Refine memory management

dust-lang/src/abstract_tree/assignment.rs

@@ -43,7 +43,7 @@ impl AbstractNode for Assignment {
         Ok(Type::None)
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, manage_memory: bool) -> Result<(), ValidationError> {
         let statement_type = self.statement.expected_type(context)?;
 
         if let Some(WithPosition {
@@ -64,13 +64,13 @@ impl AbstractNode for Assignment {
             context.set_type(self.identifier.item.clone(), statement_type)?;
         }
 
-        self.statement.validate(context)?;
+        self.statement.validate(context, manage_memory)?;
 
         Ok(())
     }
 
-    fn run(self, context: &mut Context, clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError> {
-        let action = self.statement.run(context, clear_variables)?;
+        let action = self.statement.run(context, manage_memory)?;
         let right = match action {
             Action::Return(value) => value,
             r#break => return Ok(r#break),
@@ -81,7 +81,13 @@ impl AbstractNode for Assignment {
                 context.set_value(self.identifier.item, right)?;
             }
             AssignmentOperator::AddAssign => {
-                if let Some(left) = context.use_value(&self.identifier.item)? {
+                let left_option = if manage_memory {
+                    context.use_value(&self.identifier.item)?
+                } else {
+                    context.get_value(&self.identifier.item)?
+                };
+
+                if let Some(left) = left_option {
                     let new_value = match (left.inner().as_ref(), right.inner().as_ref()) {
                         (ValueInner::Integer(left), ValueInner::Integer(right)) => {
                             let sum = left.saturating_add(*right);
@@ -120,7 +126,13 @@ impl AbstractNode for Assignment {
                 }
             }
             AssignmentOperator::SubAssign => {
-                if let Some(left) = context.use_value(&self.identifier.item)? {
+                let left_option = if manage_memory {
+                    context.use_value(&self.identifier.item)?
+                } else {
+                    context.get_value(&self.identifier.item)?
+                };
+
+                if let Some(left) = left_option {
                     let new_value = match (left.inner().as_ref(), right.inner().as_ref()) {
                         (ValueInner::Integer(left), ValueInner::Integer(right)) => {
                             let difference = left.saturating_sub(*right);

dust-lang/src/abstract_tree/async_block.rs

@@ -25,15 +25,15 @@ impl AbstractNode for AsyncBlock {
         self.statements.last().unwrap().expected_type(_context)
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, manage_memory: bool) -> Result<(), ValidationError> {
         for statement in &self.statements {
-            statement.validate(_context)?;
+            statement.validate(_context, manage_memory)?;
         }
 
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError> {
         let statement_count = self.statements.len();
         let final_result = RwLock::new(Ok(Action::None));
 
@@ -41,7 +41,7 @@ impl AbstractNode for AsyncBlock {
             .into_par_iter()
             .enumerate()
             .find_map_first(|(index, statement)| {
-                let result = statement.run(&mut _context.clone(), _clear_variables);
+                let result = statement.run(&mut _context.clone(), manage_memory);
 
                 if index == statement_count - 1 {
                     let get_write_lock = final_result.write();

dust-lang/src/abstract_tree/block.rs

@@ -29,19 +29,19 @@ impl AbstractNode for Block {
         }
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         for statement in &self.statements {
-            statement.validate(_context)?;
+            statement.validate(_context, _manage_memory)?;
         }
 
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let mut previous = Action::None;
 
         for statement in self.statements {
-            previous = statement.run(_context, _clear_variables)?;
+            previous = statement.run(_context, _manage_memory)?;
         }
 
         Ok(previous)

dust-lang/src/abstract_tree/built_in_function_call.rs

@@ -26,15 +26,17 @@ impl AbstractNode for BuiltInFunctionCall {
         }
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         match self {
             BuiltInFunctionCall::ReadLine => Ok(()),
-            BuiltInFunctionCall::Sleep(expression) => expression.validate(_context),
+            BuiltInFunctionCall::Sleep(expression) => expression.validate(_context, _manage_memory),
-            BuiltInFunctionCall::WriteLine(expression) => expression.validate(_context),
+            BuiltInFunctionCall::WriteLine(expression) => {
+                expression.validate(_context, _manage_memory)
+            }
         }
     }
 
