Index evaluation

This commit is contained in:
greg 2018-03-07 21:46:21 -08:00
parent ca67f9b4fe
commit da9aa1e29d

View File

@ -175,6 +175,26 @@ impl<'a> State<'a> {
} }
self.eval_application(*f, evaled_arguments) self.eval_application(*f, evaled_arguments)
}, },
Index { box indexee, mut indexers } => {
let evaled = self.eval_expr(indexee)?;
match evaled {
Tuple(mut exprs) => {
let len = indexers.len();
if len == 1 {
indexers.truncate(1);
let idx = indexers.pop().unwrap();
match self.eval_expr(idx)? {
UnsignedInt(n) if (n as usize) < exprs.len() => Ok(exprs.drain(n as usize..).next().unwrap()),
UnsignedInt(n) => Err(format!("Index {} out of range", n)),
other => Err(format!("{:?} is not an unsigned integer", other)),
}
} else {
Err(format!("Tuple index must be one integer"))
}
},
_ => Err(format!("Bad index expression"))
}
},
x => Err(format!("Unimplemented thing {:?}", x)), x => Err(format!("Unimplemented thing {:?}", x)),
} }
} }