libguile/procs.h

   1 /* classes: h_files */
   2
   3 #ifndef SCM_PROCS_H
   4 #define SCM_PROCS_H
   5
   6 /* Copyright (C) 1995,1996,1998,1999,2000,2001 Free Software Foundation, Inc.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this software; see the file COPYING.  If not, write to
  20  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  21  * Boston, MA 02111-1307 USA
  22  *
  23  * As a special exception, the Free Software Foundation gives permission
  24  * for additional uses of the text contained in its release of GUILE.
  25  *
  26  * The exception is that, if you link the GUILE library with other files
  27  * to produce an executable, this does not by itself cause the
  28  * resulting executable to be covered by the GNU General Public License.
  29  * Your use of that executable is in no way restricted on account of
  30  * linking the GUILE library code into it.
  31  *
  32  * This exception does not however invalidate any other reasons why
  33  * the executable file might be covered by the GNU General Public License.
  34  *
  35  * This exception applies only to the code released by the
  36  * Free Software Foundation under the name GUILE.  If you copy
  37  * code from other Free Software Foundation releases into a copy of
  38  * GUILE, as the General Public License permits, the exception does
  39  * not apply to the code that you add in this way.  To avoid misleading
  40  * anyone as to the status of such modified files, you must delete
  41  * this exception notice from them.
  42  *
  43  * If you write modifications of your own for GUILE, it is your choice
  44  * whether to permit this exception to apply to your modifications.
  45  * If you do not wish that, delete this exception notice.  */
  46
  47 \f
  48
  49 #include "libguile/__scm.h"
  50
  51 \f
  52
  53
  54 /* Subrs
  55  */
  56
  57 typedef struct
  58 {
  59   SCM handle;                   /* link back to procedure object */
  60   SCM name;
  61   SCM *generic;                 /* 0 if no generic support
  62                                  * *generic == 0 until first method
  63                                  */
  64   SCM properties;               /* procedure properties */
  65 } scm_t_subr_entry;
  66
  67 #define SCM_SUBRNUM(subr) (SCM_CELL_WORD_0 (subr) >> 8)
  68 #define SCM_SET_SUBRNUM(subr, num) \
  69         SCM_SET_CELL_WORD_0 (subr, (num << 8) + SCM_TYP7 (subr))
  70 #define SCM_SUBR_ENTRY(x) (scm_subr_table[SCM_SUBRNUM (x)])
  71 #define SCM_SNAME(x) (SCM_SUBR_ENTRY (x).name)
  72 #define SCM_SUBRF(x) ((SCM (*)()) SCM_CELL_WORD_1 (x))
  73 #define SCM_SET_SUBRF(x, v) (SCM_SET_CELL_WORD_1 ((x), (v)))
  74 #define SCM_DSUBRF(x) ((double (*)()) SCM_CELL_WORD_1 (x))
  75 #define SCM_SUBR_PROPS(x) (SCM_SUBR_ENTRY (x).properties)
  76 #define SCM_SUBR_GENERIC(x) (SCM_SUBR_ENTRY (x).generic)
  77
  78 #define SCM_CCLO_LENGTH(x) (SCM_CELL_WORD_0 (x) >> 8)
  79 #define SCM_SET_CCLO_LENGTH(x, v) (SCM_SET_CELL_WORD_0 ((x), ((v) << 8) + scm_tc7_cclo))
  80 #define SCM_CCLO_BASE(x) ((scm_t_bits *) SCM_CELL_WORD_1 (x))
  81 #define SCM_SET_CCLO_BASE(x, v) (SCM_SET_CELL_WORD_1 ((x), (v)))
  82
  83 #define SCM_CCLO_REF(x, i) (SCM_PACK (SCM_CCLO_BASE (x) [i]))
  84 #define SCM_CCLO_SET(x, i, v) (SCM_CCLO_BASE (x) [i] = SCM_UNPACK (v))
  85
  86 #define SCM_CCLO_SUBR(x) (SCM_CCLO_REF ((x), 0))
  87 #define SCM_SET_CCLO_SUBR(x, v) (SCM_CCLO_SET ((x), 0, (v)))
  88
  89 /* Closures
  90  */
  91
  92 #define SCM_CLOSUREP(x) (!SCM_IMP(x) && (SCM_TYP3 (x) == scm_tc3_closure))
  93 #define SCM_CLOSCAR(x) SCM_PACK (SCM_CELL_WORD_0 (x) - scm_tc3_closure)
  94 #define SCM_CODE(x) SCM_CAR (SCM_CLOSCAR (x))
  95 #define SCM_CLOSURE_FORMALS(x) SCM_CAR (SCM_CODE (x))
  96 #define SCM_PROCPROPS(x) SCM_CDR (SCM_CLOSCAR (x))
  97 #define SCM_SETPROCPROPS(x, p) SCM_SETCDR (SCM_CLOSCAR (x), p)
  98 #define SCM_SETCODE(x, e) (SCM_SET_CELL_WORD_0 (x, SCM_UNPACK (scm_cons ((e), SCM_EOL)) \
  99                            + scm_tc3_closure))
 100 #define SCM_ENV(x) SCM_CELL_OBJECT_1 (x)
 101 #define SCM_SETENV(x, e) SCM_SET_CELL_OBJECT_1 ((x), (e))
 102 #define SCM_TOP_LEVEL(ENV)  (SCM_NULLP (ENV) || (SCM_EQ_P (scm_procedure_p (SCM_CAR (ENV)), SCM_BOOL_T)))
 103
 104 /* Procedure-with-setter
 105
 106    Four representations for procedure-with-setters were
 107    considered before selecting this one:
 108
 109    1. A closure where the CODE and ENV slots are used to represent
 110    the getter and a new SETTER slot is used for the setter.  The
 111    original getter is stored as a `getter' procedure property.  For
 112    closure getters, the CODE and ENV slots contains a copy of the
 113    getter's CODE and ENV slots.  For subr getters, the CODE contains
 114    a call to the subr.
