--- /dev/null
+/* Copyright (C) 1995,1996,1998,2000,2001, 2003, 2006, 2008 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+\f
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <stdio.h>
+
+#include "libguile/_scm.h"
+#include "libguile/vectors.h"
+#include "libguile/lang.h"
+#include "libguile/hashtab.h"
+
+#include "libguile/validate.h"
+#include "libguile/weaks.h"
+
+\f
+
+/* 1. The current hash table implementation in hashtab.c uses weak alist
+ * vectors (formerly called weak hash tables) internally.
+ *
+ * 2. All hash table operations still work on alist vectors.
+ *
+ * 3. The weak vector and alist vector Scheme API is accessed through
+ * the module (ice-9 weak-vector).
+ */
+
+
+/* {Weak Vectors}
+ */
+
+
+SCM_DEFINE (scm_make_weak_vector, "make-weak-vector", 1, 1, 0,
+ (SCM size, SCM fill),
+ "Return a weak vector with @var{size} elements. If the optional\n"
+ "argument @var{fill} is given, all entries in the vector will be\n"
+ "set to @var{fill}. The default value for @var{fill} is the\n"
+ "empty list.")
+#define FUNC_NAME s_scm_make_weak_vector
+{
+ return scm_i_allocate_weak_vector (0, size, fill);
+}
+#undef FUNC_NAME
+
+
+SCM_REGISTER_PROC(s_list_to_weak_vector, "list->weak-vector", 1, 0, 0, scm_weak_vector);
+
+SCM_DEFINE (scm_weak_vector, "weak-vector", 0, 0, 1,
+ (SCM l),
+ "@deffnx {Scheme Procedure} list->weak-vector l\n"
+ "Construct a weak vector from a list: @code{weak-vector} uses\n"
+ "the list of its arguments while @code{list->weak-vector} uses\n"
+ "its only argument @var{l} (a list) to construct a weak vector\n"
+ "the same way @code{list->vector} would.")
+#define FUNC_NAME s_scm_weak_vector
+{
+ scm_t_array_handle handle;
+ SCM res, *data;
+ long i;
+
+ i = scm_ilength (l);
+ SCM_ASSERT (i >= 0, l, SCM_ARG1, FUNC_NAME);
+
+ res = scm_make_weak_vector (scm_from_int (i), SCM_UNSPECIFIED);
+ data = scm_vector_writable_elements (res, &handle, NULL, NULL);
+
+ while (scm_is_pair (l) && i > 0)
+ {
+ *data++ = SCM_CAR (l);
+ l = SCM_CDR (l);
+ i--;
+ }
+
+ scm_array_handle_release (&handle);
+
+ return res;
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_weak_vector_p, "weak-vector?", 1, 0, 0,
+ (SCM obj),
+ "Return @code{#t} if @var{obj} is a weak vector. Note that all\n"
+ "weak hashes are also weak vectors.")
