mossadal / math-parser Goto Github PK

Hi again! I found this other bug when I wanted to try to trigger various exceptions by writing bad equations.

$ php -v
PHP 7.0.15 (cli) (built: Feb 10 2017 16:55:27) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies

        $equation = '1(2';

        $parser = new \MathParser\StdMathParser();

        // Generate an abstract syntax tree.
        $AST = $parser->parse( $equation );

        // Evaluate the expression in the AST.
        $evaluator = new \MathParser\Interpreting\Evaluator();
        $value = $AST->accept( $evaluator );

PHP Fatal error:  Uncaught Error: Call to undefined method MathParser\Parsing\Nodes\SubExpressionNode::setLeft() in ./vendor/mossadal/math-parser/src/MathParser/Parsing/Parser.php:278

Hello @mossadal,

Will you upgrade your project to support PHP 8 as a major release 2.X any time soon ?

Best Regards

Hi! I found this bug when I wanted to try to trigger various exceptions by writing bad equations.

$ php -v
PHP 7.0.15 (cli) (built: Feb 10 2017 16:55:27) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies

        $equation = '2poww(2)';

        $parser = new \MathParser\StdMathParser();

        // Generate an abstract syntax tree.
        $AST = $parser->parse( $equation );

        // Evaluate the expression in the AST.
        $evaluator = new \MathParser\Interpreting\Evaluator();
        $value = $AST->accept( $evaluator );

PHP Warning:  array_key_exists() expects parameter 2 to be array, null given in ./vendor/mossadal/math-parser/src/MathParser/Interpreting/Evaluator.php on line 162

Warning: array_key_exists() expects parameter 2 to be array, null given in ./vendor/mossadal/math-parser/src/MathParser/Interpreting/Evaluator.php on line 162

I would like to run my own functions in evaluations. E.g.:

function doSomething($x) {
...
return $answer;
}

$AST = $parser->parse('doSomething(x)');
$evaluator->setVariables([ 'x' => 2 ]);
$value = $AST->accept($evaluator);

How to achieve this?

Package operations: 70 installs, 0 updates, 0 removals

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When I pulled your project, I tried to run the tests and this error occurred:
PHP Fatal error: Uncaught Error: Class 'PHP_Timer' not found math-parser/vendor/phpunit/phpunit/src/Framework/TestResult.php:662

I made some researches and I found this recent issue (around 6 months old) about the problem.
sebastianbergmann/phpunit#3008

Apparently, some old phpunit versions can't work with the new version of PHP_Timer. I've tried the conflict param for composer, but it didn't seem to work. I will continue to search a solution.

I must admit that I pulled your project to run the tests because I tried to evaluate round, ceil and floor functions and I got this error:
"MathParser\Exceptions\UnknownVariableException : Unknown variable r." has if round is not a function...

EDIT: Well I found out why round, ceil and floor throw exception. They seem to work on dev-master, but not on your last tag (1.3.13). But still nothing for PHP_Timer.

I needed something like the expression tree in math.js (https://mathjs.org/docs/expressions/expression_trees.html) to extract all variables from an expression. Like:

$formula = '(a+b)*c';
$variables = magic($formula);
print_r($variables);  // ['a','b','c']

Unfortunately, it wasn't that straightforward to implement (without getting deep into the code/lexer stuff). Like everyone in 2023 I struggled my way through AI and finally got a working VariableCollector class based on the Evaluate class.

I leave the following AI-generated answer as a starting point for someone who is looking for an approach to solve it. If there is a better way, please add it here.

Based on the provided code, you can create a VariableCollector class by extending the Evaluator class and overriding the visitVariableNode() method. This method is called when a VariableNode is visited during the traversal of the Abstract Syntax Tree (AST).

Here's what your VariableCollector class would look like:

namespace MathParser\Interpreting;

use MathParser\Parsing\Nodes\VariableNode;

class VariableCollector extends Evaluator
{
    private $variables = [];

    public function visitVariableNode(VariableNode $node)
    {
        $name = $node->getName();

        if (!in_array($name, $this->variables)) {
            $this->variables[] = $name;
        }
    }

    public function getVariables()
    {
        return $this->variables;
    }
}

In this class, the visitVariableNode method adds the variable name to the $variables array if it's not already there. The getVariables method returns the collected variables.

To use the VariableCollector class, you would do the following:

$collector = new VariableCollector();
$AST->accept($collector);

$variables = $collector->getVariables();
print_r($variables);

This will print an array of unique variable names that were found in the expression Source 2.

