--- /dev/null
+/* Copyright (C) 1995,1996,1998,1999,2000,2001, 2003, 2004, 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 <assert.h>
+
+#include "libguile/_scm.h"
+#include "libguile/eval.h"
+#include "libguile/alist.h"
+#include "libguile/fluids.h"
+#include "libguile/ports.h"
+#include "libguile/smob.h"
+
+#include "libguile/dynwind.h"
+\f
+
+/* {Dynamic wind}
+
+ Things that can be on the wind list:
+
+ #<frame>
+ #<winder>
+ (enter-proc . leave-proc) dynamic-wind
+ (tag . jmpbuf) catch
+ (tag . pre-unwind-data) throw-handler / lazy-catch
+ tag is either a symbol or a boolean
+
+*/
+
+
+
+SCM_DEFINE (scm_dynamic_wind, "dynamic-wind", 3, 0, 0,
+ (SCM in_guard, SCM thunk, SCM out_guard),
+ "All three arguments must be 0-argument procedures.\n"
+ "@var{in_guard} is called, then @var{thunk}, then\n"
+ "@var{out_guard}.\n"
+ "\n"
+ "If, any time during the execution of @var{thunk}, the\n"
+ "continuation of the @code{dynamic_wind} expression is escaped\n"
+ "non-locally, @var{out_guard} is called. If the continuation of\n"
+ "the dynamic-wind is re-entered, @var{in_guard} is called. Thus\n"
+ "@var{in_guard} and @var{out_guard} may be called any number of\n"
+ "times.\n"
+ "@lisp\n"
+ "(define x 'normal-binding)\n"
+ "@result{} x\n"
+ "(define a-cont (call-with-current-continuation\n"
+ " (lambda (escape)\n"
+ " (let ((old-x x))\n"
+ " (dynamic-wind\n"
+ " ;; in-guard:\n"
+ " ;;\n"
+ " (lambda () (set! x 'special-binding))\n"
+ "\n"
+ " ;; thunk\n"
+ " ;;\n"
+ " (lambda () (display x) (newline)\n"
+ " (call-with-current-continuation escape)\n"
+ " (display x) (newline)\n"
+ " x)\n"
+ "\n"
+ " ;; out-guard:\n"
+ " ;;\n"
+ " (lambda () (set! x old-x)))))))\n"
+ "\n"
+ ";; Prints:\n"
+ "special-binding\n"
+ ";; Evaluates to:\n"
+ "@result{} a-cont\n"
+ "x\n"
+ "@result{} normal-binding\n"
+ "(a-cont #f)\n"
+ ";; Prints:\n"
+ "special-binding\n"
+ ";; Evaluates to:\n"
+ "@result{} a-cont ;; the value of the (define a-cont...)\n"
+ "x\n"
+ "@result{} normal-binding\n"
+ "a-cont\n"
+ "@result{} special-binding\n"
+ "@end lisp")
+#define FUNC_NAME s_scm_dynamic_wind
+{
+ SCM ans, old_winds;
+ SCM_ASSERT (scm_is_true (scm_thunk_p (out_guard)),
+ out_guard,
+ SCM_ARG3, FUNC_NAME);
+ scm_call_0 (in_guard);
+ old_winds = scm_i_dynwinds ();
+ scm_i_set_dynwinds (scm_acons (in_guard, out_guard, old_winds));
+ ans = scm_call_0 (thunk);
+ scm_i_set_dynwinds (old_winds);
+ scm_call_0 (out_guard);
+ return ans;
+}
+#undef FUNC_NAME
+
+SCM
+scm_internal_dynamic_wind (scm_t_guard before,
+ scm_t_inner inner,
+ scm_t_guard after,
+ void *inner_data,
+ void *guard_data)
+{
+ SCM ans;
+
+ scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
+ scm_dynwind_rewind_handler (before, guard_data, SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_unwind_handler (after, guard_data, SCM_F_WIND_EXPLICITLY);
+ ans = inner (inner_data);
+ scm_dynwind_end ();
+ return ans;
+}
+
+/* Frames and winders. */
+
+static scm_t_bits tc16_frame;
+#define FRAME_P(f) SCM_SMOB_PREDICATE (tc16_frame, (f))
+
+#define FRAME_F_REWINDABLE (1 << 0)
+#define FRAME_REWINDABLE_P(f) (SCM_SMOB_FLAGS(f) & FRAME_F_REWINDABLE)
