Clean up context garbage collection

dust-lang/src/analyzer.rs

@@ -135,7 +135,6 @@ impl<'a> Analyzer<'a> {
                             StructType::Unit {
                                 name: name.inner.clone(),
                             },
-                            statement.position(),
                         )?;
                     }
                     StructDefinition::Tuple { name, items } => {
@@ -147,7 +146,6 @@ impl<'a> Analyzer<'a> {
                                 name: name.inner.clone(),
                                 fields,
                             },
-                            statement.position(),
                         )?;
                     }
                     StructDefinition::Fields { name, fields } => {
@@ -164,7 +162,6 @@ impl<'a> Analyzer<'a> {
                                 name: name.inner.clone(),
                                 fields,
                             },
-                            statement.position(),
                         )?;
                     }
                 };

dust-lang/src/context.rs

@@ -5,9 +5,9 @@ use std::{
     sync::{Arc, PoisonError, RwLock, RwLockReadGuard, RwLockWriteGuard},
 };
 
-use crate::{ast::Span, Constructor, Identifier, StructType, Type, Value};
+use crate::{Constructor, Identifier, StructType, Type, Value};
 
-pub type Associations = HashMap<Identifier, (ContextData, Span)>;
+pub type Associations = HashMap<Identifier, (ContextData, usize)>;
 
 /// Garbage-collecting context for variables.
 #[derive(Debug, Clone)]
@@ -64,7 +64,7 @@ impl Context {
     pub fn get(
         &self,
         identifier: &Identifier,
-    ) -> Result<Option<(ContextData, Span)>, ContextError> {
+    ) -> Result<Option<(ContextData, usize)>, ContextError> {
         let associations = self.associations.read()?;
 
         Ok(associations.get(identifier).cloned())
@@ -223,20 +223,13 @@ impl Context {
         &self,
         identifier: Identifier,
         struct_type: StructType,
-        position: Span,
     ) -> Result<(), ContextError> {
         log::trace!("Setting {identifier} to constructor of type {struct_type}");
 
         let mut variables = self.associations.write()?;
         let last_position = variables
             .get(&identifier)
-            .map(|(_, last_position)| {
-                if last_position.1 > position.1 {
-                    *last_position
-                } else {
-                    position
-                }
-            })
+            .map(|(_, last_position)| *last_position)
             .unwrap_or_default();
 
         variables.insert(
@@ -248,13 +241,13 @@ impl Context {
     }
 
     /// Collects garbage up to the given position, removing all variables with lesser positions.
-    pub fn collect_garbage(&self, position_end: usize) -> Result<(), ContextError> {
-        log::trace!("Collecting garbage up to {position_end}");
+    pub fn collect_garbage(&self, position: usize) -> Result<(), ContextError> {
+        log::trace!("Collecting garbage up to {position}");
 
         let mut variables = self.associations.write()?;
 
         variables.retain(|identifier, (_, last_used)| {
-            let should_drop = position_end >= last_used.1;
+            let should_drop = position >= *last_used;
 
             if should_drop {
                 log::trace!("Removing {identifier}");
@@ -274,12 +267,12 @@ impl Context {
     pub fn update_last_position(
         &self,
         identifier: &Identifier,
-        position: Span,
+        position: usize,
     ) -> Result<bool, ContextError> {
         let mut associations = self.associations.write()?;
 
         if let Some((_, last_position)) = associations.get_mut(identifier) {
-            if position.1 > last_position.1 {
+            if position > *last_position {
                 log::trace!("Updating {identifier}'s last position to {position:?}");
 
                 *last_position = position;

dust-lang/src/core_library.rs

@@ -13,7 +13,7 @@ pub fn core_library<'a>() -> &'a Context {
                     ContextData::VariableValue(Value::function(Function::BuiltIn(
                         BuiltInFunction::ToString,
                     ))),
-                    (0, 0),
+                    0,
                 ),
             ),
             (
@@ -22,7 +22,7 @@ pub fn core_library<'a>() -> &'a Context {
                     ContextData::VariableValue(Value::function(Function::BuiltIn(
                         BuiltInFunction::ReadLine,
                     ))),
-                    (0, 0),
+                    0,
                 ),
             ),
             (
@@ -31,7 +31,7 @@ pub fn core_library<'a>() -> &'a Context {
                     ContextData::VariableValue(Value::function(Function::BuiltIn(
                         BuiltInFunction::WriteLine,
                     ))),
-                    (0, 0),
+                    0,
                 ),
             ),
         ]))

dust-lang/src/parser.rs

@@ -455,7 +455,7 @@ impl<'src> Parser<'src> {
                 let identifier = Identifier::new(text);
 
                 if let ParserMode::Condition = self.mode {
-                    context.update_last_position(&identifier, start_position)?;
+                    context.update_last_position(&identifier, start_position.1)?;
 
                     return Ok(Expression::identifier(identifier, start_position));
                 }
@@ -496,7 +496,7 @@ impl<'src> Parser<'src> {
 
                     let position = (start_position.0, self.current_position.1);
 
-                    context.update_last_position(&identifier, position)?;
+                    context.update_last_position(&identifier, position.1)?;
 
                     return Ok(Expression::r#struct(
                         StructExpression::Fields { name, fields },
@@ -504,7 +504,7 @@ impl<'src> Parser<'src> {
                     ));
                 }
 
-                context.update_last_position(&identifier, start_position)?;
+                context.update_last_position(&identifier, start_position.1)?;
 
                 Ok(Expression::identifier(identifier, start_position))
             }
@@ -988,7 +988,7 @@ impl<'src> Parser<'src> {
 
             self.next_token()?;
 
-            context.update_last_position(&identifier, position)?;
+            context.update_last_position(&identifier, position.1)?;
 
             Ok(Node::new(identifier, position))
         } else {