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, 2006, 2008 Free Software Foundation, Inc.
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library 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 GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 \f
  24
  25 #include "libguile/__scm.h"
  26
  27 \f
  28
  29
  30 /* Subrs
  31  */
  32
  33 typedef struct
  34 {
  35   SCM handle;                   /* link back to procedure object */
  36   SCM name;
  37   SCM *generic;                 /* 0 if no generic support
  38                                  * *generic == 0 until first method
  39                                  */
  40   SCM properties;               /* procedure properties */
  41 } scm_t_subr_entry;
  42
  43 #define SCM_SUBRNUM(subr) (SCM_CELL_WORD_0 (subr) >> 8)
  44 #define SCM_SUBR_ENTRY(x) (scm_subr_table[SCM_SUBRNUM (x)])
  45 #define SCM_SNAME(x) (SCM_SUBR_ENTRY (x).name)
  46 #define SCM_SUBRF(x) ((SCM (*)()) SCM_CELL_WORD_1 (x))
  47 #define SCM_DSUBRF(x) ((double (*)()) SCM_CELL_WORD_1 (x))
  48 #define SCM_SUBR_PROPS(x) (SCM_SUBR_ENTRY (x).properties)
  49 #define SCM_SUBR_GENERIC(x) (SCM_SUBR_ENTRY (x).generic)
  50
  51 #define SCM_CCLO_LENGTH(x) (SCM_CELL_WORD_0 (x) >> 8)
  52 #define SCM_MAKE_CCLO_TAG(v)  (((v) << 8) + scm_tc7_cclo)
  53 #define SCM_SET_CCLO_LENGTH(x, v) (SCM_SET_CELL_WORD_0 ((x), SCM_MAKE_CCLO_TAG(v)))
  54 #define SCM_CCLO_BASE(x) ((scm_t_bits *) SCM_CELL_WORD_1 (x))
  55 #define SCM_SET_CCLO_BASE(x, v) (SCM_SET_CELL_WORD_1 ((x), (v)))
  56
  57 #define SCM_CCLO_REF(x, i) (SCM_PACK (SCM_CCLO_BASE (x) [i]))
  58 #define SCM_CCLO_SET(x, i, v) (SCM_CCLO_BASE (x) [i] = SCM_UNPACK (v))
  59
  60 #define SCM_CCLO_SUBR(x) (SCM_CCLO_REF ((x), 0))
  61 #define SCM_SET_CCLO_SUBR(x, v) (SCM_CCLO_SET ((x), 0, (v)))
  62
  63 /* Closures
  64  */
  65
  66 #define SCM_CLOSUREP(x) (!SCM_IMP(x) && (SCM_TYP3 (x) == scm_tc3_closure))
  67 #define SCM_CLOSCAR(x) SCM_PACK (SCM_CELL_WORD_0 (x) - scm_tc3_closure)
  68 #define SCM_CODE(x) SCM_CAR (SCM_CLOSCAR (x))
  69 #define SCM_CLOSURE_FORMALS(x) SCM_CAR (SCM_CODE (x))
  70 #define SCM_CLOSURE_BODY(x) SCM_CDR (SCM_CODE (x))
  71 #define SCM_PROCPROPS(x) SCM_CDR (SCM_CLOSCAR (x))
  72 #define SCM_SETPROCPROPS(x, p) SCM_SETCDR (SCM_CLOSCAR (x), p)
  73 #define SCM_SETCODE(x, e) (SCM_SET_CELL_WORD_0 (x, SCM_UNPACK (scm_cons ((e), SCM_EOL)) \
  74                            + scm_tc3_closure))
  75 #define SCM_ENV(x) SCM_CELL_OBJECT_1 (x)
  76 #define SCM_SETENV(x, e) SCM_SET_CELL_OBJECT_1 ((x), (e))
  77 #define SCM_TOP_LEVEL(ENV)  (scm_is_null (ENV) || (scm_is_true (scm_procedure_p (SCM_CAR (ENV)))))
  78
  79 /* Procedure-with-setter
  80
  81    Four representations for procedure-with-setters were
  82    considered before selecting this one:
  83
  84    1. A closure where the CODE and ENV slots are used to represent
  85    the getter and a new SETTER slot is used for the setter.  The
  86    original getter is stored as a `getter' procedure property.  For
  87    closure getters, the CODE and ENV slots contains a copy of the
  88    getter's CODE and ENV slots.  For subr getters, the CODE contains
  89    a call to the subr.
