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/* Copyright 2009-2014
* Kaz Kylheku <kaz@kylheku.com>
* Vancouver, Canada
* All rights reserved.
*
* Redistribution of this software in source and binary forms, with or without
* modification, is permitted provided that the following two conditions are met.
*
* Use of this software in any manner constitutes agreement with the disclaimer
* which follows the two conditions.
*
* 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.
*
* 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. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DAMAGES, HOWEVER CAUSED,
* AND UNDER ANY THEORY OF LIABILITY, ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <setjmp.h>
#include <dirent.h>
#include <stdarg.h>
#include <signal.h>
#include "config.h"
#include "lib.h"
#include "gc.h"
#include "stream.h"
#include "txr.h"
#include "signal.h"
#include "eval.h"
#include "parser.h"
#include "unwind.h"
static uw_frame_t *uw_stack;
static uw_frame_t *uw_env_stack;
static uw_frame_t *uw_exit_point;
static uw_frame_t toplevel_env;
/* C99 inline instantiations. */
#if __STDC_VERSION__ >= 199901L
val uw_block_return(val tag, val result);
#endif
static void uw_unwind_to_exit_point(void)
{
assert (uw_exit_point);
for (; uw_stack && uw_stack != uw_exit_point; uw_stack = uw_stack->uw.up) {
switch (uw_stack->uw.type) {
case UW_CATCH:
/* If a catch block is not visible, do
not run its unwind stuff. This
would cause infinite loops if
unwind blocks trigger a nonlocal exit. */
if (!uw_stack->ca.visible)
continue;
/* Catches catch everything, so that they
can do "finally" or "unwind protect" logic.
If a catch is invoked with a nil exception
and symbol, it must excecute the
mandatory clean-up code and then
continue the unwinding by calling uw_continue,
passing it the ca.cont value. */
uw_stack->ca.sym = nil;
uw_stack->ca.exception = nil;
uw_stack->ca.cont = uw_exit_point;
/* 1 means unwind only. */
extended_longjmp(uw_stack->ca.jb, 1);
abort();
case UW_ENV:
/* Maintain consistency of unwind stack pointer */
uw_env_stack = uw_env_stack->ev.up_env;
break;
default:
break;
}
}
if (!uw_stack)
abort();
uw_exit_point = 0;
switch (uw_stack->uw.type) {
case UW_BLOCK:
extended_longjmp(uw_stack->bl.jb, 1);
abort();
case UW_ENV: /* env frame cannot be exit point */
abort();
case UW_CATCH:
/* 2 means actual catch, not just unwind */
extended_longjmp(uw_stack->ca.jb, 2);
default:
abort();
}
}
void uw_push_block(uw_frame_t *fr, val tag)
{
memset(fr, 0, sizeof *fr);
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)
{
return uw_env_stack ? uw_env_stack : &toplevel_env;
}
void uw_push_env(uw_frame_t *fr)
{
uw_frame_t *prev_env = uw_find_env();
memset(fr, 0, sizeof *fr);
fr->ev.type = UW_ENV;
fr->ev.up_env = prev_env;
fr->ev.func_bindings = nil;
fr->ev.match_context = nil;
fr->ev.up = uw_stack;
uw_stack = fr;
uw_env_stack = fr;
}
val uw_get_func(val sym)
{
uw_frame_t *env;
for (env = uw_find_env(); env != 0; env = env->ev.up_env) {
if (env->ev.func_bindings) {
val found = assoc(sym, env->ev.func_bindings);
if (found)
return cdr(found);
}
}
return nil;
}
val uw_set_func(val sym, val value)
{
uw_frame_t *env = uw_find_env();
env->ev.func_bindings = acons_new(sym, value, env->ev.func_bindings);
return value;
}
val uw_get_match_context(void)
{
uw_frame_t *env = uw_find_env();
return env->ev.match_context;
}
val uw_set_match_context(val context)
{
uw_frame_t *env = uw_find_env();
env->ev.match_context = context;
return context;
}
void uw_push_debug(uw_frame_t *fr, val func, val args,
val ub_p_a_pairs, val env, val data,
val line, val chr)
{
memset(fr, 0, sizeof *fr);
fr->db.type = UW_DBG;
fr->db.func = func;
fr->db.args = args;
fr->db.ub_p_a_pairs = ub_p_a_pairs;
fr->db.env = env;
fr->db.data = data;
fr->db.line = line;
fr->db.chr = chr;
fr->db.up = uw_stack;
uw_stack = fr;
}
void uw_pop_frame(uw_frame_t *fr)
{
assert (fr == uw_stack);
uw_stack = fr->uw.up;
if (fr->uw.type == UW_ENV) {
assert (fr == uw_env_stack);
uw_env_stack = fr->ev.up_env;
}
}
void uw_pop_until(uw_frame_t *fr)
{
while (uw_stack != fr)
uw_pop_frame(uw_stack);
}
uw_frame_t *uw_current_frame(void)
{
return uw_stack;
}
uw_frame_t *uw_current_exit_point(void)
{
return uw_exit_point;
}
val uw_block_return_proto(val tag, val result, val protocol)
{
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;
ex->bl.protocol = protocol;
uw_exit_point = ex;
uw_unwind_to_exit_point();
abort();
}
void uw_push_catch(uw_frame_t *fr, val matches)
{
memset(fr, 0, sizeof *fr);
fr->ca.type = UW_CATCH;
fr->ca.matches = matches;
