PHPで文字列として渡された式を評価するにはどうすればよいですか？
文字列として渡された数学演算を実行するための適切で安全な方法を理解しようとしています。私のシナリオでは、画像のEXIFデータからフェッチされた値です。
少し調べた結果、2つの方法が見つかりました。
まず、evalを使用します：
function calculator1($str){
eval("\$str = $str;");
return $str;
}
次に、create_function：
function calculator2($str){
$fn = create_function("", "return ({$str});" );
return $fn();
};
どちらの例でも、悪意のあるコードの実行を回避するために文字列のクリーンアップが必要です。それを行う他のまたはより短い方法はありますか？
これは役立つかもしれません。
http://www.phpclasses.org/browse/package/2695.html
ダウンロードには迷惑なログインが必要です。ここに貼り付けてコピーしました。
- このクラスは、数式を安全に評価するために使用できます。
- クラスは、テキスト文字列内の式を取得し、変数の値を置き換えて、数学関数と演算の結果を計算することによって評価できます。
- 暗黙の乗算、多変数関数、入れ子関数をサポートしています。
- 信頼できないソースからの式を評価するために使用できます。堅牢なエラーチェックを提供し、限られた機能セットのみを評価します。
- 式の式からグラフを生成するために使用できます。
/*
================================================================================
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
$m->evalute($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); // variables (and constants)
var $f = array(); // user-defined functions
var $vb = array('e', 'pi'); // constants
var $fb = array( // built-in functions
'sin','sinh','arcsin','asin','arcsinh','asinh',
'cos','cosh','arccos','acos','arccosh','acosh',
'tan','tanh','arctan','atan','arctanh','atanh',
'sqrt','abs','ln','log');
function EvalMath() {
// make the variables a little more accurate
$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($expr)-1); // strip semicolons at the end
//===============
// is it a variable assignment?
if (preg_match('/^\s*([a-z]\w*)\s*=\s*(.+)$/', $expr, $matches)) {
if (in_array($matches[1], $this->vb)) { // make sure we're not assigning to a constant
return $this->trigger("cannot assign to constant '$matches[1]'");
}
if (($tmp = $this->pfx($this->nfx($matches[2]))) === false) return false; // get the result and make sure it's good
$this->v[$matches[1]] = $tmp; // if so, stick it in the variable array
return $this->v[$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], $this->fb)) { // make sure it isn't built in
return $this->trigger("cannot redefine built-in function '$matches[1]()'");
}
$args = explode(",", preg_replace("/\s+/", "", $matches[2])); // get the arguments
if (($stack = $this->nfx($matches[3])) === false) return false; // see if it can be converted to postfix
for ($i = 0; $i<count($stack); $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, $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)); // straight up evaluation, woo
}
}
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 $output;
}
//===================== HERE BE INTERNAL METHODS ====================\\
// Convert infix to postfix notation
function nfx($expr) {
$index = 0;
$stack = new EvalMathStack;
$output = array(); // postfix form of expression, to be passed to pfx()
$expr = trim(strtolower($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 $this->trigger("illegal character '{$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-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 $this->trigger("illegal character '_'"); // but not in the input expression
//===============
} elseif ((in_array($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 parethesis?
$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: http://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 == ')' and $expecting_op) { // ready to close a parenthesis?
while (($o2 = $stack->pop()) != '(') { // pop off the stack back to the last (
if (is_null($o2)) return $this->trigger("unexpected ')'");
else $output[] = $o2;
}
if (preg_match("/^([a-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, $this->fb)) { // check the argument count
if($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 { // did we somehow Push a non-function on the stack? this should never happen
return $this->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 $this->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-z]\w*)\($/", $stack->last(2), $matches))
return $this->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++;
$allow_neg = true;
//===============
} elseif ($ex and !$expecting_op) { // do we now have a function/variable/number?
$expecting_op = true;
$val = $match[1];
if (preg_match("/^([a-z]\w*)\($/", $val, $matches)) { // may be func, or variable w/ implicit multiplication against parentheses...
if (in_array($matches[1], $this->fb) or array_key_exists($matches[1], $this->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 $this->trigger("unexpected ')'");
} elseif (in_array($op, $ops) and !$expecting_op) {
return $this->trigger("unexpected operator '$op'");
} else { // I don't even want to know what you did to get here
return $this->trigger("an unexpected error occured");
}
if ($index == strlen($expr)) {
if (in_array($op, $ops)) { // did we end with an operator? bad.
return $this->trigger("operator '$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 $this->trigger("expecting ')'"); // if there are (s on the stack, ()s were unbalanced
$output[] = $op;
}
return $output;
}
// evaluate postfix notation
function pfx($tokens, $vars = array()) {
if ($tokens == false) return false;
$stack = new EvalMathStack;
foreach ($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 $this->trigger("internal error");
if (is_null($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, $op2)); break;
}
// if the token is a unary operator, pop one value off the stack, do the operation, and Push it back on
} elseif ($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)) { // it's a function!
$fnn = $matches[1];
if (in_array($fnn, $this->fb)) { // built-in function:
if (is_null($op1 = $stack->pop())) return $this->trigger("internal error");
$fnn = preg_replace("/^arc/", "a", $fnn); // for the 'arc' trig synonyms
if ($fnn == 'ln') $fnn = 'log';
eval('$stack->Push(' . $fnn . '($op1));'); // perfectly safe eval()
} elseif (array_key_exists($fnn, $this->f)) { // user function
// get args
$args = array();
for ($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'], $args)); // yay... recursion!!!!
