g0 v0.0.2

g0 Parser

A simple parser for arithmetic expressions. Supports positive and negative integers and floating point numbers as well as user defined symbols. See full grammar below.

Installation

npm install g0

Usage

var parse = require('g0');

parse('a + b + 5');
// Expression 'a + b + 5' was a valid arithmetic expression

parse('((a + b + -c)');
// Expression '((a + b + -c)' was NOT a valid arithmetic expression: Expected ')', but saw 'undefined' at column 13

Grammar

E -> E '+' T
   | E '-' T
   | T

T -> T '*' F 
   | T '/' F 
   | F

F -> '(' E ')'
   | [UNARY-OP] N
   | [UNARY-OP] L

UNARY-OP -> '+' | '-'
N -> INT | REAL

INT  -> D { D }
REAL -> D '.' D { D }
D    -> '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
L    -> 'a'..'z' | 'A' .. 'Z'

Tests

npm test