- <?php
-
- ================================================================================
-
- EvalMath - PHP Class to safely evaluate math expressions
- Copyright (C) 2005 Miles Kaufmann <http://www.twmagic.com/>
-
- ================================================================================
-
- NAME
- EvalMath - safely evaluate math expressions
-
- SYNOPSIS
- include('evalmath.class.php');
- $m = new EvalMath;
- // basic evaluation:
- $result = $m->evaluate('2+2');
- // supports: order of operation; parentheses; negation; built-in functions
- $result = $m->evaluate('-8(5/2)^2*(1-sqrt(4))-8');
- // create your own variables
- $m->evaluate('a = e^(ln(pi))');
- // or functions
- $m->evaluate('f(x,y) = x^2 + y^2 - 2x*y + 1');
- // and then use them
- $result = $m->evaluate('3*f(42,a)');
-
- DESCRIPTION
- Use the EvalMath class when you want to evaluate mathematical expressions
- from untrusted sources. You can define your own variables and functions,
- which are stored in the object. Try it, it's fun!
-
- METHODS
- $m->evaluate($expr)
- Evaluates the expression and returns the result. If an error occurs,
- prints a warning and returns false. If $expr is a function assignment,
- returns true on success.
-
- $m->e($expr)
- A synonym for $m->evaluate().
-
- $m->vars()
- Returns an associative array of all user-defined variables and values.
-
- $m->funcs()
- Returns an array of all user-defined functions.
-
- PARAMETERS
- $m->suppress_errors
- Set to true to turn off warnings when evaluating expressions
-
- $m->last_error
- If the last evaluation failed, contains a string describing the error.
- (Useful when suppress_errors is on).
-
- AUTHOR INFORMATION
- Copyright 2005, Miles Kaufmann.
-
- LICENSE
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions are
- met:
-
- 1 Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- 2. Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in the
- documentation and/or other materials provided with the distribution.
- 3. The name of the author may not be used to endorse or promote
- products derived from this software without specific prior written
- permission.
-
- THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
- INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- POSSIBILITY OF SUCH DAMAGE.
-
- */
-
- class EvalMath {
- var $suppress_errors = false;
- var $last_error = null;
-
- var $v = array('e'=>2.71,'pi'=>3.14);
- var $f = array();
- var $vb = array('e', 'pi');
- var $fb = array(
- 'sin','sinh','arcsin','asin','arcsinh','asinh',
- 'cos','cosh','arccos','acos','arccosh','acosh',
- 'tan','tanh','arctan','atan','arctanh','atanh',
- 'pow', 'exp',
- 'sqrt','abs','ln','log',
- 'time', 'ceil', 'floor', 'min', 'max', 'round');
-
- function __construct() {
-
- $this->v['pi'] = pi();
- $this->v['e'] = exp(1);
- }
-
- function e($expr) {
- return $this->evaluate($expr);
- }
-
- function evaluate($expr) {
- $this->last_error = null;
- $expr = trim($expr);
- if (substr($expr, -1, 1) == ';') $expr = substr($expr, 0, strlen($expr)-1);
-
-
- if (preg_match('/^\s*([a-z]\w*)\s*=\s*(.+)$/', $expr, $matches)) {
- if (in_array($matches[1], $this->vb)) {
- return $this->trigger("cannot assign to constant '$matches[1]'");
- }
- if (($tmp = $this->pfx($this->nfx($matches[2]))) === false) return false;
- $this->v[$matches[1]] = $tmp;
- return $this->v[$matches[1]];