}
// if the token is a number or variable, Push it on the stack
} else {
if (is_numeric($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'");
}
}
}
// when we're out of tokens, the stack should have a single element, the final result
if ($stack->count != 1) return $this->trigger("internal error");
return $stack->pop();
}
// trigger an error, but nicely, if need be
function trigger($msg) {
$this->last_error = $msg;
if (!$this->suppress_errors) trigger_error($msg, E_USER_WARNING);
return false;
}
}
// for internal use
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 $this->stack[$this->count-$n];
}
}
編集： Jittersは、逆ポーランド記法をサポートするバージョンを求めていました。 HP電卓があった大学時代を思い出します:)
<?php
/* This Class can be useful for writting RPN macros or FORTH like parsers
@Author: Arturo Gonzalez-Mata Santana (Spain)
[email protected]
@copyright 2007: www.phpsqlasp.com
It is part of a project to recover "macros" from some old aplications
This code is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
class RPNstack
{
var $data=array();
var $compare=0;
function pop() {return array_shift ($this->data);}
function Push($x) {array_unshift($this->data, $x);}
function count() {return count($this->data);}
function first() {return $this->data[0];}
function top() {return end($this->data);} //last element of
function swap() { // interchange tow elements
$t = $this->data[1];
$this->data[1] = $this->data[0];
$this->data[0] = $t;
}
function dup() { // put a copy of X element in the stack
array_unshift($this->data, $this->data[0]);
}
function dump(){ // dump array data for debuging
print_r($this->data);
}
function parse($tok) // execute actions with the stack for each token
{
$r = null;
$tok = strtoupper(trim($tok));
//$this->dump(); // this line is for debugging purpose only
switch ($tok) :
// FIRST "IF THEN" AND OTHER FLOW CONTROLS
case ('THEN'): break;
case('IF'):
if ($this->pop() == 0) do { // if condition is false do nothing until "THEN"
$tok = strtoupper(strtok (" "));
} while ($tok <> "THEN"); // IF THERE IS NO "THEN" THIS SHALL BE AN ENLESS LOOP
break;
// basic math operators //OPERADORES MATEMATICOS BASICOS
case('+'):
$r = $this->pop() + $this->pop();
// $r = array_shift($this->data) + array_shift($this->data); // is more efficient but less understable
break;
case('-'):
$r = $this->pop(); $r = $this->pop()-$r;
break;
case('*'):
$r = $this->pop() * $this->pop();
break;
case('/'):
$r = $this->pop(); $r = $this->pop() / $r;
break;
// stack operators //OPERADORES DE PILA
case ('DUP'):
$r=$this->dup();
break;
case ('SWAP'):
$this->swap();
break;
// COMPARISON OPERATORS
case ('='):
if ($this->data[0] == $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
case ('<>'):
if ($this->data[0] <> $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
case ('<'):
if ($this->data[0] < $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
case ('>'):
if ($this->data[0] > $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
case ('>='):
if ($this->data[0] >= $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
case ('<='):
if ($this->data[0] <= $this->data[1]) $r = $this->Push(1);
else $r = $this->Push(0);
break;
// WARNING FOR NON IMPLEMENTED FUNCTIONS
default:
return sprintf('I don\'t know how to "%s" ', $tok);
endswitch;
if (!is_null($r)) $this->Push($r);
return $r;
} // parse
function parse_line($cadena)
{
$tok = strtok ($cadena," ");
while ($tok!= '') {
if (is_numeric ($tok)) {
$this->Push($tok);
} else {
$r = $this->parse($tok);
}
$tok = strtok (" ");
}
return $r;
}
} // class RPN
?>
私はこれを行いました： PHP Formula Interpreter
それはどのように機能しますか？
まず、数式とそのパラメータを使用してFormulaInterpreterのインスタンスを作成します
_$formulaInterpreter = new FormulaInterpreter("x + y", ["x" => 10, "y" => 20]);
_execute()メソッドを使用して、式を解釈します。結果を返します：
_echo $formulaInterpreter->execute();
_一行で
_echo (new FormulaInterpreter("x + y", ["x" => 10, "y" => 20]))->execute();
_例
_# Formula: speed = distance / time
$speed = (new FormulaInterpreter("distance/time", ["distance" => 338, "time" => 5]))->execute() ;
echo $speed;
#Venezuela night overtime (ordinary_work_day in hours): (normal_salary * days_in_a_work_month)/ordinary_work_day
$parameters = ["normal_salary" => 21000, "days_in_a_work_month" => 30, "ordinary_work_day" => 8];
$venezuelaLOTTTArt118NightOvertime = (new FormulaInterpreter("(normal_salary/days_in_a_work_month)/ordinary_work_day", $parameters))->execute();
echo $venezuelaLOTTTArt118NightOvertime;
#cicle area
$cicleArea = (new FormulaInterpreter("3.1416*(radio*radio)", ["radio" => 10]))->execute();
echo $cicleArea;
_数式について
- 少なくとも2つのオペランドと演算子が含まれている必要があります。
- オペランドの名前は大文字でも小文字でもかまいません。
- 現在、sin、cos、pow…などの数学関数は含まれていません。私はそれらを含めるように取り組んでいます。
- 数式が有効でない場合、次のようなエラーメッセージが表示されます：エラー、数式（single_variable）が無効です。
- パラメータの値は数値でなければなりません。