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WC_Eval_Math{} WC 1.0

Class WC_Eval_Math. Supports basic math only (removed eval function).

Based on EvalMath by Miles Kaufman Copyright (C) 2005 Miles Kaufmann http://www.twmagic.com/.

Хуков нет.

Возвращает

Null. Ничего.

Использование

$WC_Eval_Math = new WC_Eval_Math();
// use class methods

Методы

  1. evaluate( $expr )
  2. nfx( $expr )
  3. pfx( $tokens, $vars = array() )
  4. trigger( $msg )
  5. debugPrintCallingFunction()

Код WC_Eval_Math{} WC 4.5.2

woocommerce/includes/libraries/class-wc-eval-math.php
<?php
class WC_Eval_Math {

	/**
	 * Last error.
	 *
	 * @var string
	 */
	public static $last_error = null;

	/**
	 * Variables (and constants).
	 *
	 * @var array
	 */
	public static $v = array( 'e' => 2.71, 'pi' => 3.14 );

	/**
	 * User-defined functions.
	 *
	 * @var array
	 */
	public static $f = array();

	/**
	 * Constants.
	 *
	 * @var array
	 */
	public static $vb = array( 'e', 'pi' );

	/**
	 * Built-in functions.
	 *
	 * @var array
	 */
	public static $fb = array();

	/**
	 * Evaluate maths string.
	 *
	 * @param string  $expr
	 * @return mixed
	 */
	public static function evaluate( $expr ) {
		self::$last_error = null;
		$expr = trim( $expr );
		if ( substr( $expr, -1, 1 ) == ';' ) {
			$expr = substr( $expr, 0, strlen( $expr ) -1 ); // strip semicolons at the end
		}
		// ===============
		// is it a variable assignment?
		if ( preg_match( '/^\s*([a-z]\w*)\s*=\s*(.+)$/', $expr, $matches ) ) {
			if ( in_array( $matches[1], self::$vb ) ) { // make sure we're not assigning to a constant
				return self::trigger( "cannot assign to constant '$matches[1]'" );
			}
			if ( ( $tmp = self::pfx( self::nfx( $matches[2] ) ) ) === false ) {
				return false; // get the result and make sure it's good
			}
			self::$v[ $matches[1] ] = $tmp; // if so, stick it in the variable array
			return self::$v[ $matches[1] ]; // and return the resulting value
			// ===============
			// is it a function assignment?
		} elseif ( preg_match( '/^\s*([a-z]\w*)\s*\(\s*([a-z]\w*(?:\s*,\s*[a-z]\w*)*)\s*\)\s*=\s*(.+)$/', $expr, $matches ) ) {
			$fnn = $matches[1]; // get the function name
			if ( in_array( $matches[1], self::$fb ) ) { // make sure it isn't built in
				return self::trigger( "cannot redefine built-in function '$matches[1]()'" );
			}
			$args = explode( ",", preg_replace( "/\s+/", "", $matches[2] ) ); // get the arguments
			if ( ( $stack = self::nfx( $matches[3] ) ) === false ) {
				return false; // see if it can be converted to postfix
			}
			$stack_size = count( $stack );
			for ( $i = 0; $i < $stack_size; $i++ ) { // freeze the state of the non-argument variables
				$token = $stack[ $i ];
				if ( preg_match( '/^[a-z]\w*$/', $token ) and ! in_array( $token, $args ) ) {
					if ( array_key_exists( $token, self::$v ) ) {
						$stack[ $i ] = self::$v[ $token ];
					} else {
						return self::trigger( "undefined variable '$token' in function definition" );
					}
				}
			}
			self::$f[ $fnn ] = array( 'args' => $args, 'func' => $stack );
			return true;
			// ===============
		} else {
			return self::pfx( self::nfx( $expr ) ); // straight up evaluation, woo
		}
	}

	/**
	 * Convert infix to postfix notation.
	 *
	 * @param  string $expr
	 *
	 * @return array|string
	 */
	private static function nfx( $expr ) {

		$index = 0;
		$stack = new WC_Eval_Math_Stack;
		$output = array(); // postfix form of expression, to be passed to pfx()
		$expr = trim( $expr );

		$ops   = array( '+', '-', '*', '/', '^', '_' );
		$ops_r = array( '+' => 0, '-' => 0, '*' => 0, '/' => 0, '^' => 1 ); // right-associative operator?
		$ops_p = array( '+' => 0, '-' => 0, '*' => 1, '/' => 1, '_' => 1, '^' => 2 ); // operator precedence