-
-
- } elseif (preg_match('/^\s*([a-z]\w*)\s*\(\s*([a-z]\w*(?:\s*,\s*[a-z]\w*)*)\s*\)\s*=\s*(.+)$/', $expr, $matches)) {
- $fnn = $matches[1];
- if (in_array($matches[1], $this->fb)) {
- return $this->trigger("cannot redefine built-in function '$matches[1]()'");
- }
- $args = explode(",", preg_replace("/\s+/", "", $matches[2]));
- if (($stack = $this->nfx($matches[3])) === false) return false;
- for ($i = 0; $i<count($stack); $i++) {
- $token = $stack[$i];
- if (preg_match('/^[a-z]\w*$/', $token) and !in_array($token, $args)) {
- if (array_key_exists($token, $this->v)) {
- $stack[$i] = $this->v[$token];
- } else {
- return $this->trigger("undefined variable '$token' in function definition");
- }
- }
- }
- $this->f[$fnn] = array('args'=>$args, 'func'=>$stack);
- return true;
-
- } else {
- return $this->pfx($this->nfx($expr));
- }
- }
-
- function vars() {
- $output = $this->v;
- unset($output['pi']);
- unset($output['e']);
- return $output;
- }
-
- function funcs() {
- $output = array();
- foreach ($this->f as $fnn=>$dat)
- $output[] = $fnn . '(' . implode(',', $dat['args']) . ')';
- return $output;
- }
-
-
-
-
- function nfx($expr) {
-
- $index = 0;
- $stack = new EvalMathStack;
- $output = array();
- $expr = trim(strtolower($expr));
-
- $ops = array('+', '-', '*', '/', '^', '_');
- $ops_r = array('+'=>0,'-'=>0,'*'=>0,'/'=>0,'^'=>1);
- $ops_p = array('+'=>0,'-'=>0,'*'=>1,'/'=>1,'_'=>1,'^'=>2);
-
- $expecting_op = false;
-
-
- if (preg_match("/[^\w\s+*^\/()\.,-]/", $expr, $matches)) {
- return $this->trigger("illegal character '{$matches[0]}'");
- }
-
- while(1) {
- $op = substr($expr, $index, 1);
-
- $ex = preg_match('/^([a-z]\w*\(?|\d+(?:\.\d*)?|\.\d+|\()/', substr($expr, $index), $match);
-
- if ($op == '-' and !$expecting_op) {
- $stack->push('_');
- $index++;
- } elseif ($op == '_') {
- return $this->trigger("illegal character '_'");
-
- } elseif ((in_array($op, $ops) or $ex) and $expecting_op) {
- if ($ex) {
- $op = '*'; $index--;
- }
-
- while($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();
- }
-
- $stack->push($op);
- $index++;
- $expecting_op = false;
-
- } elseif ($op == ')' and $expecting_op) {
- while (($o2 = $stack->pop()) != '(') {
- if (is_null($o2)) return $this->trigger("unexpected ')'");
- else $output[] = $o2;
- }
- if (preg_match("/^([a-z]\w*)\($/", $stack->last(2), $matches)) {
- $fnn = $matches[1];
- $arg_count = $stack->pop();
- $output[] = $stack->pop();
- if (in_array($fnn, $this->fb)) {
- if($arg_count > 1)
- return $this->trigger("too many arguments ($arg_count given, 1 expected)");
- } elseif (array_key_exists($fnn, $this->f)) {
- if ($arg_count != count($this->f[$fnn]['args']))
- return $this->trigger("wrong number of arguments ($arg_count given, " . count($this->f[$fnn]['args']) . " expected)");
- } else {
- return $this->trigger("internal error");
- }
- }
- $index++;
-
- } elseif ($op == ',' and $expecting_op) {
- while (($o2 = $stack->pop()) != '(') {
- if (is_null($o2)) return $this->trigger("unexpected ','");
- else $output[] = $o2;
- }
-
- if (!preg_match("/^([a-z]\w*)\($/", $stack->last(2), $matches))
- return $this->trigger("unexpected ','");
- $stack->push($stack->pop()+1);
- $stack->push('(');
- $index++;
- $expecting_op = false;
-
- } elseif ($op == '(' and !$expecting_op) {
- $stack->push('(');
- $index++;
-
- } elseif ($ex and !$expecting_op) {
