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413cb56ff4
feature.h, filesys.h, fluids.h, fports.c, fports.h, gc.c, gc.h, hash.c, keywords.h, macros.c, numbers.c, numbers.h, objects.c, objects.h, options.c, pairs.h, ports.c, ports.h, print.c, procs.h, ramap.c, read.c, smob.c, smob.h, srcprop.h, stacks.c, stacks.h, strports.c, struct.c, struct.h, tag.c, tags.h, throw.c, unif.c, unif.h, variable.h, vectors.h, weaks.c, weaks.h (SCM_SCM, SCM_BITS, SCM_CARBITS): Renamed from SCM_ASSCM, SCM_ASWORD, SCM_CARW).
294 lines
8.5 KiB
C
294 lines
8.5 KiB
C
/* Copyright (C) 1995, 1996, 1998, 1999 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., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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* As a special exception, the Free Software Foundation gives permission
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* for additional uses of the text contained in its release of GUILE.
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*
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* The exception is that, if you link the GUILE 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 the GUILE 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 the
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* Free Software Foundation under the name GUILE. If you copy
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* code from other Free Software Foundation releases into a copy of
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* GUILE, 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 them.
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*
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* If you write modifications of your own for GUILE, 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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/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
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gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
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#include <stdio.h>
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#include "_scm.h"
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#include "eval.h"
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#include "alist.h"
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#include "fluids.h"
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#include "genio.h"
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#include "smob.h"
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#include "dynwind.h"
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/* {Dynamic wind}
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Things that can be on the wind list:
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(enter-proc . leave-proc) dynamic-wind
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(tag . jmpbuf) catch
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(tag . lazy-catch) lazy-catch
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tag is either a symbol or a boolean
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((fluid ...) . (value ...)) with-fluids
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*/
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SCM_DEFINE (scm_dynamic_wind, "dynamic-wind", 3, 0, 0,
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(SCM thunk1, SCM thunk2, SCM thunk3),
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"All three arguments must be 0-argument procedures.\n\n"
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"@var{in-guard} is called, then @var{thunk}, then @var{out-guard}.\n\n"
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"If, any time during the execution of @var{thunk}, the continuation\n"
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"of the @code{dynamic-wind} expression is escaped non-locally, @var{out-guard}\n"
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"is called. If the continuation of the dynamic-wind is re-entered,\n"
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"@var{in-guard} is called. Thus @var{in-guard} and @var{out-guard} may\n"
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"be called any number of times.\n\n"
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"@example\n"
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"(define x 'normal-binding)\n"
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"@result{} x\n\n"
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"(define a-cont (call-with-current-continuation \n"
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" (lambda (escape)\n"
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" (let ((old-x x))\n"
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" (dynamic-wind\n"
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" ;; in-guard:\n"
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" ;;\n"
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" (lambda () (set! x 'special-binding))\n\n"
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" ;; thunk\n"
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" ;;\n"
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" (lambda () (display x) (newline)\n"
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" (call-with-current-continuation escape)\n"
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" (display x) (newline)\n"
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" x)\n\n"
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" ;; out-guard:\n"
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" ;;\n"
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" (lambda () (set! x old-x)))))))\n\n"
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";; Prints: \n"
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"special-binding\n"
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";; Evaluates to:\n"
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"@result{} a-cont\n\n"
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"x\n"
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"@result{} normal-binding\n\n"
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"(a-cont #f)\n"
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";; Prints:\n"
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"special-binding\n"
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";; Evaluates to:\n"
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"@result{} a-cont ;; the value of the (define a-cont...)\n\n"
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"x\n"
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"@result{} normal-binding\n\n"
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"a-cont\n"
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"@result{} special-binding\n"
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"@end example\n"
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"")
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#define FUNC_NAME s_scm_dynamic_wind
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{
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SCM ans;
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SCM_ASSERT (SCM_NFALSEP (scm_thunk_p (thunk3)),
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thunk3,
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SCM_ARG3, FUNC_NAME);
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scm_apply (thunk1, SCM_EOL, SCM_EOL);
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scm_dynwinds = scm_acons (thunk1, thunk3, scm_dynwinds);
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ans = scm_apply (thunk2, SCM_EOL, SCM_EOL);
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scm_dynwinds = SCM_CDR (scm_dynwinds);
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scm_apply (thunk3, SCM_EOL, SCM_EOL);
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return ans;
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}
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#undef FUNC_NAME
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/* The implementation of a C-callable dynamic-wind,
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* scm_internal_dynamic_wind, requires packaging of C pointers in a
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* smob. Objects of this type are pushed onto the dynwind chain.
