--- /dev/null
+/* Copyright (C) 1995,1996,1997,1998,1999,2000, 2001, 2002, 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 <string.h>
+#include <stdio.h>
+
+#include "libguile/_scm.h"
+#include "libguile/stackchk.h"
+#include "libguile/dynwind.h"
+#include "libguile/eval.h"
+#include "libguile/smob.h"
+#include "libguile/pairs.h"
+#include "libguile/throw.h"
+#include "libguile/fluids.h"
+#include "libguile/ports.h"
+
+#include "libguile/root.h"
+\f
+
+SCM scm_sys_protects[SCM_NUM_PROTECTS];
+
+\f
+
+/* {call-with-dynamic-root}
+ *
+ * Suspending the current thread to evaluate a thunk on the
+ * same C stack but under a new root.
+ *
+ * Calls to call-with-dynamic-root return exactly once (unless
+ * the process is somehow exitted). */
+
+/* cwdr fills out both of these structures, and then passes a pointer
+ to them through scm_internal_catch to the cwdr_body and
+ cwdr_handler functions, to tell them how to behave and to get
+ information back from them.
+
+ A cwdr is a lot like a catch, except there is no tag (all
+ exceptions are caught), and the body procedure takes the arguments
+ passed to cwdr as A1 and ARGS. The handler is also special since
+ it is not directly run from scm_internal_catch. It is executed
+ outside the new dynamic root. */
+
+struct cwdr_body_data {
+ /* Arguments to pass to the cwdr body function. */
+ SCM a1, args;
+
+ /* Scheme procedure to use as body of cwdr. */
+ SCM body_proc;
+};
+
+struct cwdr_handler_data {
+ /* Do we need to run the handler? */
+ int run_handler;
+
+ /* The tag and args to pass it. */
+ SCM tag, args;
+};
+
+
+/* Invoke the body of a cwdr, assuming that the throw handler has
+ already been set up. DATA points to a struct set up by cwdr that
+ says what proc to call, and what args to apply it to.
+
+ With a little thought, we could replace this with scm_body_thunk,
+ but I don't want to mess with that at the moment. */
+static SCM
+cwdr_body (void *data)
+{
+ struct cwdr_body_data *c = (struct cwdr_body_data *) data;
+
+ return scm_apply (c->body_proc, c->a1, c->args);
+}
+
+/* Record the fact that the body of the cwdr has thrown. Record
+ enough information to invoke the handler later when the dynamic
+ root has been deestablished. */
+
+static SCM
+cwdr_handler (void *data, SCM tag, SCM args)
+{
+ struct cwdr_handler_data *c = (struct cwdr_handler_data *) data;
+
+ c->run_handler = 1;
+ c->tag = tag;
+ c->args = args;
+ return SCM_UNSPECIFIED;
+}
+
+SCM
+scm_internal_cwdr (scm_t_catch_body body, void *body_data,
+ scm_t_catch_handler handler, void *handler_data,
+ SCM_STACKITEM *stack_start)
+{
+ struct cwdr_handler_data my_handler_data;
+ SCM answer, old_winds;
+
+ /* Exit caller's dynamic state.
+ */
+ old_winds = scm_i_dynwinds ();
+ scm_dowinds (SCM_EOL, scm_ilength (old_winds));
+
+ scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
+ scm_dynwind_current_dynamic_state (scm_make_dynamic_state (SCM_UNDEFINED));
+
+ my_handler_data.run_handler = 0;
+ answer = scm_i_with_continuation_barrier (body, body_data,
+ cwdr_handler, &my_handler_data,
+ NULL, NULL);
+
+ scm_dynwind_end ();
+
+ /* Enter caller's dynamic state.
+ */
+ scm_dowinds (old_winds, - scm_ilength (old_winds));
+
+ /* Now run the real handler iff the body did a throw. */
+ if (my_handler_data.run_handler)
+ return handler (handler_data, my_handler_data.tag, my_handler_data.args);
+ else
+ return answer;
+}
+
+/* The original CWDR for invoking Scheme code with a Scheme handler. */
+
+static SCM
+cwdr (SCM proc, SCM a1, SCM args, SCM handler, SCM_STACKITEM *stack_start)
+{
+ struct cwdr_body_data c;
+
+ c.a1 = a1;
+ c.args = args;
+ c.body_proc = proc;
+
+ return scm_internal_cwdr (cwdr_body, &c,
+ scm_handle_by_proc, &handler,
+ stack_start);
+}
+
+SCM_DEFINE (scm_call_with_dynamic_root, "call-with-dynamic-root", 2, 0, 0,
+ (SCM thunk, SCM handler),
+ "Call @var{thunk} with a new dynamic state and within"
+ "a continuation barrier. The @var{handler} catches all"
+ "otherwise uncaught throws and executes within the same"
+ "dynamic context as @var{thunk}.")
+#define FUNC_NAME s_scm_call_with_dynamic_root
+{
+ SCM_STACKITEM stack_place;
+ return cwdr (thunk, SCM_EOL, SCM_EOL, handler, &stack_place);
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_dynamic_root, "dynamic-root", 0, 0, 0,
+ (),
+ "Return an object representing the current dynamic root.\n\n"
+ "These objects are only useful for comparison using @code{eq?}.\n")
+#define FUNC_NAME s_scm_dynamic_root
+{
+ return SCM_I_CURRENT_THREAD->continuation_root;
+}
+#undef FUNC_NAME
+
+SCM
+scm_apply_with_dynamic_root (SCM proc, SCM a1, SCM args, SCM handler)
+{
+ SCM_STACKITEM stack_place;
+ return cwdr (proc, a1, args, handler, &stack_place);
+}
+
+\f
+
+void
+scm_init_root ()
+{
+#include "libguile/root.x"
+}
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
projects / lilypond.git / blobdiff