		$expecting_op = false; // we use this in syntax-checking the expression
		// and determining when a - is a negation
		if ( preg_match( "/[^\w\s+*^\/()\.,-]/", $expr, $matches ) ) { // make sure the characters are all good
			return self::trigger( "illegal character '{$matches[0]}'" );
		}

		while ( 1 ) { // 1 Infinite Loop ;)
			$op = substr( $expr, $index, 1 ); // get the first character at the current index
			// find out if we're currently at the beginning of a number/variable/function/parenthesis/operand
			$ex = preg_match( '/^([A-Za-z]\w*\(?|\d+(?:\.\d*)?|\.\d+|\()/', substr( $expr, $index ), $match );
			// ===============
			if ( '-' === $op and ! $expecting_op ) { // is it a negation instead of a minus?
				$stack->push( '_' ); // put a negation on the stack
				$index++;
			} elseif ( '_' === $op ) { // we have to explicitly deny this, because it's legal on the stack
				return self::trigger( "illegal character '_'" ); // but not in the input expression
				// ===============
			} elseif ( ( in_array( $op, $ops ) or $ex ) and $expecting_op ) { // are we putting an operator on the stack?
				if ( $ex ) { // are we expecting an operator but have a number/variable/function/opening parenthesis?
					$op = '*';
					$index--; // it's an implicit multiplication
				}
				// heart of the algorithm:
				while ( $stack->count > 0 and ( $o2 = $stack->last() ) and in_array( $o2, $ops ) and ( $ops_r[ $op ] ? $ops_p[ $op ] < $ops_p[ $o2 ] : $ops_p[ $op ] <= $ops_p[ $o2 ] ) ) {
					$output[] = $stack->pop(); // pop stuff off the stack into the output
				}
				// many thanks: https://en.wikipedia.org/wiki/Reverse_Polish_notation#The_algorithm_in_detail
				$stack->push( $op ); // finally put OUR operator onto the stack
				$index++;
				$expecting_op = false;
				// ===============
			} elseif ( ')' === $op && $expecting_op ) { // ready to close a parenthesis?
				while ( ( $o2 = $stack->pop() ) != '(' ) { // pop off the stack back to the last (
					if ( is_null( $o2 ) ) {
						return self::trigger( "unexpected ')'" );
					} else {
						$output[] = $o2;
					}
				}
				if ( preg_match( "/^([A-Za-z]\w*)\($/", $stack->last( 2 ), $matches ) ) { // did we just close a function?
					$fnn = $matches[1]; // get the function name
					$arg_count = $stack->pop(); // see how many arguments there were (cleverly stored on the stack, thank you)
					$output[] = $stack->pop(); // pop the function and push onto the output
					if ( in_array( $fnn, self::$fb ) ) { // check the argument count
						if ( $arg_count > 1 ) {
							return self::trigger( "too many arguments ($arg_count given, 1 expected)" );
						}
					} elseif ( array_key_exists( $fnn, self::$f ) ) {
						if ( count( self::$f[ $fnn ]['args'] ) != $arg_count ) {
							return self::trigger( "wrong number of arguments ($arg_count given, " . count( self::$f[ $fnn ]['args'] ) . " expected)" );
						}
					} else { // did we somehow push a non-function on the stack? this should never happen
						return self::trigger( "internal error" );
					}
				}
				$index++;
				// ===============
			} elseif ( ',' === $op and $expecting_op ) { // did we just finish a function argument?
				while ( ( $o2 = $stack->pop() ) != '(' ) {
					if ( is_null( $o2 ) ) {
						return self::trigger( "unexpected ','" ); // oops, never had a (
					} else {
						$output[] = $o2; // pop the argument expression stuff and push onto the output
					}
				}
				// make sure there was a function
				if ( ! preg_match( "/^([A-Za-z]\w*)\($/", $stack->last( 2 ), $matches ) ) {
					return self::trigger( "unexpected ','" );
				}
				$stack->push( $stack->pop() + 1 ); // increment the argument count
				$stack->push( '(' ); // put the ( back on, we'll need to pop back to it again
				$index++;
				$expecting_op = false;
				// ===============
			} elseif ( '(' === $op and ! $expecting_op ) {
				$stack->push( '(' ); // that was easy
				$index++;
				// ===============
			} elseif ( $ex and ! $expecting_op ) { // do we now have a function/variable/number?
				$expecting_op = true;
				$val = $match[1];
				if ( preg_match( "/^([A-Za-z]\w*)\($/", $val, $matches ) ) { // may be func, or variable w/ implicit multiplication against parentheses...
					if ( in_array( $matches[1], self::$fb ) or array_key_exists( $matches[1], self::$f ) ) { // it's a func
						$stack->push( $val );
						$stack->push( 1 );
						$stack->push( '(' );
						$expecting_op = false;
					} else { // it's a var w/ implicit multiplication
						$val = $matches[1];
						$output[] = $val;
					}
				} else { // it's a plain old var or num
					$output[] = $val;
				}
				$index += strlen( $val );
				// ===============
			} elseif ( ')' === $op ) { // miscellaneous error checking
				return self::trigger( "unexpected ')'" );
			} elseif ( in_array( $op, $ops ) and ! $expecting_op ) {
				return self::trigger( "unexpected operator '$op'" );
			} else { // I don't even want to know what you did to get here
				return self::trigger( "an unexpected error occurred" );
			}
			if ( strlen( $expr ) == $index ) {
				if ( in_array( $op, $ops ) ) { // did we end with an operator? bad.
					return self::trigger( "operator '$op' lacks operand" );
				} else {
					break;
				}
			}
			while ( substr( $expr, $index, 1 ) == ' ' ) { // step the index past whitespace (pretty much turns whitespace
				$index++;                             // into implicit multiplication if no operator is there)
			}
		}
		while ( ! is_null( $op = $stack->pop() ) ) { // pop everything off the stack and push onto output
			if ( '(' === $op ) {
				return self::trigger( "expecting ')'" ); // if there are (s on the stack, ()s were unbalanced
			}
			$output[] = $op;
		}
		return $output;
	}

