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dust/dust-lang/src/abstract_tree/list_index.rs

117 lines
3.8 KiB
Rust

use crate::{
context::Context,
error::{RuntimeError, ValidationError},
};
use super::{AbstractNode, Action, Expression, Type, ValueNode, WithPosition};
#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
pub struct ListIndex {
left: Expression,
right: Expression,
}
impl ListIndex {
pub fn new(left: Expression, right: Expression) -> Self {
Self { left, right }
}
}
impl AbstractNode for ListIndex {
fn expected_type(&self, _context: &Context) -> Result<Type, ValidationError> {
let left_type = self.left.expected_type(_context)?;
if let (
Expression::Value(WithPosition {
node: ValueNode::List(expression_list),
..
}),
Expression::Value(WithPosition {
node: ValueNode::Integer(index),
..
}),
) = (&self.left, &self.right)
{
let expression = if let Some(expression) = expression_list.get(*index as usize) {
expression
} else {
return Ok(Type::None);
};
expression.expected_type(_context)
} else {
Err(ValidationError::CannotIndex {
r#type: left_type,
position: self.left.position(),
})
}
}
fn validate(&self, context: &Context) -> Result<(), ValidationError> {
let left_type = self.left.expected_type(context)?;
match left_type {
Type::List => todo!(),
Type::ListOf(_) => todo!(),
Type::ListExact(_) => {
let right_type = self.right.expected_type(context)?;
if let Type::Integer = right_type {
Ok(())
} else {
Err(ValidationError::CannotIndexWith {
collection_type: left_type,
collection_position: self.left.position(),
index_type: right_type,
index_position: self.right.position(),
})
}
}
_ => Err(ValidationError::CannotIndex {
r#type: left_type,
position: self.left.position(),
}),
}
}
fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
let left_position = self.left.position();
let left_action = self.left.run(context, _clear_variables)?;
let left_value = if let Action::Return(value) = left_action {
value
} else {
return Err(RuntimeError::ValidationFailure(
ValidationError::InterpreterExpectedReturn(left_position),
));
};
let right_position = self.right.position();
let right_action = self.right.run(context, _clear_variables)?;
let right_value = if let Action::Return(value) = right_action {
value
} else {
return Err(RuntimeError::ValidationFailure(
ValidationError::InterpreterExpectedReturn(right_position),
));
};
if let (Some(list), Some(index)) = (left_value.as_list(), right_value.as_integer()) {
let found_item = list.get(index as usize);
if let Some(item) = found_item {
Ok(Action::Return(item.node.clone()))
} else {
Ok(Action::None)
}
} else {
Err(RuntimeError::ValidationFailure(
ValidationError::CannotIndexWith {
collection_type: left_value.r#type(context)?,
collection_position: left_position,
index_type: right_value.r#type(context)?,
index_position: right_position,
},
))
}
}
}