Compile a Script (to AST)

To repeatedly evaluate a script, compile it first with Engine::compile into an AST (Abstract Syntax Tree) form.

Engine::eval_ast_XXX and Engine::run_ast_XXX evaluate a pre-compiled AST.


#![allow(unused)]
fn main() {
// Compile to an AST and store it for later evaluations
let ast = engine.compile("40 + 2")?;

for _ in 0..42 {
    let result: i64 = engine.eval_ast(&ast)?;

    println!("Answer #{}: {}", i, result);      // prints 42
}
}

Compiling a script file is also supported with Engine::compile_file (not available under no_std or in WASM builds).


#![allow(unused)]
fn main() {
let ast = engine.compile_file("hello_world.rhai".into())?;
}

AST Manipulation API

Advanced users may want to manipulate an AST, especially the functions contained within.

See the section on Manage AST’s for more details.