-    fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         match self {
             BuiltInFunctionCall::ReadLine => {
                 let mut buffer = String::new();
@@ -44,7 +46,7 @@ impl AbstractNode for BuiltInFunctionCall {
                 Ok(Action::Return(Value::string(buffer)))
             }
             BuiltInFunctionCall::Sleep(expression) => {
-                let action = expression.clone().run(context, _clear_variables)?;
+                let action = expression.clone().run(context, _manage_memory)?;
                 let value = if let Action::Return(value) = action {
                     value
                 } else {
@@ -60,7 +62,7 @@ impl AbstractNode for BuiltInFunctionCall {
                 Ok(Action::None)
             }
             BuiltInFunctionCall::WriteLine(expression) => {
-                let action = expression.clone().run(context, _clear_variables)?;
+                let action = expression.clone().run(context, _manage_memory)?;
                 let value = if let Action::Return(value) = action {
                     value
                 } else {

dust-lang/src/abstract_tree/expression.rs

@@ -61,11 +61,17 @@ impl AbstractNode for Expression {
         }
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, manage_memory: bool) -> Result<(), ValidationError> {
         match self {
-            Expression::FunctionCall(function_call) => function_call.item.validate(context),
+            Expression::FunctionCall(function_call) => {
+                function_call.item.validate(context, manage_memory)
+            }
             Expression::Identifier(identifier) => {
-                let found = context.add_expected_use(&identifier.item)?;
+                let found = if manage_memory {
+                    context.add_expected_use(&identifier.item)?
+                } else {
+                    context.contains(&identifier.item)?
+                };
 
                 if found {
                     Ok(())
@@ -76,24 +82,30 @@ impl AbstractNode for Expression {
                     })
                 }
             }
-            Expression::MapIndex(map_index) => map_index.item.validate(context),
+            Expression::MapIndex(map_index) => map_index.item.validate(context, manage_memory),
-            Expression::ListIndex(list_index) => list_index.item.validate(context),
+            Expression::ListIndex(list_index) => list_index.item.validate(context, manage_memory),
-            Expression::Logic(logic) => logic.item.validate(context),
+            Expression::Logic(logic) => logic.item.validate(context, manage_memory),
-            Expression::Math(math) => math.item.validate(context),
+            Expression::Math(math) => math.item.validate(context, manage_memory),
-            Expression::Value(value_node) => value_node.item.validate(context),
+            Expression::Value(value_node) => value_node.item.validate(context, manage_memory),
             Expression::BuiltInFunctionCall(built_in_function_call) => {
-                built_in_function_call.item.validate(context)
+                built_in_function_call.item.validate(context, manage_memory)
             }
         }
     }
 
-    fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError> {
         match self {
             Expression::FunctionCall(function_call) => {
-                function_call.item.run(context, _clear_variables)
+                function_call.item.run(context, manage_memory)
             }
             Expression::Identifier(identifier) => {
-                if let Some(value) = context.use_value(&identifier.item)? {
+                let value_option = if manage_memory {
+                    context.use_value(&identifier.item)?
+                } else {
+                    context.get_value(&identifier.item)?
+                };
+
+                if let Some(value) = value_option {
                     Ok(Action::Return(value))
                 } else {
                     Err(RuntimeError::ValidationFailure(
@@ -104,13 +116,13 @@ impl AbstractNode for Expression {
                     ))
                 }
             }
-            Expression::MapIndex(map_index) => map_index.item.run(context, _clear_variables),
+            Expression::MapIndex(map_index) => map_index.item.run(context, manage_memory),
-            Expression::ListIndex(list_index) => list_index.item.run(context, _clear_variables),
+            Expression::ListIndex(list_index) => list_index.item.run(context, manage_memory),
-            Expression::Logic(logic) => logic.item.run(context, _clear_variables),
+            Expression::Logic(logic) => logic.item.run(context, manage_memory),
-            Expression::Math(math) => math.item.run(context, _clear_variables),
+            Expression::Math(math) => math.item.run(context, manage_memory),
-            Expression::Value(value_node) => value_node.item.run(context, _clear_variables),
+            Expression::Value(value_node) => value_node.item.run(context, manage_memory),
             Expression::BuiltInFunctionCall(built_in_function_call) => {
-                built_in_function_call.item.run(context, _clear_variables)
+                built_in_function_call.item.run(context, manage_memory)
             }
         }
     }

