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|
/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifndef TEST
/**
* Check whether inverting a sentence would require
* it to be relaxes before it can be represented
*
* @param this The sentence to check
* @param flags Flags from `libnormalform_express`
* @return 1 if the inversion can be exactly represented,
* 0 if the inversion requires relaxation be
*/
PURE static int
inversion_would_relax(struct expression *this, uint64_t flags)
{
size_t i;
beginning:
switch (this->type) {
case LIBNORMALFORM_CONJUNCTION:
case LIBNORMALFORM_DISJUNCTION:
for (i = 0; i < this->nterms; i++)
if (inversion_would_relax(this->terms[i], flags))
return 1;
return 0;
case LIBNORMALFORM_EXCLUSIVE_DISJUNCTION:
for (i = 0; i < this->nterms; i++)
if (!inversion_would_relax(this->terms[i], flags))
return 0;
return 1;
case LIBNORMALFORM_VARIABLE:
return flags & LIBNORMALFORM_ELIMINATE_NEGATED_VARIABLE;
case LIBNORMALFORM_NEGATED_VARIABLE:
return flags & LIBNORMALFORM_ELIMINATE_VARIABLE;
case LIBNORMALFORM_FUNCTION:
return flags & LIBNORMALFORM_ELIMINATE_NEGATED_FUNCTION;
case LIBNORMALFORM_NEGATED_FUNCTION:
return flags & LIBNORMALFORM_ELIMINATE_FUNCTION;
case LIBNORMALFORM_TRANSFORMATION:
this = this->terms[0];
goto beginning;
case LIBNORMALFORM_FOR_ALL:
if (!(flags & LIBNORMALFORM_ELIMINATE_NEGATED_FOR_ALL))
return 0;
if (flags & LIBNORMALFORM_ELIMINATE_FOR_ANY)
return 1;
this = this->terms[this->nterms - 1];
goto beginning;
case LIBNORMALFORM_NEGATED_FOR_ALL:
if (!(flags & LIBNORMALFORM_ELIMINATE_FOR_ALL))
return 0;
if (flags & LIBNORMALFORM_ELIMINATE_NEGATED_FOR_ANY)
return 1;
this = this->terms[this->nterms - 1];
goto beginning;
case LIBNORMALFORM_FOR_ANY:
if (!(flags & LIBNORMALFORM_ELIMINATE_NEGATED_FOR_ANY))
return 0;
if (flags & LIBNORMALFORM_ELIMINATE_FOR_ALL)
return 1;
this = this->terms[this->nterms - 1];
goto beginning;
case LIBNORMALFORM_NEGATED_FOR_ANY:
if (!(flags & LIBNORMALFORM_ELIMINATE_FOR_ANY))
return 0;
if (flags & LIBNORMALFORM_ELIMINATE_NEGATED_FOR_ALL)
return 1;
this = this->terms[this->nterms - 1];
goto beginning;
case LIBNORMALFORM_FOR_ONE:
return flags & LIBNORMALFORM_ELIMINATE_NEGATED_FOR_ONE;
case LIBNORMALFORM_NEGATED_FOR_ONE:
return flags & LIBNORMALFORM_ELIMINATE_FOR_ONE;
default:
abort();
}
}
int
(libnormalform_fix_presentation__)(struct expression *this, uint64_t flags, unsigned char *require_inversion, int *reduced)
{
#define WILL_ELIMINATE(BASETYPE, INVERT)\
(flags & (LIBNORMALFORM_ELIMINATE_##BASETYPE <<\
((this->type ^ ((LIBNORMALFORM_##BASETYPE ^ LIBNORMALFORM_NEGATED_##BASETYPE) *\
(INVERT))) -\
LIBNORMALFORM_##BASETYPE)))
size_t i;
unsigned char zero = 0;
struct expression *new;
int may_switch = 1;
switch (this->type) {
case LIBNORMALFORM_CONJUNCTION:
case LIBNORMALFORM_DISJUNCTION:
this->type ^= LIBNORMALFORM_CONJUNCTION ^ LIBNORMALFORM_DISJUNCTION;
