libguile/macros.c

   1 /* Copyright (C) 1995,1996,1997,1998,2000,2001 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 /* 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/alist.h" /* for SCM_EXTEND_ENV (well...) */
  49 #include "libguile/eval.h"
  50 #include "libguile/ports.h"
  51 #include "libguile/print.h"
  52 #include "libguile/root.h"
  53 #include "libguile/smob.h"
  54
  55 #include "libguile/validate.h"
  56 #include "libguile/macros.h"
  57
  58 scm_bits_t scm_tc16_macro;
  59
  60
  61 static int
  62 macro_print (SCM macro, SCM port, scm_print_state *pstate)
  63 {
  64   SCM code = SCM_MACRO_CODE (macro);
  65   if (!SCM_CLOSUREP (code)
  66       || SCM_FALSEP (scm_procedure_p (SCM_PRINT_CLOSURE))
  67       || SCM_FALSEP (scm_printer_apply (SCM_PRINT_CLOSURE,
  68                                         macro, port, pstate)))
  69     {
  70       if (!SCM_CLOSUREP (code))
  71         scm_puts ("#<primitive-", port);
  72       else
  73         scm_puts ("#<", port);
  74
  75       if (SCM_MACRO_TYPE (macro) == 0)
  76         scm_puts ("syntax", port);
  77       else if (SCM_MACRO_TYPE (macro) == 1)
  78         scm_puts ("macro", port);
  79       if (SCM_MACRO_TYPE (macro) == 2)
  80         scm_puts ("macro!", port);
  81       scm_putc (' ', port);
  82       scm_iprin1 (scm_macro_name (macro), port, pstate);
  83
  84       if (SCM_CLOSUREP (code) && SCM_PRINT_SOURCE_P)
  85         {
  86           SCM formals = SCM_CLOSURE_FORMALS (code);
  87           SCM env = SCM_ENV (code);
  88           SCM xenv = SCM_EXTEND_ENV (formals, SCM_EOL, env);
  89           SCM src = scm_unmemocopy (SCM_CODE (code), xenv);
  90           scm_putc (' ', port);
  91           scm_iprin1 (src, port, pstate);
  92         }
  93
  94       scm_putc ('>', port);
  95     }
  96
  97   return 1;
  98 }
  99
 100
 101 SCM_DEFINE (scm_makacro, "procedure->syntax", 1, 0, 0,
 102             (SCM code),
 103             "Return a @dfn{macro} which, when a symbol defined to this value\n"
 104             "appears as the first symbol in an expression, returns the\n"
 105             "result of applying @var{code} to the expression and the\n"
 106             "environment.")
 107 #define FUNC_NAME s_scm_makacro
 108 {
 109   SCM_VALIDATE_PROC (1,code);
 110   SCM_RETURN_NEWSMOB (scm_tc16_macro, SCM_UNPACK (code));
 111 }
 112 #undef FUNC_NAME
 113
 114
 115 SCM_DEFINE (scm_makmacro, "procedure->macro", 1, 0, 0,
 116            (SCM code),
 117             "Return a @dfn{macro} which, when a symbol defined to this value\n"
 118             "appears as the first symbol in an expression, evaluates the\n"
 119             "result of applying @var{code} to the expression and the\n"
 120             "environment.  The value returned from @var{code} which has been\n"
 121             "passed to @code{procedure->memoizing-macro} replaces the form\n"
 122             "passed to @var{code}.  For example:\n"
 123             "\n"
 124             "@lisp\n"
 125             "(define trace\n"
 126             "  (procedure->macro\n"
 127             "   (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x))))))\n\n"
 128             "(trace @i{foo}) @equiv{} (set! @i{foo} (tracef @i{foo} '@i{foo})).\n"
 129             "@end lisp")
 130 #define FUNC_NAME s_scm_makmacro
 131 {
 132   SCM_VALIDATE_PROC (1,code);
 133   SCM_RETURN_NEWSMOB (scm_tc16_macro | (1L << 16), SCM_UNPACK (code));
 134 }
 135 #undef FUNC_NAME
 136
 137
 138 SCM_DEFINE (scm_makmmacro, "procedure->memoizing-macro", 1, 0, 0,
 139            (SCM code),
 140             "Return a @dfn{macro} which, when a symbol defined to this value\n"
 141             "appears as the first symbol in an expression, evaluates the\n"
 142             "result of applying @var{proc} to the expression and the\n"
 143             "environment.  The value returned from @var{proc} which has been\n"
 144             "passed to @code{procedure->memoizing-macro} replaces the form\n"
 145             "passed to @var{proc}.  For example:\n"
 146             "\n"
 147             "@lisp\n"
 148             "(define trace\n"
 149             "  (procedure->macro\n"
 150             "   (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x))))))\n\n"
 151             "(trace @i{foo}) @equiv{} (set! @i{foo} (tracef @i{foo} '@i{foo})).\n"
 152             "@end lisp")
 153 #define FUNC_NAME s_scm_makmmacro
 154 {
 155   SCM_VALIDATE_PROC (1,code);
 156   SCM_RETURN_NEWSMOB (scm_tc16_macro | (2L << 16), SCM_UNPACK (code));
 157 }
 158 #undef FUNC_NAME
 159
 160
 161 SCM_DEFINE (scm_macro_p, "macro?", 1, 0, 0,
 162             (SCM obj),
 163             "Return @code{#t} if @var{obj} is a regular macro, a memoizing macro or a\n"
 164             "syntax transformer.")
 165 #define FUNC_NAME s_scm_macro_p
 166 {
 167   return SCM_BOOL (SCM_TYP16_PREDICATE (scm_tc16_macro, obj));
 168 }
 169 #undef FUNC_NAME
 170
 171
 172 SCM_SYMBOL (scm_sym_syntax, "syntax");
 173 SCM_SYMBOL (scm_sym_macro, "macro");
 174 SCM_SYMBOL (scm_sym_mmacro, "macro!");
 175
 176 SCM_DEFINE (scm_macro_type, "macro-type", 1, 0, 0,
 177             (SCM m),
 178             "Return one of the symbols @code{syntax}, @code{macro} or\n"
 179             "@code{macro!}, depending on whether @var{m} is a syntax\n"
 180             "tranformer, a regular macro, or a memoizing macro,\n"
 181             "respectively.  If @var{m} is not a macro, @code{#f} is\n"
 182             "returned.")
 183 #define FUNC_NAME s_scm_macro_type
 184 {
 185   if (!SCM_TYP16_PREDICATE (scm_tc16_macro, m))
 186     return SCM_BOOL_F;
 187   switch (SCM_MACRO_TYPE (m))
 188     {
 189     case 0: return scm_sym_syntax;
 190     case 1: return scm_sym_macro;
 191     case 2: return scm_sym_mmacro;
 192     default: scm_wrong_type_arg (FUNC_NAME, 1, m);
 193     }
 194 }
 195 #undef FUNC_NAME
 196
 197
 198 SCM_DEFINE (scm_macro_name, "macro-name", 1, 0, 0,
 199             (SCM m),
 200             "Return the name of the macro @var{m}.")
 201 #define FUNC_NAME s_scm_macro_name
 202 {
 203   SCM_VALIDATE_SMOB (1,m,macro);
 204   return scm_procedure_name (SCM_PACK (SCM_SMOB_DATA (m)));
 205 }
 206 #undef FUNC_NAME
 207
 208
 209 SCM_DEFINE (scm_macro_transformer, "macro-transformer", 1, 0, 0,
 210             (SCM m),
 211             "Return the transformer of the macro @var{m}.")
 212 #define FUNC_NAME s_scm_macro_transformer
 213 {
 214   SCM_VALIDATE_SMOB (1,m,macro);
 215   return ((SCM_CLOSUREP (SCM_PACK (SCM_SMOB_DATA (m)))) ?
 216           SCM_PACK(SCM_SMOB_DATA (m)) : SCM_BOOL_F);
 217 }
 218 #undef FUNC_NAME
 219
 220 SCM
 221 scm_make_synt (const char *name, SCM (*macroizer) (), SCM (*fcn)() )
 222 {
 223   SCM var = scm_c_define (name, SCM_UNDEFINED);
 224   SCM transformer = scm_c_make_subr (name, scm_tc7_subr_2, fcn);
 225   SCM_VARIABLE_SET (var, macroizer (transformer));
 226   return SCM_UNSPECIFIED;
 227 }
 228
 229 void
 230 scm_init_macros ()
 231 {
 232   scm_tc16_macro = scm_make_smob_type ("macro", 0);
 233   scm_set_smob_mark (scm_tc16_macro, scm_markcdr);
 234   scm_set_smob_print (scm_tc16_macro, macro_print);
 235 #ifndef SCM_MAGIC_SNARFER
 236 #include "libguile/macros.x"
 237 #endif
 238 }
 239
 240 /*
 241   Local Variables:
 242   c-file-style: "gnu"
 243   End:
 244 */