dust-lang/src/abstract_tree/function_call.rs

@@ -41,11 +41,11 @@ impl AbstractNode for FunctionCall {
         }
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, manage_memory: bool) -> Result<(), ValidationError> {
-        self.function.validate(context)?;
+        self.function.validate(context, manage_memory)?;
 
         for expression in &self.arguments {
-            expression.validate(context)?;
+            expression.validate(context, manage_memory)?;
         }
 
         let function_node_type = self.function.expected_type(context)?;

dust-lang/src/abstract_tree/if_else.rs

@@ -35,16 +35,16 @@ impl AbstractNode for IfElse {
         self.if_block.item.expected_type(_context)
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, manage_memory: bool) -> Result<(), ValidationError> {
-        self.if_expression.validate(context)?;
+        self.if_expression.validate(context, manage_memory)?;
-        self.if_block.item.validate(context)?;
+        self.if_block.item.validate(context, manage_memory)?;
 
         let expected_type = self.if_block.item.expected_type(context)?;
         let if_expression_type = self.if_expression.expected_type(context)?;
 
         if let Type::Boolean = if_expression_type {
             if let Some(else_block) = &self.else_block {
-                else_block.item.validate(context)?;
+                else_block.item.validate(context, manage_memory)?;
 
                 let actual = else_block.item.expected_type(context)?;
 
@@ -67,7 +67,7 @@ impl AbstractNode for IfElse {
             let expression_type = expression.expected_type(context)?;
 
             if let Type::Boolean = expression_type {
-                block.item.validate(context)?;
+                block.item.validate(context, manage_memory)?;
 
                 let actual = block.item.expected_type(context)?;
 

dust-lang/src/abstract_tree/list_index.rs

@@ -47,9 +47,9 @@ impl AbstractNode for ListIndex {
         }
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
-        self.left.validate(context)?;
+        self.left.validate(context, _manage_memory)?;
-        self.right.validate(context)?;
+        self.right.validate(context, _manage_memory)?;
 
         let left_type = self.left.expected_type(context)?;
 

dust-lang/src/abstract_tree/logic.rs

@@ -25,7 +25,7 @@ impl AbstractNode for Logic {
         Ok(Type::Boolean)
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         match self {
             Logic::Equal(left, right)
             | Logic::NotEqual(left, right)
@@ -33,6 +33,9 @@ impl AbstractNode for Logic {
             | Logic::Less(left, right)
             | Logic::GreaterOrEqual(left, right)
             | Logic::LessOrEqual(left, right) => {
+                left.validate(context, _manage_memory)?;
+                right.validate(context, _manage_memory)?;
+
                 let left_type = left.expected_type(context)?;
                 let right_type = right.expected_type(context)?;
 
@@ -47,6 +50,9 @@ impl AbstractNode for Logic {
                 Ok(())
             }
             Logic::And(left, right) | Logic::Or(left, right) => {
+                left.validate(context, _manage_memory)?;
+                right.validate(context, _manage_memory)?;
+
                 let left_type = left.expected_type(context)?;
                 let right_type = right.expected_type(context)?;
 
@@ -69,6 +75,8 @@ impl AbstractNode for Logic {
                 Ok(())
             }
             Logic::Not(expression) => {
+                expression.validate(context, _manage_memory)?;
+
                 let expression_type = expression.expected_type(context)?;
 
                 if let Type::Boolean = expression_type {
@@ -83,10 +91,10 @@ impl AbstractNode for Logic {
         }
     }
 
-    fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let run_and_expect_value = |expression: Expression| -> Result<Value, RuntimeError> {
             let expression_position = expression.position();
-            let action = expression.run(&mut context.clone(), _clear_variables)?;
+            let action = expression.run(&mut context.clone(), _manage_memory)?;
             let value = if let Action::Return(value) = action {
                 value
             } else {
@@ -100,7 +108,7 @@ impl AbstractNode for Logic {
 
         let run_and_expect_boolean = |expression: Expression| -> Result<bool, RuntimeError> {
             let expression_position = expression.position();
-            let action = expression.run(&mut context.clone(), _clear_variables)?;
+            let action = expression.run(&mut context.clone(), _manage_memory)?;
             let value = if let Action::Return(value) = action {
                 value
             } else {

dust-lang/src/abstract_tree/loop.rs

@@ -21,15 +21,15 @@ impl AbstractNode for Loop {
         Ok(Type::None)
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         for statement in &self.statements {
-            statement.validate(_context)?;
+            statement.validate(_context, false)?;
         }
 
