antlr-calculator

This calculator is using the ANTLR4 TypeScript target to calculate results from formulas that are passed in as string. Both JavaScript and TypeScript are supported.

Whenever a calculation is performed, a CalculationResult is returned with the following properties:

Property	Type
isValid	boolean	true if the formula could be parsed and calculated, else false
errorPosition	number	Position of the offending symbol in the line, 0 based index, for invalid results, else null
errorMessage	string	ANTLR error message for invalid formulas, else null
result	number	NaN for invalid formulas, else the actual result

You can check out the live demo here!

You can find the .NET version here: https://github.com/GeorgDangl/Dangl.Calculator

Installation

Clone this repository or just go with npm install antlr-calculator.

JavaScript

Just reference dist/bundle.js and the global variable antlrCalc is available.

var result = antlrCalc.Calculator.calculate('4*5');
console.log(JSON.stringify(result, null, 2));

//  {
//    "isValid": true,
//    "errorPosition": null,
//    "errorMessage": null,
//    "result": 20
//  }

TypeScript

Import the Calculator class and use the static calculate(formula: string) method to evaluate formulas.

import { Calculator } from 'antlr-calculator';

var result = Calculator.calculate('4*5');
console.log(JSON.stringify(result, null, 2));

//  {
//    "isValid": true,
//    "errorPosition": null,
//    "errorMessage": null,
//    "result": 20
//  }

Supported functions

| Expression | | | ------------------------------------------- | --------------------------------------------------------------- | ----------------------------- | | FLOOR expression | Round down to zero accuracy | | CEIL expression | Round up to zero accuracy | | ABS expression | Absolute value | | ROUNDK '(' expression ';' expression ')' | Round expr_1 with expr_2 accuracy | | ROUND expression | Round with zero accuracy | | TRUNC expression | Trim decimal digits | | SIN expression | Sinus | | COS expression | Cosinus | | TAN expression | Tangens | | COT expression | Cotangens | | SINH expression | Sinus Hypererbolicus | | COSH expression | Cosinus Hyperbolicus | | TANH expression | Tangens Hyperbolicus | | ARCSIN expression | Inverse Sinus | | ARCCOS expression | Inverse Cosinus | | ARCTAN expression | Inverse Tangens | | ARCTAN2 '(' expression ';' expression ')' | Atan2 | | ARCCOT expression | Inverse Cotangens | | EXP expression | e ^ expr | | LN expression | Logarithm to e | | EEX expression | 10 ^ expr | | LOG expression | Logarithm to 10 | | RAD expression | Angle to radians (360° base) | | DEG expression | Radians to angle (360° base) | | SQRT expression | Square root | | SQR expression | Square product | | expression op = ('^' | '\*\*') expression | expr_1 to the expr_2 th power | | expression (MOD | '%' ) expression | Modulo | | expression DIV expression | Whole part of division rest | | expression op = ('~' | '//') expression | expr_1 nth root of expr_2 | | expression op = ('\*' | '/') expression | Multiplication or division | | expression op = ('+' | '-') expression | Addition or subtraction | | NUMBER | Single integer or float number | | '(' expression ')' | Expression within parentheses | | MIN '(' expression (';' expression)* ')' | Minimum | | MAX '(' expression (';' expression)* ')' | Maximum | | PI '()'? | Mathematical constant pi = 3,141593 | | expression E+ expression | Exponent, e.g. 10e+43 | | expression E- expression | Inverted Exponent, e.g. 10e-43 | | EULER | Mathematical constant e = 2,718282 | | '-' expression | Unary minus sign (negative numbers) | | '+' expression | Unary plus sign (positive numbers) | | '(' expression ')' expression | Expressions without multiplication sign, e.g. 2(3) -> 2*(3) | | expression '(' expression ')' | Expressions without multiplication sign, e.g. 2(3) -> 2*(3) |

expression may be any expression as functions can be nested. Example: DEG(2*PI) or LOG(10^3).

Formulas can be case invariant, e.g. SIN, sin and siN are all considered the same.

Comments in Formulas

Comments in Formulas are supported by encapsulating them either in /*...*/, '...' or "..." quote styles. Examples:

4/*Length*/*3/*Width*/ resolves to 12

4'Length'*3'Width' resolves to 12

4"Length"*3"Width" resolves to 12

Substitutions

The calculator can be called with an overload that accepts a callback function for substitution values. For example, take the following formula:
1,2*#Z4+3
Here, #Z4 is a substitution, which is a placeholder that can be externally supplied. Let's say you want to resolve #Z4 to the value three, you could make this simple call:

const formula = '1,2*#Z4+3';
const result = Calculator.calculate(formula, (substitution) => {
  if (substitution === '#Z4') {
    return 3;
  }

  return null;
});

The callback is in the form of a (substitution: string) => number, and it will be called for every substitution found in the formula. Multiple substitutions are supported. If duplicates in substitutions are present, the calculator will request each one individually. If a substitution resolves to null, the formula is considered invalid.

Substitutions must always start with the # character and can then have the following characters: [a-z] | [A-Z] | [äÄöÖüÜ] | [0-9]

Trailing comments

Formulas may be terminated with a semicolon ; at the end, followed by extra input that is not evaluated. This is useful when, instead of regular comments, you just want to attach some trailing formation at the end of a formula. For example, the following formula:
1 + 3; As per our counting
Would just evaluate the 1 + 3 portion and return a valid result with the value 4, ignoring the trailing semicolon and all input that follows.

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MIT License