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https://github.com/danog/psalm.git
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471 lines
15 KiB
PHP
471 lines
15 KiB
PHP
<?php
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namespace Psalm\Checker;
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use PhpParser;
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use Psalm\Checker\Statements\Expression\AssertionFinder;
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use Psalm\Clause;
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use Psalm\CodeLocation;
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use Psalm\Issue\ParadoxicalCondition;
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use Psalm\IssueBuffer;
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use Psalm\StatementsSource;
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class AlgebraChecker
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{
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/**
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* @param PhpParser\Node\Expr $conditional
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* @param string|null $this_class_name
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* @param StatementsSource $source
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* @return array<int, Clause>
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*/
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public static function getFormula(
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PhpParser\Node\Expr $conditional,
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$this_class_name,
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StatementsSource $source
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) {
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if ($conditional instanceof PhpParser\Node\Expr\BinaryOp\BooleanAnd ||
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$conditional instanceof PhpParser\Node\Expr\BinaryOp\LogicalAnd
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) {
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$left_assertions = self::getFormula(
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$conditional->left,
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$this_class_name,
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$source
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);
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$right_assertions = self::getFormula(
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$conditional->right,
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$this_class_name,
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$source
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);
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return array_merge(
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$left_assertions,
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$right_assertions
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);
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}
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if ($conditional instanceof PhpParser\Node\Expr\BinaryOp\BooleanOr ||
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$conditional instanceof PhpParser\Node\Expr\BinaryOp\LogicalOr
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) {
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// at the moment we only support formulae in CNF
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if (!$conditional->left instanceof PhpParser\Node\Expr\BinaryOp\BooleanAnd &&
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!$conditional->left instanceof PhpParser\Node\Expr\BinaryOp\LogicalAnd
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) {
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$left_clauses = self::getFormula(
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$conditional->left,
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$this_class_name,
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$source
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);
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} else {
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$left_clauses = [new Clause([], true)];
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}
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if (!$conditional->right instanceof PhpParser\Node\Expr\BinaryOp\BooleanAnd &&
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!$conditional->right instanceof PhpParser\Node\Expr\BinaryOp\LogicalAnd
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) {
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$right_clauses = self::getFormula(
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$conditional->right,
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$this_class_name,
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$source
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);
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} else {
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$right_clauses = [new Clause([], true)];
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}
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return self::combineOredClauses($left_clauses, $right_clauses);
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}
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$assertions = AssertionFinder::getAssertions(
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$conditional,
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$this_class_name,
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$source
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);
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if ($assertions) {
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$clauses = [];
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foreach ($assertions as $var => $type) {
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if ($type === 'isset') {
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$key_parts = preg_split(
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'/(\]|\[)/',
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$var,
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-1,
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PREG_SPLIT_NO_EMPTY
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);
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$base = array_shift($key_parts);
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$clauses[] = new Clause([$base => ['isset']]);
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if (count($key_parts)) {
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$clauses[] = new Clause([$base => ['!false']]);
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$clauses[] = new Clause([$base => ['!int']]);
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}
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foreach ($key_parts as $i => $key_part_dim) {
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$base .= '[' . $key_part_dim . ']';
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$clauses[] = new Clause([$base => ['isset']]);
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if ($i < count($key_parts) - 1) {
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$clauses[] = new Clause([$base => ['!false']]);
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$clauses[] = new Clause([$base => ['!int']]);
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}
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}
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} else {
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$clauses[] = new Clause([$var => [$type]]);
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}
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}
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return $clauses;
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}
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return [new Clause([], true)];
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}
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/**
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* Negates a set of clauses
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* negateClauses([$a || $b]) => !$a && !$b
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* negateClauses([$a, $b]) => !$a || !$b
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* negateClauses([$a, $b || $c]) =>
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* (!$a || !$b) &&
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* (!$a || !$c)
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* negateClauses([$a, $b || $c, $d || $e || $f]) =>
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* (!$a || !$b || !$d) &&
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* (!$a || !$b || !$e) &&
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* (!$a || !$b || !$f) &&
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* (!$a || !$c || !$d) &&
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* (!$a || !$c || !$e) &&
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* (!$a || !$c || !$f)
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*
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* @param array<int, Clause> $clauses
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* @return array<int, Clause>
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*/
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public static function negateFormula(array $clauses)
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{
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foreach ($clauses as $clause) {
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self::calculateNegation($clause);
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}
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return self::groupImpossibilities($clauses);
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}
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/**
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* @param Clause $clause
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* @return void
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*/
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public static function calculateNegation(Clause $clause)
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{
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if ($clause->impossibilities !== null) {
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return;
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}
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$impossibilities = [];
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foreach ($clause->possibilities as $var_id => $possiblity) {
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$impossibility = [];
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foreach ($possiblity as $type) {
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if ($type[0] !== '^') {
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$impossibility[] = TypeChecker::negateType($type);
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}
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}
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if ($impossibility) {
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$impossibilities[$var_id] = $impossibility;
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}
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}
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$clause->impossibilities = $impossibilities;
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}
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/**
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* This looks to see if there are any clauses in one formula that contradict
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* clauses in another formula
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*
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* e.g.
