mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/ParserFunctions
synced 2024-11-15 11:59:54 +00:00
430 lines
11 KiB
PHP
430 lines
11 KiB
PHP
<?php
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if ( !defined( 'MEDIAWIKI' ) ) {
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die( 'This file is a MediaWiki extension, it is not a valid entry point' );
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}
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// Character classes
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define( 'EXPR_WHITE_CLASS', " \t\r\n" );
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define( 'EXPR_NUMBER_CLASS', '0123456789.' );
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// Token types
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define( 'EXPR_WHITE', 1 );
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define( 'EXPR_NUMBER', 2 );
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define( 'EXPR_NEGATIVE', 3 );
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define( 'EXPR_POSITIVE', 4 );
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define( 'EXPR_PLUS', 5 );
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define( 'EXPR_MINUS', 6 );
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define( 'EXPR_TIMES', 7 );
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define( 'EXPR_DIVIDE', 8 );
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define( 'EXPR_MOD', 9 );
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define( 'EXPR_OPEN', 10 );
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define( 'EXPR_CLOSE', 11 );
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define( 'EXPR_AND', 12 );
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define( 'EXPR_OR', 13 );
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define( 'EXPR_NOT', 14 );
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define( 'EXPR_EQUALITY', 15 );
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define( 'EXPR_LESS', 16 );
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define( 'EXPR_GREATER', 17 );
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define( 'EXPR_LESSEQ', 18 );
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define( 'EXPR_GREATEREQ', 19 );
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define( 'EXPR_NOTEQ', 20 );
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define( 'EXPR_ROUND', 21 );
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class ExprParser {
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var $maxStackSize = 1000;
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var $precedence = array(
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EXPR_NEGATIVE => 9,
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EXPR_POSITIVE => 9,
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EXPR_NOT => 9,
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EXPR_TIMES => 8,
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EXPR_DIVIDE => 8,
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EXPR_MOD => 8,
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EXPR_PLUS => 6,
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EXPR_MINUS => 6,
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EXPR_ROUND => 5,
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EXPR_EQUALITY => 4,
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EXPR_LESS => 4,
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EXPR_GREATER => 4,
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EXPR_LESSEQ => 4,
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EXPR_GREATEREQ => 4,
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EXPR_NOTEQ => 4,
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EXPR_AND => 3,
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EXPR_OR => 2,
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EXPR_OPEN => -1,
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EXPR_CLOSE => -1
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);
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var $names = array(
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EXPR_NEGATIVE => '-',
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EXPR_POSITIVE => '+',
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EXPR_NOT => 'not',
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EXPR_TIMES => '*',
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EXPR_DIVIDE => '/',
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EXPR_MOD => 'mod',
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EXPR_PLUS => '+',
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EXPR_MINUS => '-',
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EXPR_ROUND => 'round',
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EXPR_EQUALITY => '=',
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EXPR_LESS => '<',
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EXPR_GREATER => '>',
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EXPR_LESSEQ => '<=',
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EXPR_GREATEREQ => '>=',
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EXPR_NOTEQ => '<>',
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EXPR_AND => 'and',
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EXPR_OR => 'or',
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);
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var $words = array(
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'mod' => EXPR_MOD,
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'and' => EXPR_AND,
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'or' => EXPR_OR,
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'not' => EXPR_NOT,
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'round' => EXPR_ROUND,
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);
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/**
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* Add expression messages to the message cache
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* @static
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*/
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function addMessages() {
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global $wgMessageCache;
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$wgMessageCache->addMessages( array(
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'expr_stack_exhausted' => 'Expression error: stack exhausted',
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'expr_unexpected_number' => 'Expression error: unexpected number',
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'expr_preg_match_failure' => 'Expression error: unexpected preg_match failure',
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'expr_unrecognised_word' => 'Expression error: unrecognised word "$1"',
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'expr_unexpected_operator' => 'Expression error: unexpected $1 operator',
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'expr_missing_operand' => 'Expression error: Missing operand for $1',
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'expr_unexpected_closing_bracket' => 'Expression error: unexpected closing bracket',
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'expr_unrecognised_punctuation' => 'Expression error: unrecognised punctuation character "$1"',
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'expr_unclosed_bracket' => 'Expression error: unclosed bracket',
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));
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}
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function error( $msg, $parameter = false ) {
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$this->lastErrorKey = $msg;
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$this->lastErrorParameter = $parameter;
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if ( $parameter === false ) {
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$this->lastErrorMessage = wfMsg( "expr_$msg" );
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} else {
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$this->lastErrorMessage = wfMsg( "expr_$msg", htmlspecialchars( $parameter ) );
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}
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}
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/**
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* Evaluate a mathematical expression
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*
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* The algorithm here is based on the infix to RPN algorithm given in
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* http://montcs.bloomu.edu/~bobmon/Information/RPN/infix2rpn.shtml
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* It's essentially the same as Dijkstra's shunting yard algorithm.