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         loop {
             for statement in &self.statements {
                 let action = statement.clone().run(_context, false)?;

dust-lang/src/abstract_tree/map_index.rs

@@ -105,13 +105,13 @@ impl AbstractNode for MapIndex {
         })
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
-        self.collection.validate(context)
+        self.collection.validate(_context, _manage_memory)
     }
 
-    fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let collection_position = self.collection.position();
-        let action = self.collection.run(context, _clear_variables)?;
+        let action = self.collection.run(context, _manage_memory)?;
         let collection = if let Action::Return(value) = action {
             value
         } else {

dust-lang/src/abstract_tree/math.rs

@@ -40,7 +40,7 @@ impl AbstractNode for Math {
         }
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         match self {
             Math::Add(left, right) => {
                 let left_position = left.position();

dust-lang/src/abstract_tree/mod.rs

@@ -101,14 +101,14 @@ impl AbstractTree {
     pub fn run(
         self,
         context: &mut Context,
-        clear_variables: bool,
+        manage_memory: bool,
     ) -> Result<Option<Value>, Vec<Error>> {
-        let valid_statements = self.validate(context)?;
+        let valid_statements = self.validate(context, manage_memory)?;
         let mut previous_value = None;
 
         for statement in valid_statements {
             let position = statement.position();
-            let run = statement.run(context, clear_variables);
+            let run = statement.run(context, manage_memory);
 
             match run {
                 Ok(action) => match action {
@@ -128,12 +128,16 @@ impl AbstractTree {
         Ok(previous_value)
     }
 
-    fn validate(self, context: &mut Context) -> Result<Vec<Statement>, Vec<Error>> {
+    fn validate(
+        self,
+        context: &mut Context,
+        add_variable_uses: bool,
+    ) -> Result<Vec<Statement>, Vec<Error>> {
         let mut errors = Vec::new();
         let mut valid_statements = Vec::new();
 
         for statement in self.0 {
-            let validation = statement.validate(context);
+            let validation = statement.validate(context, add_variable_uses);
 
             if let Err(validation_error) = validation {
                 errors.push(Error::Validation {
@@ -179,6 +183,6 @@ impl Index<usize> for AbstractTree {
 
 pub trait AbstractNode: Sized {
     fn expected_type(&self, context: &Context) -> Result<Type, ValidationError>;
-    fn validate(&self, context: &Context) -> Result<(), ValidationError>;
+    fn validate(&self, context: &Context, manage_memory: bool) -> Result<(), ValidationError>;
-    fn run(self, context: &mut Context, clear_variables: bool) -> Result<Action, RuntimeError>;
+    fn run(self, context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError>;
 }

dust-lang/src/abstract_tree/statement.rs

@@ -54,67 +54,43 @@ impl AbstractNode for Statement {
         }
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         match self {
-            Statement::Assignment(assignment) => assignment.item.validate(_context),
+            Statement::Assignment(assignment) => assignment.item.validate(_context, _manage_memory),
-            Statement::AsyncBlock(async_block) => async_block.item.validate(_context),
+            Statement::AsyncBlock(async_block) => {
-            Statement::Block(block) => block.item.validate(_context),
+                async_block.item.validate(_context, _manage_memory)
+            }
+            Statement::Block(block) => block.item.validate(_context, _manage_memory),
             Statement::Break(_) => Ok(()),
-            Statement::Expression(expression) => expression.validate(_context),
+            Statement::Expression(expression) => expression.validate(_context, _manage_memory),
-            Statement::IfElse(if_else) => if_else.item.validate(_context),
+            Statement::IfElse(if_else) => if_else.item.validate(_context, _manage_memory),
-            Statement::Loop(r#loop) => r#loop.item.validate(_context),
+            Statement::Loop(r#loop) => r#loop.item.validate(_context, _manage_memory),
-            Statement::While(r#while) => r#while.item.validate(_context),
+            Statement::While(r#while) => r#while.item.validate(_context, _manage_memory),
             Statement::StructureDefinition(structure_definition) => {
-                structure_definition.item.validate(_context)
+                structure_definition.item.validate(_context, _manage_memory)
             }
         }
     }
 
