<?php
/* SVN FILE: $Id$ */
/**
 * SassLiteral class file.
 * @author      Chris Yates <chris.l.yates@gmail.com>
 * @copyright   Copyright (c) 2010 PBM Web Development
 * @license      http://phamlp.googlecode.com/files/license.txt
 * @package      PHamlP
 * @subpackage  Sass.script.literals
 */

require_once('SassLiteralExceptions.php');

/**
 * SassLiteral class.
 * Base class for all Sass literals.
 * Sass data types are extended from this class and these override the operation
 * methods to provide the appropriate semantics.
 * @package      PHamlP
 * @subpackage  Sass.script.literals
 */
abstract class SassLiteral {
  /**
   * @var array maps class names to data types
   */
  static public $typeOf = array(
    'SassBoolean' => 'bool',
    'SassColour'  => 'color',
    'SassNumber'  => 'number',
    'SassString'  => 'string',
    'SassList' => 'list'
  );

  /**
   * @var mixed value of the literal type
   */
  public $value;

  /**
   * class constructor
   * @param string value of the literal type
   * @return SassLiteral
   */
  public function __construct($value = null, $context) {
    $this->value = $value;
    $this->context = $context;
  }

  /**
   * Getter.
   * @param string name of property to get
   * @return mixed return value of getter function
   */
  public function __get($name) {
    $getter = 'get' . ucfirst($name);
    if (method_exists($this, $getter)) {
      return $this->$getter();
    }
    else {
      throw new SassLiteralException('No getter function for ' . $name, SassScriptParser::$context->node);
    }
  }

  public function __toString() {
    return $this->toString();
  }

  /**
   * Returns the boolean representation of the value of this
   * @return boolean the boolean representation of the value of this
   */
  public function toBoolean() {
    return (boolean)$this->value || $this->value === null;
  }

  /**
   * Returns the type of this
   * @return string the type of this
   */
  public function getTypeOf() {
    return self::$typeOf[get_class($this)];
  }

  /**
   * Returns the value of this
   * @return mixed the value of this
   */
  public function getValue() {
    throw new SassLiteralException('Child classes must override this method', SassScriptParser::$context->node);
  }

  public function getChildren() {
    return array();
  }

  /**
   * Adds a child object to this.
   * @param sassLiteral the child object
   */
  public function addChild($sassLiteral) {
    $this->children[] = $sassLiteral;
  }

  /**
   * SassScript '+' operation.
   * @param sassLiteral value to add
   * @return sassString the string values of this and other with no seperation
   */
  public function op_plus($other) {
    return new SassString($this->toString().$other->toString());
  }

  /**
   * SassScript '-' operation.
   * @param SassLiteral value to subtract
   * @return sassString the string values of this and other seperated by '-'
   */
  public function op_minus($other) {
    return new SassString($this->toString().'-'.$other->toString());
  }

  /**
   * SassScript '*' operation.
   * @param SassLiteral value to multiply by
   * @return sassString the string values of this and other seperated by '*'
   */
  public function op_times($other) {
    return new SassString($this->toString().'*'.$other->toString());
  }

  /**
   * SassScript '/' operation.
   * @param SassLiteral value to divide by
   * @return sassString the string values of this and other seperated by '/'
   */
  public function op_div($other) {
    return new SassString($this->toString().' / '.$other->toString());
  }

  /**
   * SassScript '%' operation.
   * @param SassLiteral value to take the modulus of
   * @return SassLiteral result
   * @throws Exception if modulo not supported for the data type
   */
  public function op_modulo($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Modulus', SassScriptParser::$context->node);
  }

  /**
   * Bitwise AND the value of other and this value
   * @param string value to bitwise AND with
   * @return string result
   * @throws Exception if bitwise AND not supported for the data type
   */
  public function op_bw_and($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise AND', SassScriptParser::$context->node);
  }

  /**
   * Bitwise OR the value of other and this value
   * @param SassNumber value to bitwise OR with
   * @return string result
   * @throws Exception if bitwise OR not supported for the data type
   */
  public function op_bw_or($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise OR', SassScriptParser::$context->node);
  }

  /**
   * Bitwise XOR the value of other and the value of this
   * @param SassNumber value to bitwise XOR with
   * @return string result
   * @throws Exception if bitwise XOR not supported for the data type
   */
  public function op_bw_xor($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise XOR', SassScriptParser::$context->node);
  }

  /**
   * Bitwise NOT the value of other and the value of this
   * @param SassNumber value to bitwise NOT with
   * @return string result
   * @throws Exception if bitwise NOT not supported for the data type
   */
  public function op_bw_not() {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise NOT', SassScriptParser::$context->node);
  }

  /**
   * Shifts the value of this left by the number of bits given in value
   * @param SassNumber amount to shift left by
   * @return string result
   * @throws Exception if bitwise Shift Left not supported for the data type
   */
  public function op_shiftl($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise Shift Left', SassScriptParser::$context->node);
  }

