mirror of
https://git.savannah.gnu.org/git/guile.git
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399 lines
11 KiB
C
399 lines
11 KiB
C
/* Copyright (C) 1995,1996,1998,2000,2001, 2003, 2006 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*
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* As a special exception, Free Software Foundation gives permission
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* for additional uses of the text contained in its release of this library.
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*
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* The exception is that, if you link this library with other files
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* to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking this library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by
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* Free Software Foundation as part of this library. If you copy
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* code from other releases distributed under the terms of the GPL into a copy of
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* this library, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from such code.
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*
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* If you write modifications of your own for this library, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice. */
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#include <stdio.h>
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#include "libguile/_scm.h"
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#include "libguile/vectors.h"
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#include "libguile/lang.h"
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#include "libguile/hashtab.h"
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#include "libguile/validate.h"
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#include "libguile/weaks.h"
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/* 1. The current hash table implementation in hashtab.c uses weak alist
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* vectors (formerly called weak hash tables) internally.
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*
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* 2. All hash table operations still work on alist vectors.
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*
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* 3. The weak vector and alist vector Scheme API is accessed through
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* the module (ice-9 weak-vector).
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*/
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/* {Weak Vectors}
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*/
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SCM_DEFINE (scm_make_weak_vector, "make-weak-vector", 1, 1, 0,
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(SCM size, SCM fill),
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"Return a weak vector with @var{size} elements. If the optional\n"
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"argument @var{fill} is given, all entries in the vector will be\n"
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"set to @var{fill}. The default value for @var{fill} is the\n"
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"empty list.")
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#define FUNC_NAME s_scm_make_weak_vector
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{
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return scm_i_allocate_weak_vector (0, size, fill);
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}
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#undef FUNC_NAME
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SCM_REGISTER_PROC(s_list_to_weak_vector, "list->weak-vector", 1, 0, 0, scm_weak_vector);
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SCM_DEFINE (scm_weak_vector, "weak-vector", 0, 0, 1,
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(SCM l),
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"@deffnx {Scheme Procedure} list->weak-vector l\n"
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"Construct a weak vector from a list: @code{weak-vector} uses\n"
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"the list of its arguments while @code{list->weak-vector} uses\n"
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"its only argument @var{l} (a list) to construct a weak vector\n"
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"the same way @code{list->vector} would.")
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#define FUNC_NAME s_scm_weak_vector
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{
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scm_t_array_handle handle;
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SCM res, *data;
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long i;
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i = scm_ilength (l);
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SCM_ASSERT (i >= 0, l, SCM_ARG1, FUNC_NAME);
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res = scm_make_weak_vector (scm_from_int (i), SCM_UNSPECIFIED);
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data = scm_vector_writable_elements (res, &handle, NULL, NULL);
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while (scm_is_pair (l) && i > 0)
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{
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*data++ = SCM_CAR (l);
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l = SCM_CDR (l);
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i--;
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}
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scm_array_handle_release (&handle);
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return res;
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_weak_vector_p, "weak-vector?", 1, 0, 0,
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(SCM obj),
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"Return @code{#t} if @var{obj} is a weak vector. Note that all\n"
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"weak hashes are also weak vectors.")
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#define FUNC_NAME s_scm_weak_vector_p
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{
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return scm_from_bool (SCM_I_WVECTP (obj) && !SCM_IS_WHVEC (obj));
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_make_weak_key_alist_vector, "make-weak-key-alist-vector", 0, 1, 0,
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(SCM size),
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"@deffnx {Scheme Procedure} make-weak-value-alist-vector size\n"
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"@deffnx {Scheme Procedure} make-doubly-weak-alist-vector size\n"
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"Return a weak hash table with @var{size} buckets. As with any\n"
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"hash table, choosing a good size for the table requires some\n"
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"caution.\n"
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"\n"
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"You can modify weak hash tables in exactly the same way you\n"
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"would modify regular hash tables. (@pxref{Hash Tables})")
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#define FUNC_NAME s_scm_make_weak_key_alist_vector
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{
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return scm_i_allocate_weak_vector
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(1, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_make_weak_value_alist_vector, "make-weak-value-alist-vector", 0, 1, 0,
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(SCM size),
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"Return a hash table with weak values with @var{size} buckets.\n"
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"(@pxref{Hash Tables})")
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#define FUNC_NAME s_scm_make_weak_value_alist_vector
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{
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return scm_i_allocate_weak_vector
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(2, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_make_doubly_weak_alist_vector, "make-doubly-weak-alist-vector", 1, 0, 0,
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(SCM size),
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"Return a hash table with weak keys and values with @var{size}\n"
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"buckets. (@pxref{Hash Tables})")
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#define FUNC_NAME s_scm_make_doubly_weak_alist_vector
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{
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return scm_i_allocate_weak_vector
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(3, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_weak_key_alist_vector_p, "weak-key-alist-vector?", 1, 0, 0,
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(SCM obj),
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"@deffnx {Scheme Procedure} weak-value-alist-vector? obj\n"
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"@deffnx {Scheme Procedure} doubly-weak-alist-vector? obj\n"
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"Return @code{#t} if @var{obj} is the specified weak hash\n"
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"table. Note that a doubly weak hash table is neither a weak key\n"
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"nor a weak value hash table.")
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#define FUNC_NAME s_scm_weak_key_alist_vector_p
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{
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return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC (obj));
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_weak_value_alist_vector_p, "weak-value-alist-vector?", 1, 0, 0,
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(SCM obj),
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"Return @code{#t} if @var{obj} is a weak value hash table.")