if (this->invert) {
if (*require_inversion) {
this->invert ^= 1;
*require_inversion = 0;
}
for (i = 0; i < this->nterms; i++)
this->terms[i]->invert ^= 1;
}
require_inversion = &zero;
break;
case LIBNORMALFORM_EXCLUSIVE_DISJUNCTION:
if (!this->nterms)
abort();
if (*require_inversion) { /* TODO always? */
this->invert ^= 1;
*require_inversion = 0;
}
for (i = 0; i < this->nterms; i++)
if (libnormalform_fix_presentation__(this->terms[i], flags, &this->invert, reduced))
return -1;
if (this->invert) {
/* TODO this is not necessarily the best element to invert,
* possibly the previous loop could be used to determine
* which is best (notably, clauses are not analysed) */
this->invert = 0;
this->terms[0]->invert ^= 1;
if (libnormalform_fix_presentation__(this->terms[0], flags, &zero, reduced))
return -1;
}
return 0;
case LIBNORMALFORM_VARIABLE:
case LIBNORMALFORM_NEGATED_VARIABLE:
if (!WILL_ELIMINATE(VARIABLE, this->invert ^ *require_inversion)) {
this->invert ^= *require_inversion;
*require_inversion = 0;
} else if (WILL_ELIMINATE(VARIABLE, this->invert)) {
goto eliminate;
}
this->type ^= (LIBNORMALFORM_VARIABLE ^ LIBNORMALFORM_NEGATED_VARIABLE) * this->invert;
break;
case LIBNORMALFORM_FUNCTION:
case LIBNORMALFORM_NEGATED_FUNCTION:
if (!WILL_ELIMINATE(FUNCTION, this->invert ^ *require_inversion)) {
this->invert ^= *require_inversion;
*require_inversion = 0;
} else if (WILL_ELIMINATE(FUNCTION, this->invert)) {
goto eliminate;
}
this->type ^= (LIBNORMALFORM_FUNCTION ^ LIBNORMALFORM_NEGATED_FUNCTION) * this->invert;
break;
case LIBNORMALFORM_TRANSFORMATION:
this->terms[0]->invert ^= this->invert;
break;
case LIBNORMALFORM_FOR_ALL:
case LIBNORMALFORM_NEGATED_FOR_ALL:
if (!WILL_ELIMINATE(FOR_ALL, this->invert ^ *require_inversion)) {
this->invert ^= *require_inversion;
*require_inversion = 0;
} else for_all: if (WILL_ELIMINATE(FOR_ALL, this->invert)) {
if (!may_switch)
goto eliminate;
may_switch = 0;
this->invert = 0;
this->terms[this->nterms - 1]->invert ^= 1;
this->type = LIBNORMALFORM_NEGATED_FOR_ANY - (this->type - LIBNORMALFORM_FOR_ALL);
goto for_any;
}
this->type ^= (LIBNORMALFORM_FOR_ALL ^ LIBNORMALFORM_NEGATED_FOR_ALL) * this->invert;
this->invert = 0;
if (flags & (LIBNORMALFORM_AVOID_FOR_ALL << (this->type - LIBNORMALFORM_FOR_ALL))) {
if (!inversion_would_relax(this, flags)) {
this->terms[this->nterms - 1]->invert ^= 1;
this->type = LIBNORMALFORM_NEGATED_FOR_ANY - (this->type - LIBNORMALFORM_FOR_ALL);
goto for_any_maybe_join_sides;
}
}
for_all_maybe_join_sides:
if (this->nterms > 1)
break;
if (flags & (LIBNORMALFORM_JOIN_SIDES_IN_FOR_ALL << (this->type - LIBNORMALFORM_FOR_ALL)))
goto for_all_join_sides;
break;
case LIBNORMALFORM_FOR_ANY:
case LIBNORMALFORM_NEGATED_FOR_ANY:
if (!WILL_ELIMINATE(FOR_ANY, this->invert ^ *require_inversion)) {
this->invert ^= *require_inversion;