+
+static scm_t_bits tc16_winder;
+#define WINDER_P(w) SCM_SMOB_PREDICATE (tc16_winder, (w))
+#define WINDER_PROC(w) ((void (*)(void *))SCM_SMOB_DATA (w))
+#define WINDER_DATA(w) ((void *)SCM_SMOB_DATA_2 (w))
+
+#define WINDER_F_EXPLICIT (1 << 0)
+#define WINDER_F_REWIND (1 << 1)
+#define WINDER_F_MARK (1 << 2)
+#define WINDER_EXPLICIT_P(w) (SCM_SMOB_FLAGS(w) & WINDER_F_EXPLICIT)
+#define WINDER_REWIND_P(w) (SCM_SMOB_FLAGS(w) & WINDER_F_REWIND)
+#define WINDER_MARK_P(w) (SCM_SMOB_FLAGS(w) & WINDER_F_MARK)
+
+void
+scm_dynwind_begin (scm_t_dynwind_flags flags)
+{
+ SCM f;
+ SCM_NEWSMOB (f, tc16_frame, 0);
+ if (flags & SCM_F_DYNWIND_REWINDABLE)
+ SCM_SET_SMOB_FLAGS (f, FRAME_F_REWINDABLE);
+ scm_i_set_dynwinds (scm_cons (f, scm_i_dynwinds ()));
+}
+
+void
+scm_dynwind_end (void)
+{
+ SCM winds;
+
+ /* Unwind upto and including the next frame entry. We can only
+ encounter #<winder> entries on the way.
+ */
+
+ winds = scm_i_dynwinds ();
+ while (scm_is_pair (winds))
+ {
+ SCM entry = SCM_CAR (winds);
+ winds = SCM_CDR (winds);
+
+ scm_i_set_dynwinds (winds);
+
+ if (FRAME_P (entry))
+ return;
+
+ assert (WINDER_P (entry));
+ if (!WINDER_REWIND_P (entry) && WINDER_EXPLICIT_P (entry))
+ WINDER_PROC(entry) (WINDER_DATA (entry));
+ }
+
+ assert (0);
+}
+
+static SCM
+winder_mark (SCM w)
+{
+ if (WINDER_MARK_P (w))
+ return SCM_PACK (WINDER_DATA (w));
+ return SCM_BOOL_F;
+}
+
+void
+scm_dynwind_unwind_handler (void (*proc) (void *), void *data,
+ scm_t_wind_flags flags)
+{
+ SCM w;
+ SCM_NEWSMOB2 (w, tc16_winder, (scm_t_bits) proc, (scm_t_bits) data);
+ if (flags & SCM_F_WIND_EXPLICITLY)
+ SCM_SET_SMOB_FLAGS (w, WINDER_F_EXPLICIT);
+ scm_i_set_dynwinds (scm_cons (w, scm_i_dynwinds ()));
+}
+
+void
+scm_dynwind_rewind_handler (void (*proc) (void *), void *data,
+ scm_t_wind_flags flags)
+{
+ SCM w;
+ SCM_NEWSMOB2 (w, tc16_winder, (scm_t_bits) proc, (scm_t_bits) data);
+ SCM_SET_SMOB_FLAGS (w, WINDER_F_REWIND);
+ scm_i_set_dynwinds (scm_cons (w, scm_i_dynwinds ()));
+ if (flags & SCM_F_WIND_EXPLICITLY)
+ proc (data);
+}
+
+void
+scm_dynwind_unwind_handler_with_scm (void (*proc) (SCM), SCM data,
+ scm_t_wind_flags flags)
+{
+ SCM w;
+ scm_t_bits fl = ((flags&SCM_F_WIND_EXPLICITLY)? WINDER_F_EXPLICIT : 0);
+ SCM_NEWSMOB2 (w, tc16_winder, (scm_t_bits) proc, SCM_UNPACK (data));
+ SCM_SET_SMOB_FLAGS (w, fl | WINDER_F_MARK);
+ scm_i_set_dynwinds (scm_cons (w, scm_i_dynwinds ()));
+}
+
+void
+scm_dynwind_rewind_handler_with_scm (void (*proc) (SCM), SCM data,
+ scm_t_wind_flags flags)
+{
+ SCM w;
+ SCM_NEWSMOB2 (w, tc16_winder, (scm_t_bits) proc, SCM_UNPACK (data));
+ SCM_SET_SMOB_FLAGS (w, WINDER_F_REWIND | WINDER_F_MARK);
+ scm_i_set_dynwinds (scm_cons (w, scm_i_dynwinds ()));
+ if (flags & SCM_F_WIND_EXPLICITLY)
+ proc (data);
+}
+
+void
+scm_dynwind_free (void *mem)
+{
+ scm_dynwind_unwind_handler (free, mem, SCM_F_WIND_EXPLICITLY);
+}
+
+#ifdef GUILE_DEBUG
+SCM_DEFINE (scm_wind_chain, "wind-chain", 0, 0, 0,
+ (),
+ "Return the current wind chain. The wind chain contains all\n"
+ "information required by @code{dynamic-wind} to call its\n"
+ "argument thunks when entering/exiting its scope.")
