7 releases
0.1.6 | Oct 8, 2019 |
---|---|
0.1.5 | Sep 9, 2019 |
0.1.4 | Aug 31, 2019 |
#1708 in Parser implementations
28 downloads per month
30KB
600 lines
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(())
}
See rule::op for more supported operators.
ToDos
- add more built-in
Op
s - support register custom
Op
s - support
rule!
macro
License
Dependencies
~2.6–4MB
~71K SLoC