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*/
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typedef struct guardsmem {
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scm_guard_t before;
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scm_guard_t after;
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void *data;
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} guardsmem;
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#define SCM_GUARDSMEM(obj) ((guardsmem *) SCM_CDR (obj))
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#define SCM_BEFORE_GUARD(obj) (SCM_GUARDSMEM (obj)->before)
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#define SCM_AFTER_GUARD(obj) (SCM_GUARDSMEM (obj)->after)
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#define SCM_GUARD_DATA(obj) (SCM_GUARDSMEM (obj)->data)
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#define SCM_GUARDSP(obj) (SCM_NIMP(obj) && (SCM_CARBITS (obj) == tc16_guards))
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static long tc16_guards;
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static scm_sizet
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freeguards (SCM guards)
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{
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scm_must_free ((char *) SCM_CDR (guards));
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return sizeof (guardsmem);
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}
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static int
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printguards (SCM exp, SCM port, scm_print_state *pstate)
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{
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scm_puts ("#<guards ", port);
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scm_intprint (SCM_BITS (SCM_CDR (exp)), 16, port);
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scm_putc ('>', port);
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return 1;
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}
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SCM
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scm_internal_dynamic_wind (scm_guard_t before,
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scm_inner_t inner,
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scm_guard_t after,
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void *inner_data,
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void *guard_data)
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{
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SCM guards, ans;
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guardsmem *g;
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before (guard_data);
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g = (guardsmem *) scm_must_malloc (sizeof (*g), "guards");
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g->before = before;
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g->after = after;
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g->data = guard_data;
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SCM_NEWSMOB (guards, tc16_guards, g);
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scm_dynwinds = scm_acons (guards, SCM_BOOL_F, scm_dynwinds);
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ans = inner (inner_data);
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scm_dynwinds = SCM_CDR (scm_dynwinds);
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after (guard_data);
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return ans;
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}
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#ifdef GUILE_DEBUG
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SCM_DEFINE (scm_wind_chain, "wind-chain", 0, 0, 0,
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(),
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"")
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#define FUNC_NAME s_scm_wind_chain
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{
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return scm_dynwinds;
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}
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#undef FUNC_NAME
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#endif
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static void
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scm_swap_bindings (SCM glocs, SCM vals)
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{
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SCM tmp;
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while (SCM_NIMP (vals))
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{
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tmp = SCM_GLOC_VAL (SCM_CAR (glocs));
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SCM_SETCDR (SCM_CAR (glocs) - 1L, SCM_CAR (vals));
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SCM_SETCAR (vals, tmp);
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glocs = SCM_CDR (glocs);
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vals = SCM_CDR (vals);
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}
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}
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void
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scm_dowinds (SCM to, long delta)
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{
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tail:
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if (scm_dynwinds == to);
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else if (0 > delta)
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{
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SCM wind_elt;
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SCM wind_key;
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scm_dowinds (SCM_CDR (to), 1 + delta);
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wind_elt = SCM_CAR (to);
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#if 0
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if (SCM_INUMP (wind_elt))
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{
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scm_cross_dynwind_binding_scope (wind_elt, 0);
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}
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else
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#endif
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{
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wind_key = SCM_CAR (wind_elt);
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/* key = #t | symbol | thunk | list of glocs | list of fluids */
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if (SCM_NIMP (wind_key))
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{
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if (SCM_TYP3 (wind_key) == scm_tc3_cons_gloc)
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scm_swap_bindings (wind_key, SCM_CDR (wind_elt));
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else if (SCM_TYP3 (wind_key) == scm_tc3_cons)
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scm_swap_fluids (wind_key, SCM_CDR (wind_elt));
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else if (SCM_GUARDSP (wind_key))
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SCM_BEFORE_GUARD (wind_key) (SCM_GUARD_DATA (wind_key));
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else if (SCM_TYP3 (wind_key) == scm_tc3_closure)
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scm_apply (wind_key, SCM_EOL, SCM_EOL);
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}
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}
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scm_dynwinds = to;
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}
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else
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{
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SCM from;
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SCM wind_elt;
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SCM wind_key;
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from = SCM_CDR (SCM_CAR (scm_dynwinds));
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wind_elt = SCM_CAR (scm_dynwinds);
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scm_dynwinds = SCM_CDR (scm_dynwinds);
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#if 0
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if (SCM_INUMP (wind_elt))
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{
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scm_cross_dynwind_binding_scope (wind_elt, 0);
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}
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else
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#endif
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{
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wind_key = SCM_CAR (wind_elt);
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if (SCM_NIMP (wind_key))
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{
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if (SCM_TYP3 (wind_key) == scm_tc3_cons_gloc)
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scm_swap_bindings (wind_key, from);
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else if (SCM_TYP3 (wind_key) == scm_tc3_cons)
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scm_swap_fluids_reverse (wind_key, from);
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else if (SCM_GUARDSP (wind_key))
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SCM_AFTER_GUARD (wind_key) (SCM_GUARD_DATA (wind_key));
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else if (SCM_TYP3 (wind_key) == scm_tc3_closure)
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scm_apply (from, SCM_EOL, SCM_EOL);
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}
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}
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delta--;
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goto tail; /* scm_dowinds(to, delta-1); */
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}
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}
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void
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scm_init_dynwind ()
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{
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tc16_guards = scm_make_smob_type_mfpe ("guards", sizeof (struct guardsmem),
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NULL, freeguards, printguards, NULL);
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#include "dynwind.x"
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}
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