- $expecting_op = true;
- $val = $match[1];
- if (preg_match("/^([a-z]\w*)\($/", $val, $matches)) {
- if (in_array($matches[1], $this->fb) or array_key_exists($matches[1], $this->f)) {
- $stack->push($val);
- $stack->push(1);
- $stack->push('(');
- $expecting_op = false;
- } else {
- $val = $matches[1];
- $output[] = $val;
- }
- } else {
- $output[] = $val;
- }
- $index += strlen($val);
-
- } elseif ($op == ')') {
- return $this->trigger("unexpected ')'");
- } elseif (in_array($op, $ops) and !$expecting_op) {
- return $this->trigger("unexpected operator '$op'");
- } else {
- return $this->trigger("an unexpected error occurred");
- }
- if ($index == strlen($expr)) {
- if (in_array($op, $ops)) {
- return $this->trigger("operator '$op' lacks operand");
- } else {
- break;
- }
- }
- while (substr($expr, $index, 1) == ' ') {
- $index++;
- }
-
- }
- while (!is_null($op = $stack->pop())) {
- if ($op == '(') return $this->trigger("expecting ')'");
- $output[] = $op;
- }
- return $output;
- }
-
-
- function pfx($tokens, $vars = array()) {
-
- if ($tokens == false) return false;
-
- $stack = new EvalMathStack;
-
- foreach ($tokens as $token) {
-
- if (in_array($token, array('+', '-', '*', '/', '^'))) {
- if (is_null($op2 = $stack->pop())) return $this->trigger("internal error");
- if (is_null($op1 = $stack->pop())) return $this->trigger("internal error");
- switch ($token) {
- case '+':
- $stack->push($op1+$op2); break;
- case '-':
- $stack->push($op1-$op2); break;
- case '*':
- $stack->push($op1*$op2); break;
- case '/':
- if ($op2 == 0) return $this->trigger("division by zero");
- $stack->push($op1/$op2); break;
- case '^':
- $stack->push(pow($op1, $op2)); break;
- }
-
- } elseif ($token == "_") {
- $stack->push(-1*$stack->pop());
-
- } elseif (preg_match("/^([a-z]\w*)\($/", $token, $matches)) {
- $fnn = $matches[1];
- if (in_array($fnn, $this->fb)) {
- if (is_null($op1 = $stack->pop())) return $this->trigger("internal error");
- $fnn = preg_replace("/^arc/", "a", $fnn);
- if ($fnn == 'ln') $fnn = 'log';
- eval('$stack->push(' . $fnn . '($op1));');
- } elseif (array_key_exists($fnn, $this->f)) {
-
- $args = array();
- for ($i = count($this->f[$fnn]['args'])-1; $i >= 0; $i--) {
- if (is_null($args[$this->f[$fnn]['args'][$i]] = $stack->pop())) return $this->trigger("internal error");
- }
- $stack->push($this->pfx($this->f[$fnn]['func'], $args));
- }
-
- } else {
- if (is_numeric($token)) {
- $stack->push($token);
- } elseif (array_key_exists($token, $this->v)) {
- $stack->push($this->v[$token]);
- } elseif (array_key_exists($token, $vars)) {
- $stack->push($vars[$token]);
- } else {
- return $this->trigger("undefined variable '$token'");
- }
- }
- }
-
- if ($stack->count != 1) return $this->trigger("internal error");
- return $stack->pop();
- }
-
-
- function trigger($msg) {
- $this->last_error = $msg;
- if (!$this->suppress_errors) trigger_error($msg, E_USER_WARNING);
- return false;
- }
- }
-
- class EvalMathStack {
-
- var $stack = array();
- var $count = 0;
-
- function push($val) {
- $this->stack[$this->count] = $val;
- $this->count++;
- }
-
- function pop() {
- if ($this->count > 0) {
- $this->count--;
- return $this->stack[$this->count];
- }
- return null;
- }
-
- function last($n=1) {
- return !empty($this->stack[$this->count-$n]) ? $this->stack[$this->count-$n] : NULL;
- }
- }