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<?php

/* vim: set shiftwidth=2 expandtab softtabstop=2: */

namespace Boris;

/**
 * The ShallowParser takes whatever is currently buffered and chunks it into individual statements.
 */
class ShallowParser {
  private $_pairs = array(
    '('   => ')',
    '{'   => '}',
    '['   => ']',
    '"'   => '"',
    "'"   => "'",
    '//'  => "\n",
    '#'   => "\n",
    '/*'  => '*/',
    '<<<' => '_heredoc_special_case_'
  );

private $_initials;

public function __construct() {
    $this->_initials   = '/^(' . implode('|', array_map(array($this, 'quote'), array_keys($this->_pairs))) . ')/';
  }

/**
   * Break the $buffer into chunks, with one for each highest-level construct possible.
   *
   * If the buffer is incomplete, returns an empty array.
   *
   * @param string $buffer
   *
   * @return array
   */
  public function statements($buffer) {
    $result = $this->_createResult($buffer);

while (strlen($result->buffer) > 0) {
      $this->_resetResult($result);

if ($result->state == '<<<') {
        if (!$this->_initializeHeredoc($result)) {
          continue;
        }
      }

$rules = array('_scanEscapedChar', '_scanRegion', '_scanStateEntrant', '_scanWsp', '_scanChar');

foreach ($rules as $method) {
        if ($this->$method($result)) {
          break;
        }
      }

if ($result->stop) {
        break;
      }
    }

if (!empty($result->statements) && trim($result->stmt) === '' && strlen($result->buffer) == 0) {
      $this->_combineStatements($result);
      $this->_prepareForDebug($result);
      return $result->statements;
    }
  }

public function quote($token) {
    return preg_quote($token, '/');
  }

// -- Private Methods

private function _createResult($buffer) {
    $result = new \stdClass();
    $result->buffer     = $buffer;
    $result->stmt       = '';
    $result->state      =  null;
    $result->states     = array();
    $result->statements = array();
    $result->stop       = false;

return $result;
  }

private function _resetResult($result) {
    $result->stop       = false;
    $result->state      = end($result->states);
    $result->terminator = $result->state
      ? '/^(.*?' . preg_quote($this->_pairs[$result->state], '/') . ')/s'
      : null
      ;
  }

private function _combineStatements($result) {
    $combined = array();

foreach ($result->statements as $scope) {
      if (trim($scope) == ';' || substr(trim($scope), -1) != ';') {
        $combined[] = ((string) array_pop($combined)) . $scope;
      } else {
        $combined[] = $scope;
      }
    }

$result->statements = $combined;
  }

private function _prepareForDebug($result) {
    $result->statements []= $this->_prepareDebugStmt(array_pop($result->statements));
  }

private function _initializeHeredoc($result) {
    if (preg_match('/^([\'"]?)([a-z_][a-z0-9_]*)\\1/i', $result->buffer, $match)) {
      $docId = $match[2];
      $result->stmt .= $match[0];
      $result->buffer = substr($result->buffer, strlen($match[0]));

$result->terminator = '/^(.*?\n' . $docId . ');?\n/s';