rhai/tests/syntax.rs
2020-07-22 17:05:13 +08:00

81 lines
2.5 KiB
Rust

use rhai::{
Engine, EvalAltResult, EvalContext, Expression, ParseError, ParseErrorType, Scope, INT,
};
#[test]
fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
let mut engine = Engine::new();
engine.consume("while false {}")?;
// Disable 'while' and make sure it still works with custom syntax
engine.disable_symbol("while");
assert!(matches!(
*engine.compile("while false {}").expect_err("should error").0,
ParseErrorType::Reserved(err) if err == "while"
));
assert!(matches!(
*engine.compile("let while = 0").expect_err("should error").0,
ParseErrorType::Reserved(err) if err == "while"
));
engine
.register_custom_syntax(
&[
"do", "|", "$ident$", "|", "->", "$block$", "while", "$expr$",
],
1,
|engine: &Engine,
context: &mut EvalContext,
scope: &mut Scope,
inputs: &[Expression]| {
let var_name = inputs[0].get_variable_name().unwrap().to_string();
let stmt = inputs.get(1).unwrap();
let expr = inputs.get(2).unwrap();
scope.push(var_name, 0 as INT);
loop {
engine.eval_expression_tree(context, scope, stmt)?;
if !engine
.eval_expression_tree(context, scope, expr)?
.as_bool()
.map_err(|_| {
EvalAltResult::ErrorBooleanArgMismatch(
"do-while".into(),
expr.position(),
)
})?
{
break;
}
}
Ok(().into())
},
)
.unwrap();
// 'while' is now a custom keyword so this it can no longer be a variable
engine.consume("let while = 0").expect_err("should error");
assert_eq!(
engine.eval::<INT>(
r"
do |x| -> { x += 1 } while x < 42;
x
"
)?,
42
);
// The first symbol must be an identifier
assert!(matches!(
*engine.register_custom_syntax(&["!"], 0, |_, _, _, _| Ok(().into())).expect_err("should error"),
ParseError(err, _) if *err == ParseErrorType::BadInput("Improper symbol for custom syntax: '!'".to_string())
));
Ok(())
}