I18N: Introduce the `Plural_Forms` class.
Historically, we've evaluated the plural forms for each language using `create_function()`. This is being deprecated in PHP 7.2, so needs to be replaced. The `Plural_Forms` class parses the `Plural-Forms` header from the PO file, and internally caches the result of all subsequent plural form tests, allowing it to match the performance of the existing code. Props rmccue. Fixes #41562. Built from https://develop.svn.wordpress.org/trunk@41722 git-svn-id: http://core.svn.wordpress.org/trunk@41556 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Gary Pendergast
parent
5f7a5c1246
commit
0a3b7d8e31
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<?php
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/**
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* A gettext Plural-Forms parser.
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*
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* @since 4.9.0
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*/
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class Plural_Forms {
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/**
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* Operator characters.
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*
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* @since 4.9.0
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* @var string OP_CHARS Operator characters.
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*/
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const OP_CHARS = '|&><!=%?:';
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/**
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* Valid number characters.
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*
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* @since 4.9.0
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* @var string NUM_CHARS Valid number characters.
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*/
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const NUM_CHARS = '0123456789';
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/**
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* Operator precedence.
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*
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* Operator precedence from highest to lowest. Higher numbers indicate
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* higher precedence, and are executed first.
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*
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* @see https://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B#Operator_precedence
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*
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* @since 4.9.0
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* @var array $op_precedence Operator precedence from highest to lowest.
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*/
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protected static $op_precedence = array(
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'%' => 6,
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'<' => 5,
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'<=' => 5,
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'>' => 5,
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'>=' => 5,
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'==' => 4,
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'!=' => 4,
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'&&' => 3,
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'||' => 2,
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'?:' => 1,
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'?' => 1,
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'(' => 0,
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')' => 0,
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);
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/**
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* Tokens generated from the string.
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*
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* @since 4.9.0
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* @var array $tokens List of tokens.
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*/
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protected $tokens = array();
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/**
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* Cache for repeated calls to the function.
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*
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* @since 4.9.0
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* @var array $cache Map of $n => $result
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*/
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protected $cache = [];
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/**
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* Constructor.
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*
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* @since 4.9.0
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*
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* @param string $str Plural function (just the bit after `plural=` from Plural-Forms)
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*/
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public function __construct( $str ) {
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$this->parse( $str );
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}
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/**
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* Parse a Plural-Forms string into tokens.
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*
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* Uses the shunting-yard algorithm to convert the string to Reverse Polish
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* Notation tokens.
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*
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* @since 4.9.0
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*
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* @param string $str String to parse.
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*/
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protected function parse( $str ) {
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$pos = 0;
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$len = strlen( $str );
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// Convert infix operators to postfix using the shunting-yard algorithm.
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$output = array();
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$stack = array();
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while ( $pos < $len ) {
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$next = substr( $str, $pos, 1 );
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switch ( $next ) {
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// Ignore whitespace
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case ' ':
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case "\t":
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$pos++;
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break;
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// Variable (n)
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case 'n':
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$output[] = [ 'var' ];
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$pos++;
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break;
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// Parentheses
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case '(':
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$stack[] = $next;
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$pos++;
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break;
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case ')':
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$found = false;
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while ( ! empty( $stack ) ) {
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$o2 = $stack[ count( $stack ) - 1 ];
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if ( $o2 !== '(' ) {
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$output[] = [ 'op', array_pop( $stack ) ];
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continue;
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}
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// Discard open paren.
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array_pop( $stack );
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$found = true;
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break;
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}
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if ( ! $found ) {
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throw new Exception( 'Mismatched parentheses' );
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}
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$pos++;
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break;
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// Operators
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case '|':
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case '&':
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case '>':
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case '<':
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case '!':
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case '=':
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case '%':
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case '?':
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$end_operator = strspn( $str, self::OP_CHARS, $pos );
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$operator = substr( $str, $pos, $end_operator );
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if ( ! array_key_exists( $operator, self::$op_precedence ) ) {
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throw new Exception( sprintf( 'Unknown operator "%s"', $operator ) );
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}
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while ( ! empty( $stack ) ) {
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$o2 = $stack[ count( $stack ) - 1 ];
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// Ternary is right-associative in C
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if ( $operator === '?:' || $operator === '?' ) {
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if ( self::$op_precedence[ $operator ] >= self::$op_precedence[ $o2 ] ) {
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break;
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}
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} elseif ( self::$op_precedence[ $operator ] > self::$op_precedence[ $o2 ] ) {
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break;
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}
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$output[] = [ 'op', array_pop( $stack ) ];
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}
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$stack[] = $operator;
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$pos += $end_operator;
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break;
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// Ternary "else"
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case ':':
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$found = false;
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$s_pos = count( $stack ) - 1;
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while ( $s_pos >= 0 ) {
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$o2 = $stack[ $s_pos ];
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if ( $o2 !== '?' ) {
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$output[] = [ 'op', array_pop( $stack ) ];
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$s_pos--;
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continue;
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}
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// Replace.