+#define FUNC_NAME s_scm_weak_vector_p
+{
+ return scm_from_bool (SCM_I_WVECTP (obj) && !SCM_IS_WHVEC (obj));
+}
+#undef FUNC_NAME
+
+\f
+
+SCM_DEFINE (scm_make_weak_key_alist_vector, "make-weak-key-alist-vector", 0, 1, 0,
+ (SCM size),
+ "@deffnx {Scheme Procedure} make-weak-value-alist-vector size\n"
+ "@deffnx {Scheme Procedure} make-doubly-weak-alist-vector size\n"
+ "Return a weak hash table with @var{size} buckets. As with any\n"
+ "hash table, choosing a good size for the table requires some\n"
+ "caution.\n"
+ "\n"
+ "You can modify weak hash tables in exactly the same way you\n"
+ "would modify regular hash tables. (@pxref{Hash Tables})")
+#define FUNC_NAME s_scm_make_weak_key_alist_vector
+{
+ return scm_i_allocate_weak_vector
+ (1, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_make_weak_value_alist_vector, "make-weak-value-alist-vector", 0, 1, 0,
+ (SCM size),
+ "Return a hash table with weak values with @var{size} buckets.\n"
+ "(@pxref{Hash Tables})")
+#define FUNC_NAME s_scm_make_weak_value_alist_vector
+{
+ return scm_i_allocate_weak_vector
+ (2, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_make_doubly_weak_alist_vector, "make-doubly-weak-alist-vector", 1, 0, 0,
+ (SCM size),
+ "Return a hash table with weak keys and values with @var{size}\n"
+ "buckets. (@pxref{Hash Tables})")
+#define FUNC_NAME s_scm_make_doubly_weak_alist_vector
+{
+ return scm_i_allocate_weak_vector
+ (3, SCM_UNBNDP (size) ? scm_from_int (31) : size, SCM_EOL);
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_weak_key_alist_vector_p, "weak-key-alist-vector?", 1, 0, 0,
+ (SCM obj),
+ "@deffnx {Scheme Procedure} weak-value-alist-vector? obj\n"
+ "@deffnx {Scheme Procedure} doubly-weak-alist-vector? obj\n"
+ "Return @code{#t} if @var{obj} is the specified weak hash\n"
+ "table. Note that a doubly weak hash table is neither a weak key\n"
+ "nor a weak value hash table.")
+#define FUNC_NAME s_scm_weak_key_alist_vector_p
+{
+ return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC (obj));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_weak_value_alist_vector_p, "weak-value-alist-vector?", 1, 0, 0,
+ (SCM obj),
+ "Return @code{#t} if @var{obj} is a weak value hash table.")
+#define FUNC_NAME s_scm_weak_value_alist_vector_p
+{
+ return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC_V (obj));
+}
+#undef FUNC_NAME
+
+
+SCM_DEFINE (scm_doubly_weak_alist_vector_p, "doubly-weak-alist-vector?", 1, 0, 0,
+ (SCM obj),
+ "Return @code{#t} if @var{obj} is a doubly weak hash table.")
+#define FUNC_NAME s_scm_doubly_weak_alist_vector_p
+{
+ return scm_from_bool (SCM_I_WVECTP (obj) && SCM_IS_WHVEC_B (obj));
+}
+#undef FUNC_NAME
+
+#define UNMARKED_CELL_P(x) (SCM_NIMP(x) && !SCM_GC_MARK_P (x))
+
+static SCM weak_vectors;
+
+void
+scm_i_init_weak_vectors_for_gc ()
+{
+ weak_vectors = SCM_EOL;
+}
+
+void
+scm_i_mark_weak_vector (SCM w)
+{
+ SCM_I_SET_WVECT_GC_CHAIN (w, weak_vectors);
+ weak_vectors = w;
+}
+
+static int
+scm_i_mark_weak_vector_non_weaks (SCM w)
+{
+ int again = 0;
+
+ if (SCM_IS_WHVEC_ANY (w))
+ {
+ SCM *ptr;
+ long n = SCM_I_WVECT_LENGTH (w);
+ long j;
+ int weak_keys = SCM_IS_WHVEC (w) || SCM_IS_WHVEC_B (w);
+ int weak_values = SCM_IS_WHVEC_V (w) || SCM_IS_WHVEC_B (w);
+
+ ptr = SCM_I_WVECT_GC_WVELTS (w);
+
+ for (j = 0; j < n; ++j)
+ {
+ SCM alist, slow_alist;
+ int slow_toggle = 0;
+
+ /* We do not set the mark bits of the alist spine cells here
+ since we do not want to ever create the situation where a
+ marked cell references an unmarked cell (except in
+ scm_gc_mark, where the referenced cells will be marked
+ immediately). Thus, we can not use mark bits to stop us
+ from looping indefinitely over a cyclic alist. Instead,
+ we use the standard tortoise and hare trick to catch
+ cycles. The fast walker does the work, and stops when it
+ catches the slow walker to ensure that the whole cycle
+ has been worked on.
