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 License
  10  * as published by the Free Software Foundation; either version 3 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * 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
  21  * 02110-1301 USA
  22  */
  23
  24 \f
  25
  26 #include "libguile/__scm.h"
  27
  28 \f
  29
  30
  31 /* Subrs
  32  */
  33
  34 #define SCM_SUBR_META_INFO(x)  ((SCM *) SCM_CELL_WORD_3 (x))
  35 #define SCM_SNAME(x) (SCM_SUBR_META_INFO (x) [0])
  36 #define SCM_SUBRF(x) ((SCM (*)()) SCM_CELL_WORD_1 (x))
  37 #define SCM_SET_SUBRF(x, v) (SCM_SET_CELL_WORD_1 ((x), (v)))
  38 #define SCM_DSUBRF(x) ((double (*)()) SCM_CELL_WORD_1 (x))
  39 #define SCM_SUBR_PROPS(x) (SCM_SUBR_META_INFO (x) [1])
  40 #define SCM_SUBR_GENERIC(x) ((SCM *) SCM_CELL_WORD_2 (x))
  41 #define SCM_SET_SUBR_GENERIC(x, g) (*((SCM *) SCM_CELL_WORD_2 (x)) = (g))
  42 #define SCM_SET_SUBR_GENERIC_LOC(x, g) (SCM_SET_CELL_WORD_2 (x, (scm_t_bits) g))
  43
  44 /* Closures
  45  */
  46
  47 #define SCM_CLOSUREP(x) (!SCM_IMP(x) && (SCM_TYP3 (x) == scm_tc3_closure))
  48 #define SCM_CLOSCAR(x) SCM_PACK (SCM_CELL_WORD_0 (x) - scm_tc3_closure)
  49 #define SCM_CODE(x) SCM_CAR (SCM_CLOSCAR (x))
  50 #define SCM_CLOSURE_FORMALS(x) SCM_CAR (SCM_CODE (x))
  51 #define SCM_CLOSURE_BODY(x) SCM_CDR (SCM_CODE (x))
  52 #define SCM_PROCPROPS(x) SCM_CDR (SCM_CLOSCAR (x))
  53 #define SCM_SETPROCPROPS(x, p) SCM_SETCDR (SCM_CLOSCAR (x), p)
  54 #define SCM_SETCODE(x, e) (SCM_SET_CELL_WORD_0 (x, SCM_UNPACK (scm_cons ((e), SCM_EOL)) \
  55                            + scm_tc3_closure))
  56 #define SCM_ENV(x) SCM_CELL_OBJECT_1 (x)
  57 #define SCM_SETENV(x, e) SCM_SET_CELL_OBJECT_1 ((x), (e))
  58 #define SCM_TOP_LEVEL(ENV)  (scm_is_null (ENV) || (scm_is_true (scm_procedure_p (SCM_CAR (ENV)))))
  59
  60 /* Procedure-with-setter
  61
  62    Four representations for procedure-with-setters were
  63    considered before selecting this one:
  64
  65    1. A closure where the CODE and ENV slots are used to represent
  66    the getter and a new SETTER slot is used for the setter.  The
  67    original getter is stored as a `getter' procedure property.  For
  68    closure getters, the CODE and ENV slots contains a copy of the
  69    getter's CODE and ENV slots.  For subr getters, the CODE contains
  70    a call to the subr.
  71
  72    2. A compiled closure with a call to the getter in the cclo
  73    procedure.  The getter and setter are stored in slots 1 and 2.
  74
  75    3. An entity (i.e. a struct with an associated procedure) with a
  76    call to the getter in the entity procedure and the setter stored
  77    in slot 0.  The original getter is stored in slot 1.
  78
  79    4. A new primitive procedure type supported in the evaluator.  The
  80    getter and setter are stored in a GETTER and SETTER slot.  A call
  81    to this procedure type results in a retrieval of the getter and a
  82    jump back to the correct eval dispatcher.
  83
  84    Representation 4 was selected because of efficiency and
  85    simplicity.
  86
  87    Rep 1 has the advantage that there is zero penalty for closure
  88    getters, but primitive getters will get considerable overhead
  89    because the procedure-with-getter will be a closure which calls
  90    the getter.
  91
  92    Rep 3 has the advantage that a GOOPS accessor can be a subclass of
  93    <procedure-with-setter>, but together with rep 2 it suffers from a
  94    three level dispatch for non-GOOPS getters:
  95
  96      cclo/struct --> dispatch proc --> getter
  97
  98    This is because the dispatch procedure must take an extra initial
  99    argument (cclo for rep 2, struct for rep 3).
 100
 101    Rep 4 has the single disadvantage that it uses up one tc7 type
 102    code, but the plan for uniform vectors will very likely free tc7
 103    codes, so this is probably no big problem.  Also note that the
 104    GETTER and SETTER slots can live directly on the heap, using the
 105    new four-word cells.  */
 106
 107 #define SCM_PROCEDURE_WITH_SETTER_P(obj) (!SCM_IMP(obj) && (SCM_TYP7 (obj) == scm_tc7_pws))
 108 #define SCM_PROCEDURE(obj) SCM_CELL_OBJECT_1 (obj)
 109 #define SCM_SETTER(obj) SCM_CELL_OBJECT_2 (obj)
 110
 111
 112 \f
 113
 114 SCM_API void scm_free_subr_entry (SCM subr);
 115 SCM_API SCM scm_c_make_subr (const char *name, long type, SCM (*fcn)());
 116 SCM_API SCM scm_c_make_subr_with_generic (const char *name, long type,
 117                                           SCM (*fcn)(), SCM *gf);
 118 SCM_API SCM scm_c_define_subr (const char *name, long type, SCM (*fcn)());
 119 SCM_API SCM scm_c_define_subr_with_generic (const char *name, long type,
 120                                             SCM (*fcn)(), SCM *gf);
 121 SCM_API SCM scm_procedure_p (SCM obj);
 122 SCM_API SCM scm_closure_p (SCM obj);
 123 SCM_API SCM scm_thunk_p (SCM obj);
 124 SCM_API int scm_subr_p (SCM obj);
 125 SCM_API SCM scm_procedure_documentation (SCM proc);
 126 SCM_API SCM scm_procedure_with_setter_p (SCM obj);
 127 SCM_API SCM scm_make_procedure_with_setter (SCM procedure, SCM setter);
 128 SCM_API SCM scm_procedure (SCM proc);
 129 SCM_API SCM scm_setter (SCM proc);
 130 SCM_INTERNAL void scm_init_procs (void);
 131
 132 #endif  /* SCM_PROCS_H */
 133
 134 /*
 135   Local Variables:
 136   c-file-style: "gnu"
 137   End:
 138 */