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* if ($a) { }
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* elseif ($a) { }
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*
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* @param array<int, Clause> $formula1
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* @param array<int, Clause> $formula2
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* @param StatementsChecker $statements_checker,
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* @param PhpParser\Node $stmt
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* @return void
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*/
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public static function checkForParadox(
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array $formula1,
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array $formula2,
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StatementsChecker $statements_checker,
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PhpParser\Node $stmt
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) {
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// remove impossible types
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foreach ($formula1 as $clause_a) {
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if (!$clause_a->reconcilable || $clause_a->wedge) {
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continue;
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}
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self::calculateNegation($clause_a);
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foreach ($formula2 as $clause_b) {
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if ($clause_a === $clause_b || !$clause_b->reconcilable || $clause_b->wedge) {
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continue;
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}
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if ($clause_a->impossibilities == $clause_b->possibilities) {
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if (IssueBuffer::accepts(
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new ParadoxicalCondition(
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'Encountered a paradox when evaluating the conditional',
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new CodeLocation($statements_checker, $stmt)
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),
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$statements_checker->getSuppressedIssues()
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)) {
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// fall through
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}
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return;
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}
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}
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}
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}
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/**
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* This is a very simple simplification heuristic
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* for CNF formulae.
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*
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* It simplifies formulae:
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* ($a) && ($a || $b) => $a
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* (!$a) && (!$b) && ($a || $b || $c) => $c
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*
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* @param array<int, Clause> $clauses
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* @return array<int, Clause>
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*/
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public static function simplifyCNF(array $clauses)
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{
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$cloned_clauses = [];
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// avoid strict duplicates
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foreach ($clauses as $clause) {
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$cloned_clauses[$clause->getHash()] = clone $clause;
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}
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// remove impossible types
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foreach ($cloned_clauses as $clause_a) {
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if (count($clause_a->possibilities) !== 1 || count(array_values($clause_a->possibilities)[0]) !== 1) {
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continue;
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}
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if (!$clause_a->reconcilable || $clause_a->wedge) {
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continue;
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}
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$clause_var = array_keys($clause_a->possibilities)[0];
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$only_type = array_pop(array_values($clause_a->possibilities)[0]);
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$negated_clause_type = TypeChecker::negateType($only_type);
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foreach ($cloned_clauses as $clause_b) {
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if ($clause_a === $clause_b || !$clause_b->reconcilable || $clause_b->wedge) {
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continue;
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}
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if (isset($clause_b->possibilities[$clause_var]) &&
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in_array($negated_clause_type, $clause_b->possibilities[$clause_var])
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) {
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$clause_b->possibilities[$clause_var] = array_filter(
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$clause_b->possibilities[$clause_var],
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/**
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* @param string $possible_type
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* @return bool
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*/
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function ($possible_type) use ($negated_clause_type) {
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return $possible_type !== $negated_clause_type;
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}
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);
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if (count($clause_b->possibilities[$clause_var]) === 0) {
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unset($clause_b->possibilities[$clause_var]);
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}
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}
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}
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}
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$cloned_clauses = array_filter(
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$cloned_clauses,
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/**
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* @return bool
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*/
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function (Clause $clause) {
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return (bool)count($clause->possibilities);
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}
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);
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$simplified_clauses = [];
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foreach ($cloned_clauses as $clause_a) {
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$is_redundant = false;
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foreach ($cloned_clauses as $clause_b) {
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if ($clause_a === $clause_b || !$clause_b->reconcilable || $clause_b->wedge) {
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continue;
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}
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if ($clause_a->contains($clause_b)) {
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$is_redundant = true;
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break;
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}
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}
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if (!$is_redundant) {
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$simplified_clauses[] = $clause_a;
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}
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}
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return $simplified_clauses;
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}
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/**
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* Look for clauses with only one possible value
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*
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* @param array<int, Clause> $clauses
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* @return array<string, string>
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*/
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public static function getTruthsFromFormula(array $clauses)