 115
 116    2. A compiled closure with a call to the getter in the cclo
 117    procedure.  The getter and setter are stored in slots 1 and 2.
 118
 119    3. An entity (i.e. a struct with an associated procedure) with a
 120    call to the getter in the entity procedure and the setter stored
 121    in slot 0.  The original getter is stored in slot 1.
 122
 123    4. A new primitive procedure type supported in the evaluator.  The
 124    getter and setter are stored in a GETTER and SETTER slot.  A call
 125    to this procedure type results in a retrieval of the getter and a
 126    jump back to the correct eval dispatcher.
 127
 128    Representation 4 was selected because of efficiency and
 129    simplicity.
 130
 131    Rep 1 has the advantage that there is zero penalty for closure
 132    getters, but primitive getters will get considerable overhead
 133    because the procedure-with-getter will be a closure which calls
 134    the getter.
 135
 136    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
 137    <procedure-with-setter>, but together with rep 2 it suffers from a
 138    three level dispatch for non-GOOPS getters:
 139
 140      cclo/struct --> dispatch proc --> getter
 141
 142    This is because the dispatch procedure must take an extra initial
 143    argument (cclo for rep 2, struct for rep 3).
 144
 145    Rep 4 has the single disadvantage that it uses up one tc7 type
 146    code, but the plan for uniform vectors will very likely free tc7
 147    codes, so this is probably no big problem.  Also note that the
 148    GETTER and SETTER slots can live directly on the heap, using the
 149    new four-word cells.  */
 150
 151 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (!SCM_IMP(obj) && (SCM_TYP7 (obj) == scm_tc7_pws))
 152 #define SCM_PROCEDURE(obj) SCM_CELL_OBJECT_1 (obj)
 153 #define SCM_SETTER(obj) SCM_CELL_OBJECT_2 (obj)
 154
 155 extern scm_t_subr_entry *scm_subr_table;
 156 extern long scm_subr_table_size;
 157 extern long scm_subr_table_room;
 158
 159 \f
 160
 161 extern void scm_mark_subr_table (void);
 162 extern void scm_free_subr_entry (SCM subr);
 163 extern SCM scm_c_make_subr (const char *name, long type, SCM (*fcn)());
 164 extern SCM scm_c_make_subr_with_generic (const char *name, long type,
 165                                          SCM (*fcn)(), SCM *gf);
 166 extern SCM scm_c_define_subr (const char *name, long type, SCM (*fcn)());
 167 extern SCM scm_c_define_subr_with_generic (const char *name, long type,
 168                                            SCM (*fcn)(), SCM *gf);
 169 extern SCM scm_makcclo (SCM proc, size_t len);
 170 extern SCM scm_procedure_p (SCM obj);
 171 extern SCM scm_closure_p (SCM obj);
 172 extern SCM scm_thunk_p (SCM obj);
 173 extern int scm_subr_p (SCM obj);
 174 extern SCM scm_procedure_documentation (SCM proc);
 175 extern SCM scm_procedure_with_setter_p (SCM obj);
 176 extern SCM scm_make_procedure_with_setter (SCM procedure, SCM setter);
 177 extern SCM scm_procedure (SCM proc);
 178 extern SCM scm_setter (SCM proc);
 179 extern void scm_init_subr_table (void);
 180 extern void scm_init_procs (void);
 181
 182 #ifdef GUILE_DEBUG
 183 extern SCM scm_make_cclo (SCM proc, SCM len);
 184 #endif /*GUILE_DEBUG*/
 185
 186 #endif  /* SCM_PROCS_H */
 187
 188 /*
 189   Local Variables:
 190   c-file-style: "gnu"
 191   End:
 192 */