<?php
// $Id$

/**
 * @file
 */
// Basic structure: Identifiers, UnaryOperation and BinaryOperation
class TqlNodeVisitor {
  // basic Visitor
  function visitIdentifier($tqlIdentifier) {}

  function visitUnaryOperation($tqlUnaryOperation) {}

  function visitBinaryOperation($tqlBinaryOperation) {}
}

// Operations: Not, And, Or, Xor
class TqlOperationVisitor extends TqlNodeVisitor {
  function visitNot($tqlNot) {}

  function visitAnd($tqlAnd) {}

  function visitOr($tqlOr) {}

  function visitXor($tqlXor) {}
}


// Basic AST Visitor
class TqlASTVisitor extends TqlOperationVisitor {}


// Nodes
class TqlNode {
  // fields
  public $type;
  public $value;
  public $column;
  public $line;
  public $previous;
  public $next;

  function accept($nodeVisitor) {}
}

class TqlIdentifier extends TqlNode {
  function accept($nodeVisitor) {
    return $nodeVisitor->visitIdentifier($this);
  }
}

class TqlOperation extends TqlNode {
  function acceptOperation($operationVisitor) {}
}

class TqlUnaryOperation extends TqlOperation {
  //child
  public $operand;

  // do not overwrite this function
  function accept($nodeVisitor) {
    return $nodeVisitor->visitUnaryOperation($this);
  }
}

class TqlBinaryOperation extends TqlOperation {
  // children
  public $left;
  public $right;

  // do not overwrite this function
  function accept($nodeVisitor) {
    return $nodeVisitor->visitBinaryOperation($this);
  }
}


class TqlNot extends TqlUnaryOperation {
  // do not overwrite this function
  function acceptOperation($operationVisitor) {
    return $operationVisitor->visitNot($this);
  }
}

class TqlAnd extends TqlBinaryOperation {
  // do not overwrite this function
  function acceptOperation($operationVisitor) {
    return $operationVisitor->visitAnd($this);
  }
}

class TqlOr extends TqlBinaryOperation {
  // do not overwrite this function
  function acceptOperation($operationVisitor) {
    return $operationVisitor->visitOr($this);
  }
}

class TqlXor extends TqlBinaryOperation {
  // do not overwrite this function
  function acceptOperation($operationVisitor) {
    return $operationVisitor->visitXor($this);
  }
}