  /**
   * Shifts the value of this right by the number of bits given in value
   * @param SassNumber amount to shift right by
   * @return string result
   * @throws Exception if bitwise Shift Right not supported for the data type
   */
  public function op_shiftr($other) {
    throw new SassLiteralException(get_class($this) . ' does not support Bitwise Shift Right', SassScriptParser::$context->node);
  }

  /**
   * The SassScript and operation.
   * @param sassLiteral the value to and with this
   * @return SassLiteral other if this is boolean true, this if false
   */
  public function op_and($other) {
    return ($this->toBoolean() ? $other : $this);
  }

  /**
   * The SassScript or operation.
   * @param sassLiteral the value to or with this
   * @return SassLiteral this if this is boolean true, other if false
   */
  public function op_or($other) {
    return ($this->toBoolean() ? $this : $other);
  }

    public function op_assign($other) {
        return $other;
    }

  /**
   * The SassScript xor operation.
   * @param sassLiteral the value to xor with this
   * @return SassBoolean SassBoolean object with the value true if this or
   * other, but not both, are true, false if not
   */
  public function op_xor($other) {
    return new SassBoolean($this->toBoolean() xor $other->toBoolean());
  }

  /**
   * The SassScript not operation.
   * @return SassBoolean SassBoolean object with the value true if the
   * boolean of this is false or false if it is true
   */
  public function op_not() {
    return new SassBoolean(!$this->toBoolean());
  }

  /**
   * The SassScript > operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if the values
   * of this is greater than the value of other, false if it is not
   */
  public function op_gt($other) {
    return new SassBoolean($this->value > $other->value);
  }

  /**
   * The SassScript >= operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if the values
   * of this is greater than or equal to the value of other, false if it is not
   */
  public function op_gte($other) {
    return new SassBoolean($this->value >= $other->value);
  }

  /**
   * The SassScript < operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if the values
   * of this is less than the value of other, false if it is not
   */
  public function op_lt($other) {
    return new SassBoolean($this->value < $other->value);
  }

  /**
   * The SassScript <= operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if the values
   * of this is less than or equal to the value of other, false if it is not
   */
  public function op_lte($other) {
    return new SassBoolean($this->value <= $other->value);
  }

  /**
   * The SassScript == operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if this and
   * other are equal, false if they are not
   */
  public function op_eq($other) {
    return new SassBoolean($this == $other);
  }

  /**
   * The SassScript != operation.
   * @param sassLiteral the value to compare to this
   * @return SassBoolean SassBoolean object with the value true if this and
   * other are not equal, false if they are
   */
  public function op_neq($other) {
    return new SassBoolean(!$this->op_eq($other)->toBoolean());
  }

  /**
   * The SassScript default operation (e.g. $a $b, "foo" "bar").
   * @param sassLiteral the value to concatenate with a space to this
   * @return sassString the string values of this and other seperated by " "
   */
  public function op_concat($other) {
    return new SassString($this->toString().' '.$other->toString());
  }

  /**
   * SassScript ',' operation.
   * @param sassLiteral the value to concatenate with a comma to this
   * @return sassString the string values of this and other seperated by ","
   */
  public function op_comma($other) {
    return new SassString($this->toString().', '.$other->toString());
  }

  /**
   * Asserts that the literal is the expected type
   * @param SassLiteral the literal to test
   * @param string expected type
   * @throws SassScriptFunctionException if value is not the expected type
   */
  public static function assertType($literal, $type) {
    if (!$literal instanceof $type) {
      throw new SassScriptFunctionException(($literal instanceof SassLiteral ? get_class($literal) : 'literal') . ' must be a ' . $type, SassScriptParser::$context->node);
    }
  }

  /**
   * Asserts that the value of a literal is within the expected range
   * @param SassLiteral the literal to test
   * @param float the minimum value
   * @param float the maximum value
   * @param string the units.
   * @throws SassScriptFunctionException if value is not the expected type
   */
   public static function assertInRange($literal, $min, $max, $units = '') {
      if ($literal->value < $min || $literal->value > $max) {
      throw new SassScriptFunctionException($literal->typeOf . ' must be between ' . $min.$units . ' and ' . $max.$units . ' inclusive', SassScriptParser::$context->node);
    }
  }

  /**
   * Returns a string representation of the value.
   * @return string string representation of the value.
   */
  abstract public function toString();

  public function render() {
    return $this->toString();
  }

  /**
   * Returns a value indicating if a token of this type can be matched at
   * the start of the subject string.
   * @param string the subject string
   * @return mixed match at the start of the string or false if no match
   */
  public static function isa($subject){
    throw new SassLiteralException('Child classes must override this method');
  }
}
