libguile/procs.h

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