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, 2009 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 #define SCM_SUBR_META_INFO(x)  ((SCM *) SCM_CELL_WORD_3 (x))
  34 #define SCM_SNAME(x) (SCM_SUBR_META_INFO (x) [0])
  35 #define SCM_SUBRF(x) ((SCM (*)()) SCM_CELL_WORD_1 (x))
  36 #define SCM_DSUBRF(x) ((double (*)()) SCM_CELL_WORD_1 (x))
  37 #define SCM_SUBR_PROPS(x) (SCM_SUBR_META_INFO (x) [1])
  38 #define SCM_SUBR_GENERIC(x) ((SCM *) SCM_CELL_WORD_2 (x))
  39 #define SCM_SET_SUBR_GENERIC(x, g) (*((SCM *) SCM_CELL_WORD_2 (x)) = (g))
  40 #define SCM_SET_SUBR_GENERIC_LOC(x, g) (SCM_SET_CELL_WORD_2 (x, (scm_t_bits) g))
  41
  42 #define SCM_CCLO_LENGTH(x) (SCM_CELL_WORD_0 (x) >> 8)
  43 #define SCM_MAKE_CCLO_TAG(v)  (((v) << 8) + scm_tc7_cclo)
  44 #define SCM_SET_CCLO_LENGTH(x, v) (SCM_SET_CELL_WORD_0 ((x), SCM_MAKE_CCLO_TAG(v)))
  45 #define SCM_CCLO_BASE(x) ((scm_t_bits *) SCM_CELL_WORD_1 (x))
  46 #define SCM_SET_CCLO_BASE(x, v) (SCM_SET_CELL_WORD_1 ((x), (v)))
  47
  48 #define SCM_CCLO_REF(x, i) (SCM_PACK (SCM_CCLO_BASE (x) [i]))
  49 #define SCM_CCLO_SET(x, i, v) (SCM_CCLO_BASE (x) [i] = SCM_UNPACK (v))
  50
  51 #define SCM_CCLO_SUBR(x) (SCM_CCLO_REF ((x), 0))
  52 #define SCM_SET_CCLO_SUBR(x, v) (SCM_CCLO_SET ((x), 0, (v)))
  53
  54 /* Closures
  55  */
  56
  57 #define SCM_CLOSUREP(x) (!SCM_IMP(x) && (SCM_TYP3 (x) == scm_tc3_closure))
  58 #define SCM_CLOSCAR(x) SCM_PACK (SCM_CELL_WORD_0 (x) - scm_tc3_closure)
  59 #define SCM_CODE(x) SCM_CAR (SCM_CLOSCAR (x))
  60 #define SCM_CLOSURE_FORMALS(x) SCM_CAR (SCM_CODE (x))
  61 #define SCM_CLOSURE_BODY(x) SCM_CDR (SCM_CODE (x))
  62 #define SCM_PROCPROPS(x) SCM_CDR (SCM_CLOSCAR (x))
  63 #define SCM_SETPROCPROPS(x, p) SCM_SETCDR (SCM_CLOSCAR (x), p)
  64 #define SCM_ENV(x) SCM_CELL_OBJECT_1 (x)
  65 #define SCM_TOP_LEVEL(ENV)  (scm_is_null (ENV) || (scm_is_true (scm_procedure_p (SCM_CAR (ENV)))))
  66
  67 /* Procedure-with-setter
  68
  69    Four representations for procedure-with-setters were
  70    considered before selecting this one:
  71
  72    1. A closure where the CODE and ENV slots are used to represent
  73    the getter and a new SETTER slot is used for the setter.  The
  74    original getter is stored as a `getter' procedure property.  For
  75    closure getters, the CODE and ENV slots contains a copy of the
  76    getter's CODE and ENV slots.  For subr getters, the CODE contains
  77    a call to the subr.
  78
  79    2. A compiled closure with a call to the getter in the cclo
  80    procedure.  The getter and setter are stored in slots 1 and 2.
  81
  82    3. An entity (i.e. a struct with an associated procedure) with a
  83    call to the getter in the entity procedure and the setter stored
  84    in slot 0.  The original getter is stored in slot 1.
  85
  86    4. A new primitive procedure type supported in the evaluator.  The
  87    getter and setter are stored in a GETTER and SETTER slot.  A call
  88    to this procedure type results in a retrieval of the getter and a
  89    jump back to the correct eval dispatcher.
  90
  91    Representation 4 was selected because of efficiency and
  92    simplicity.
  93
  94    Rep 1 has the advantage that there is zero penalty for closure
  95    getters, but primitive getters will get considerable overhead
  96    because the procedure-with-getter will be a closure which calls
  97    the getter.
  98
  99    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
 100    <procedure-with-setter>, but together with rep 2 it suffers from a
 101    three level dispatch for non-GOOPS getters:
 102
 103      cclo/struct --> dispatch proc --> getter
 104
 105    This is because the dispatch procedure must take an extra initial
 106    argument (cclo for rep 2, struct for rep 3).
 107
 108    Rep 4 has the single disadvantage that it uses up one tc7 type
 109    code, but the plan for uniform vectors will very likely free tc7
 110    codes, so this is probably no big problem.  Also note that the
 111    GETTER and SETTER slots can live directly on the heap, using the
 112    new four-word cells.  */
 113
 114 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (!SCM_IMP(obj) && (SCM_TYP7 (obj) == scm_tc7_pws))
 115 #define SCM_PROCEDURE(obj) SCM_CELL_OBJECT_1 (obj)
 116 #define SCM_SETTER(obj) SCM_CELL_OBJECT_2 (obj)
 117
 118
 119 \f
 120
 121 SCM_API SCM scm_c_make_subr (const char *name, long type, SCM (*fcn)());
 122 SCM_API SCM scm_c_make_subr_with_generic (const char *name, long type,
 123                                           SCM (*fcn)(), SCM *gf);
 124 SCM_API SCM scm_c_define_subr (const char *name, long type, SCM (*fcn)());
 125 SCM_API SCM scm_c_define_subr_with_generic (const char *name, long type,
 126                                             SCM (*fcn)(), SCM *gf);
 127 SCM_API SCM scm_makcclo (SCM proc, size_t len);
 128 SCM_API SCM scm_procedure_p (SCM obj);
 129 SCM_API SCM scm_closure_p (SCM obj);
 130 SCM_API SCM scm_thunk_p (SCM obj);
 131 SCM_API int scm_subr_p (SCM obj);
 132 SCM_API SCM scm_procedure_documentation (SCM proc);
 133 SCM_API SCM scm_procedure_with_setter_p (SCM obj);
 134 SCM_API SCM scm_make_procedure_with_setter (SCM procedure, SCM setter);
 135 SCM_API SCM scm_procedure (SCM proc);
 136 SCM_API SCM scm_setter (SCM proc);
 137 SCM_INTERNAL void scm_init_procs (void);
 138
 139 #ifdef GUILE_DEBUG
 140 SCM_API SCM scm_make_cclo (SCM proc, SCM len);
 141 #endif /*GUILE_DEBUG*/
 142
 143 #endif  /* SCM_PROCS_H */
 144
 145 /*
 146   Local Variables:
 147   c-file-style: "gnu"
 148   End:
 149 */