  90
  91    2. A compiled closure with a call to the getter in the cclo
  92    procedure.  The getter and setter are stored in slots 1 and 2.
  93
  94    3. An entity (i.e. a struct with an associated procedure) with a
  95    call to the getter in the entity procedure and the setter stored
  96    in slot 0.  The original getter is stored in slot 1.
  97
  98    4. A new primitive procedure type supported in the evaluator.  The
  99    getter and setter are stored in a GETTER and SETTER slot.  A call
 100    to this procedure type results in a retrieval of the getter and a
 101    jump back to the correct eval dispatcher.
 102
 103    Representation 4 was selected because of efficiency and
 104    simplicity.
 105
 106    Rep 1 has the advantage that there is zero penalty for closure
 107    getters, but primitive getters will get considerable overhead
 108    because the procedure-with-getter will be a closure which calls
 109    the getter.
 110
 111    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
 112    <procedure-with-setter>, but together with rep 2 it suffers from a
 113    three level dispatch for non-GOOPS getters:
 114
 115      cclo/struct --> dispatch proc --> getter
 116
 117    This is because the dispatch procedure must take an extra initial
 118    argument (cclo for rep 2, struct for rep 3).
 119
 120    Rep 4 has the single disadvantage that it uses up one tc7 type
 121    code, but the plan for uniform vectors will very likely free tc7
 122    codes, so this is probably no big problem.  Also note that the
 123    GETTER and SETTER slots can live directly on the heap, using the
 124    new four-word cells.  */
 125
 126 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (!SCM_IMP(obj) && (SCM_TYP7 (obj) == scm_tc7_pws))
 127 #define SCM_PROCEDURE(obj) SCM_CELL_OBJECT_1 (obj)
 128 #define SCM_SETTER(obj) SCM_CELL_OBJECT_2 (obj)
 129
 130 SCM_API scm_t_subr_entry *scm_subr_table;
 131 SCM_API long scm_subr_table_size;
 132 SCM_API long scm_subr_table_room;
 133
 134 \f
 135
 136 SCM_API SCM scm_c_make_subr (const char *name, long type, SCM (*fcn)());
 137 SCM_API SCM scm_c_make_subr_with_generic (const char *name, long type,
 138                                           SCM (*fcn)(), SCM *gf);
 139 SCM_API SCM scm_c_define_subr (const char *name, long type, SCM (*fcn)());
 140 SCM_API SCM scm_c_define_subr_with_generic (const char *name, long type,
 141                                             SCM (*fcn)(), SCM *gf);
 142 SCM_API SCM scm_makcclo (SCM proc, size_t len);
 143 SCM_API SCM scm_procedure_p (SCM obj);
 144 SCM_API SCM scm_closure_p (SCM obj);
 145 SCM_API SCM scm_thunk_p (SCM obj);
 146 SCM_API int scm_subr_p (SCM obj);
 147 SCM_API SCM scm_procedure_documentation (SCM proc);
 148 SCM_API SCM scm_procedure_with_setter_p (SCM obj);
 149 SCM_API SCM scm_make_procedure_with_setter (SCM procedure, SCM setter);
 150 SCM_API SCM scm_procedure (SCM proc);
 151 SCM_API SCM scm_setter (SCM proc);
 152 SCM_INTERNAL void scm_init_subr_table (void);
 153 SCM_INTERNAL void scm_init_procs (void);
 154
 155 #ifdef GUILE_DEBUG
 156 SCM_API SCM scm_make_cclo (SCM proc, SCM len);
 157 #endif /*GUILE_DEBUG*/
 158
 159 #endif  /* SCM_PROCS_H */
 160
 161 /*
 162   Local Variables:
 163   c-file-style: "gnu"
 164   End:
 165 */