--- /dev/null
+<?php
+/**
+ * @author Tim Starling
+ * @author Niklas Laxström
+ * @license GPL-2.0+
+ * @file
+ */
+
+namespace CLDRPluralRuleParser;
+
+/**
+ * Parse and evaluate a plural rule.
+ *
+ * UTS #35 Revision 33
+ * http://www.unicode.org/reports/tr35/tr35-33/tr35-numbers.html#Language_Plural_Rules
+ */
+class Evaluator {
+ /**
+ * Evaluate a number against a set of plural rules. If a rule passes,
+ * return the index of plural rule.
+ *
+ * @param int $number The number to be evaluated against the rules
+ * @param array $rules The associative array of plural rules in pluralform => rule format.
+ * @return int The index of the plural form which passed the evaluation
+ */
+ public static function evaluate( $number, array $rules ) {
+ $rules = self::compile( $rules );
+
+ return self::evaluateCompiled( $number, $rules );
+ }
+
+ /**
+ * Convert a set of rules to a compiled form which is optimised for
+ * fast evaluation. The result will be an array of strings, and may be cached.
+ *
+ * @param array $rules The rules to compile
+ * @return array An array of compile rules.
+ */
+ public static function compile( array $rules ) {
+ // We can't use array_map() for this because it generates a warning if
+ // there is an exception.
+ foreach ( $rules as &$rule ) {
+ $rule = Converter::convert( $rule );
+ }
+
+ return $rules;
+ }
+
+ /**
+ * Evaluate a compiled set of rules returned by compile(). Do not allow
+ * the user to edit the compiled form, or else PHP errors may result.
+ *
+ * @param string $number The number to be evaluated against the rules, in English, or it
+ * may be a type convertible to string.
+ * @param array $rules The associative array of plural rules in pluralform => rule format.
+ * @return int The index of the plural form which passed the evaluation
+ */
+ public static function evaluateCompiled( $number, array $rules ) {
+ // Calculate the values of the operand symbols
+ $number = strval( $number );
+ if ( !preg_match( '/^ -? ( ([0-9]+) (?: \. ([0-9]+) )? )$/x', $number, $m ) ) {
+ wfDebug( __METHOD__ . ": invalid number input, returning 'other'\n" );
+
+ return count( $rules );
+ }
+ if ( !isset( $m[3] ) ) {
+ $operandSymbols = array(
+ 'n' => intval( $m[1] ),
+ 'i' => intval( $m[1] ),
+ 'v' => 0,
+ 'w' => 0,
+ 'f' => 0,
+ 't' => 0
+ );
+ } else {
+ $absValStr = $m[1];
+ $intStr = $m[2];
+ $fracStr = $m[3];
+ $operandSymbols = array(
+ 'n' => floatval( $absValStr ),
+ 'i' => intval( $intStr ),
+ 'v' => strlen( $fracStr ),
+ 'w' => strlen( rtrim( $fracStr, '0' ) ),
+ 'f' => intval( $fracStr ),
+ 't' => intval( rtrim( $fracStr, '0' ) ),
+ );
+ }
+
+ // The compiled form is RPN, with tokens strictly delimited by
+ // spaces, so this is a simple RPN evaluator.
+ foreach ( $rules as $i => $rule ) {
+ $stack = array();
+ $zero = ord( '0' );
+ $nine = ord( '9' );
+
+ foreach ( explode( ' ', $rule ) as $token ) {
+ $ord = ord( $token );
+ if ( isset( $operandSymbols[$token] ) ) {
+ $stack[] = $operandSymbols[$token];
+ } elseif ( $ord >= $zero && $ord <= $nine ) {
+ $stack[] = intval( $token );
+ } else {
+ $right = array_pop( $stack );
+ $left = array_pop( $stack );
+ $result = self::doOperation( $token, $left, $right );
+ $stack[] = $result;
+ }
+ }
+ if ( $stack[0] ) {
+ return $i;
+ }
+ }
+ // None of the provided rules match. The number belongs to category
+ // 'other', which comes last.
+ return count( $rules );
+ }
+
+ /**
+ * Do a single operation
+ *
+ * @param string $token The token string
+ * @param mixed $left The left operand. If it is an object, its state may be destroyed.
+ * @param mixed $right The right operand
+ * @throws Error
+ * @return mixed The operation result
+ */
+ private static function doOperation( $token, $left, $right ) {
+ if ( in_array( $token, array( 'in', 'not-in', 'within', 'not-within' ) ) ) {
+ if ( !$right instanceof Range ) {
+ $right = new Range( $right );
+ }
+ }
+ switch ( $token ) {
+ case 'or':
+ return $left || $right;
+ case 'and':
+ return $left && $right;
+ case 'is':
+ return $left == $right;
+ case 'is-not':
+ return $left != $right;
+ case 'in':
+ return $right->isNumberIn( $left );
+ case 'not-in':
+ return !$right->isNumberIn( $left );
+ case 'within':
+ return $right->isNumberWithin( $left );
+ case 'not-within':
+ return !$right->isNumberWithin( $left );
+ case 'mod':
+ if ( is_int( $left ) ) {
+ return (int)fmod( $left, $right );
+ }
+
+ return fmod( $left, $right );
+ case ',':
+ if ( $left instanceof Range ) {
+ $range = $left;
+ } else {
+ $range = new Range( $left );
+ }
+ $range->add( $right );
+
+ return $range;
+ case '..':
+ return new Range( $left, $right );
+ default:
+ throw new Error( "Invalid RPN token" );
+ }
+ }
+}
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