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_ENV(x) SCM_CELL_OBJECT_1 (x)
  74 #define SCM_TOP_LEVEL(ENV)  (scm_is_null (ENV) || (scm_is_true (scm_procedure_p (SCM_CAR (ENV)))))
  75
  76 /* Procedure-with-setter
  77
  78    Four representations for procedure-with-setters were
  79    considered before selecting this one:
  80
  81    1. A closure where the CODE and ENV slots are used to represent
  82    the getter and a new SETTER slot is used for the setter.  The
  83    original getter is stored as a `getter' procedure property.  For
  84    closure getters, the CODE and ENV slots contains a copy of the
  85    getter's CODE and ENV slots.  For subr getters, the CODE contains
  86    a call to the subr.
  87
  88    2. A compiled closure with a call to the getter in the cclo
  89    procedure.  The getter and setter are stored in slots 1 and 2.
  90
  91    3. An entity (i.e. a struct with an associated procedure) with a
  92    call to the getter in the entity procedure and the setter stored
  93    in slot 0.  The original getter is stored in slot 1.
  94
  95    4. A new primitive procedure type supported in the evaluator.  The
  96    getter and setter are stored in a GETTER and SETTER slot.  A call
  97    to this procedure type results in a retrieval of the getter and a
  98    jump back to the correct eval dispatcher.
  99
 100    Representation 4 was selected because of efficiency and
 101    simplicity.
 102
 103    Rep 1 has the advantage that there is zero penalty for closure
 104    getters, but primitive getters will get considerable overhead
 105    because the procedure-with-getter will be a closure which calls
 106    the getter.
 107
 108    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
 109    <procedure-with-setter>, but together with rep 2 it suffers from a
 110    three level dispatch for non-GOOPS getters:
 111
 112      cclo/struct --> dispatch proc --> getter
 113
 114    This is because the dispatch procedure must take an extra initial
 115    argument (cclo for rep 2, struct for rep 3).
 116
 117    Rep 4 has the single disadvantage that it uses up one tc7 type
 118    code, but the plan for uniform vectors will very likely free tc7
 119    codes, so this is probably no big problem.  Also note that the
 120    GETTER and SETTER slots can live directly on the heap, using the
 121    new four-word cells.  */
 122
 123 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (!SCM_IMP(obj) && (SCM_TYP7 (obj) == scm_tc7_pws))
 124 #define SCM_PROCEDURE(obj) SCM_CELL_OBJECT_1 (obj)
 125 #define SCM_SETTER(obj) SCM_CELL_OBJECT_2 (obj)
 126
 127 SCM_API scm_t_subr_entry *scm_subr_table;
 128 SCM_API long scm_subr_table_size;
 129 SCM_API long scm_subr_table_room;
 130
 131 \f
 132
 133 SCM_API SCM scm_c_make_subr (const char *name, long type, SCM (*fcn)());
 134 SCM_API SCM scm_c_make_subr_with_generic (const char *name, long type,
 135                                           SCM (*fcn)(), SCM *gf);
 136 SCM_API SCM scm_c_define_subr (const char *name, long type, SCM (*fcn)());
 137 SCM_API SCM scm_c_define_subr_with_generic (const char *name, long type,
 138                                             SCM (*fcn)(), SCM *gf);
 139 SCM_API SCM scm_makcclo (SCM proc, size_t len);
 140 SCM_API SCM scm_procedure_p (SCM obj);
 141 SCM_API SCM scm_closure_p (SCM obj);
 142 SCM_API SCM scm_thunk_p (SCM obj);
 143 SCM_API int scm_subr_p (SCM obj);
 144 SCM_API SCM scm_procedure_documentation (SCM proc);
 145 SCM_API SCM scm_procedure_with_setter_p (SCM obj);
 146 SCM_API SCM scm_make_procedure_with_setter (SCM procedure, SCM setter);
 147 SCM_API SCM scm_procedure (SCM proc);
 148 SCM_API SCM scm_setter (SCM proc);
 149 SCM_INTERNAL void scm_init_subr_table (void);
 150 SCM_INTERNAL void scm_init_procs (void);
 151
 152 #ifdef GUILE_DEBUG
 153 SCM_API SCM scm_make_cclo (SCM proc, SCM len);
 154 #endif /*GUILE_DEBUG*/
 155
 156 #endif  /* SCM_PROCS_H */
 157
 158 /*
 159   Local Variables:
 160   c-file-style: "gnu"
 161   End:
 162 */