mathexpvalidator
Mathematical Expression Validator
Dependencies:
mathtokenizer: ^1.0.8
Library:
shunt: shunting function that takes string input and returns either 0 (if mismatched parentheses) or an array of objects {type, value}, an implementation of the shunting-yard algorithm (with unary operator, and nested function support)
validate: validating function that takes string input and returns an array: [0 || 1, "Error or Success message"] validate can also take optional arguments such as an array fuctions of accepted function names, and an array of variables: validate(expression, functions(optional),variables(optional))**
Examples:
To run these examples, just install the package in your directory:
npm i mathexpvalidator
And add the example code to your js file and then run it
Example 1:
const validator = require('mathexpvalidator');
let output = validator.shunt("-sin(1/x)");
/*
output = [
token { type: 'number', value: '1' },
token { type: 'variable', value: 'x' },
token { type: 'operator', value: '/' },
token { type: 'function', value: 'sin' },
token { type: 'unary_operator', value: '-' }
]
*/
let status = validator.validate("-sin(1/x)");
//status = [ 1, 'Valid expression' ]
Example 2:
const validator = require('mathexpvalidator');
let output = validator.shunt("(1+x)\*(x-");
//output = 0 (because of mismatched parentheses)
let status = validator.validate("(1+x)\*(x-");
//status = [ 0, 'Mismatched parenthesis' ]
Example 3:
const validator = require('mathexpvalidator');
let output = validator.shunt("x-1+");
/*
output = [
token { type: 'variable', value: 'x' },
token { type: 'number', value: '1' },
token { type: 'operator', value: '-' },
token { type: 'operator', value: '+' }
]
*/
let status = validator.validate("x-1+");
//status = [ 0, 'Insufficient operands' ]
Example 4: Using functions, variables optional arguments
const validator = require('mathexpvalidator');
const func = ["cos", "cosh", "acos", "sin", "sinh", "asin"];
const vari = ["x"];
let status = validator.validate("cosh(x)", func, vari);
//status = [1, 'Valid expression']
Example 5: Using the same func and vari arguments from example 4 but with an added variable t in the expression
const validator = require('mathexpvalidator');
const func = ["cos", "cosh", "acos", "sin", "sinh", "asin"];
const vari = ["x"];
let status = validator.validate("cosh(x*t)", func, vari);
//status = [0, 'Variable name not allowed']
