The Common Expression Language (CEL) is a non-Turing complete language designed for simplicity, speed, safety, and portability. CEL's C-like syntax looks nearly identical to equivalent expressions in C++, Go, Java, and TypeScript. CEL is ideal for lightweight expression evaluation when a fully sandboxed scripting language is too resource intensive.
java
// Check whether a resource name starts with a group name.
resource.name.startsWith("/groups/" + auth.claims.group)
go
// Determine whether the request is in the permitted time window.
request.time - resource.age < duration("24h")
typescript
// Check whether all resource names in a list match a given filter.
auth.claims.email_verified && resources.all(r, r.startsWith(auth.claims.email))
This project includes a parser and an interpreter which means that it can be used to evaluate CEL-expressions. The library aims to be very simple to use, while still being fast, safe, and customizable.
```rust use cel_interpreter::{Context, Program};
fn main() { // Compile a CEL program let program = Program::compile("add(2, 3)").unwrap();
// Add any variables or functions that the program will need
let mut context = Context::default();
context.add_function("add", |a: i32, b: i32| a + b);
// Run the program
let value = program.execute(&context).unwrap();
assert_eq!(value, 5.into());
} ```
Check out these other examples to learn how to use this library: