libguile/macros.c

   1 /* Copyright (C) 1995,1996,1997,1998,2000,2001,2002,2003, 2006, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include "libguile/_scm.h"
  26 #include "libguile/ports.h"
  27 #include "libguile/print.h"
  28 #include "libguile/smob.h"
  29 #include "libguile/validate.h"
  30 #include "libguile/macros.h"
  31
  32 #include "libguile/private-options.h"
  33
  34
  35 static scm_t_bits scm_tc16_macro;
  36
  37 #define SCM_MACROP(x) SCM_SMOB_PREDICATE (scm_tc16_macro, (x))
  38 #define SCM_MACRO_PRIMITIVE(m) ((scm_t_macro_primitive)SCM_SMOB_DATA (m))
  39 #define SCM_MACRO_NAME(m) (SCM_SMOB_OBJECT_2 (m))
  40 #define SCM_MACRO_TYPE(m) (SCM_SMOB_OBJECT_3 (m))
  41 #define SCM_MACRO_BINDING(m) (SCM_CELL_OBJECT ((m), 4))
  42 #define SCM_VALIDATE_MACRO(p,v) SCM_MAKE_VALIDATE ((p), (v), MACROP)
  43
  44
  45 SCM_API scm_t_bits scm_tc16_macro;
  46
  47
  48 static int
  49 macro_print (SCM macro, SCM port, scm_print_state *pstate)
  50 {
  51   if (scm_is_false (SCM_MACRO_TYPE (macro)))
  52     scm_puts_unlocked ("#<primitive-syntax-transformer ", port);
  53   else
  54     scm_puts_unlocked ("#<syntax-transformer ", port);
  55   scm_iprin1 (scm_macro_name (macro), port, pstate);
  56   scm_putc_unlocked ('>', port);
  57
  58   return 1;
  59 }
  60
  61 /* Return a mmacro that is known to be one of guile's built in macros. */
  62 SCM
  63 scm_i_make_primitive_macro (const char *name, scm_t_macro_primitive fn)
  64 {
  65   SCM z = scm_words (scm_tc16_macro, 5);
  66   SCM_SET_SMOB_DATA_N (z, 1, (scm_t_bits)fn);
  67   SCM_SET_SMOB_OBJECT_N (z, 2, scm_from_utf8_symbol (name));
  68   SCM_SET_SMOB_OBJECT_N (z, 3, SCM_BOOL_F);
  69   SCM_SET_SMOB_OBJECT_N (z, 4, SCM_BOOL_F);
  70   return z;
  71 }
  72
  73 scm_t_macro_primitive
  74 scm_i_macro_primitive (SCM macro)
  75 {
  76   return SCM_MACRO_PRIMITIVE (macro);
  77 }
  78
  79
  80 SCM_DEFINE (scm_make_syntax_transformer, "make-syntax-transformer", 3, 0, 0,
  81             (SCM name, SCM type, SCM binding),
  82             "Construct a @dfn{syntax transformer}.\n\n"
  83             "This function is part of Guile's low-level support for the psyntax\n"
  84             "syntax expander. Users should not call this function.")
  85 #define FUNC_NAME s_scm_make_syntax_transformer
  86 {
  87   SCM z;
  88   SCM (*prim)(SCM,SCM) = NULL;
  89
  90   if (scm_is_true (name))
  91     {
  92       SCM existing_var;
  93
  94       SCM_VALIDATE_SYMBOL (1, name);
  95
  96       existing_var = scm_module_variable (scm_current_module (), name);
  97       if (scm_is_true (existing_var)
  98           && scm_is_true (scm_variable_bound_p (existing_var))
  99           && SCM_MACROP (SCM_VARIABLE_REF (existing_var)))
 100         prim = SCM_MACRO_PRIMITIVE (SCM_VARIABLE_REF (existing_var));
 101     }
 102
 103   SCM_VALIDATE_SYMBOL (2, type);
 104
 105   z = scm_words (scm_tc16_macro, 5);
 106   SCM_SET_SMOB_DATA_N (z, 1, prim);
 107   SCM_SET_SMOB_OBJECT_N (z, 2, name);
 108   SCM_SET_SMOB_OBJECT_N (z, 3, type);
 109   SCM_SET_SMOB_OBJECT_N (z, 4, binding);
 110   return z;
 111 }
 112 #undef FUNC_NAME
 113
 114 SCM_DEFINE (scm_macro_p, "macro?", 1, 0, 0,
 115             (SCM obj),
 116             "Return @code{#t} if @var{obj} is a syntax transformer (an object that "
 117             "transforms Scheme expressions at expansion-time).\n\n"
 118             "Macros are actually just one kind of syntax transformer; this\n"
 119             "procedure has its name due to historical reasons.")
 120 #define FUNC_NAME s_scm_macro_p
 121 {
 122   return scm_from_bool (SCM_MACROP (obj));
 123 }
 124 #undef FUNC_NAME
 125
 126 SCM_DEFINE (scm_macro_type, "macro-type", 1, 0, 0,
 127             (SCM m),
 128             "Return the type of the syntax transformer @var{m}, as passed to\n"
 129             "@code{make-syntax-transformer}. If @var{m} is a primitive syntax\n"
 130             "transformer, @code{#f} will be returned.")
 131 #define FUNC_NAME s_scm_macro_type
 132 {
 133   SCM_VALIDATE_MACRO (1, m);
 134   return SCM_MACRO_TYPE (m);
 135 }
 136 #undef FUNC_NAME
 137
 138 SCM_DEFINE (scm_macro_name, "macro-name", 1, 0, 0,
 139             (SCM m),
 140             "Return the name of the syntax transformer @var{m}.")
 141 #define FUNC_NAME s_scm_macro_name
 142 {
 143   SCM_VALIDATE_MACRO (1, m);
 144   return SCM_MACRO_NAME (m);
 145 }
 146 #undef FUNC_NAME
 147
 148 SCM_DEFINE (scm_macro_transformer, "macro-transformer", 1, 0, 0,
 149             (SCM m),
 150             "Return the transformer procedure of the macro @var{m}.\n\n"
 151             "If @var{m} is a syntax transformer but not a macro, @code{#f}\n"
 152             "will be returned. (This can happen, for example, with primitive\n"
 153             "syntax transformers).")
 154 #define FUNC_NAME s_scm_macro_transformer
 155 {
 156   SCM_VALIDATE_MACRO (1, m);
 157   /* here we rely on knowledge of how psyntax represents macro bindings, but
 158      hey, there is code out there that calls this function, and expects to get
 159      a procedure in return... */
 160   if (scm_is_true (scm_procedure_p (SCM_MACRO_BINDING (m))))
 161     return SCM_MACRO_BINDING (m);
 162   else
 163     return SCM_BOOL_F;
 164 }
 165 #undef FUNC_NAME
 166
 167 SCM_DEFINE (scm_macro_binding, "macro-binding", 1, 0, 0,
 168             (SCM m),
 169             "Return the binding of the syntax transformer @var{m}, as passed to\n"
 170             "@code{make-syntax-transformer}. If @var{m} is a primitive syntax\n"
 171             "transformer, @code{#f} will be returned.")
 172 #define FUNC_NAME s_scm_macro_binding
 173 {
 174   SCM_VALIDATE_MACRO (1, m);
 175   return SCM_MACRO_BINDING (m);
 176 }
 177 #undef FUNC_NAME
 178
 179
 180 static SCM syntax_session_id;
 181
 182 #define SESSION_ID_LENGTH      22  /* bytes */
 183 #define BASE64_RADIX_BITS  6
 184 #define BASE64_RADIX       (1 << (BASE64_RADIX_BITS))
 185 #define BASE64_MASK        (BASE64_RADIX - 1)
 186
 187 static SCM
 188 fresh_syntax_session_id (void)
 189 {
 190   static const char base64[BASE64_RADIX] =
 191     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$@";
 192
 193   unsigned char digit_buf[SESSION_ID_LENGTH];
 194   char char_buf[SESSION_ID_LENGTH];
 195   size_t i;
 196
 197   scm_i_random_bytes_from_platform (digit_buf, SESSION_ID_LENGTH);
 198   for (i = 0; i < SESSION_ID_LENGTH; ++i)
 199     char_buf[i] = base64[digit_buf[i] & BASE64_MASK];
 200
 201   return scm_from_latin1_stringn (char_buf, SESSION_ID_LENGTH);
 202 }
 203
 204 static SCM
 205 scm_syntax_session_id (void)
 206 {
 207   return syntax_session_id;
 208 }
 209
 210
 211 void
 212 scm_init_macros ()
 213 {
 214   scm_tc16_macro = scm_make_smob_type ("macro", 0);
 215   scm_set_smob_print (scm_tc16_macro, macro_print);
 216 #include "libguile/macros.x"
 217
 218   syntax_session_id = fresh_syntax_session_id();
 219   scm_c_define_gsubr ("syntax-session-id", 0, 0, 0, scm_syntax_session_id);
 220 }
 221
 222 /*
 223   Local Variables:
 224   c-file-style: "gnu"
 225   End:
 226 */