/**
* {@inheritDoc}
*/
public function parse(TokenStream $stream)
{
$stateStack = array($currentState = 0);
$args = array();
foreach ($stream as $token) {
while (true) {
$type = $token->getType();
if (!isset($this->parseTable['action'][$currentState][$type])) {
// unexpected token
throw new UnexpectedTokenException($token, array_keys($this->parseTable['action'][$currentState]));
}
$action = $this->parseTable['action'][$currentState][$type];
if ($action > 0) {
// shift
$args[] = $token;
$stateStack[] = $currentState = $action;
break;
} elseif ($action < 0) {
// reduce
$rule = $this->grammar->getRule(-$action);
$popCount = count($rule->getComponents());
array_splice($stateStack, -$popCount);
$newArgs = array_splice($args, -$popCount);
if ($callback = $rule->getCallback()) {
$args[] = call_user_func_array($callback, $newArgs);
} else {
$args[] = $newArgs[0];
}
$state = $stateStack[count($stateStack) - 1];
$stateStack[] = $currentState = $this->parseTable['goto'][$state][$rule->getName()];
} else {
// accept
return $args[0];
}
}
}
}
protected function writeAction($trigger, $action)
{
if ($action > 0) {
$this->writer->writeLine(sprintf('// on %s shift and go to state %d', $trigger, $action));
} elseif ($action < 0) {
$rule = $this->grammar->getRule(-$action);
$components = $rule->getComponents();
if (empty($components)) {
$rhs = '/* empty */';
} else {
$rhs = implode(' ', $components);
}
$this->writer->writeLine(sprintf('// on %s reduce by rule %s -> %s', $trigger, $rule->getName(), $rhs));
} else {
$this->writer->writeLine(sprintf('// on %s accept the input', $trigger));
}
$this->writer->writeLine(sprintf("'%s' => %d,", $trigger, $action));
}
/**
* Encodes the handle-finding FSA as a LR parse table.
*
* @param \Dissect\Parser\LALR1\Analysis\Automaton $automaton
*
* @return array The parse table.
*/
protected function buildParseTable(Automaton $automaton, Grammar $grammar)
{
$nonterminals = array_keys($grammar->getGroupedRules());
$conflictsMode = $grammar->getConflictsMode();
$conflicts = array();
// initialize the table
$table = array('action' => array(), 'goto' => array());
foreach ($automaton->getTransitionTable() as $num => $transitions) {
foreach ($transitions as $trigger => $destination) {
if (!in_array($trigger, $nonterminals)) {
// terminal implies shift
$table['action'][$num][$trigger] = $destination;
} else {
// nonterminal goes in the goto table
$table['goto'][$num][$trigger] = $destination;
}
}
}
foreach ($automaton->getStates() as $num => $state) {
if (!isset($table['action'][$num])) {
$table['action'][$num] = array();
}
foreach ($state->getItems() as $item) {
if ($item->isReduceItem()) {
$ruleNumber = $item->getRule()->getNumber();
foreach ($item->getLookahead() as $token) {
if (array_key_exists($token, $table['action'][$num])) {
// conflict
$instruction = $table['action'][$num][$token];
if ($instruction > 0) {
// s/r
if ($conflictsMode & Grammar::SHIFT) {
$conflicts[] = array('state' => $num, 'lookahead' => $token, 'rule' => $item->getRule(), 'resolution' => Grammar::SHIFT);
continue;
} else {
throw new ShiftReduceConflictException($num, $item->getRule(), $token, $automaton);
}
} else {
// r/r
$originalRule = $grammar->getRule(-$instruction);
$newRule = $item->getRule();
if ($conflictsMode & Grammar::LONGER_REDUCE) {
$count1 = count($originalRule->getComponents());
$count2 = count($newRule->getComponents());
if ($count1 > $count2) {
// original rule is longer
$resolvedRules = array($originalRule, $newRule);
$conflicts[] = array('state' => $num, 'lookahead' => $token, 'rules' => $resolvedRules, 'resolution' => Grammar::LONGER_REDUCE);
continue;
} elseif ($count2 > $count1) {
// new rule is longer
$table['action'][$num][$token] = -$ruleNumber;
$resolvedRules = array($newRule, $originalRule);
$conflicts[] = array('state' => $num, 'lookahead' => $token, 'rules' => $resolvedRules, 'resolution' => Grammar::LONGER_REDUCE);
continue;
}
}
if ($conflictsMode & Grammar::EARLIER_REDUCE) {
if (-$instruction < $ruleNumber) {
// original rule was earlier
$resolvedRules = array($originalRule, $newRule);
$conflicts[] = array('state' => $num, 'lookahead' => $token, 'rules' => $resolvedRules, 'resolution' => Grammar::EARLIER_REDUCE);
continue;
} else {
// new rule was earlier
$table['action'][$num][$token] = -$ruleNumber;
$conflicts[] = array('state' => $num, 'lookahead' => $token, 'rules' => $resolvedRules, 'resolution' => Grammar::EARLIER_REDUCE);
$resolvedRules = array($newRule, $originalRule);
continue;
}
}
// everything failed, throw an exception
throw new ReduceReduceConflictException($num, $originalRule, $newRule, $token, $automaton);
}
}
$table['action'][$num][$token] = -$ruleNumber;
}
}
}
}
return array($table, $conflicts);
}