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*/
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function doExpression( $expr ) {
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$operands = array();
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$operators = array();
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# Unescape inequality operators
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$expr = strtr( $expr, array( '<' => '<', '>' => '>' ) );
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$p = 0;
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$end = strlen( $expr );
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$expecting = 'expression';
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while ( $p < $end ) {
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if ( count( $operands ) > $this->maxStackSize || count( $operands ) > $this->maxStackSize ) {
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$this->error( 'stack_exhausted' );
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}
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$char = $expr[$p];
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$char2 = substr( $expr, $p, 2 );
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// Mega if-elseif-else construct
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// Only binary operators fall through for processing at the bottom, the rest
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// finish their processing and continue
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// First the unlimited length classes
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if ( false !== strpos( EXPR_WHITE_CLASS, $char ) ) {
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// Whitespace
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$p += strspn( $expr, EXPR_WHITE_CLASS, $p );
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continue;
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} elseif ( false !== strpos( EXPR_NUMBER_CLASS, $char ) ) {
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// Number
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if ( $expecting != 'expression' ) {
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$this->error( 'unexpected_number' );
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return false;
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}
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// Find the rest of it
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$length = strspn( $expr, EXPR_NUMBER_CLASS, $p );
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// Convert it to float, silently removing double decimal points
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$operands[] = floatval( substr( $expr, $p, $length ) );
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$p += $length;
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$expecting = 'operator';
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continue;
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} elseif ( ctype_alpha( $char ) ) {
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// Word
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// Find the rest of it
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$remaining = substr( $expr, $p );
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if ( !preg_match( '/^[A-Za-z]*/', $remaining, $matches ) ) {
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// This should be unreachable
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$this->error( 'preg_match_failure' );
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return false;
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}
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$word = strtolower( $matches[0] );
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$p += strlen( $word );
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// Interpret the word
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if ( !isset( $this->words[$word] ) ){
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$this->error( 'unrecognised_word', $word );
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return false;
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}
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$op = $this->words[$word];
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if ( $op == EXPR_NOT ) {
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// Unary operator
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if ( $expecting != 'expression' ) {
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$this->error( 'unexpected_operator', $word );
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return false;
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}
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$operators[] = $op;
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continue;
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}
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// Binary operator, fall through
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$name = $word;
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}
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// Next the two-character operators
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elseif ( $char2 == '<=' ) {
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$name = $char2;
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$op = EXPR_LESSEQ;
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$p += 2;
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} elseif ( $char2 == '>=' ) {
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$name = $char2;
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$op = EXPR_GREATEREQ;
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$p += 2;
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} elseif ( $char2 == '<>' || $char2 == '!=' ) {
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$name = $char2;
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$op = EXPR_NOTEQ;
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$p += 2;
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}
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// Finally the single-character operators
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elseif ( $char == '+' ) {
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++$p;
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if ( $expecting == 'expression' ) {
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// Unary plus
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$operators[] = EXPR_POSITIVE;
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continue;
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} else {
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// Binary plus
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$op = EXPR_PLUS;
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}
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} elseif ( $char == '-' ) {
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++$p;
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if ( $expecting == 'expression' ) {
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// Unary minus
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$operators[] = EXPR_NEGATIVE;
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continue;
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} else {
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// Binary minus
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$op = EXPR_MINUS;
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}
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} elseif ( $char == '*' ) {
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$name = $char;
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$op = EXPR_TIMES;
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++$p;
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} elseif ( $char == '/' ) {
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$name = $char;
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$op = EXPR_DIVIDE;
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++$p;
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} elseif ( $char == '(' ) {
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if ( $expecting == 'operator' ) {
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$this->error( 'unexpected_operator', '(' );
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return false;
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}
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$operators[] = EXPR_OPEN;
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++$p;
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continue;
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} elseif ( $char == ')' ) {
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$lastOp = end( $operators );
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while ( $lastOp && $lastOp != EXPR_OPEN ) {
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if ( !$this->doOperation( $lastOp, $operands ) ) {
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$this->error( 'missing_operand', $this->names[$lastOp] );
