in src/lint/linter/xhpast/rules/ArcanistReusedAsIteratorXHPASTLinterRule.php [12:275]
public function process(XHPASTNode $root) {
$defs = $root->selectDescendantsOfTypes(array(
'n_FUNCTION_DECLARATION',
'n_METHOD_DECLARATION',
));
foreach ($defs as $def) {
// We keep track of the first offset where scope becomes unknowable, and
// silence any warnings after that. Default it to INT_MAX so we can min()
// it later to keep track of the first problem we encounter.
$scope_destroyed_at = PHP_INT_MAX;
$declarations = array(
'$this' => 0,
) + array_fill_keys($this->getSuperGlobalNames(), 0);
$declaration_tokens = array();
$exclude_tokens = array();
$vars = array();
// First up, find all the different kinds of declarations, as explained
// above. Put the tokens into the $vars array.
$param_list = $def->getChildOfType(3, 'n_DECLARATION_PARAMETER_LIST');
$param_vars = $param_list->selectDescendantsOfType('n_VARIABLE');
foreach ($param_vars as $var) {
$vars[] = $var;
}
// This is PHP5.3 closure syntax: function () use ($x) {};
$lexical_vars = $def
->getChildByIndex(4)
->selectDescendantsOfType('n_VARIABLE');
foreach ($lexical_vars as $var) {
$vars[] = $var;
}
$body = $def->getChildByIndex(6);
if ($body->getTypeName() === 'n_EMPTY') {
// Abstract method declaration.
continue;
}
$static_vars = $body
->selectDescendantsOfType('n_STATIC_DECLARATION')
->selectDescendantsOfType('n_VARIABLE');
foreach ($static_vars as $var) {
$vars[] = $var;
}
$global_vars = $body
->selectDescendantsOfType('n_GLOBAL_DECLARATION_LIST');
foreach ($global_vars as $var_list) {
foreach ($var_list->getChildren() as $var) {
if ($var->getTypeName() === 'n_VARIABLE') {
$vars[] = $var;
} else {
// Dynamic global variable, i.e. "global $$x;".
$scope_destroyed_at = min($scope_destroyed_at, $var->getOffset());
// An error is raised elsewhere, no need to raise here.
}
}
}
// Include "catch (Exception $ex)", but not variables in the body of the
// catch block.
$catches = $body->selectDescendantsOfType('n_CATCH');
foreach ($catches as $catch) {
$vars[] = $catch->getChildOfType(1, 'n_VARIABLE');
}
$binary = $body->selectDescendantsOfType('n_BINARY_EXPRESSION');
foreach ($binary as $expr) {
if ($expr->getChildByIndex(1)->getConcreteString() !== '=') {
continue;
}
$lval = $expr->getChildByIndex(0);
if ($lval->getTypeName() === 'n_VARIABLE') {
$vars[] = $lval;
} else if ($lval->getTypeName() === 'n_LIST') {
// Recursivey grab everything out of list(), since the grammar
// permits list() to be nested. Also note that list() is ONLY valid
// as an lval assignments, so we could safely lift this out of the
// n_BINARY_EXPRESSION branch.
$assign_vars = $lval->selectDescendantsOfType('n_VARIABLE');
foreach ($assign_vars as $var) {
$vars[] = $var;
}
}
if ($lval->getTypeName() === 'n_VARIABLE_VARIABLE') {
$scope_destroyed_at = min($scope_destroyed_at, $lval->getOffset());
// No need to raise here since we raise an error elsewhere.
}
}
$calls = $body->selectDescendantsOfType('n_FUNCTION_CALL');
foreach ($calls as $call) {
$name = strtolower($call->getChildByIndex(0)->getConcreteString());
if ($name === 'empty' || $name === 'isset') {
$params = $call
->getChildOfType(1, 'n_CALL_PARAMETER_LIST')
->selectDescendantsOfType('n_VARIABLE');
foreach ($params as $var) {
$exclude_tokens[$var->getID()] = true;
}
continue;
}
if ($name !== 'extract') {
continue;
}
$scope_destroyed_at = min($scope_destroyed_at, $call->getOffset());
}
// Now we have every declaration except foreach(), handled below. Build
// two maps, one which just keeps track of which tokens are part of
// declarations ($declaration_tokens) and one which has the first offset
// where a variable is declared ($declarations).
foreach ($vars as $var) {
$concrete = $this->getConcreteVariableString($var);
$declarations[$concrete] = min(
idx($declarations, $concrete, PHP_INT_MAX),
$var->getOffset());
$declaration_tokens[$var->getID()] = true;
}
// Excluded tokens are ones we don't "count" as being used, described
// above. Put them into $exclude_tokens.