Please note that this example assumes that your variable names are single characters. If you use multi-character variable names, you will need to create a custom Lexer, as described in previous responses.

Source: https://www.phind.com/search?cache=xs6ryq72b7ofro516tfah9s5 -> last answer

If you supply a variable named e, the number e is used instead of the supplied value.
Maybe throw an exception when a variable named e is supplied?

If you use a negative number on the right hand side, the StdMathParser will return a Syntax Error.

For example: 6 + -1 which is valid and would result in 5.

"1+.1" (or ".1") triggers an exception saying Unknown token 0 encountered.

Maybe add some parsing logic to say "if period, assume a zero to the left"?

So that "1+.1" is treated as "1+0.1".

Does that make sense? Or is this a bad idea? ;-)

Right now the parser has some really useful interpretation exceptions. Unfortunately I found no possibility to get the, let's say an unknown token, from the exception. It's being merged with the exception's message. This forces me to inform an user with a generic error description.

This can easily be accomplished by adding an exception variable, with an accessor. For example, the token exception could get a public getToken() method which will return the token only. If you agree and would like this feature, I can create a pull request for this.

Greetings!

I'm a little surprised that this super-functional library doesn't support calculating the remainder of the division (%)

Maybe I didn't study the code carefully?

If it really does not exist, please add.

I've studied the code, it should be a pretty simple action. At the same time, I have not found an opportunity to extend expressions in child classes

Thank you for your work and attention

Thanks for sharing this work! I would like to parse dollar values in my expression, for example:

$1,500.75 - $200.00

I'm not sure the best way to do this, but it looks like I can create a custom Lexer and add a token definition with an custom pattern that will match dollar values.

However, I would still need to parse the token into a float. For TokenType::RealNumber this happens in the Node::factory method which is called from the private function shuntingYard in the the Parser class. This doesn't look easily extendable.

Do you have any suggestions on how I should go about this?

We have expressions that may use some of from a lot of variables, more than 10K.
Does your parser have something like onVariable or onFunction events to catch and provide custom variables?

Hello and thank you for publishing the package.

I've been trying pow() and log() with two parameters but the , returned the Unknown token exception.

The ** operator returned a Syntax error exception.

Code example

$parser = new StdMathParser();
$AST = $parser->parse( 'pow(33,10)' );
$evaluator = new Evaluator();
//$total returns the exceptions explained above
$total = $AST->accept($evaluator);

$parser = new StdMathParser();
$AST = $parser->parse( '3**10' );
$evaluator = new Evaluator();
//$total returns the exceptions explained above
$total = $AST->accept($evaluator);

Did I forget a step for those scenarios ?
All the other math functions and operator work as expected in my case.
Thanks again

        $expression = 'a + i';
        $variableValues = ['a' => 1, 'i' => 1];
        // Generate an abstract syntax tree
        $AST = $this->parser->parse($expression);

        // Set variables with value ['x' => 1, ..]
        $this->evaluator->setVariables($variableValues);

        // pass evaluator to Abstract Syntax Tree
        $value = $AST->accept($this->evaluator);
        
        return $value;

Any expression that contains i seems the throw the following expception:

MathParser\Exceptions\UnknownConstantException: Unknown constant i.

Replacing i with any other alphabet seems to fix the issue.

Hello. Nice lib and examples of code. But how can i start to use it? Do i need compile somehow this code? If i just wanna use it on my web form to prevent some hacks in input (without php eval function). what i need to do to use your lib? Sorry for my bad English

Intelij (idea) doesn't understand @retval. It works with @return. The namespaces are different too.

Are you open for a pr?

Is there a simple way to add custom constants similar to 'pi' such as
epsilon_o = 8.8541878128e-12
speed_of_light = 299792458.0
electron_mass = 9.1e-31
...

so they can be utilized?

"0.148*speed_of_light^2"

First of all, thanks for this great library! I really love how its structured with an AST and the code quality is great! We are using it at the Larachat's slackbot "Eve" and encountered some unexpected behaviours. You can view the whole discussion over here btw. Here are the expressions we used, what we expected and the result.

Is this something you would agree on?

Hi, can u please add Maximum, Minimum Functions?
For Example:
max(1,3) + 7
// return 10

min(5,0) + 10
//return 10

or if possible:

max(1,2,3,4,5) + 1
//return 6

//x=1 , y=2
max(x,y) + 10
// return 12

Hi,
how can add a new Operator "pipe ( | )" that acts as "add ( + )" put 0 whereas a variable is null (or blank)?

This is an example how to get it worked:
a=5, b=null
a+b = null (actual working)
a|b = 5 (desidered)

Thanks