-    fn run(self, context: &mut Context, clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, manage_memory: bool) -> Result<Action, RuntimeError> {
         let result = match self {
-            Statement::Assignment(assignment) => {
+            Statement::Assignment(assignment) => assignment.item.run(context, manage_memory),
-                let run_result = assignment.item.run(context, clear_variables);
+            Statement::AsyncBlock(async_block) => async_block.item.run(context, manage_memory),
-
+            Statement::Block(block) => block.item.run(context, manage_memory),
-                if clear_variables {
-                    context.clean()?;
-                }
-
-                run_result
-            }
-            Statement::AsyncBlock(async_block) => async_block.item.run(context, clear_variables),
-            Statement::Block(block) => block.item.run(context, clear_variables),
             Statement::Break(_) => Ok(Action::Break),
-            Statement::Expression(expression) => {
+            Statement::Expression(expression) => expression.run(context, manage_memory),
-                let run_result = expression.run(context, clear_variables);
+            Statement::IfElse(if_else) => if_else.item.run(context, manage_memory),
-
+            Statement::Loop(r#loop) => r#loop.item.run(context, manage_memory),
-                if clear_variables {
+            Statement::While(r#while) => r#while.item.run(context, manage_memory),
-                    context.clean()?;
-                }
-
-                run_result
-            }
-            Statement::IfElse(if_else) => {
-                let run_result = if_else.item.run(context, clear_variables);
-
-                if clear_variables {
-                    context.clean()?;
-                }
-
-                run_result
-            }
-            Statement::Loop(r#loop) => r#loop.item.run(context, clear_variables),
-            Statement::While(r#while) => r#while.item.run(context, clear_variables),
             Statement::StructureDefinition(structure_definition) => {
-                let run_result = structure_definition.item.run(context, clear_variables);
+                structure_definition.item.run(context, manage_memory)
-
-                if clear_variables {
-                    context.clean()?;
-                }
-
-                run_result
             }
         };
 
+        if manage_memory {
+            context.clean()?;
+        }
+
         result
     }
 }

dust-lang/src/abstract_tree/structure_definition.rs

@@ -23,11 +23,11 @@ impl AbstractNode for StructureDefinition {
         Ok(Type::None)
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         Ok(())
     }
 
-    fn run(self, context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let struct_type = Type::Structure {
             name: self.name.clone(),
             fields: self.fields,

dust-lang/src/abstract_tree/type.rs

@@ -148,11 +148,11 @@ impl AbstractNode for Type {
         Ok(Type::None)
     }
 
-    fn validate(&self, _: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         Ok(Action::None)
     }
 }

dust-lang/src/abstract_tree/value_node.rs

@@ -91,7 +91,7 @@ impl AbstractNode for ValueNode {
         Ok(r#type)
     }
 
-    fn validate(&self, context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
         if let ValueNode::Map(map_assignments) = self {
             for (_identifier, r#type, expression) in map_assignments {
                 if let Some(expected_type) = r#type {
@@ -131,7 +131,7 @@ impl AbstractNode for ValueNode {
                 function_context.set_type(identifier.clone(), r#type.item.clone())?;
             }
 
-            body.item.validate(&function_context)?;
+            body.item.validate(&function_context, _manage_memory)?;
 
             let actual_return_type = body.item.expected_type(&function_context)?;
 
@@ -181,7 +181,7 @@ impl AbstractNode for ValueNode {
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let value = match self {
             ValueNode::Boolean(boolean) => Value::boolean(boolean),
             ValueNode::Float(float) => Value::float(float),
@@ -191,7 +191,7 @@ impl AbstractNode for ValueNode {
 
                 for expression in expression_list {
                     let expression_position = expression.position();
-                    let action = expression.run(_context, _clear_variables)?;
+                    let action = expression.run(_context, _manage_memory)?;
                     let value = if let Action::Return(value) = action {
                         WithPosition {
                             item: value,
@@ -213,7 +213,7 @@ impl AbstractNode for ValueNode {
 
