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antlr-calculator

Build Status npm

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.


MIT License