Crate rule

A rule engine written in rust. There’s also a python fork.

The rule is a json string or rust object of a list expression. The expression is like [op, arg0, arg1, ..., argn], the op is the operator, and arg0..n is the arguments for the operator. Any argument can be another expression.

For writing convenience, the first argument will be tried to resolve as the context parameter. Or, you can just use the special var operator to indicate the context parameter.

Usage

#[macro_use]
extern crate rule;
 
use rule::{Rule, Result};
 
fn main() -> Result<()> {
    let context = json!({"a": 1, "world": "hello"});
 
    // match the context with rules
    assert!(Rule::new(json!(["=", "a", 1]))?.matches(&context)?);
    assert!(Rule::new(json!(["=", ["var", "a"], 1]))?.matches(&context)?);
    assert!(Rule::from_str(r#"["=", ["var", "a"], 1]"#)?.matches(&context)?);
    assert!(Rule::from_value(["=", "world", "hello"])?.matches(&context)?);
 
    // rule! macro
    assert!(rule!["=", "a", 1]?.matches(&context)?);
 
    // collection operators
    assert!(rule!["in", 1, 1, 2, 3]?.matches(&json!({}))?);
    assert!(rule!["startswith", "hello", "he"]?.matches(&json!({}))?);
    assert!(rule!["startswith", "arr", "foo", "bar"]?.matches(&json!({"arr": ["foo", "bar", "baz"]}))?);
    assert!(rule!["endswith", "arr", "bar", "baz"]?.matches(&json!({"arr": ["foo", "bar", "baz"]}))?);
 
    Ok(())
}

Modules

arg

error

macros

op

rule

Macros

json

Construct a serde_json::Value from a JSON literal.

rule

Construct a Resule<rule::Rule, rule::Error> from a JSON array literal.

Structs

Rule

The Rule type, contains an Expr.

Enums

Error

Type Aliases

Result