                 for (identifier, _type, expression) in property_list {
                     let expression_position = expression.position();
-                    let action = expression.run(_context, _clear_variables)?;
+                    let action = expression.run(_context, _manage_memory)?;
                     let value = if let Action::Return(value) = action {
                         value
                     } else {
@@ -243,7 +243,7 @@ impl AbstractNode for ValueNode {
 
                 for (identifier, expression) in expressions {
                     let expression_position = expression.position();
-                    let action = expression.run(_context, _clear_variables)?;
+                    let action = expression.run(_context, _manage_memory)?;
                     let value = if let Action::Return(value) = action {
                         value
                     } else {

dust-lang/src/abstract_tree/while.rs

@@ -27,23 +27,23 @@ impl AbstractNode for While {
         Ok(Type::None)
     }
 
-    fn validate(&self, _context: &Context) -> Result<(), ValidationError> {
+    fn validate(&self, _context: &Context, _manage_memory: bool) -> Result<(), ValidationError> {
-        self.expression.validate(_context)?;
+        self.expression.validate(_context, _manage_memory)?;
 
         for statement in &self.statements {
-            statement.validate(_context)?;
+            statement.validate(_context, _manage_memory)?;
         }
 
         Ok(())
     }
 
-    fn run(self, _context: &mut Context, _clear_variables: bool) -> Result<Action, RuntimeError> {
+    fn run(self, _context: &mut Context, _manage_memory: bool) -> Result<Action, RuntimeError> {
         let get_boolean = || -> Result<Value, RuntimeError> {
             let expression_position = self.expression.position();
             let action = self
                 .expression
                 .clone()
-                .run(&mut _context.clone(), _clear_variables)?;
+                .run(&mut _context.clone(), _manage_memory)?;
 
             if let Action::Return(value) = action {
                 Ok(value)
@@ -58,7 +58,7 @@ impl AbstractNode for While {
             for statement in &self.statements {
                 let action = statement
                     .clone()
-                    .run(&mut _context.clone(), _clear_variables)?;
+                    .run(&mut _context.clone(), _manage_memory)?;
 
                 match action {
                     Action::Return(_) => {}

dust-lang/src/context.rs

@@ -13,18 +13,14 @@ use crate::{
 #[derive(Clone, Debug)]
 pub struct Context {
     variables: Arc<RwLock<BTreeMap<Identifier, (ValueData, UsageData)>>>,
+    is_clean: bool,
 }
 
 impl Context {
     pub fn new() -> Self {
         Self {
             variables: Arc::new(RwLock::new(BTreeMap::new())),
-        }
+            is_clean: true,
-    }
-
-    pub fn with_data(data: BTreeMap<Identifier, (ValueData, UsageData)>) -> Self {
-        Self {
-            variables: Arc::new(RwLock::new(data)),
         }
     }
 
@@ -95,6 +91,16 @@ impl Context {
         }
     }
 
+    pub fn get_value(&self, identifier: &Identifier) -> Result<Option<Value>, RwLockPoisonError> {
+        if let Some((ValueData::Value(value), _)) = self.variables.read()?.get(identifier) {
+            log::trace!("Getting {identifier}'s value.");
+
+            Ok(Some(value.clone()))
+        } else {
+            Ok(None)
+        }
+    }
+
     pub fn set_type(&self, identifier: Identifier, r#type: Type) -> Result<(), RwLockPoisonError> {
         log::debug!("Setting {identifier} to type {}.", r#type);
 
@@ -123,20 +129,30 @@ impl Context {
     }
 
     pub fn clean(&mut self) -> Result<(), RwLockPoisonError> {
+        if self.is_clean {
+            return Ok(());
+        }
+
         self.variables
             .write()?
-            .retain(|identifier, (_, usage_data)| {
+            .retain(|identifier, (value_data, usage_data)| {
-                let usage = usage_data.inner().read().unwrap();
+                if let ValueData::Value(_) = value_data {
+                    let usage = usage_data.inner().read().unwrap();
 
-                if usage.actual < usage.expected {
+                    if usage.actual < usage.expected {
-                    true
+                        true
+                    } else {
+                        log::trace!("Removing variable {identifier}.");
+
+                        false
+                    }
                 } else {
-                    log::trace!("Removing variable {identifier}.");
-
                     false
                 }
             });
 
+        self.is_clean = true;
+
         Ok(())
     }