*require_inversion = 0;
} else for_any: if (WILL_ELIMINATE(FOR_ANY, this->invert)) {
if (!may_switch)
goto eliminate;
may_switch = 0;
this->invert = 0;
this->terms[this->nterms - 1]->invert ^= 1;
this->type = LIBNORMALFORM_NEGATED_FOR_ALL - (this->type - LIBNORMALFORM_FOR_ANY);
goto for_all;
}
this->type ^= (LIBNORMALFORM_FOR_ANY ^ LIBNORMALFORM_NEGATED_FOR_ANY) * this->invert;
this->invert = 0;
if (flags & (LIBNORMALFORM_AVOID_FOR_ANY << (this->type - LIBNORMALFORM_FOR_ANY))) {
if (!inversion_would_relax(this, flags)) {
this->terms[this->nterms - 1]->invert ^= 1;
this->type = LIBNORMALFORM_NEGATED_FOR_ALL - (this->type - LIBNORMALFORM_FOR_ANY);
goto for_all_maybe_join_sides;
}
}
for_any_maybe_join_sides:
if (this->nterms > 1)
break;
if (flags & (LIBNORMALFORM_JOIN_SIDES_IN_FOR_ANY << (this->type - LIBNORMALFORM_FOR_ANY)))
goto for_any_join_sides;
break;
case LIBNORMALFORM_FOR_ONE:
case LIBNORMALFORM_NEGATED_FOR_ONE:
if (!WILL_ELIMINATE(FOR_ONE, this->invert ^ *require_inversion)) {
this->invert ^= *require_inversion;
*require_inversion = 0;
} else if (WILL_ELIMINATE(FOR_ONE, this->invert)) {
this->type ^= (LIBNORMALFORM_FOR_ONE ^ LIBNORMALFORM_NEGATED_FOR_ONE) * this->invert;
if (this->type == LIBNORMALFORM_FOR_ONE) {
this->invert = 0;
this->reduced = 1;
*reduced = 1;
goto for_any;
}
goto eliminate;
}
this->type ^= (LIBNORMALFORM_FOR_ONE ^ LIBNORMALFORM_NEGATED_FOR_ONE) * this->invert;
if (this->type == LIBNORMALFORM_FOR_ONE) {
if (flags & LIBNORMALFORM_ELIMINATE_FOR_ONE) {
this->type = LIBNORMALFORM_FOR_ANY;
this->invert = 0;
this->reduced = 1;
*reduced = 1;
goto for_any;
}
}
if (this->nterms > 1)
break;
if (flags & (LIBNORMALFORM_JOIN_SIDES_IN_FOR_ONE << (this->type - LIBNORMALFORM_FOR_ONE)))
goto for_any_join_sides;
break;
default:
abort();
}
this->invert = 0;
for (i = 0; i < this->nterms; i++)
if (libnormalform_fix_presentation__(this->terms[i], flags, require_inversion, reduced))
return -1;
return 0;
eliminate:
*require_inversion = 0;
this->refcount = 1;
this->reduced = 1;
this->invert = 0;
while (this->nterms)
libnormalform_free_expression__(this->terms[--this->nterms]);
free(this->terms);
this->terms = NULL;
this->type = LIBNORMALFORM_CONJUNCTION;
*reduced = 1;
return 0;
for_all_join_sides:
new = libnormalform_make_binary__(1, this->terms[0], 0, this->terms[1], LIBNORMALFORM_DISJUNCTION);
goto join_sides;
for_any_join_sides:
new = libnormalform_make_binary__(0, this->terms[0], 0, this->terms[1], LIBNORMALFORM_CONJUNCTION);
join_sides:
if (!new)
return -1;
this->terms[0] = new;
this->nterms--;
if (libnormalform_apply_transformation__(this->terms[0]->terms[0], LIBNORMALFORM_DOMAIN_VIEW))
return -1;
if (libnormalform_apply_transformation__(this->terms[0]->terms[1], LIBNORMALFORM_IMAGE_VIEW))
return -1;
*reduced = 1;
return 0;
#undef WILL_ELIMINATE
}
#else
TODO_TEST
#endif
|