fr->ca.exception = nil;
fr->ca.cont = 0;
fr->ca.visible = 1;
fr->ca.up = uw_stack;
uw_stack = fr;
}
static val exception_subtypes;
val uw_exception_subtype_p(val sub, val sup)
{
if (sub == nil || sup == t || sub == sup) {
return t;
} else {
val entry = assoc(sub, exception_subtypes);
return memq(sup, entry) ? t : nil;
}
}
val uw_throw(val sym, val exception)
{
uw_frame_t *ex;
for (ex = uw_stack; ex != 0; ex = ex->uw.up) {
if (ex->uw.type == UW_CATCH && ex->ca.visible) {
/* The some_satisfy would require us to
cons up a function; we want to
avoid consing in exception handling, if we can. */
val matches = ex->ca.matches;
val match;
for (match = matches; match; match = cdr(match))
if (uw_exception_subtype_p(sym, car(match)))
break;
if (match)
break;
}
}
if (ex == 0) {
if (std_error == 0) {
fprintf(stderr, "unhandled exception in early initialization\n");
abort();
}
if (opt_loglevel >= 1) {
val s = stringp(exception);
val info = if2(source_loc(last_form_evaled),
source_loc_str(last_form_evaled));
format(std_error, lit("~a: unhandled exception of type ~a:\n"),
prog_string, sym, nao);
if (info && sym != eval_error_s)
format(std_error, lit("~a: possibly triggered by ~a\n"),
prog_string, info, nao);
format(std_error, s ? lit("~a: ~a\n") : lit("~a: ~s\n"),
prog_string, exception, nao);
}
if (uw_exception_subtype_p(sym, query_error_s) ||
uw_exception_subtype_p(sym, file_error_s)) {
if (opt_print_bindings)
put_line(lit("false"), std_output);
exit(EXIT_FAILURE);
}
abort();
}
ex->ca.sym = sym;
ex->ca.exception = exception;
uw_exit_point = ex;
uw_unwind_to_exit_point();
abort();
}
val uw_throwf(val sym, val fmt, ...)
{
va_list vl;
val stream = make_string_output_stream();
va_start (vl, fmt);
(void) vformat(stream, fmt, vl);
va_end (vl);
uw_throw(sym, get_string_from_stream(stream));
abort();
}
val uw_throwfv(val sym, val fmt, val args)
{
val stream = make_string_output_stream();
(void) formatv(stream, fmt, args);
uw_throw(sym, get_string_from_stream(stream));
abort();
}
val uw_errorf(val fmt, ...)
{
va_list vl;
val stream = make_string_output_stream();
va_start (vl, fmt);
(void) vformat(stream, fmt, vl);
va_end (vl);
uw_throw(error_s, get_string_from_stream(stream));
abort();
}
val uw_errorfv(val fmt, val args)
{
val stream = make_string_output_stream();
(void) formatv(stream, fmt, args);
uw_throw(error_s, get_string_from_stream(stream));
abort();
}
val type_mismatch(val fmt, ...)
{
va_list vl;
val stream = make_string_output_stream();
va_start (vl, fmt);
(void) vformat(stream, fmt, vl);
va_end (vl);
uw_throw(type_error_s, get_string_from_stream(stream));
abort();
}
val uw_register_subtype(val sub, val sup)
{
val t_entry = assoc(t, exception_subtypes);
val sub_entry = assoc(sub, exception_subtypes);
val sup_entry = assoc(sup, exception_subtypes);
assert (t_entry != 0);
if (sub == nil)
return sup;
if (sub == t) {
if (sup == t)
return sup;
uw_throwf(type_error_s,
lit("cannot define ~a as an exception subtype of ~a"),
sub, sup, nao);
}
if (sup == nil) {
uw_throwf(type_error_s,
lit("cannot define ~a as an exception subtype of ~a"),
sub, sup, nao);
}
if (uw_exception_subtype_p(sub, sup))
uw_throwf(type_error_s, lit("~a is already an exception subtype of ~a"),
sub, sup, nao);
if (uw_exception_subtype_p(sup, sub))
uw_throwf(type_error_s, lit("~a is already an exception supertype of ~a"),
sub, sup, nao);
/* If sup symbol not registered, then we make it
an immediate subtype of t. */
if (!sup_entry) {
sup_entry = cons(sup, t_entry);
exception_subtypes = cons(sup_entry, exception_subtypes);
}
/* Make sub an immediate subtype of sup.
If sub already registered, we just repoint it. */
if (sub_entry) {
set(cdr_l(sub_entry), sup_entry);
} else {
sub_entry = cons(sub, sup_entry);
exception_subtypes = cons(sub_entry, exception_subtypes);
}
return sup;
}
void uw_continue(uw_frame_t *current, uw_frame_t *cont)
{
uw_pop_frame(current);
uw_exit_point = cont;
uw_unwind_to_exit_point();
}
void uw_init(void)
{
protect(&toplevel_env.ev.func_bindings,
&toplevel_env.ev.match_context,
&exception_subtypes, (val *) 0);
exception_subtypes = cons(cons(t, nil), exception_subtypes);
uw_register_subtype(type_error_s, error_s);
uw_register_subtype(internal_error_s, error_s);
uw_register_subtype(numeric_error_s, error_s);
uw_register_subtype(range_error_s, error_s);
uw_register_subtype(query_error_s, error_s);
uw_register_subtype(file_error_s, error_s);
uw_register_subtype(process_error_s, error_s);
uw_register_subtype(assert_s, error_s);
uw_register_subtype(syntax_error_s, error_s);
}
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