eq_parser

Description:

eq parser

A light, fast equation parser that supports functions and variables.
Features #

Supports many number formats. E.g.:

12
-1.234
1.234e5
0xff12
0b1101101


Mathematical operators and brackets

+ - * / ^ % ( )


Common functions are built-in

sin, acos, max, min, floor, round, log, etc


Supports user-defined functions
Supports user-defined variables (references)
User-defined error handling

Getting started #

Add eq_parser to your pubspec.yaml
Add import 'package:eq_parser/eq_parser.dart'; to your code

Usage #
num result = EqParser()..parse('12 + 3 ^ (5.12 * sin(pi/2))');
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var parser = EqParser();
parser.onError = (m, p)=>throw Exception('$m at position $p');
parser.references.addAll({
'x': 3,
'y': 4,
});
parser.functions['multiply'] = FunctionDef((a, b)=>a * b, 2);
num result = parser.parse('multiply(x, y)');
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Additional information #
This parser is not based on the shunting yard algorithm or reverse polish
notation. I am not sure if it actually matches any existing algorithm or if
it is novel. It's based on a single stack, and does not use recursion. Tokens
are pushed to the stack just once, and popped/processed just once, so performance is
fast and linear with respect to the length of the equation.
There is a minimal implementation included for reference purposes. It can be
used like this:
import 'package:eq_parser/src/eq_parser_lite.dart';

num result = EqParserLite()..parse('(17 - 7.12) * 2 ^ 4');
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