libguile/macros.c

   1 /*      Copyright (C) 1995,1996,1997,1998, 2000 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 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 #include "libguile/_scm.h"
  48 #include "libguile/root.h"
  49 #include "libguile/smob.h"
  50
  51 #include "libguile/validate.h"
  52 #include "libguile/macros.h"
  53
  54 long scm_tc16_macro;
  55
  56 SCM_DEFINE (scm_makacro, "procedure->syntax", 1, 0, 0,
  57             (SCM code),
  58             "Returns a @dfn{macro} which, when a symbol defined to this value\n"
  59             "appears as the first symbol in an expression, returns the result\n"
  60             "of applying @var{code} to the expression and the environment.")
  61 #define FUNC_NAME s_scm_makacro
  62 {
  63   SCM_VALIDATE_PROC (1,code);
  64   SCM_RETURN_NEWSMOB (scm_tc16_macro, SCM_UNPACK (code));
  65 }
  66 #undef FUNC_NAME
  67
  68
  69 SCM_DEFINE (scm_makmacro, "procedure->macro", 1, 0, 0,
  70            (SCM code),
  71             "Returns a @dfn{macro} which, when a symbol defined to this value\n"
  72             "appears as the first symbol in an expression, evaluates the result\n"
  73             "of applying @var{code} to the expression and the environment.\n"
  74             "The value returned from @var{code} which has been passed to\n"
  75             "@code{procedure->memoizing-macro} replaces the form passed to\n"
  76             "@var{code}.  For example:\n\n"
  77             "@example\n"
  78             "(define trace\n"
  79             "  (procedure->macro\n"
  80             "   (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x))))))\n\n"
  81             "(trace @i{foo}) @equiv{} (set! @i{foo} (tracef @i{foo} '@i{foo})).\n"
  82             "@end example\n")
  83 #define FUNC_NAME s_scm_makmacro
  84 {
  85   SCM_VALIDATE_PROC (1,code);
  86   SCM_RETURN_NEWSMOB (scm_tc16_macro | (1L << 16), SCM_UNPACK (code));
  87 }
  88 #undef FUNC_NAME
  89
  90
  91 SCM_DEFINE (scm_makmmacro, "procedure->memoizing-macro", 1, 0, 0,
  92            (SCM code),
  93             "Returns a @dfn{macro} which, when a symbol defined to this value\n"
  94             "appears as the first symbol in an expression, evaluates the result\n"
  95             "of applying @var{proc} to the expression and the environment.\n"
  96             "The value returned from @var{proc} which has been passed to\n"
  97             "@code{procedure->memoizing-macro} replaces the form passed to\n"
  98             "@var{proc}.  For example:\n\n"
  99             "@example\n"
 100             "(define trace\n"
 101             "  (procedure->macro\n"
 102             "   (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x))))))\n\n"
 103             "(trace @i{foo}) @equiv{} (set! @i{foo} (tracef @i{foo} '@i{foo})).\n"
 104             "@end example\n")
 105 #define FUNC_NAME s_scm_makmmacro
 106 {
 107   SCM_VALIDATE_PROC (1,code);
 108   SCM_RETURN_NEWSMOB (scm_tc16_macro | (2L << 16), SCM_UNPACK (code));
 109 }
 110 #undef FUNC_NAME
 111
 112
 113 SCM_DEFINE (scm_macro_p, "macro?", 1, 0, 0,
 114             (SCM obj),
 115             "Return @code{#t} if @var{obj} is a regular macro, a memoizing macro or a\n"
 116             "syntax transformer.")
 117 #define FUNC_NAME s_scm_macro_p
 118 {
 119   return SCM_BOOL(SCM_NIMP (obj) && SCM_TYP16 (obj) == scm_tc16_macro);
 120 }
 121 #undef FUNC_NAME
 122
 123
 124 SCM_SYMBOL (scm_sym_syntax, "syntax");
 125 SCM_SYMBOL (scm_sym_macro, "macro");
 126 SCM_SYMBOL (scm_sym_mmacro, "macro!");
 127
 128 SCM_DEFINE (scm_macro_type, "macro-type", 1, 0, 0,
 129             (SCM m),
 130             "Return one of the symbols @code{syntax}, @code{macro} or @code{macro!},\n"
 131             "depending on whether @var{obj} is a syntax tranformer, a regular macro,\n"
 132             "or a memoizing macro, respectively.  If @var{obj} is not a macro,\n"
 133             "@code{#f} is returned.")
 134 #define FUNC_NAME s_scm_macro_type
 135 {
 136   if (!(SCM_NIMP (m) && SCM_TYP16 (m) == scm_tc16_macro))
 137     return SCM_BOOL_F;
 138   switch (SCM_CELL_WORD_0 (m) >> 16)
 139     {
 140     case 0: return scm_sym_syntax;
 141     case 1: return scm_sym_macro;
 142     case 2: return scm_sym_mmacro;
 143     default: scm_wrong_type_arg (FUNC_NAME, 1, m);
 144     }
 145 }
 146 #undef FUNC_NAME
 147
 148
 149 SCM_DEFINE (scm_macro_name, "macro-name", 1, 0, 0,
 150             (SCM m),
 151             "")
 152 #define FUNC_NAME s_scm_macro_name
 153 {
 154   SCM_VALIDATE_SMOB (1,m,macro);
 155   return scm_procedure_name (SCM_CDR (m));
 156 }
 157 #undef FUNC_NAME
 158
 159
 160 SCM_DEFINE (scm_macro_transformer, "macro-transformer", 1, 0, 0,
 161             (SCM m),
 162             "")
 163 #define FUNC_NAME s_scm_macro_transformer
 164 {
 165   SCM_VALIDATE_SMOB (1,m,macro);
 166   return SCM_CLOSUREP (SCM_CDR (m)) ? SCM_CDR (m) : SCM_BOOL_F;
 167 }
 168 #undef FUNC_NAME
 169
 170 SCM
 171 scm_make_synt (const char *name, SCM (*macroizer) (), SCM (*fcn)() )
 172 {
 173   SCM symcell = scm_sysintern (name, SCM_UNDEFINED);
 174   SCM transformer = scm_make_subr_opt (name, scm_tc7_subr_2, fcn, 0);
 175   SCM_SETCDR (symcell, macroizer (transformer));
 176   return SCM_CAR (symcell);
 177 }
 178
 179 void
 180 scm_init_macros ()
 181 {
 182   scm_tc16_macro = scm_make_smob_type_mfpe ("macro", 0,
 183                                            scm_markcdr, NULL, NULL, NULL);
 184 #include "libguile/macros.x"
 185 }
 186
 187 /*
 188   Local Variables:
 189   c-file-style: "gnu"
 190   End:
 191 */