 'primitive-syntax #t))
  96           primitive-syntax)
  97
  98 ;;; Hooks needed by the syntax-case macro package
  99
 100 (define (void) *unspecified*)
 101
 102 (define andmap
 103   (lambda (f first . rest)
 104     (or (null? first)
 105         (if (null? rest)
 106             (let andmap ((first first))
 107               (let ((x (car first)) (first (cdr first)))
 108                 (if (null? first)
 109                     (f x)
 110                     (and (f x) (andmap first)))))
 111             (let andmap ((first first) (rest rest))
 112               (let ((x (car first))
 113                     (xr (map car rest))
 114                     (first (cdr first))
 115                     (rest (map cdr rest)))
 116                 (if (null? first)
 117                     (apply f (cons x xr))
 118                     (and (apply f (cons x xr)) (andmap first rest)))))))))
 119
 120 (define (error who format-string why what)
 121   (start-stack 'syncase-stack
 122                (scm-error 'misc-error
 123                           who
 124                           "~A ~S"
 125                           (list why what)
 126                           '())))
 127
 128 (define the-syncase-module (current-module))
 129
 130 (define (putprop symbol key binding)
 131   (let* ((m (current-module))
 132          (v (or (module-variable m symbol)
 133                 (module-make-local-var! m symbol))))
 134     (if (symbol-property symbol 'primitive-syntax)
 135         (if (eq? (current-module) the-syncase-module)
 136             (set-object-property! (module-variable the-root-module symbol)
 137                                   key
 138                                   binding))
 139         (variable-set! v sc-macro))
 140     (set-object-property! v key binding)))
 141
 142 (define (getprop symbol key)
 143   (let* ((m (current-module))
 144          (v (module-variable m symbol)))
 145     (and v (or (object-property v key)
 146                (let ((root-v (module-local-variable the-root-module symbol)))
 147                  (and (equal? root-v v)
 148                       (object-property root-v key)))))))
 149
 150 (define generated-symbols (make-weak-key-hash-table 1019))
 151
 152 ;; We define our own gensym here because the Guile built-in one will
 153 ;; eventually produce uninterned and unreadable symbols (as needed for
 154 ;; safe macro expansions) and will the be inappropriate for dumping to
 155 ;; pssyntax.pp.
 156 ;;
 157 ;; syncase is supposed to only require that gensym produce unique
 158 ;; readable symbols, and they only need be unique with respect to
 159 ;; multiple calls to gensym, not globally unique.
 160 ;;
 161 (define gensym
 162   (let ((counter 0))
 163
 164     (define next-id
 165       (if (provided? 'threads)
 166           (let ((symlock (make-mutex)))
 167             (lambda ()
 168               (let ((result #f))
 169                 (with-mutex symlock
 170                   (set! result counter)
 171                   (set! counter (+ counter 1)))
 172                 result)))
 173           ;; faster, non-threaded case.
 174           (lambda ()
 175             (let ((result counter))
 176               (set! counter (+ counter 1))
 177               result))))
 178
 179     ;; actual gensym body code.
 180     (lambda (. rest)
 181       (let* ((next-val (next-id))
 182              (valstr (number->string next-val)))
 183           (cond
 184            ((null? rest)
 185             (string->symbol (string-append "syntmp-" valstr)))
 186            ((null? (cdr rest))
 187             (string->symbol (string-append "syntmp-" (car rest) "-" valstr)))
 188            (else
 189             (error
 190              (string-append
 191               "syncase's gensym expected 0 or 1 arguments, got "
 192               (length rest)))))))))
 193
 194 ;;; Load the preprocessed code
 195
 196 (let ((old-debug #f)
 197       (old-read #f))
 198   (dynamic-wind (lambda ()
 199                   (set! old-debug (debug-options))
 200                   (set! old-read (read-options)))
 201                 (lambda ()
 202                   (debug-disable 'debug 'procnames)
 203                   (read-disable 'positions)
 204                   (load-from-path "ice-9/psyntax.pp"))
 205                 (lambda ()
 206                   (debug-options old-debug)
 207                   (read-options old-read))))
 208
 209
 210 ;;; The following lines are necessary only if we start making changes
 211 ;; (use-syntax sc-expand)
 212 ;; (load-from-path "ice-9/psyntax.ss")
 213
 214 (define internal-eval (nested-ref the-scm-module '(app modules guile eval)))
 215
 216 (define (eval x environment)
 217   (internal-eval (if (and (pair? x)
 218                           (equal? (car x) "noexpand"))
 219                      (cadr x)
 220                      (sc-expand x))
 221                  environment))
 222
 223 ;;; Hack to make syncase macros work in the slib module
 224 (let ((m (nested-ref the-root-module '(app modules ice-9 slib))))
 225   (if m
 226       (set-object-property! (module-local-variable m 'define)
 227                             '*sc-expander*
 228                             '(define))))
 229
 230 (define syncase sc-expand)