From 92f098b58b24b951775a8b310205908bd842baab Mon Sep 17 00:00:00 2001
From: Jeff <dev@jeffa.io>
Date: Mon, 1 Jul 2024 17:49:49 -0400
Subject: [PATCH] Implement null statement

---
 dust-lang/src/abstract_tree/statement.rs |  9 ++++--
 dust-lang/src/parser/mod.rs              | 35 ++++++++++++------------
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/dust-lang/src/abstract_tree/statement.rs b/dust-lang/src/abstract_tree/statement.rs
index 09e2703..08278ec 100644
--- a/dust-lang/src/abstract_tree/statement.rs
+++ b/dust-lang/src/abstract_tree/statement.rs
@@ -20,6 +20,7 @@ pub enum Statement {
     Break(WithPosition<()>),
     IfElse(WithPosition<IfElse>),
     Loop(WithPosition<Loop>),
+    Null(WithPosition<()>),
     StructureDefinition(WithPosition<StructureDefinition>),
     TypeAlias(WithPosition<TypeAlias>),
     EnumDeclaration(WithPosition<EnumDeclaration>),
@@ -38,6 +39,7 @@ impl Statement {
             Statement::Expression(expression) => expression.position(),
             Statement::IfElse(inner) => inner.position,
             Statement::Loop(inner) => inner.position,
+            Statement::Null(inner) => inner.position,
             Statement::StructureDefinition(inner) => inner.position,
             Statement::TypeAlias(inner) => inner.position,
             Statement::EnumDeclaration(inner) => inner.position,
@@ -65,7 +67,6 @@ impl AbstractNode for Statement {
             Statement::Block(block) => block.node.define_types(_context),
             Statement::AsyncBlock(async_block) => async_block.node.define_types(_context),
             Statement::Assignment(assignment) => assignment.node.define_types(_context),
-            Statement::Break(_) => Ok(()),
             Statement::Loop(r#loop) => r#loop.node.define_types(_context),
             Statement::StructureDefinition(struct_definition) => {
                 struct_definition.node.define_types(_context)
@@ -76,6 +77,7 @@ impl AbstractNode for Statement {
             }
             Statement::While(r#while) => r#while.node.define_types(_context),
             Statement::Use(r#use) => r#use.node.define_types(_context),
+            Statement::Break(_) | Statement::Null(_) => Ok(()),
         }
     }
 
@@ -88,7 +90,6 @@ impl AbstractNode for Statement {
                 async_block.node.validate(_context, _manage_memory)
             }
             Statement::Block(block) => block.node.validate(_context, _manage_memory),
-            Statement::Break(_) => Ok(()),
             Statement::Expression(expression) => expression.validate(_context, _manage_memory),
             Statement::IfElse(if_else) => if_else.node.validate(_context, _manage_memory),
             Statement::Loop(r#loop) => r#loop.node.validate(_context, _manage_memory),
@@ -113,6 +114,7 @@ impl AbstractNode for Statement {
             Statement::Expression(expression) => expression.evaluate(context, manage_memory),
             Statement::IfElse(if_else) => if_else.node.evaluate(context, manage_memory),
             Statement::Loop(r#loop) => r#loop.node.evaluate(context, manage_memory),
+            Statement::Null(_) => Ok(None),
             Statement::StructureDefinition(structure_definition) => {
                 structure_definition.node.evaluate(context, manage_memory)
             }
@@ -138,7 +140,6 @@ impl AbstractNode for Statement {
             Statement::Block(block) => block.node.expected_type(_context),
             Statement::AsyncBlock(async_block) => async_block.node.expected_type(_context),
             Statement::Assignment(assignment) => assignment.node.expected_type(_context),
-            Statement::Break(_) => Ok(None),
             Statement::Loop(r#loop) => r#loop.node.expected_type(_context),
             Statement::StructureDefinition(struct_definition) => {
                 struct_definition.node.expected_type(_context)
@@ -149,6 +150,7 @@ impl AbstractNode for Statement {
             }
             Statement::While(r#while) => r#while.node.expected_type(_context),
             Statement::Use(r#use) => r#use.node.expected_type(_context),
+            Statement::Break(_) | Statement::Null(_) => Ok(None),
         }
     }
 }
@@ -162,6 +164,7 @@ impl Display for Statement {
             Statement::Break(_) => write!(f, "break"),
             Statement::IfElse(inner) => write!(f, "{}", inner.node),
             Statement::Loop(inner) => write!(f, "{}", inner.node),
+            Statement::Null(_) => write!(f, ";"),
             Statement::StructureDefinition(inner) => write!(f, "{}", inner.node),
             Statement::TypeAlias(inner) => write!(f, "{}", inner.node),
             Statement::EnumDeclaration(inner) => write!(f, "{}", inner.node),
diff --git a/dust-lang/src/parser/mod.rs b/dust-lang/src/parser/mod.rs
index 10f35c1..4608082 100644
--- a/dust-lang/src/parser/mod.rs
+++ b/dust-lang/src/parser/mod.rs
@@ -781,23 +781,24 @@ pub fn parser<'src>(
             Statement::Use(Use::new(text.to_string()).with_position(state.span()))
         });
 
-        comment
-            .repeated()
-            .or_not()
-            .ignore_then(choice((
-                assignment,
-                expression_statement,
-                async_block,
-                if_else,
-                r#break,
-                block_statement,
-                r#loop,
-                r#while,
-                type_alias,
-                enum_declaration,
-                r#use,
-            )))
-            .then_ignore(just(Token::Symbol(Symbol::Semicolon)).or_not())
+        let null = just(Token::Symbol(Symbol::Semicolon))
+            .ignored()
+            .map_with(|_, state| Statement::Null(().with_position(state.span())));
+
+        comment.repeated().or_not().ignore_then(choice((
+            assignment,
+            expression_statement,
+            async_block,
+            if_else,
+            r#break,
+            block_statement,
+            r#loop,
+            r#while,
+            type_alias,
+            enum_declaration,
+            r#use,
+            null,
+        )))
     });
 
     statement