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{
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$truths = [];
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if (empty($clauses)) {
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return [];
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}
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foreach ($clauses as $clause) {
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if (!$clause->reconcilable) {
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continue;
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}
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foreach ($clause->possibilities as $var => $possible_types) {
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// if there's only one possible type, return it
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if (count($clause->possibilities) === 1 && count($possible_types) === 1) {
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if (isset($truths[$var])) {
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$truths[$var] .= '&' . array_pop($possible_types);
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} else {
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$truths[$var] = array_pop($possible_types);
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}
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} elseif (count($clause->possibilities) === 1) {
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// if there's only one active clause, return all the non-negation clause members ORed together
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$things_that_can_be_said = array_filter(
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$possible_types,
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/**
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* @param string $possible_type
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* @return bool
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*/
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function ($possible_type) {
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return $possible_type[0] !== '!';
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}
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);
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if ($things_that_can_be_said && count($things_that_can_be_said) === count($possible_types)) {
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$things_that_can_be_said = array_unique($things_that_can_be_said);
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$truths[$var] = implode('|', array_unique($things_that_can_be_said));
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}
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}
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}
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}
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return $truths;
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}
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/**
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* @param array<int, Clause> $clauses
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* @return array<int, Clause>
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*/
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protected static function groupImpossibilities(array $clauses)
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{
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$clause = array_pop($clauses);
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$new_clauses = [];
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if (count($clauses)) {
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$grouped_clauses = self::groupImpossibilities($clauses);
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foreach ($grouped_clauses as $grouped_clause) {
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if ($clause->impossibilities === null) {
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throw new \UnexpectedValueException('$clause->impossibilities should not be null');
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}
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foreach ($clause->impossibilities as $var => $impossible_types) {
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foreach ($impossible_types as $impossible_type) {
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$new_clause_possibilities = $grouped_clause->possibilities;
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if (isset($grouped_clause->possibilities[$var])) {
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$new_clause_possibilities[$var][] = $impossible_type;
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} else {
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$new_clause_possibilities[$var] = [$impossible_type];
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}
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$new_clauses[] = new Clause($new_clause_possibilities);
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}
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}
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}
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} elseif ($clause && !$clause->wedge) {
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if ($clause->impossibilities === null) {
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throw new \UnexpectedValueException('$clause->impossibilities should not be null');
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}
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foreach ($clause->impossibilities as $var => $impossible_types) {
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foreach ($impossible_types as $impossible_type) {
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$new_clauses[] = new Clause([$var => [$impossible_type]]);
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}
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}
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}
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return $new_clauses;
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}
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/**
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* @param array<int, Clause> $left_clauses
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* @param array<int, Clause> $right_clauses
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* @return array<int, Clause>
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*/
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public static function combineOredClauses(array $left_clauses, array $right_clauses)
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{
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// we cannot deal, at the moment, with orring non-CNF clauses
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if (count($left_clauses) !== 1 || count($right_clauses) !== 1) {
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return [new Clause([], true)];
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}
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/** @var array<string, array<string>> */
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$possibilities = [];
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if ($left_clauses[0]->wedge && $right_clauses[0]->wedge) {
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return [new Clause([], true)];
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}
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$can_reconcile = true;
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if ($left_clauses[0]->wedge ||
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$right_clauses[0]->wedge ||
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!$left_clauses[0]->reconcilable ||
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!$right_clauses[0]->reconcilable
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) {
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$can_reconcile = false;
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}
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foreach ($left_clauses[0]->possibilities as $var => $possible_types) {
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if (isset($possibilities[$var])) {
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$possibilities[$var] = array_merge($possibilities[$var], $possible_types);
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} else {
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$possibilities[$var] = $possible_types;
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}
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}
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foreach ($right_clauses[0]->possibilities as $var => $possible_types) {
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if (isset($possibilities[$var])) {
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$possibilities[$var] = array_merge($possibilities[$var], $possible_types);
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} else {
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$possibilities[$var] = $possible_types;
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}
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}
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return [new Clause($possibilities, false, $can_reconcile)];
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}
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}
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