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/*
* Copyright (c) 2002-2005 The TenDRA Project <http://www.tendra.org/>.
* All rights reserved.
*
* 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. Neither the name of The TenDRA Project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $Id$
*/
/*
Crown Copyright (c) 1997
This TenDRA(r) Computer Program is subject to Copyright
owned by the United Kingdom Secretary of State for Defence
acting through the Defence Evaluation and Research Agency
(DERA). It is made available to Recipients with a
royalty-free licence for its use, reproduction, transfer
to other parties and amendment for any purpose not excluding
product development provided that any such use et cetera
shall be deemed to be acceptance of the following conditions:-
(1) Its Recipients shall ensure that this Notice is
reproduced upon any copies or amended versions of it;
(2) Any amended version of it shall be clearly marked to
show both the nature of and the organisation responsible
for the relevant amendment or amendments;
(3) Its onward transfer from a recipient to another
party shall be deemed to be that party's acceptance of
these conditions;
(4) DERA gives no warranty or assurance as to its
quality or suitability for any purpose and DERA accepts
no liability whatsoever in relation to any use to which
it may be put.
*/
/*** rule-check.c --- Checks for grammar validity.
*
** Author: Steve Folkes <smf@hermes.mod.uk>
*
*** Commentary:
*
* This file implements the routines that check to see if the grammar is
* valid. There are for checks that are made:
*
* - The first sets of all alternatives in a rule are checked to ensure
* that they are disjoint (this includes the predicate first sets). This
* also includes checking that there is only one see through alternative.
*
* - The follow set of each rule is computed, and checked to ensure that
* if the rule is see through, its follow set does not intersect with its
* first set (this includes predicate follow and first sets).
*
* - If there is a see through alternative, this is computed.
*
* - The first set of each alternative is computed.
*
*** Change Log:
* $Log: rule-check.c,v $
* Revision 1.1.1.1 1998/01/17 15:57:46 release
* First version to be checked into rolling release.
*
* Revision 1.3 1994/12/15 09:58:35 smf
* Brought into line with OSSG C Coding Standards Document, as per
* "CR94_178.sid+tld-update".
*
* Revision 1.2 1994/08/22 09:37:22 smf
* Fixed bug DR114:ids-too-long.
*
* Revision 1.1.1.1 1994/07/25 16:04:38 smf
* Initial import of SID 1.8 non shared files.
*
**/
/****************************************************************************/
#include "rule.h"
#include "basic.h"
#include "bitvec.h"
#include "gen-errors.h"
/*--------------------------------------------------------------------------*/
static void
rule_check_first_set_1(RuleP rule, GrammarP grammar)
{
BoolT is_empty = rule_has_empty_alt(rule);
BoolT is_empty_mesg_shown = FALSE;
BitVecT test;
EntryListT predicate_list;
AltP alt;
BasicClosureT closure;
closure.grammar = grammar;
bitvec_init(&test);
entry_list_init(&predicate_list);
for (alt = rule_alt_head(rule); alt; alt = alt_next(alt)) {
ItemP item = alt_item_head(alt);
ItemP initial = item;
BoolT see_through = TRUE;
for (; see_through && item; item = item_next(item)) {
EntryP entry = item_entry(item);
switch (item_type(item))EXHAUSTIVE {
case ET_PREDICATE:
ASSERT(item == initial);
if (entry_list_contains(&predicate_list, entry)) {
E_predicate_collision(rule, entry_key(entry));
} else {
entry_list_add(&predicate_list, entry);
}
see_through = FALSE;
break;
case ET_ACTION:
case ET_RENAME:
break;
case ET_BASIC: {
unsigned terminal = basic_terminal(entry_get_basic(entry));
see_through = FALSE;
