PHP的Pear库中已经定义好了RPN类用于计算逆波兰式，并同时可以让我们来计算中缀表达式的值。其使用方法也比较简单，且支持功能完善。
在工资项目的计算中，根据需要对RPN类库进行了修改，让调用更加简洁。
<?php /** * Math::Rpn * * 作用: * 计算中缀表达式的值 * 将表达式转换为逆波兰式，计算逆波兰式的值 * Change Expression To RPN (Reverse Polish Notation), Evaluate RPN Expression * * 示例: * 1、计算中缀表达式的值 $infix_expression = "(255.3*2)+33.2"; $rpn = new Math_Rpn(); * echo $rpn->calculate($infix_expression,false); * //若表达式中包含角的计算，若需要定义角的单位（弧度:rad,度:deg.默认的角度为rad,即弧度) * $expression = "(2^3)+sin(30)-(!4)+(3/4)"; * echo $rpn->calculate($expression,false,'deg'); * * * @author Maciej Szczytowski <admin@e-rower.pl> kelite 修改 2013-2-23 * @version 1.1.1 * @package math * @access public */ class Math_Rpn { /** * Input expression * * @var string * @access private */ var $_input = ''; /** * Array with input expression * * @var array * @access private */ var $_input_array = array(); /** * Array with output expression in RPN * * @var array * @access private */ var $_output = array(); /** * Temporary stack * * @var array * @access private */ var $_stack = array(); /** * Value of expression * * @var float * @access private */ var $_value = 0.0; /** * Angle's unit: rad - true, deg - false * * @var boolean * @access private */ var $_angle = true; /** * PEAR Error * * @var object PEAR * @access private */ var $_error = null; /** * Timer * * @var float * @access private */ var $_timer = 0.0; /** * Array of operators whit priority and math function * operator => (name, priority, number of arguments, function) * * @var array * @access private */ var $_operation = array ( '(' => array ('left bracket', 0), ')' => array ('right bracket', 1), '+' => array ('sum', 1, 2, '_sum'), '-' => array ('difference', 1, 2, '_difference'), '*' => array ('multiplication', 2, 2, '_multiplication'), '/' => array ('division', 2, 2, '_division'), 'r' => array ('root', 3, 2, '_root'), '^' => array ('power', 3, 2, '_power'), 'sin' => array ('sine', 3, 1, '_sin'), 'cos' => array ('cosine', 3, 1, '_cos'), 'tan' => array ('tangent', 3, 1, '_tan'), 'asin' => array ('asine', 3, 1, '_asin'), 'acos' => array ('acosine', 3, 1, '_acos'), 'atan' => array ('atangent', 3, 1, '_atan'), 'sqrt' => array ('square root', 3, 1, '_sqrt'), 'exp' => array ('power of e', 3, 1, '_exp'), 'log' => array ('logarithm', 3, 1, '_log'), 'ln' => array ('natural logarithm', 3, 1, '_ln'), 'E' => array ('power of 10', 3, 1, '_E'), 'abs' => array ('absolute value', 3, 1, '_abs'), '!' => array ('factorial', 3, 1, '_factorial'), 'pi' => array ('value of pi', 4, 0, '_const_pi'), 'e' => array ('value of e', 4, 0, '_const_e'), 'mod' => array ('modulo', 3, 2, '_mod'), 'div' => array ('integer division', 3, 2, '_div'), ); /** * Return a PEAR error * * @return object PEAR error * @access private */ function _raiseError ($error) { // return PEAR::raiseError($error); return ($error); } /** * Return a operator's array * * @return array Array with operator's name, priority, arguments, function's name and syntax * @access public */ function getOperators () { $return = array(); while(list($key, $val) = each($this->_operation)) { if (array_key_exists (2, $val) && $val[2] == 2) { $syntax = 'A ' . $key . ' B'; $arguments = 2; } elseif (array_key_exists (2, $val) && $val[2] == 1) { $syntax = $key . ' A'; $arguments = 1; } else { $syntax = $key; $arguments = 0; } if(array_key_exists (3, $val)) $function = $val[3]; else $function = ''; $return[] = array ( 'operator' => $key, 'name' => $val[0], 'priority' => $val[1], 'arguments' => $arguments, 'function' => $function, 'syntax' => $syntax ); } return $return; } /** * Add new operator * * @param string $operator New operator * @param string $function Function name * @param integer $priority New operator's priority * @param integer $no_of_arg Number of function's arguments * @param string $text New operator's description * @access public */ function addOperator ($operator, $function_name, $priority = 3, $no_of_arg = 0, $text = '') { if(preg_match("/^([\W\w]+)\:\:([\W\w]+)$/",$function_name,$match)) { $class = $match[1]; $method = $match[2]; $function = array ( 'type' => 'userMethod', 'class' => $class, 'method' => $method ); } else { $function = array ( 'type' => 'userFunction', 'function' => $function_name ); } $this->_operation[$operator] = array ($text, $priority, $no_of_arg, $function); } /** * Calculate the $input expression * * @param mixed $input Infix expression string or RPN expression string 中缀表达式或逆波兰式 * @param string $angle Angle's unit - 'rad' or 'deg' 角的单位 rad表弧度，deg表示度 * @param boolean $is_rpn True if $input is RPN expression or false if $input is infix expression * @return mixed Value of $input expression or a PEAR error * @access public */ function calculate($input = '',$is_rpn = true,$angle = 'rad') { $this->_angle = (boolean) ($angle == 'rad'); if($input == '') { $this->_error = $this->_raiseError('Empty input expression'); return $this->_error; } if(!