evaluator_rs

A evaluation engine library for Rust.

Usage

Please see the Documentation for more details.

Add to your Cargo.toml:

[dependencies]
evaluator_rs = "0.1"

Examples:

extern crate evaluator_rs;

use std::collections::HashMap;

use evaluator_rs::{evaluate, parse_expr_from_str, parse_expr_from_json, Value};

fn main() {
    // from str expression
    let expr = parse_expr_from_str("{a} + 2 + 3").unwrap();
    let parameters = HashMap::from([("a", Value::from(1))]);
    let rs = evaluate(&expr, &parameters).unwrap();
    assert_eq!(rs, Value::from(6));

    let expr = parse_expr_from_str("{a} in [1, 2 , 3]").unwrap();
    let parameters = HashMap::from([("a", Value::from(1))]);
    let rs = evaluate(&expr, &parameters).unwrap();
    assert_eq!(rs, Value::from(true));

    // from json expression
    let json_expr = r#"{
        "lhs": "{a}",
        "op": "in",
        "rhs": [4, 5, 6] 
    }"#;
    let expr = parse_expr_from_json(json_expr).unwrap();
    let parameters = HashMap::from([("a", Value::from(4))]);
    let rs = evaluate(&expr, &parameters).unwrap();
    assert_eq!(rs, Value::from(true));
}

Data types

Type	Examples
Number	1
String	'hello world'
Bool	true
Array	[1, 2, 3]

Supported operators

Operator	Precedence	Description
&&	1	And
||	1	Or
==	2	Equal
>	2	Greater than
>=	2	Greater than or equal
<	2	Lower than
<=	2	Lower than or equal
in	2	Array contains
*	3	Product
/	3	Division
+	4	Sum
-	4	Sub

Identifier

Identifiers are wrapped by curly brace. When expression is evaluated, parameters must be provided identifier value.

Examples:

    let expr = parse_expr("{a} in [1, 2 , 3]").unwrap();
    let parameters = HashMap::from([("a", Value::from(1))]);
    let rs = evaluate(&expr, &parameters).unwrap();
    assert_eq!(rs, Value::from(true));

License

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)