$class_statics = $body
->selectDescendantsOfType('n_CLASS_STATIC_ACCESS');
$class_static_vars = $class_statics
->selectDescendantsOfType('n_VARIABLE');
foreach ($class_static_vars as $var) {
$exclude_tokens[$var->getID()] = true;
}
// Find all the variables in scope, and figure out where they are used.
// We want to find foreach() iterators which are both declared before and
// used after the foreach() loop.
$uses = array();
$all_vars = $body->selectDescendantsOfType('n_VARIABLE');
$all = array();
// NOTE: $all_vars is not a real array so we can't unset() it.
foreach ($all_vars as $var) {
// Be strict since it's easier; we don't let you reuse an iterator you
// declared before a loop after the loop, even if you're just assigning
// to it.
$concrete = $this->getConcreteVariableString($var);
$uses[$concrete][$var->getID()] = $var->getOffset();
if (isset($declaration_tokens[$var->getID()])) {
// We know this is part of a declaration, so it's fine.
continue;
}
if (isset($exclude_tokens[$var->getID()])) {
// We know this is part of isset() or similar, so it's fine.
continue;
}
$all[$var->getOffset()] = $concrete;
}
// Do foreach() last, we want to handle implicit redeclaration of a
// variable already in scope since this probably means we're ovewriting a
// local.
// NOTE: Processing foreach expressions in order allows programs which
// reuse iterator variables in other foreach() loops -- this is fine. We
// have a separate warning to prevent nested loops from reusing the same
// iterators.
$foreaches = $body->selectDescendantsOfType('n_FOREACH');
$all_foreach_vars = array();
foreach ($foreaches as $foreach) {
$foreach_expr = $foreach->getChildOfType(0, 'n_FOREACH_EXPRESSION');
$foreach_vars = array();
// Determine the end of the foreach() loop.
$foreach_tokens = $foreach->getTokens();
$last_token = end($foreach_tokens);
$foreach_end = $last_token->getOffset();
$key_var = $foreach_expr->getChildByIndex(1);
if ($key_var->getTypeName() === 'n_VARIABLE') {
$foreach_vars[] = $key_var;
}
$value_var = $foreach_expr->getChildByIndex(2);
if ($value_var->getTypeName() === 'n_VARIABLE') {
$foreach_vars[] = $value_var;
} else {
// The root-level token may be a reference, as in:
// foreach ($a as $b => &$c) { ... }
// Reach into the n_VARIABLE_REFERENCE node to grab the n_VARIABLE
// node.
$var = $value_var->getChildByIndex(0);
if ($var->getTypeName() === 'n_VARIABLE_VARIABLE') {
$var = $var->getChildByIndex(0);
}
$foreach_vars[] = $var;
}
// Remove all uses of the iterators inside of the foreach() loop from
// the $uses map.
foreach ($foreach_vars as $var) {
$concrete = $this->getConcreteVariableString($var);
$offset = $var->getOffset();
foreach ($uses[$concrete] as $id => $use_offset) {
if (($use_offset >= $offset) && ($use_offset < $foreach_end)) {
unset($uses[$concrete][$id]);
}
}
$all_foreach_vars[] = $var;
}
}
foreach ($all_foreach_vars as $var) {
$concrete = $this->getConcreteVariableString($var);
$offset = $var->getOffset();
// If a variable was declared before a foreach() and is used after
// it, raise a message.
if (isset($declarations[$concrete])) {
if ($declarations[$concrete] < $offset) {
if (!empty($uses[$concrete]) &&
max($uses[$concrete]) > $offset) {
$message = $this->raiseLintAtNode(
$var,
pht(
'This iterator variable is a previously declared local '.
'variable. To avoid overwriting locals, do not reuse them '.
'as iterator variables.'));
$message->setOtherLocations(array(
$this->getOtherLocation($declarations[$concrete]),
$this->getOtherLocation(max($uses[$concrete])),
));
}
}
}
// This is a declaration, exclude it from the "declare variables prior
// to use" check below.
unset($all[$var->getOffset()]);
$vars[] = $var;
}
}
}