Maths Parser

A simple maths parser that can parse and evaluate mathematical expressions. It uses a recursive descent parser to parse the expression and then evaluates the expression using a simple recursive algorithm. The parser can handle the following operators: +, -, *, /, ^.

It handles operator precedence and associativity. The precedence of the operators is as follows:

1. ^
2. *, /
3. +, -

Grammar

expression = term { ( "+" | "-" ) term }
term = factor { ( "*" | "/" ) factor }
factor = number | "(" expression ")"
number = [0-9]+

Lexical analysis

Token types

• NUMBER - A number
• OPERATOR - An operator

Token structure

NUMBER

• type - NUMBER
• value - The number

OPERATOR

• type - OPERATOR
• value - The operator
• left - The left operand
• right - The right operand

Usage

npm run build
npm run start

You can a cli where you can enter a mathematical expression and it will be parsed and evaluated.

Example

> 3 + 3 ^ 2

{
    "type": "operator",
    "value": "+",
    "left": {
        "type": "number",
        "value": 3
    },
    "right": {
        "type": "operator",
        "value": "^",
        "left": {
            "type": "number",
            "value": 3
        },
        "right": {
            "type": "number",
            "value": 2
        }
    }
}

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