$is_rpn) { $this->_input = $input; $this->_stringToArray (); if($this->_error <> null) return $this->_error; $this->_arrayToRpn(); if($this->_error <> null) return $this->_error; } else { if (is_array($input)) { $input = implode(' ', $input); } $this->_input = $input; $this->_input_array = explode(' ',$input); $this->_output = explode(' ',$input); } $this->_rpnToValue(); if($this->_error <> null) return $this->_error; return $this->_value; } /** * Calculate the $input expression (alias of calculate()) * @author kelite 修改参数顺序 * @param mixed $input Infix expression string or RPN expression array * @param string $angle Angle's unit - 'rad' or 'deg' * @param boolean $is_rpn True if $input is RPN expression or false if $input is infix expression * @return mixed Value of $input expression or a PEAR error * @access public */ function evaluate($input = '', $angle = 'rad', $is_rpn = false) { //原顺序return $this-> calculate($input,$angle,$is_rpn); return $this-> calculate($input,$is_rpn,$angle); } /** * Return a input array * * @return array Input array * @access public */ function getInputArray() { return $this->_input_array; } /** * Return a RPN array * * @return array RPN array * @access public */ function getRpnArray() { return $this->_output; } /** * Return a counting time in second * * @return float Counting time in seconds * @access public */ function getTimer() { return $this->_timer; } /** * Check that $key is a key of $array (conformity to php<4.1.0) * * @param string $key * @param array $array * @param integer $type 0 - return true if $key is $array's key, 1 - return true if $key is $array's key and there isn't any occurrence of $key in another $array's key * @return boolean true when $key is a key of $array, or false * @access private */ function _keyExists($key,$array,$type) { $keys = array_keys($array); if($type == 1) { $count = 0; while (list($keys_key, $keys_val) = each($keys)) { if(is_integer(strpos($keys_val, $key)) && (strpos($keys_val, $key)==0)) $count++; } if(($count==1) && in_array($key,$keys)) return true; else return false; } else { if(in_array($key,$keys)) return true; else return false; } } /** * Check that $value is nan (conformity to php<4.2.0) * * @param float $value checking value * @return boolean true when $value is nan, or false * @access private */ function _isNan($value) { if(function_exists('is_nan')) { return is_nan($value); } else { if((substr($value,-3) == 'IND') || (substr($value,-3) == 'NAN')) return true; else return false; } } /** * Check that $value is infinite (conformity to php<4.2.0) * * @param float $value checking value * @return boolean true when $value is infinite, or false * @access private */ function _isInfinite($value) { if(function_exists('is_finite')) { return !is_finite($value); } else { if(substr($value,-3) == 'INF') return true; else return false; } } /** * Change input expression into array * * @return array Input expression changed into array * @access private */ function _stringToArray () { $temp_operator = null; $temp_value = null; $this->_input = str_replace(" ","",$this->_input); for($i = 0; $i < strlen($this->_input); $i++) { if ($this->_input[$i] == ' ') { if ($temp_operator != null) { array_push($this->_input_array, $temp_operator); $temp_operator = null; } if ($temp_value != null) { array_push($this->_input_array, $temp_value); $temp_value = null; } } elseif (($temp_value == null) && $temp_operator != ')' && (!array_key_exists($temp_operator,$this->_operation) || !array_key_exists(2,$this->_operation[$temp_operator]) || $this->_operation[$temp_operator][2]>0) && ($this->_input[$i] == '-')) { if ($temp_operator != null) { array_push($this->_input_array, $temp_operator); $temp_operator = null; } array_push($this->_input_array, '-1'); array_push($this->_input_array, '*'); } elseif ((is_numeric($this->_input[$i])) || ($this->_input[$i] == '.')) { if ($temp_operator != null) { array_push($this->_input_array, $temp_operator); $temp_operator = null; } $temp_value .= $this->_input[$i]; } else { if ($this->_keyExists($temp_operator, $this->_operation, 1)) { array_push($this->_input_array, $temp_operator); $temp_operator = null; } if ($temp_value != null) { array_push($this->_input_array, $temp_value); $temp_value = null; } $temp_operator .