+ */
+
+ alist = slow_alist = ptr[j];
+
+ while (scm_is_pair (alist))
+ {
+ SCM elt = SCM_CAR (alist);
+
+ if (UNMARKED_CELL_P (elt))
+ {
+ if (scm_is_pair (elt))
+ {
+ SCM key = SCM_CAR (elt);
+ SCM value = SCM_CDR (elt);
+
+ if (!((weak_keys && UNMARKED_CELL_P (key))
+ || (weak_values && UNMARKED_CELL_P (value))))
+ {
+ /* The item should be kept. We need to mark it
+ recursively.
+ */
+ scm_gc_mark (elt);
+ again = 1;
+ }
+ }
+ else
+ {
+ /* A non-pair cell element. This should not
+ appear in a real alist, but when it does, we
+ need to keep it.
+ */
+ scm_gc_mark (elt);
+ again = 1;
+ }
+ }
+
+ alist = SCM_CDR (alist);
+
+ if (slow_toggle && scm_is_pair (slow_alist))
+ {
+ slow_alist = SCM_CDR (slow_alist);
+ slow_toggle = !slow_toggle;
+ if (scm_is_eq (slow_alist, alist))
+ break;
+ }
+ }
+ if (!scm_is_pair (alist))
+ scm_gc_mark (alist);
+ }
+ }
+
+ return again;
+}
+
+int
+scm_i_mark_weak_vectors_non_weaks ()
+{
+ int again = 0;
+ SCM w = weak_vectors;
+ while (!scm_is_null (w))
+ {
+ if (scm_i_mark_weak_vector_non_weaks (w))
+ again = 1;
+ w = SCM_I_WVECT_GC_CHAIN (w);
+ }
+ return again;
+}
+
+static void
+scm_i_remove_weaks (SCM w)
+{
+ SCM *ptr = SCM_I_WVECT_GC_WVELTS (w);
+ size_t n = SCM_I_WVECT_LENGTH (w);
+ size_t i;
+
+ if (!SCM_IS_WHVEC_ANY (w))
+ {
+ for (i = 0; i < n; ++i)
+ if (UNMARKED_CELL_P (ptr[i]))
+ ptr[i] = SCM_BOOL_F;
+ }
+ else
+ {
+ size_t delta = 0;
+
+ for (i = 0; i < n; ++i)
+ {
+ SCM alist, *fixup;
+
+ fixup = ptr + i;
+ alist = *fixup;
+ while (scm_is_pair (alist) && !SCM_GC_MARK_P (alist))
+ {
+ if (UNMARKED_CELL_P (SCM_CAR (alist)))
+ {
+ *fixup = SCM_CDR (alist);
+ delta++;
+ }
+ else
+ {
+ SCM_SET_GC_MARK (alist);
+ fixup = SCM_CDRLOC (alist);
+ }
+ alist = *fixup;
+ }
+ }
+#if 0
+ if (delta)
+ fprintf (stderr, "vector %p, delta %d\n", w, delta);
+#endif
+ SCM_I_SET_WVECT_DELTA (w, delta);
+ }
+}
+
+void
+scm_i_remove_weaks_from_weak_vectors ()
+{
+ SCM w = weak_vectors;
+ while (!scm_is_null (w))
+ {
+ scm_i_remove_weaks (w);
+ w = SCM_I_WVECT_GC_CHAIN (w);
+ }
+}
+
+\f
+
+SCM
+scm_init_weaks_builtins ()
+{
+#include "libguile/weaks.x"
+ return SCM_UNSPECIFIED;
+}
+
+void
+scm_init_weaks ()
+{
+ scm_c_define_gsubr ("%init-weaks-builtins", 0, 0, 0,
+ scm_init_weaks_builtins);
+}
+
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
projects / lilypond.git / blobdiff