JezK
Edit File: plural-forms.php
<?php /** * A gettext Plural-Forms parser. * * @since 4.9.0 */ if ( ! class_exists( 'Plural_Forms', false ) ) : #[AllowDynamicProperties] class Plural_Forms { /** * Operator characters. * * @since 4.9.0 * @var string OP_CHARS Operator characters. */ const OP_CHARS = '|&><!=%?:'; /** * Valid number characters. * * @since 4.9.0 * @var string NUM_CHARS Valid number characters. */ const NUM_CHARS = '0123456789'; /** * Operator precedence. * * Operator precedence from highest to lowest. Higher numbers indicate * higher precedence, and are executed first. * * @see https://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B#Operator_precedence * * @since 4.9.0 * @var array $op_precedence Operator precedence from highest to lowest. */ protected static $op_precedence = array( '%' => 6, '<' => 5, '<=' => 5, '>' => 5, '>=' => 5, '==' => 4, '!=' => 4, '&&' => 3, '||' => 2, '?:' => 1, '?' => 1, '(' => 0, ')' => 0, ); /** * Tokens generated from the string. * * @since 4.9.0 * @var array $tokens List of tokens. */ protected $tokens = array(); /** * Cache for repeated calls to the function. * * @since 4.9.0 * @var array $cache Map of $n => $result */ protected $cache = array(); /** * Constructor. * * @since 4.9.0 * * @param string $str Plural function (just the bit after `plural=` from Plural-Forms) */ public function __construct( $str ) { $this->parse( $str ); } /** * Parse a Plural-Forms string into tokens. * * Uses the shunting-yard algorithm to convert the string to Reverse Polish * Notation tokens. * * @since 4.9.0 * * @throws Exception If there is a syntax or parsing error with the string. * * @param string $str String to parse. */ protected function parse( $str ) { $pos = 0; $len = strlen( $str ); // Convert infix operators to postfix using the shunting-yard algorithm. $output = array(); $stack = array(); while ( $pos < $len ) { $next = substr( $str, $pos, 1 ); switch ( $next ) { // Ignore whitespace. case ' ': case "\t": ++$pos; break; // Variable (n). case 'n': $output[] = array( 'var' ); ++$pos; break; // Parentheses. case '(': $stack[] = $next; ++$pos; break; case ')': $found = false; while ( ! empty( $stack ) ) { $o2 = array_last( $stack ); if ( '(' !== $o2 ) { $output[] = array( 'op', array_pop( $stack ) ); continue; } // Discard open paren. array_pop( $stack ); $found = true; break; } if ( ! $found ) { throw new Exception( 'Mismatched parentheses' ); } ++$pos; break; // Operators. case '|': case '&': case '>': case '<': case '!': case '=': case '%': case '?': $end_operator = strspn( $str, self::OP_CHARS, $pos ); $operator = substr( $str, $pos, $end_operator ); if ( ! array_key_exists( $operator, self::$op_precedence ) ) { throw new Exception( sprintf( 'Unknown operator "%s"', $operator ) ); } while ( ! empty( $stack ) ) { $o2 = array_last( $stack ); // Ternary is right-associative in C. if ( '?:' === $operator || '?' === $operator ) { if ( self::$op_precedence[ $operator ] >= self::$op_precedence[ $o2 ] ) { break; } } elseif ( self::$op_precedence[ $operator ] > self::$op_precedence[ $o2 ] ) { break; } $output[] = array( 'op', array_pop( $stack ) ); } $stack[] = $operator; $pos += $end_operator; break; // Ternary "else". case ':': $found = false; $s_pos = count( $stack ) - 1; while ( $s_pos >= 0 ) { $o2 = $stack[ $s_pos ]; if ( '?' !== $o2 ) { $output[] = array( 'op', array_pop( $stack ) ); --$s_pos; continue; } // Replace. $stack[ $s_pos ] = '?:'; $found = true; break; } if ( ! $found ) { throw new Exception( 'Missing starting "?" ternary operator' ); } ++$pos; break; // Default - number or invalid. default: if ( $next >= '0' && $next <= '9' ) { $span = strspn( $str, self::NUM_CHARS, $pos ); $output[] = array( 'value', intval( substr( $str, $pos, $span ) ) ); $pos += $span; break; } throw new Exception( sprintf( 'Unknown symbol "%s"', $next ) ); } } while ( ! empty( $stack ) ) { $o2 = array_pop( $stack ); if ( '(' === $o2 || ')' === $o2 ) { throw new Exception( 'Mismatched parentheses' ); } $output[] = array( 'op', $o2 ); } $this->tokens = $output; } /** * Get the plural form for a number. * * Caches the value for repeated calls. * * @since 4.9.0 * * @param int $num Number to get plural form for. * @return int Plural form value. */ public function get( $num ) { if ( isset( $this->cache[ $num ] ) ) { return $this->cache[ $num ]; } $this->cache[ $num ] = $this->execute( $num ); return $this->cache[ $num ]; } /** * Execute the plural form function. * * @since 4.9.0 * * @throws Exception If the plural form value cannot be calculated. * * @param int $n Variable "n" to substitute. * @return int Plural form value. */ public function execute( $n ) { $stack = array(); $i = 0; $total = count( $this->tokens ); while ( $i < $total ) { $next = $this->tokens[ $i ]; ++$i; if ( 'var' === $next[0] ) { $stack[] = $n; continue; } elseif ( 'value' === $next[0] ) { $stack[] = $next[1]; continue; } // Only operators left. switch ( $next[1] ) { case '%': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 % $v2; break; case '||': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 || $v2; break; case '&&': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 && $v2; break; case '<': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 < $v2; break; case '<=': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 <= $v2; break; case '>': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 > $v2; break; case '>=': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 >= $v2; break; case '!=': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 !== $v2; break; case '==': $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 === $v2; break; case '?:': $v3 = array_pop( $stack ); $v2 = array_pop( $stack ); $v1 = array_pop( $stack ); $stack[] = $v1 ? $v2 : $v3; break; default: throw new Exception( sprintf( 'Unknown operator "%s"', $next[1] ) ); } } if ( count( $stack ) !== 1 ) { throw new Exception( 'Too many values remaining on the stack' ); } return (int) $stack[0]; } } endif;