if (bitvec_is_set(&test, terminal)) {
BitVecT tmp;
bitvec_init(&tmp);
bitvec_set(&tmp, terminal);
bitvec_and(&tmp, &test);
closure.bitvec = &tmp;
E_first_set_collision(rule, &closure);
bitvec_destroy(&tmp);
} else {
bitvec_set(&test, terminal);
}
}
break;
case ET_RULE: {
RuleP item_rule = entry_get_rule(entry);
EntryListP item_preds = rule_predicate_first(item_rule);
EntryListT tmp_list;
BitVecP bitvec;
entry_list_intersection(&tmp_list, &predicate_list,
item_preds);
if (!entry_list_is_empty(&tmp_list)) {
E_predicate_list_collision(rule, &tmp_list);
}
entry_list_destroy(&tmp_list);
entry_list_append(&predicate_list, item_preds);
bitvec = rule_first_set(item_rule);
see_through = rule_is_see_through(item_rule);
if (bitvec_intersects(&test, bitvec)) {
BitVecT tmp;
bitvec_copy(&tmp, bitvec);
bitvec_and(&tmp, &test);
closure.bitvec = &tmp;
E_first_set_collision(rule, &closure);
bitvec_destroy(&tmp);
} else {
bitvec_or(&test, bitvec);
}
}
break;
case ET_NON_LOCAL:
case ET_TYPE:
case ET_NAME:
UNREACHED;
}
}
if (see_through) {
if (is_empty) {
if (!is_empty_mesg_shown) {
E_multiple_see_through_alts(rule);
is_empty_mesg_shown = TRUE;
}
} else {
is_empty = TRUE;
}
}
}
bitvec_destroy(&test);
}
static void rule_compute_follow_set_1(RuleP, GrammarP, BitVecP, EntryListP,
ClashListP);
static void
rule_compute_follow_set_3(GrammarP grammar, ItemP item, BitVecP context,
EntryListP pred_context, ClashListP clashes)
{
if (item != NIL(ItemP)) {
EntryP entry;
rule_compute_follow_set_3(grammar, item_next(item), context,
pred_context, clashes);
entry = item_entry(item);
switch (item_type(item))EXHAUSTIVE {
case ET_PREDICATE:
entry_list_destroy(pred_context);
entry_list_init(pred_context);
entry_list_add(pred_context, entry);
clashes->next = NIL(ClashListP);
break;
case ET_ACTION:
case ET_RENAME:
break;
case ET_RULE: {
RuleP rule = entry_get_rule(entry);
clashes->item = item;
rule_compute_follow_set_1(rule, grammar, context, pred_context,
clashes);
if (rule_is_see_through(rule)) {
bitvec_or(context, rule_first_set(rule));
entry_list_append(pred_context, rule_predicate_first(rule));
} else {
bitvec_replace(context, rule_first_set(rule));
entry_list_destroy(pred_context);
entry_list_init(pred_context);
entry_list_append(pred_context, rule_predicate_first(rule));
clashes->next = NIL(ClashListP);
}
}
break;
case ET_BASIC: {
BasicP basic = entry_get_basic(entry);
bitvec_empty(context);
bitvec_set(context, basic_terminal(basic));
clashes->next = NIL(ClashListP);
}
break;
case ET_NON_LOCAL:
case ET_NAME:
case ET_TYPE:
UNREACHED;
}
}
}
static void
rule_compute_follow_set_2(RuleP rule, GrammarP grammar, AltP alt,
BitVecP context, EntryListP pred_context,
ClashListP clashes)
{
BitVecT tmp;
EntryListT tmp_list;
ClashListT clash;
clash.next = clashes;
clash.rule = rule;
clash.alt = alt;
bitvec_copy(&tmp, context);
entry_list_copy(&tmp_list, pred_context);
rule_compute_follow_set_3(grammar, alt_item_head(alt), &tmp, &tmp_list,
&clash);
bitvec_destroy(&tmp);
entry_list_destroy(&tmp_list);
}
static void
rule_compute_follow_set_1(RuleP rule, GrammarP grammar, BitVecP context,
EntryListP pred_context, ClashListP clashes)
{
BitVecP follow = rule_follow_set(rule);
EntryListP pred_follow = rule_predicate_follow(rule);
BitVecP first = rule_first_set(rule);
EntryListP pred_first = rule_predicate_first(rule);
BitVecT test;
AltP alt;
BasicClosureT closure;
if (rule_has_started_follows(rule)) {
bitvec_copy(&test, follow);
bitvec_or(follow, context);
if (bitvec_equal(&test, follow) &&
entry_list_includes(pred_follow, pred_context)) {
bitvec_destroy(&test);
return;
}
entry_list_append(pred_follow, pred_context);
bitvec_destroy(&test);
} else {
bitvec_replace(follow, context);
entry_list_append(pred_follow, pred_context);
