111 lines
3.8 KiB
Rust
111 lines
3.8 KiB
Rust
use serde::{Deserialize, Serialize};
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use tree_sitter::Node;
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use crate::{AbstractTree, Error, IndexExpression, List, Map, Result, Type, Value};
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/// Abstract representation of an index expression.
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///
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/// An index is a means of accessing values stored in list, maps and strings.
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#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
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pub struct Index {
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pub collection: IndexExpression,
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pub index: IndexExpression,
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pub index_end: Option<IndexExpression>,
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}
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impl AbstractTree for Index {
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fn from_syntax_node(source: &str, node: Node, context: &Map) -> Result<Self> {
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Error::expect_syntax_node(source, "index", node)?;
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let collection_node = node.child(0).unwrap();
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let collection = IndexExpression::from_syntax_node(source, collection_node, context)?;
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let index_node = node.child(2).unwrap();
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let index = IndexExpression::from_syntax_node(source, index_node, context)?;
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let index_end_node = node.child(4);
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let index_end = if let Some(index_end_node) = index_end_node {
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Some(IndexExpression::from_syntax_node(
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source,
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index_end_node,
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context,
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)?)
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} else {
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None
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};
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Ok(Index {
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collection,
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index,
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index_end,
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})
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}
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fn run(&self, source: &str, context: &Map) -> Result<Value> {
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let collection = self.collection.run(source, context)?;
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match collection {
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Value::List(list) => {
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let index = self.index.run(source, context)?.as_integer()? as usize;
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let item = if let Some(index_end) = &self.index_end {
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let index_end = index_end.run(source, context)?.as_integer()? as usize;
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let sublist = list.items()[index..=index_end].to_vec();
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Value::List(List::with_items(sublist))
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} else {
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list.items().get(index).cloned().unwrap_or_default()
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};
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Ok(item)
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}
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Value::Map(map) => {
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let value = if let IndexExpression::Identifier(identifier) = &self.index {
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let key = identifier.inner();
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map.variables()?
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.get(key)
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.map(|(value, _)| value.clone())
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.unwrap_or_default()
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} else {
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let value = self.index.run(source, context)?;
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let key = value.as_string()?;
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map.variables()?
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.get(key.as_str())
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.map(|(value, _)| value.clone())
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.unwrap_or_default()
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};
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Ok(value)
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}
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Value::String(string) => {
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let index = self.index.run(source, context)?.as_integer()? as usize;
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let item = string.read()?.chars().nth(index).unwrap_or_default();
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Ok(Value::string(item.to_string()))
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}
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_ => Err(Error::ExpectedCollection { actual: collection }),
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}
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}
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fn expected_type(&self, context: &Map) -> Result<Type> {
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match self.collection.expected_type(context)? {
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Type::List(item_type) => Ok(*item_type.clone()),
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Type::Map(identifier_types) => {
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if let IndexExpression::Identifier(index_identifier) = &self.index {
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for (identifier, r#type) in identifier_types {
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if &identifier == index_identifier {
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return Ok(r#type.take_inner());
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}
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}
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}
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Ok(Type::None)
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}
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Type::None => Ok(Type::None),
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r#type => Ok(r#type),
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}
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}
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}
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