Summery Summery
Parse a Plural-Forms string into tokens.
Syntax Syntax
Description Description
Uses the shunting-yard algorithm to convert the string to Reverse Polish Notation tokens.
Parameters Parameters
- $str
-
(Required) String to parse.
Source Source
File: wp-includes/pomo/plural-forms.php
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 = $stack[ count( $stack ) - 1 ]; 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 = $stack[ count( $stack ) - 1 ]; // 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; }
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Changelog Changelog
Version | Description |
---|---|
4.9.0 | Introduced. |