rule_started_follows(rule);
}
closure.grammar = grammar;
if (rule_is_see_through(rule)) {
EntryListT tmp_list;
if (bitvec_intersects(follow, first)) {
bitvec_copy(&test, follow);
bitvec_and(&test, first);
closure.bitvec = &test;
E_follow_set_collision(rule, &closure, clashes);
bitvec_not(&test);
bitvec_and(first, &test);
bitvec_destroy(&test);
}
entry_list_intersection(&tmp_list, pred_follow, pred_first);
if (!entry_list_is_empty(&tmp_list)) {
E_predicate_follow_set_coll(rule, &tmp_list, clashes);
entry_list_unlink_used(pred_first, &tmp_list);
}
entry_list_destroy(&tmp_list);
}
if ((alt = rule_get_handler(rule)) != NIL(AltP)) {
rule_compute_follow_set_2(rule, grammar, alt, follow, pred_follow,
clashes);
}
for (alt = rule_alt_head(rule); alt; alt = alt_next(alt)) {
rule_compute_follow_set_2(rule, grammar, alt, follow, pred_follow,
clashes);
}
}
static void
rule_compute_see_through_alt_1(RuleP rule)
{
if (!rule_has_empty_alt(rule)) {
AltP alt;
for (alt = rule_alt_head(rule); alt; alt = alt_next(alt)) {
ItemP item;
for (item = alt_item_head(alt); item; item = item_next(item)) {
RuleP item_rule;
if ((!item_is_action(item)) && (!item_is_rename(item)) &&
((!item_is_rule(item)) ||
((item_rule = entry_get_rule(item_entry(item))),
(!rule_is_see_through(item_rule))))) {
goto next_alt;
}
}
rule_set_see_through_alt(rule, alt);
return;
next_alt:;
}
}
}
static void
rule_compute_alt_first_sets_1(RuleP rule)
{
AltP alt;
for (alt = rule_alt_head(rule); alt; alt = alt_next(alt)) {
BitVecP alt_firsts = alt_first_set(alt);
ItemP item = alt_item_head(alt);
ItemP initial = item;
BoolT see_through = TRUE;
for (; see_through && item; item = item_next(item)) {
EntryP entry = item_entry(item);
switch (item_type(item))EXHAUSTIVE {
case ET_PREDICATE:
ASSERT(item == initial);
see_through = FALSE;
break;
case ET_ACTION:
case ET_RENAME:
break;
case ET_BASIC:
see_through = FALSE;
bitvec_set(alt_firsts, basic_terminal(entry_get_basic(entry)));
break;
case ET_RULE: {
RuleP item_rule = entry_get_rule(entry);
see_through = rule_is_see_through(item_rule);
bitvec_or(alt_firsts, rule_first_set(item_rule));
}
break;
case ET_NON_LOCAL:
case ET_TYPE:
case ET_NAME:
UNREACHED;
}
}
if (see_through) {
bitvec_or(alt_firsts, rule_follow_set(rule));
}
}
}
/*--------------------------------------------------------------------------*/
void
rule_check_first_set(EntryP entry, GenericP gclosure)
{
GrammarP grammar = (GrammarP)gclosure;
if (entry_is_rule(entry)) {
RuleP rule = entry_get_rule(entry);
rule_check_first_set_1(rule, grammar);
}
}
void
rule_compute_follow_set(EntryP entry, GenericP gclosure)
{
GrammarP grammar = (GrammarP)gclosure;
if (entry_is_rule(entry)) {
RuleP rule = entry_get_rule(entry);
BitVecT outer;
EntryListT pred_outer;
bitvec_init(&outer);
entry_list_init(&pred_outer);
rule_compute_follow_set_1(rule, grammar, &outer, &pred_outer,
NIL(ClashListP));
bitvec_destroy(&outer);
entry_list_destroy(&pred_outer);
}
}
void
rule_compute_see_through_alt(EntryP entry, GenericP gclosure)
{
UNUSED(gclosure);
if (entry_is_rule(entry)) {
RuleP rule = entry_get_rule(entry);
rule_compute_see_through_alt_1(rule);
}
}
void
rule_compute_alt_first_sets(EntryP entry, GenericP gclosure)
{
UNUSED(gclosure);
if (entry_is_rule(entry)) {
RuleP rule = entry_get_rule(entry);
rule_compute_alt_first_sets_1(rule);
}
}
void
write_clashes(OStreamP ostream, ClashListP clashes)
{
write_newline(ostream);
while (clashes) {
write_rule_lhs(ostream, clashes->rule);
write_alt_highlighting(ostream, clashes->alt, clashes->item);
write_cstring(ostream, "};");
write_newline(ostream);
clashes = clashes->next;
}
}
/*
* Local variables(smf):
* eval: (include::add-path-entry "../os-interface" "../library")
* eval: (include::add-path-entry "../generated")
* end:
**/