libguile/procs.h

   1 /* classes: h_files */
   2
   3 #ifndef PROCSH
   4 #define PROCSH
   5 /*      Copyright (C) 1995, 1996, 1998, 1999 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 \f
  46
  47 #include "libguile/__scm.h"
  48
  49 \f
  50
  51
  52 /* Subrs
  53  */
  54
  55 typedef struct scm_subr
  56 {
  57   long sname;
  58   SCM (*cproc) ();
  59 } scm_subr;
  60
  61 typedef struct scm_iproc
  62 {
  63   char *scm_string;
  64   SCM (*cproc) ();
  65 } scm_iproc;
  66
  67 typedef struct scm_dsubr
  68 {
  69   long sname;
  70   double (*dproc) ();
  71 } scm_dsubr;
  72
  73 typedef struct
  74 {
  75   SCM handle;                   /* link back to procedure object */
  76   SCM name;
  77   SCM *generic;                 /* 0 if no generic support
  78                                  * *generic == 0 until first method
  79                                  */
  80   SCM properties;               /* procedure properties */
  81   SCM documentation;
  82 } scm_subr_entry;
  83
  84 #define SCM_SUBRNUM(subr) (SCM_CAR (subr) >> 8)
  85 #define SCM_SET_SUBRNUM(subr, num) \
  86         SCM_SETCAR (subr, (num >> 8) + SCM_TYP7 (subr))
  87 #define SCM_SUBR_ENTRY(x) (scm_subr_table[SCM_SUBRNUM (x)])
  88 #define SCM_SNAME(x) (SCM_SUBR_ENTRY (x).name)
  89 #define SCM_SUBRF(x) (((scm_subr *)(SCM2PTR(x)))->cproc)
  90 #define SCM_DSUBRF(x) (((scm_dsubr *)(SCM2PTR(x)))->dproc)
  91 #define SCM_CCLO_SUBR(x) (SCM_VELTS(x)[0])
  92
  93 #define SCM_SUBR_GENERIC(x) (SCM_SUBR_ENTRY (x).generic)
  94 #define SCM_SUBR_PROPS(x) (SCM_SUBR_ENTRY (x).properties)
  95 #define SCM_SUBR_DOC(x) (SCM_SUBR_ENTRY (x).documentation)
  96
  97 /* Closures
  98  */
  99
 100 #define SCM_CLOSUREP(x) (SCM_TYP3(x)==scm_tc3_closure)
 101 #define SCM_CLOSCAR(x) (SCM_CAR(x)-scm_tc3_closure)
 102 #define SCM_CODE(x) SCM_CAR(SCM_CLOSCAR (x))
 103 #define SCM_PROCPROPS(x) SCM_CDR(SCM_CLOSCAR (x))
 104 #define SCM_SETPROCPROPS(x, p) SCM_SETCDR(SCM_CLOSCAR (x), p)
 105 #define SCM_SETCODE(x, e) (SCM_SETCAR (x, scm_cons ((e), SCM_EOL) + scm_tc3_closure))
 106 #define SCM_ENV(x) SCM_CDR(x)
 107 #define SCM_SETENV(x, e) SCM_SETCDR (x, e)
 108 #define SCM_TOP_LEVEL(SCM_ENV)  (SCM_NULLP(SCM_ENV) || (SCM_BOOL_T == scm_procedure_p (SCM_CAR (SCM_ENV))))
 109
 110 /* Procedure-with-setter
 111
 112    Four representations for procedure-with-setters were
 113    considered before selecting this one:
 114
 115    1. A closure where the CODE and ENV slots are used to represent
 116    the getter and a new SETTER slot is used for the setter.  The
 117    original getter is stored as a `getter' procedure property.  For
 118    closure getters, the CODE and ENV slots contains a copy of the
 119    getter's CODE and ENV slots.  For subr getters, the CODE contains
 120    a call to the subr.
 121
 122    2. A compiled closure with a call to the getter in the cclo
 123    procedure.  The getter and setter are stored in slots 1 and 2.
 124
 125    3. An entity (i.e. a struct with an associated procedure) with a
 126    call to the getter in the entity procedure and the setter stored
 127    in slot 0.  The original getter is stored in slot 1.
 128
 129    4. A new primitive procedure type supported in the evaluator.  The
 130    getter and setter are stored in a GETTER and SETTER slot.  A call
 131    to this procedure type results in a retrieval of the getter and a
 132    jump back to the correct eval dispatcher.
 133
 134    Representation 4 was selected because of efficiency and
 135    simplicity.
 136
 137    Rep 1 has the advantage that there is zero penalty for closure
 138    getters, but primitive getters will get considerable overhead
 139    because the procedure-with-getter will be a closure which calls
 140    the getter.
 141
 142    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
 143    <procedure-with-setter>, but together with rep 2 it suffers from a
 144    three level dispatch for non-GOOPS getters:
 145
 146      cclo/struct --> dispatch proc --> getter
 147
 148    This is because the dispatch procedure must take an extra initial
 149    argument (cclo for rep 2, struct for rep 3).
 150
 151    Rep 4 has the single disadvantage that it uses up one tc7 type
 152    code, but the plan for uniform vectors will very likely free tc7
 153    codes, so this is probably no big problem.  Also note that the
 154    GETTER and SETTER slots can live directly on the heap, using the
 155    new four-word cells.  */
 156
 157 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (SCM_TYP7 (obj) == scm_tc7_pws)
 158 #define SCM_PROCEDURE(obj) SCM_CADR (obj)
 159 #define SCM_SETTER(obj) SCM_CDDR (obj)
 160
 161 extern scm_subr_entry *scm_subr_table;
 162 extern int scm_subr_table_size;
 163 extern int scm_subr_table_room;
 164
 165 \f
 166
 167 extern void scm_mark_subr_table (void);
 168 extern void scm_free_subr_entry (SCM subr);
 169 extern SCM scm_make_subr SCM_P ((const char *name, int type, SCM (*fcn) ()));
 170 extern SCM scm_make_subr_with_generic (const char *name,
 171                                        int type,
 172                                        SCM (*fcn) (),
 173                                        SCM *gf);
 174 extern SCM scm_make_subr_opt SCM_P ((const char *name,
 175                                      int type,
 176                                      SCM (*fcn) (),
 177                                      int set));
 178 extern SCM scm_makcclo SCM_P ((SCM proc, long len));
 179 extern SCM scm_procedure_p SCM_P ((SCM obj));
 180 extern SCM scm_closure_p SCM_P ((SCM obj));
 181 extern SCM scm_thunk_p SCM_P ((SCM obj));
 182 extern int scm_subr_p (SCM obj);
 183 extern SCM scm_procedure_documentation SCM_P ((SCM proc));
 184 extern SCM scm_procedure_with_setter_p SCM_P ((SCM obj));
 185 extern SCM scm_make_procedure_with_setter SCM_P ((SCM procedure, SCM setter));
 186 extern SCM scm_procedure SCM_P ((SCM proc));
 187 extern SCM scm_setter SCM_P ((SCM proc));
 188 extern void scm_init_iprocs SCM_P ((const scm_iproc *subra, int type));
 189 extern void scm_init_subr_table (void);
 190 extern void scm_init_procs SCM_P ((void));
 191
 192 #ifdef GUILE_DEBUG
 193 extern SCM scm_make_cclo SCM_P ((SCM proc, SCM len));
 194 #endif /*GUILE_DEBUG*/
 195
 196 \f
 197 #endif  /* PROCSH */