	/**
	 * Evaluate postfix notation.
	 *
	 * @param  mixed $tokens
	 * @param  array $vars
	 *
	 * @return mixed
	 */
	private static function pfx( $tokens, $vars = array() ) {
		if ( false == $tokens ) {
			return false;
		}
		$stack = new WC_Eval_Math_Stack;

		foreach ( $tokens as $token ) { // nice and easy
			// if the token is a binary operator, pop two values off the stack, do the operation, and push the result back on
			if ( in_array( $token, array( '+', '-', '*', '/', '^' ) ) ) {
				if ( is_null( $op2 = $stack->pop() ) ) {
					return self::trigger( "internal error" );
				}
				if ( is_null( $op1 = $stack->pop() ) ) {
					return self::trigger( "internal error" );
				}
				switch ( $token ) {
					case '+':
						$stack->push( $op1 + $op2 );
						break;
					case '-':
						$stack->push( $op1 - $op2 );
						break;
					case '*':
						$stack->push( $op1 * $op2 );
						break;
					case '/':
						if ( 0 == $op2 ) {
							return self::trigger( 'division by zero' );
						}
						$stack->push( $op1 / $op2 );
						break;
					case '^':
						$stack->push( pow( $op1, $op2 ) );
						break;
				}
				// if the token is a unary operator, pop one value off the stack, do the operation, and push it back on
			} elseif ( '_' === $token ) {
				$stack->push( -1 * $stack->pop() );
				// if the token is a function, pop arguments off the stack, hand them to the function, and push the result back on
			} elseif ( ! preg_match( "/^([a-z]\w*)\($/", $token, $matches ) ) {
				if ( is_numeric( $token ) ) {
					$stack->push( $token );
				} elseif ( array_key_exists( $token, self::$v ) ) {
					$stack->push( self::$v[ $token ] );
				} elseif ( array_key_exists( $token, $vars ) ) {
					$stack->push( $vars[ $token ] );
				} else {
					return self::trigger( "undefined variable '$token'" );
				}
			}
		}
		// when we're out of tokens, the stack should have a single element, the final result
		if ( 1 != $stack->count ) {
			return self::trigger( "internal error" );
		}
		return $stack->pop();
	}

	/**
	 * Trigger an error, but nicely, if need be.
	 *
	 * @param  string $msg
	 *
	 * @return bool
	 */
	private static function trigger( $msg ) {
		self::$last_error = $msg;
		if ( ! Constants::is_true( 'DOING_AJAX' ) && Constants::is_true( 'WP_DEBUG' ) ) {
			echo "\nError found in:";
			self::debugPrintCallingFunction();
			trigger_error( $msg, E_USER_WARNING );
		}
		return false;
	}

	/**
	 * Prints the file name, function name, and
	 * line number which called your function
	 * (not this function, then one that  called
	 * it to begin with)
	 */
	private static function debugPrintCallingFunction() {
		$file = 'n/a';
		$func = 'n/a';
		$line = 'n/a';
		$debugTrace = debug_backtrace();
		if ( isset( $debugTrace[1] ) ) {
			$file = $debugTrace[1]['file'] ? $debugTrace[1]['file'] : 'n/a';
			$line = $debugTrace[1]['line'] ? $debugTrace[1]['line'] : 'n/a';
		}
		if ( isset( $debugTrace[2] ) ) {
			$func = $debugTrace[2]['function'] ? $debugTrace[2]['function'] : 'n/a';
		}
		echo "\n$file, $func, $line\n";
	}
}