<?php
/**
* Zend Framework (http://framework.zend.com/)
*
* @link http://github.com/zendframework/zf2 for the canonical source repository
* @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
*/
namespace Zend\I18n\Translator\Plural;
use Zend\I18n\Exception;
/**
* Plural rule evaluator.
*/
class Rule
{
/**
* Parser instance.
*
* @var Parser
*/
protected static $parser;
/**
* Abstract syntax tree.
*
* @var array
*/
protected $ast;
/**
* Number of plurals in this rule.
*
* @var int
*/
protected $numPlurals;
/**
* Create a new plural rule.
*
* @param int $numPlurals
* @param array $ast
* @return Rule
*/
protected function __construct($numPlurals, array $ast)
{
$this->numPlurals = $numPlurals;
$this->ast = $ast;
}
/**
* Evaluate a number and return the plural index.
*
* @param int $number
* @return int
* @throws Exception\RangeException
*/
public function evaluate($number)
{
$result = $this->evaluateAstPart($this->ast, abs((int) $number));
if ($result < 0 || $result >= $this->numPlurals) {
throw new Exception\RangeException(sprintf(
'Calculated result %s is between 0 and %d',
$result, ($this->numPlurals - 1)
));
}
return $result;
}
/**
* Get number of possible plural forms.
*
* @return int
*/
public function getNumPlurals()
{
return $this->numPlurals;
}
/**
* Evaluate a part of an ast.
*
* @param array $ast
* @param int $number
* @return int
* @throws Exception\ParseException
*/
protected function evaluateAstPart(array $ast, $number)
{
switch ($ast['id']) {
case 'number':
return $ast['arguments'][0];
case 'n':
return $number;
case '+':
return $this->evaluateAstPart($ast['arguments'][0], $number)
+ $this->evaluateAstPart($ast['arguments'][1], $number);
case '-':
return $this->evaluateAstPart($ast['arguments'][0], $number)
- $this->evaluateAstPart($ast['arguments'][1], $number);
case '/':
// Integer division
return floor(
$this->evaluateAstPart($ast['arguments'][0], $number)
/ $this->evaluateAstPart($ast['arguments'][1], $number)
);
case '*':
return $this->evaluateAstPart($ast['arguments'][0], $number)
* $this->evaluateAstPart($ast['arguments'][1], $number);
case '%':
return $this->evaluateAstPart($ast['arguments'][0], $number)
% $this->evaluateAstPart($ast['arguments'][1], $number);
case '>':
return $this->evaluateAstPart($ast['arguments'][0], $number)
> $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '>=':
return $this->evaluateAstPart($ast['arguments'][0], $number)
>= $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '<':
return $this->evaluateAstPart($ast['arguments'][0], $number)
< $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '<=':
return $this->evaluateAstPart($ast['arguments'][0], $number)
<= $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '==':
return $this->evaluateAstPart($ast['arguments'][0], $number)
== $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '!=':
return $this->evaluateAstPart($ast['arguments'][0], $number)
!= $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '&&':
return $this->evaluateAstPart($ast['arguments'][0], $number)
&& $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '||':
return $this->evaluateAstPart($ast['arguments'][0], $number)
|| $this->evaluateAstPart($ast['arguments'][1], $number)
? 1 : 0;
case '!':
return !$this->evaluateAstPart($ast['arguments'][0], $number)
? 1 : 0;
case '?':
return $this->evaluateAstPart($ast['arguments'][0], $number)
? $this->evaluateAstPart($ast['arguments'][1], $number)
: $this->evaluateAstPart($ast['arguments'][2], $number);
default:
throw new Exception\ParseException(sprintf(
'Unknown token: %s',
$ast['id']
));
}
}
/**
* Create a new rule from a string.
*
* @param string $string
* @throws Exception\ParseException
* @return Rule
*/
public static function fromString($string)
{
if (static::$parser === null) {
static::$parser = new Parser();
}
if (!preg_match('(nplurals=(?P<nplurals>\d+))', $string, $match)) {
throw new Exception\ParseException(sprintf(
'Unknown or invalid parser rule: %s',
$string
));
}
$numPlurals = (int) $match['nplurals'];
if (!preg_match('(plural=(?P<plural>[^;\n]+))', $string, $match)) {
throw new Exception\ParseException(sprintf(
'Unknown or invalid parser rule: %s',
$string
));
}
$tree = static::$parser->parse($match['plural']);
$ast = static::createAst($tree);
return new static($numPlurals, $ast);
}
/**
* Create an AST from a tree.
*
* Theoretically we could just use the given Symbol, but that one is not
* so easy to serialize and also takes up more memory.
*
* @param Symbol $symbol
* @return array
*/
protected static function createAst(Symbol $symbol)
{
$ast = array('id' => $symbol->id, 'arguments' => array());
switch ($symbol->id) {
case 'n':
break;
case 'number':
$ast['arguments'][] = $symbol->value;
break;
case '!':
$ast['arguments'][] = static::createAst($symbol->first);
break;
case '?':
$ast['arguments'][] = static::createAst($symbol->first);
$ast['arguments'][] = static::createAst($symbol->second);
$ast['arguments'][] = static::createAst($symbol->third);
break;
default:
$ast['arguments'][] = static::createAst($symbol->first);
$ast['arguments'][] = static::createAst($symbol->second);
break;
}
return $ast;
}
}