= $this->_input[$i]; } } if ($temp_operator != null && $temp_operator != ' ') { array_push($this->_input_array, $temp_operator); } elseif($temp_value != null && $temp_value != ' ') { array_push($this->_input_array, $temp_value); } $this->_testInput(); return $this->_input_array; } /** * Check input array and return correct array or a PEAR Error * * @return object Null or a PEAR Error * @access private */ function _testInput() { if (!count($this->_input_array)) { $this->_input_array = null; $this->_error = $this->_raiseError('Undefined input array'); return $this->_error; } $bracket = 0; for($i = 0; $i < count($this->_input_array); $i++) if ($this->_input_array[$i] == '(') $bracket++; for($i = 0; $i < count($this->_input_array); $i++) if ($this->_input_array[$i] == ')') $bracket--; if ($bracket <> 0) { $this->_input_array = null; $this->_error = $this->_raiseError('Syntax error'); return $this->_error; } for($i = 0; $i < count($this->_input_array); $i++) { if ((!is_numeric($this->_input_array[$i])) && (!$this->_keyExists($this->_input_array[$i], $this->_operation, 0))) { $error_operator = $this->_input_array[$i]; $this->_input_array = null; $this->_error = $this->_raiseError('Undefined operator \''. $error_operator.'\''); return $this->_error; } } $this->_error = null; return $this->_error; } /** * Add value to the end of stack * * @param string $value Value to add into stack * @access private */ function _stackAdd($value) { array_push($this->_stack, $value); } /** * Delete and return value from the end of stack * * @return string Value deleted from stack * @access private */ function _stackDelete() { return array_pop($this->_stack); } /** * Return priority of value * * @param string $value Value to get priority * @return integer Priority * @access private */ function _priority($value) { return $this->_operation[$value][1]; } /** * Return priority of value from the end of stack * * @return integer Priority of operator from stack's top * @access private */ function _stackPriority() { $value = $this->_stackDelete(); $this->_stackAdd($value); return $this->_priority($value); } /** * Return true whene the stack is empty * * @return boolean Stack is empty (true) or not (false) * @access private */ function _stackEmpty() { if (count($this->_stack)) { return false; } else return true; } /** * Add value into output array * * @param string $value Value to add into output array * @access private */ function _outputAdd($value) { if ($value<>'(') { array_push($this->_output, $value); } } /** * Change input array into RPN array * * @return array Array with RPN expression * @access private */ function _arrayToRpn() { if ($this->_error <> null) { $this->_output = array(); return $this->_output; } for($i = 0; $i < count($this->_input_array); $i++) { $temp = $this->_input_array[$i]; if (is_numeric($temp)) { $this->_outputAdd($temp); } else { if ($temp == ')') { while(!$this->_stackEmpty() && ($this->_stackPriority() >= 1)) { $this->_outputAdd($this->_stackDelete()); } if (!$this->_stackEmpty()) { $this->_stackDelete(); } } elseif ($temp=='(') { $this->_stackAdd($temp); } elseif (($this->_stackEmpty()) || (($this->_priority($temp) > $this->_stackPriority()))) { $this-> _stackAdd($temp); } else { while(!$this->_stackEmpty() && ($this->_priority($temp) <= $this->_stackPriority())) { $this->_outputAdd($this->_stackDelete()); } $this->_stackAdd($temp); } } } while(!$this->_stackEmpty()) { $this->_outputAdd($this->_stackDelete()); } return $this->_output; } /** * Return position of the first operator in array * * @param array $array Temporary array * @return integer Position of the first operator * @access private */ function _nextOperator($array) { $pos = 0; while(is_numeric($array[$pos])) { $pos++; if ($pos >= count($array)) { return -1; } } return $pos; } /** * Delete from array operator [posision $pos] and its argument and insert new value * * @param array $temp Temporary array * @param integer $pos Position of the last operator * @param integer $arg Number of last operator's arguments * @param float $result Last operation result * @return array New temporary array * @access private */ function _refresh($temp, $pos, $arg, $result) { $temp1 = array_slice($temp, 0, $pos-$arg); $temp1[] = $result; $temp2 = array_slice($temp, $pos+1); return array_merge($temp1, $temp2); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _sum($temp, $pos) { return $temp[$pos-2]+$temp[$pos-1]; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _difference($temp, $pos) { return $temp[$pos-2]-$temp[$pos-1]; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _multiplication($temp, $pos) { return $temp[$pos-2]*$temp[$pos-1]; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _division($temp, $pos) { if ($temp[$pos-1]==0) { $this->_error = $this->_raiseError('Division by 0'); $this->_value = null; return $this->_value; } return $temp[$pos-2]/$temp[$pos-1]; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _root($temp, $pos) { return pow($temp[$pos-1], (1/$temp[$pos-2])); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _power($temp, $pos) { return pow($temp[$pos-2], $temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _sin($temp, $pos) { if ($this->_angle) { $angle = $temp[$pos-1]; } else { $angle = deg2rad($temp[$pos-1]); } return sin($angle); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _cos($temp, $pos) { if ($this->_angle) { $angle = $temp[$pos-1]; } else { $angle = deg2rad($temp[$pos-1]); } return cos($angle); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _tan($temp, $pos) { if ($this->_angle) { $angle = $temp[$pos-1]; } else { $angle = deg2rad($temp[$pos-1]); } return tan($angle); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _asin($temp, $pos) { $angle = asin($temp[$pos-1]); if (!$this->_angle) { $angle = rad2deg($angle); } return $angle; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _acos($temp, $pos) { $angle = acos($temp[$pos-1]); if (!$this->_angle) { $angle = rad2deg($angle); } return $angle; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _atan($temp, $pos) { $angle = atan($temp[$pos-1]); if (!$this->_angle) { $angle = rad2deg($angle); } return $angle; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _sqrt($temp, $pos) { return sqrt($temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _exp($temp, $pos) { return exp($temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _log($temp, $pos) { return log10($temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _ln($temp, $pos) { return log($temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _const_pi($temp, $pos) { return M_PI; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _const_e($temp, $pos) { return M_E; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _E($temp, $pos) { return pow(10, $temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _factorial($temp, $pos) { $factorial = 1; for($i=1;$i<=$temp[$pos-1];$i++) { $factorial *= $i; } return $factorial; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _abs($temp, $pos) { return abs($temp[$pos-1]); } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _mod($temp, $pos) { return $temp[$pos-2]%$temp[$pos-1]; } /** * Math function * * @param array $temp Temporary array * @param integer $pos Position of operator * @return float Function's relult * @access private */ function _div($temp, $pos) { return floor($temp[$pos-2]/$temp[$pos-1]); } /** * Calculate RPN Expression and return value * * @return float Result of input expression * @access private */ function _rpnToValue() { $time1 = $this->_getMicroTime(); if ($this->_error <> null) { $this->_value = null; return $this->_value; } $this->_value = 0; $temp = $this->_output; do { $pos = $this->_nextOperator($temp); if ($pos == -1) { $this->_error = $this->_raiseError('Syntax error'); $this->_value = null; return $this->_value; } $operator = $this->_operation[$temp[$pos]]; $arg = $operator[2]; $function = $operator[3]; if (($arg==2) && (!isset($temp[$pos-1]) || !is_numeric($temp[$pos-1]) || !isset($temp[$pos-2]) || !is_numeric($temp[$pos-2]))) { $this->_error = $this->_raiseError('Syntax error'); $this->_value = null; return $this->_value; } elseif (($arg==1) && (!isset($temp[$pos-1]) || !is_numeric($temp[$pos-1]))) { $this->_error = $this->_raiseError('Syntax error'); $this->_value = null; return $this->_value; } if(is_array($function)) { if($arg==2) $arg_array = array($temp[$pos-2],$temp[$pos-1]); elseif($arg==1) $arg_array = array($temp[$pos-1]); else $arg_array = array(); if($function['type'] == 'userFunction') { $this->_value = call_user_func_array($function['function'], $arg_array); } else { $function_array = array(&$function['class'], $function['method']); $this->_value = call_user_func_array($function_array, $arg_array); } } else { $this->_value = $this->$function($temp, $pos); } if ($this->_isNan($this->_value)) { $this->_error = $this->_raiseError('NAN value'); $this->_value = null; return $this->_value; } elseif ($this->_isInfinite($this->_value)) { $this->_error = $this->_raiseError('Infinite value'); $this->_value = null; return $this->_value; } elseif (is_null($this->_value)) { return $this->_value; } $temp = $this->_refresh($temp, $pos, $arg, $this->_value); } while(count($temp) > 1); $this->_value = $temp[0]; $time2 = $this->_getMicroTime(); $this->_timer = $time2 - $time1; return $this->_value; } /** * Return a time in second * * @return float Current time in seconds * @access private */ function _getMicroTime() { list($usec, $sec) = explode(" ", microtime()); return ((float)$usec + (float)$sec); } } ?>