Clean up context

dust-lang/src/ast/mod.rs

@@ -13,7 +13,7 @@ use std::{
 
 use serde::{Deserialize, Serialize};
 
-use crate::{Context, ContextError};
+use crate::{core_library, Context, ContextError};
 
 pub type Span = (usize, usize);
 
@@ -68,6 +68,13 @@ impl AbstractSyntaxTree {
             context: Context::new(),
         }
     }
+
+    pub fn with_core_library() -> Self {
+        Self {
+            statements: VecDeque::new(),
+            context: core_library().create_child(),
+        }
+    }
 }
 
 impl Default for AbstractSyntaxTree {

dust-lang/src/context.rs

@@ -13,7 +13,7 @@ pub type Associations = HashMap<Identifier, (ContextData, usize)>;
 #[derive(Debug, Clone)]
 pub struct Context {
     associations: Arc<RwLock<Associations>>,
-    parent: Arc<RwLock<Option<Context>>>,
+    parent: Option<Box<Context>>,
 }
 
 impl Context {
@@ -24,7 +24,7 @@ impl Context {
     pub fn with_data(data: Associations) -> Self {
         Self {
             associations: Arc::new(RwLock::new(data)),
-            parent: Arc::new(RwLock::new(None)),
+            parent: None,
         }
     }
 
@@ -36,14 +36,10 @@ impl Context {
     pub fn create_child(&self) -> Self {
         Self {
             associations: Arc::new(RwLock::new(HashMap::new())),
-            parent: Arc::new(RwLock::new(Some(self.clone()))),
+            parent: Some(Box::new(self.clone())),
         }
     }
 
-    pub fn assign_parent(&self, parent: Self) {
-        self.parent.write().unwrap().replace(parent);
-    }
-
     /// Returns the number of associated identifiers in the context.
     pub fn association_count(&self) -> Result<usize, ContextError> {
         Ok(self.associations.read()?.len())
@@ -53,7 +49,7 @@ impl Context {
     pub fn contains(&self, identifier: &Identifier) -> Result<bool, ContextError> {
         if self.associations.read()?.contains_key(identifier) {
             Ok(true)
-        } else if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        } else if let Some(parent) = &self.parent {
             parent.contains(identifier)
         } else {
             Ok(false)
@@ -81,7 +77,7 @@ impl Context {
             _ => {}
         }
 
-        if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        if let Some(parent) = &self.parent {
             parent.get_type(identifier)
         } else {
             Ok(None)
@@ -92,7 +88,7 @@ impl Context {
     pub fn get_data(&self, identifier: &Identifier) -> Result<Option<ContextData>, ContextError> {
         if let Some((variable_data, _)) = self.associations.read()?.get(identifier) {
             Ok(Some(variable_data.clone()))
-        } else if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        } else if let Some(parent) = &self.parent {
             parent.get_data(identifier)
         } else {
             Ok(None)
@@ -108,7 +104,7 @@ impl Context {
             self.associations.read()?.get(identifier)
         {
             Ok(Some(value.clone()))
-        } else if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        } else if let Some(parent) = &self.parent {
             parent.get_variable_value(identifier)
         } else {
             Ok(None)
@@ -124,7 +120,7 @@ impl Context {
             self.associations.read()?.get(identifier)
         {
             Ok(Some(constructor.clone()))
-        } else if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        } else if let Some(parent) = &self.parent {
             parent.get_constructor(identifier)
         } else {
             Ok(None)
@@ -144,7 +140,7 @@ impl Context {
                 ContextData::ConstructorType(struct_type) => Ok(Some(struct_type.clone())),
                 _ => Ok(None),
             }
-        } else if let Some(parent) = self.parent.read().unwrap().as_ref() {
+        } else if let Some(parent) = &self.parent {
             parent.get_constructor_type(identifier)
         } else {
             Ok(None)
@@ -280,7 +276,7 @@ impl Context {
 
             Ok(true)
         } else {
-            let ancestor_contains = if let Some(parent) = self.parent.read().unwrap().as_ref() {
+            let ancestor_contains = if let Some(parent) = &self.parent {
                 parent.contains(identifier)?
             } else {
                 false
@@ -300,9 +296,8 @@ impl Context {
 
     /// Recovers the context from a poisoned state by recovering data from an error.
     ///
-    /// This method is not used. The context's other methods do not return poison errors because
+    /// This method is not used.
-    /// they are infallible.
+    pub fn _recover_from_poison(&mut self, error: &ContextError) {
-    pub fn recover_from_poison(&mut self, error: &ContextError) {
         log::debug!("Context is recovering from poison error");
 
         let ContextError::PoisonErrorRecovered(recovered) = error;

dust-lang/src/parser.rs

@@ -11,8 +11,8 @@ use std::{
 };
 
 use crate::{
-    ast::*, core_library, Context, ContextError, DustError, Identifier, LexError, Lexer, Token,
+    ast::*, Context, ContextError, DustError, Identifier, LexError, Lexer, Token, TokenKind,
-    TokenKind, TokenOwned, Type,
+    TokenOwned, Type,
 };
 
 /// Parses the input into an abstract syntax tree.
@@ -38,9 +38,7 @@ use crate::{
 /// );
 /// ```
 pub fn parse(source: &str) -> Result<AbstractSyntaxTree, DustError> {
-    let mut tree = AbstractSyntaxTree::new();
+    let mut tree = AbstractSyntaxTree::with_core_library();
-
-    tree.context.assign_parent(core_library().clone());
 
     let lexer = Lexer::new(source);
     let mut parser = Parser::new(lexer);

dust-lang/src/vm.rs

@@ -357,20 +357,20 @@ impl Vm {
         if let Some(ContextData::Constructor(constructor)) = get_data {
             let construct_result = constructor.construct_unit();
 
-            match construct_result {
+            return match construct_result {
                 Ok(value) => Ok(Evaluation::Return(Some(value))),
                 Err(ConstructError::ExpectedUnit) => Ok(Evaluation::Constructor(constructor)),
                 Err(error) => Err(RuntimeError::ConstructError {
                     error,
                     position: identifier.position,
                 }),
-            }
+            };
-        } else {
-            Err(RuntimeError::UnassociatedIdentifier {
-                identifier: identifier.inner,
-                position: identifier.position,
-            })
         }
+
+        Err(RuntimeError::UnassociatedIdentifier {
+            identifier: identifier.inner,
+            position: identifier.position,
+        })
     }
 
     fn run_struct(