public withScope ( Scope $scope ) : |
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$scope | Scope | |
리턴 | A new context with the given scope |
/** * @param Node $node * A node to parse * * @return Context * A new or an unchanged context resulting from * parsing the node */ public function visitIf(Node $node) : Context { // Get the list of scopes for each branch of the // conditional $scope_list = array_map(function (Context $context) { return $context->getScope(); }, $this->child_context_list); $has_else = array_reduce($node->children ?? [], function (bool $carry, $child_node) { return $carry || $child_node instanceof Node && empty($child_node->children['cond']); }, false); // If we're not guaranteed to hit at least one // branch, mark the incoming scope as a possibility if (!$has_else) { $scope_list[] = $this->context->getScope(); } // If there weren't multiple branches, continue on // as if the conditional never happened if (count($scope_list) < 2) { return array_values($this->child_context_list)[0]; } // Get a list of all variables in all scopes $variable_map = []; foreach ($scope_list as $scope) { foreach ($scope->getVariableMap() as $name => $variable) { $variable_map[$name] = $variable; } } // A function that determins if a variable is defined on // every branch $is_defined_on_all_branches = function (string $variable_name) use($scope_list) { return array_reduce($scope_list, function (bool $has_variable, Scope $scope) use($variable_name) { return $has_variable && $scope->hasVariableWithName($variable_name); }, true); }; // Get the intersection of all types for all versions of // the variable from every side of the branch $common_union_type = function (string $variable_name) use($scope_list) { // Get a list of all variables with the given name from // each scope $variable_list = array_filter(array_map(function (Scope $scope) use($variable_name) { if (!$scope->hasVariableWithName($variable_name)) { return null; } return $scope->getVariableWithName($variable_name); }, $scope_list)); // Get the list of types for each version of the variable $type_set_list = array_map(function (Variable $variable) : Set { return $variable->getUnionType()->getTypeSet(); }, $variable_list); if (count($type_set_list) < 2) { return new UnionType($type_set_list[0] ?? []); } return new UnionType(Set::intersectAll($type_set_list)); }; $scope = new Scope(); foreach ($variable_map as $name => $variable) { // Skip variables that are only partially defined if (!$is_defined_on_all_branches($name)) { continue; } // Limit the type of the variable to the subset // of types that are common to all branches $variable = clone $variable; $variable->setUnionType($common_union_type($name)); // Add the variable to the outgoing scope $scope->addVariable($variable); } // print '<'.implode("\t", $scope_list) . "\n"; // print '>'.$scope."\n"; // Set the new scope with only the variables and types // that are common to all branches return $this->context->withScope($scope); }