ympons / go-expr

Runtime evaluation of Go-like expressions

Runtime evaluation of Go-like expressions

What?

eg.

e := expr.MustCompile("a + 1 > 2")
e.Bool(expr.V{"a": 0}) == false
e.Bool(expr.V{"a": 1}) == false
e.Bool(expr.V{"a": 2}) == true

and

e = expr.MustCompile("(a + 2) * 10")
n, err := e.Eval(expr.V{"a": 1})
n.(int64) == 30

It does not support:

• Function calls (though this would be useful).
• Slices or arrays.

It does support:

• Truthiness evaluation, ala Python: eg. given V{"a": 1}, evaluating a will be true.
• Automatic type coercion. eg. "a" + 10 == "a10"
• Nested fields. eg. A.B == 2

Why?

If you want to add simple expression-based filtering or numeric evaluation, this might fit your needs.

Where?

Install

$ go get github.com/alecthomas/expr

Docs

You can find the API documentation on godoc.