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#define FUNC_NAME s_scm_weak_value_alist_vector_p
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{
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return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC_V (obj));
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_doubly_weak_alist_vector_p, "doubly-weak-alist-vector?", 1, 0, 0,
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(SCM obj),
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"Return @code{#t} if @var{obj} is a doubly weak hash table.")
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#define FUNC_NAME s_scm_doubly_weak_alist_vector_p
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{
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return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC_B (obj));
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}
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#undef FUNC_NAME
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#define UNMARKED_CELL_P(x) (SCM_NIMP(x) && !SCM_GC_MARK_P (x))
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static SCM weak_vectors;
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void
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scm_i_init_weak_vectors_for_gc ()
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{
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weak_vectors = SCM_EOL;
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}
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void
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scm_i_mark_weak_vector (SCM w)
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{
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SCM_I_SET_WVECT_GC_CHAIN (w, weak_vectors);
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weak_vectors = w;
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}
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static int
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scm_i_mark_weak_vector_non_weaks (SCM w)
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{
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int again = 0;
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if (SCM_IS_WHVEC_ANY (w))
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{
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SCM *ptr;
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long n = SCM_I_WVECT_LENGTH (w);
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long j;
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int weak_keys = SCM_IS_WHVEC (w) || SCM_IS_WHVEC_B (w);
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int weak_values = SCM_IS_WHVEC_V (w) || SCM_IS_WHVEC_B (w);
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ptr = SCM_I_WVECT_GC_WVELTS (w);
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for (j = 0; j < n; ++j)
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{
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SCM alist, slow_alist;
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int slow_toggle = 0;
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/* We do not set the mark bits of the alist spine cells here
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since we do not want to ever create the situation where a
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marked cell references an unmarked cell (except in
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scm_gc_mark, where the referenced cells will be marked
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immediately). Thus, we can not use mark bits to stop us
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from looping indefinitely over a cyclic alist. Instead,
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we use the standard tortoise and hare trick to catch
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cycles. The fast walker does the work, and stops when it
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catches the slow walker to ensure that the whole cycle
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has been worked on.
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*/
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alist = slow_alist = ptr[j];
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while (scm_is_pair (alist))
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{
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SCM elt = SCM_CAR (alist);
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if (UNMARKED_CELL_P (elt))
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{
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if (scm_is_pair (elt))
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{
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SCM key = SCM_CAR (elt);
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SCM value = SCM_CDR (elt);
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if (!((weak_keys && UNMARKED_CELL_P (key))
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|| (weak_values && UNMARKED_CELL_P (value))))
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{
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/* The item should be kept. We need to mark it
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recursively.
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*/
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scm_gc_mark (elt);
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again = 1;
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}
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}
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else
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{
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/* A non-pair cell element. This should not
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appear in a real alist, but when it does, we
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need to keep it.
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*/
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scm_gc_mark (elt);
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again = 1;
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}
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}
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alist = SCM_CDR (alist);
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if (slow_toggle && scm_is_pair (slow_alist))
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{
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slow_alist = SCM_CDR (slow_alist);
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slow_toggle = !slow_toggle;
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if (scm_is_eq (slow_alist, alist))
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break;
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}
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}
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if (!scm_is_pair (alist))
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scm_gc_mark (alist);
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}
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}
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return again;
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}
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int
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scm_i_mark_weak_vectors_non_weaks ()
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{
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int again = 0;
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SCM w = weak_vectors;
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while (!scm_is_null (w))
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{
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if (scm_i_mark_weak_vector_non_weaks (w))
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again = 1;
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w = SCM_I_WVECT_GC_CHAIN (w);
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}
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return again;
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}
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static void
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scm_i_remove_weaks (SCM w)
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{
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SCM *ptr = SCM_I_WVECT_GC_WVELTS (w);
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size_t n = SCM_I_WVECT_LENGTH (w);
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size_t i;
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if (!SCM_IS_WHVEC_ANY (w))
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{
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for (i = 0; i < n; ++i)
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if (UNMARKED_CELL_P (ptr[i]))
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ptr[i] = SCM_BOOL_F;
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}
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else
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{
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size_t delta = 0;
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for (i = 0; i < n; ++i)
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{
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SCM alist, *fixup;
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fixup = ptr + i;
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alist = *fixup;
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while (scm_is_pair (alist) && !SCM_GC_MARK_P (alist))
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{
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if (UNMARKED_CELL_P (SCM_CAR (alist)))
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{
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*fixup = SCM_CDR (alist);
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delta++;
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}
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else
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{
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SCM_SET_GC_MARK (alist);
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fixup = SCM_CDRLOC (alist);
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}
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alist = *fixup;
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}
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}
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#if 0
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if (delta)
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fprintf (stderr, "vector %p, delta %d\n", w, delta);
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#endif
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SCM_I_SET_WVECT_DELTA (w, delta);
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}
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}
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void
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scm_i_remove_weaks_from_weak_vectors ()
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{
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SCM w = weak_vectors;
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while (!scm_is_null (w))
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{
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scm_i_remove_weaks (w);
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w = SCM_I_WVECT_GC_CHAIN (w);
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}
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}
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SCM
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scm_init_weaks_builtins ()
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{
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#include "libguile/weaks.x"
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return SCM_UNSPECIFIED;
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}
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void
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scm_init_weaks ()
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{
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scm_c_define_gsubr ("%init-weaks-builtins", 0, 0, 0,
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scm_init_weaks_builtins);
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}
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/*
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Local Variables:
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c-file-style: "gnu"
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End:
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*/
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