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