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return false;
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}
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array_pop( $operators );
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$lastOp = end( $operators );
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}
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if ( $lastOp ) {
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array_pop( $operators );
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} else {
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$this->error( "unexpected_closing_bracket" );
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return false;
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}
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$expecting = 'operator';
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++$p;
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continue;
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} elseif ( $char == '=' ) {
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$name = $char;
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$op = EXPR_EQUALITY;
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++$p;
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} elseif ( $char == '<' ) {
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$name = $char;
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$op = EXPR_LESS;
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++$p;
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} elseif ( $char == '>' ) {
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$name = $char;
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$op = EXPR_GREATER;
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++$p;
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} else {
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$this->error( 'unrecognised_punctuation', $char );
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return false;
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}
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// Binary operator processing
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if ( $expecting == 'expression' ) {
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$this->error( 'unexpected_operator', $name );
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return false;
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}
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// Shunting yard magic
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$lastOp = end( $operators );
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while ( $lastOp && $this->precedence[$op] <= $this->precedence[$lastOp] ) {
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if ( !$this->doOperation( $lastOp, $operands ) ) {
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$this->error( 'missing_operand', $this->names[$lastOp] );
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return false;
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}
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array_pop( $operators );
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$lastOp = end( $operators );
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}
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$operators[] = $op;
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$expecting = 'expression';
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}
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// Finish off the operator array
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while ( $op = array_pop( $operators ) ) {
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if ( $op == EXPR_OPEN ) {
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$this->error( 'unclosed_bracket' );
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return false;
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}
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if ( !$this->doOperation( $op, $operands ) ) {
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$this->error( 'missing_operand', $this->names[$op] );
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return false;
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}
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}
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return implode( "<br/>\n", $operands );
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}
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function doOperation( $op, &$stack ) {
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switch ( $op ) {
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case EXPR_NEGATIVE:
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if ( count( $stack ) < 1 ) return false;
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$arg = array_pop( $stack );
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$stack[] = -$arg;
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break;
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case EXPR_POSITIVE:
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if ( count( $stack ) < 1 ) return false;
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break;
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case EXPR_TIMES:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = $left * $right;
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break;
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case EXPR_DIVIDE:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = $left / $right;
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break;
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case EXPR_MOD:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = $left % $right;
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break;
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case EXPR_PLUS:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = $left + $right;
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break;
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case EXPR_MINUS:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = $left - $right;
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break;
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case EXPR_AND:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left && $right ) ? 1 : 0;
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break;
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case EXPR_OR:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left || $right ) ? 1 : 0;
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break;
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case EXPR_EQUALITY:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left == $right ) ? 1 : 0;
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break;
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case EXPR_NOT:
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if ( count( $stack ) < 1 ) return false;
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$arg = array_pop( $stack );
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$stack[] = (!$arg) ? 1 : 0;
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break;
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case EXPR_ROUND:
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if ( count( $stack ) < 2 ) return false;
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$digits = intval( array_pop( $stack ) );
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$value = array_pop( $stack );
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$stack[] = round( $value, $digits );
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break;
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case EXPR_LESS:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left < $right ) ? 1 : 0;
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break;
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case EXPR_GREATER:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left > $right ) ? 1 : 0;
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break;
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case EXPR_LESSEQ:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left <= $right ) ? 1 : 0;
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break;
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case EXPR_GREATEREQ:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left >= $right ) ? 1 : 0;
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break;
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case EXPR_NOTEQ:
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if ( count( $stack ) < 2 ) return false;
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$right = array_pop( $stack );
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$left = array_pop( $stack );
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$stack[] = ( $left != $right ) ? 1 : 0;
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break;
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}
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return true;
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}
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}
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?>
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