infix-postfix

This package allows you to convert infix expressions to postfix expressions.

Installation

``bash
npm install infix-postfix
`

Usage

#### Importing
`typescript
import infixToPostfix from "infix-postfix";
`
or
`javascript
const infixToPostfix = require("infix-postfix");
`
#### Converting
##### to a string
`javascript
console.log(infixToPostfix("(a+2b)^-2").toString());

/* Output:
a 2 b * + 2 − ^
*/
`
##### to an array
`javascript
console.log(infixToPostfix("(a+2b)^-2").toArray());

/* Output:
[
'a', 2, 'b', '*',
'+', 2, '−', '^'
]
*/
`

Examples

2+34 ▶ 2 3 4 +

a b(3+4)2 ▶ a b 3 4 + 2 *

-12-3 ▶ 12 − 3 -

12^-2 ▶ 12 2 − ^

((2cm+112)12.2/3)^2 ▶ 2 cm 112 + 12.2 * 3 / 2 ^


Features

#### Operator parsing
+, -, , /, (), ^ get parsed to + (addition), - (subtraction), − (negation), (multiplication), / (division) and ^ (exponentiation). The difference between - and − is, that − (negation) is an unary operator (e.g. -4 gets parsed to 4 −) and - (subtraction) is
a binary operator (e.g. 2-6 gets parsed to 2 6 -).
There is no unary + operator, because one can simply ignore such for mathematical reasons.

#### Operator reduction
Unnecessary operators get removed automatically.
For example ---+4 gets parsed to 4 −, +(12) gets parsed to 12.

#### Number parsing support
Numbers get parsed. Obviously only works with the toArray() method.

#### Variable support
Any variable not containing operator characters (+, -, ...) is supported. For example a-6 gets parsed to a 6 -.

#### Multiplication shortcut support
A common parser would parse b/10b to b 10b / - which is unfortunately wrong. This parser recognizes that 10 and b are different operands. It parses the string to b 10 b * /.
Added to that a b gets parsed to a b . Furthermore a(3)2 is translated to a 3 2 *`.