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/* Copyright 2009
* Kaz Kylheku <kkylheku@gmail.com>
* Vancouver, Canada
* All rights reserved.
*
* BSD License:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <setjmp.h>
#include <dirent.h>
#include "lib.h"
#include "gc.h"
#include "unwind.h"
static uw_frame_t *uw_stack;
static uw_frame_t *uw_exit_point;
static uw_frame_t toplevel_env;
static void uw_unwind_to_exit_point()
{
while (uw_stack && uw_stack != uw_exit_point)
uw_stack = uw_stack->uw.up;
if (!uw_stack)
abort();
uw_exit_point = 0;
switch (uw_stack->uw.type) {
case UW_BLOCK:
longjmp(uw_stack->bl.jb, 1);
break;
case UW_ENV: /* env frame cannot be exit point */
abort();
default:
abort();
}
}
void uw_init(void)
{
protect(&toplevel_env.ev.func_bindings, 0);
}
void uw_push_block(uw_frame_t *fr, obj_t *tag)
{
fr->bl.type = UW_BLOCK;
fr->bl.tag = tag;
fr->bl.result = nil;
fr->bl.up = uw_stack;
uw_stack = fr;
}
static uw_frame_t *uw_find_env(void)
{
uw_frame_t *fr;
for (fr = uw_stack; fr != 0; fr = fr->uw.up) {
if (fr->uw.type == UW_ENV)
break;
}
return fr ? fr : &toplevel_env;
}
void uw_push_env(uw_frame_t *fr)
{
uw_frame_t *prev_env = uw_find_env();
fr->ev.type = UW_ENV;
if (prev_env) {
fr->ev.func_bindings = copy_alist(prev_env->ev.func_bindings);
} else {
fr->ev.func_bindings = nil;
}
fr->ev.up = uw_stack;
uw_stack = fr;
}
obj_t *uw_get_func(obj_t *sym)
{
uw_frame_t *env = uw_find_env();
return cdr(assoc(env->ev.func_bindings, sym));
}
obj_t *uw_set_func(obj_t *sym, obj_t *value)
{
uw_frame_t *env = uw_find_env();
env->ev.func_bindings = acons_new(env->ev.func_bindings, sym, value);
return value;
}
void uw_pop_frame(uw_frame_t *fr)
{
assert (fr == uw_stack);
uw_stack = uw_stack->uw.up;
}
obj_t *uw_block_return(obj_t *tag, obj_t *result)
{
uw_frame_t *ex;
for (ex = uw_stack; ex != 0; ex = ex->uw.up) {
if (ex->uw.type == UW_BLOCK && ex->bl.tag == tag)
break;
}
if (ex == 0)
return nil;
ex->bl.result = result;
uw_exit_point = ex;
uw_unwind_to_exit_point();
abort();
}
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