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$stack[ $s_pos ] = '?:';
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$found = true;
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break;
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}
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if ( ! $found ) {
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throw new Exception( 'Missing starting "?" ternary operator' );
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}
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$pos++;
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break;
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// Default - number or invalid
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default:
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if ( $next >= '0' && $next <= '9' ) {
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$span = strspn( $str, self::NUM_CHARS, $pos );
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$output[] = [ 'value', intval( substr( $str, $pos, $span ) ) ];
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$pos += $span;
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continue;
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}
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throw new Exception( sprintf( 'Unknown symbol "%s"', $next ) );
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}
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}
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while ( ! empty( $stack ) ) {
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$o2 = array_pop( $stack );
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if ( $o2 === '(' || $o2 === ')' ) {
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throw new Exception( 'Mismatched parentheses' );
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}
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$output[] = [ 'op', $o2 ];
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}
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$this->tokens = $output;
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}
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/**
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* Get the plural form for a number.
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*
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* Caches the value for repeated calls.
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*
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* @since 4.9.0
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*
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* @param int $num Number to get plural form for.
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* @return int Plural form value.
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*/
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public function get( $num ) {
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if ( isset( $this->cache[ $num ] ) ) {
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return $this->cache[ $num ];
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}
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return $this->cache[ $num ] = $this->execute( $num );
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}
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/**
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* Execute the plural form function.
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*
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* @since 4.9.0
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*
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* @param int $n Variable "n" to substitute.
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* @return int Plural form value.
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*/
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public function execute( $n ) {
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$stack = array();
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$i = 0;
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$total = count( $this->tokens );
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while ( $i < $total ) {
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$next = $this->tokens[$i];
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$i++;
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if ( $next[0] === 'var' ) {
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$stack[] = $n;
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continue;
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} elseif ( $next[0] === 'value' ) {
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$stack[] = $next[1];
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continue;
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}
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// Only operators left.
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switch ( $next[1] ) {
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case '%':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 % $v2;
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break;
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case '||':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 || $v2;
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break;
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case '&&':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 && $v2;
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break;
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case '<':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 < $v2;
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break;
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case '<=':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 <= $v2;
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break;
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case '>':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 > $v2;
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break;
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case '>=':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 >= $v2;
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break;
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case '!=':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 != $v2;
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break;
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case '==':
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 == $v2;
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break;
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case '?:':
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$v3 = array_pop( $stack );
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$v2 = array_pop( $stack );
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$v1 = array_pop( $stack );
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$stack[] = $v1 ? $v2 : $v3;
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break;
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default:
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throw new Exception( sprintf( 'Unknown operator "%s"', $next[1] ) );
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}
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}
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if ( count( $stack ) !== 1 ) {
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throw new Exception( 'Too many values remaining on the stack' );
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}
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return (int) $stack[0];
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}
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}
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@ -7,6 +7,7 @@
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* @subpackage translations
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*/
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require_once dirname(__FILE__) . '/plural-forms.php';
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require_once dirname(__FILE__) . '/entry.php';
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if ( ! class_exists( 'Translations', false ) ):
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@ -187,7 +188,7 @@ class Gettext_Translations extends Translations {
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function nplurals_and_expression_from_header($header) {
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if (preg_match('/^\s*nplurals\s*=\s*(\d+)\s*;\s+plural\s*=\s*(.+)$/', $header, $matches)) {
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$nplurals = (int)$matches[1];
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$expression = trim($this->parenthesize_plural_exression($matches[2]));
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$expression = trim( $matches[2] );
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return array($nplurals, $expression);
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} else {
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return array(2, 'n != 1');
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@ -201,11 +202,13 @@ class Gettext_Translations extends Translations {
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* @param string $expression
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*/
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function make_plural_form_function($nplurals, $expression) {
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$expression = str_replace('n', '$n', $expression);
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$func_body = "
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\$index = (int)($expression);
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return (\$index < $nplurals)? \$index : $nplurals - 1;";
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return create_function('$n', $func_body);
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try {
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$handler = new Plural_Forms( rtrim( $expression, ';' ) );
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return array( $handler, 'get' );
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} catch ( Exception $e ) {
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// Fall back to default plural-form function.
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return $this->make_plural_form_function( 2, 'n != 1' );
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}
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}
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/**
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@ -4,7 +4,7 @@
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*
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* @global string $wp_version
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*/
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$wp_version = '4.9-alpha-41721';
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$wp_version = '4.9-alpha-41722';
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/**
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* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
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