+#define FUNC_NAME s_scm_wind_chain
+{
+ return scm_i_dynwinds ();
+}
+#undef FUNC_NAME
+#endif
+
+void
+scm_swap_bindings (SCM vars, SCM vals)
+{
+ SCM tmp;
+ while (SCM_NIMP (vals))
+ {
+ tmp = SCM_VARIABLE_REF (SCM_CAR (vars));
+ SCM_VARIABLE_SET (SCM_CAR (vars), SCM_CAR (vals));
+ SCM_SETCAR (vals, tmp);
+ vars = SCM_CDR (vars);
+ vals = SCM_CDR (vals);
+ }
+}
+
+void
+scm_dowinds (SCM to, long delta)
+{
+ scm_i_dowinds (to, delta, NULL, NULL);
+}
+
+void
+scm_i_dowinds (SCM to, long delta, void (*turn_func) (void *), void *data)
+{
+ tail:
+ if (scm_is_eq (to, scm_i_dynwinds ()))
+ {
+ if (turn_func)
+ turn_func (data);
+ }
+ else if (delta < 0)
+ {
+ SCM wind_elt;
+ SCM wind_key;
+
+ scm_i_dowinds (SCM_CDR (to), 1 + delta, turn_func, data);
+ wind_elt = SCM_CAR (to);
+
+ if (FRAME_P (wind_elt))
+ {
+ if (!FRAME_REWINDABLE_P (wind_elt))
+ scm_misc_error ("dowinds",
+ "cannot invoke continuation from this context",
+ SCM_EOL);
+ }
+ else if (WINDER_P (wind_elt))
+ {
+ if (WINDER_REWIND_P (wind_elt))
+ WINDER_PROC (wind_elt) (WINDER_DATA (wind_elt));
+ }
+ else
+ {
+ wind_key = SCM_CAR (wind_elt);
+ /* key = #t | symbol | thunk | list of variables */
+ if (SCM_NIMP (wind_key))
+ {
+ if (scm_is_pair (wind_key))
+ {
+ if (SCM_VARIABLEP (SCM_CAR (wind_key)))
+ scm_swap_bindings (wind_key, SCM_CDR (wind_elt));
+ }
+ else if (SCM_TYP3 (wind_key) == scm_tc3_closure)
+ scm_call_0 (wind_key);
+ }
+ }
+
+ scm_i_set_dynwinds (to);
+ }
+ else
+ {
+ SCM wind;
+ SCM wind_elt;
+ SCM wind_key;
+
+ wind = scm_i_dynwinds ();
+ wind_elt = SCM_CAR (wind);
+ scm_i_set_dynwinds (SCM_CDR (wind));
+
+ if (FRAME_P (wind_elt))
+ {
+ /* Nothing to do. */
+ }
+ else if (WINDER_P (wind_elt))
+ {
+ if (!WINDER_REWIND_P (wind_elt))
+ WINDER_PROC (wind_elt) (WINDER_DATA (wind_elt));
+ }
+ else
+ {
+ wind_key = SCM_CAR (wind_elt);
+ if (SCM_NIMP (wind_key))
+ {
+ if (scm_is_pair (wind_key))
+ {
+ if (SCM_VARIABLEP (SCM_CAR (wind_key)))
+ scm_swap_bindings (wind_key, SCM_CDR (wind_elt));
+ }
+ else if (SCM_TYP3 (wind_key) == scm_tc3_closure)
+ scm_call_0 (SCM_CDR (wind_elt));
+ }
+ }
+
+ delta--;
+ goto tail; /* scm_dowinds(to, delta-1); */
+ }
+}
+
+void
+scm_init_dynwind ()
+{
+ tc16_frame = scm_make_smob_type ("frame", 0);
+
+ tc16_winder = scm_make_smob_type ("winder", 0);
+ scm_set_smob_mark (tc16_winder, winder_mark);
+
+#include "libguile/dynwind.x"
+}
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
projects / lilypond.git / blobdiff