Rework how scopes work to support excluding sibling scopes

dust-lang/src/chunk.rs

@@ -1,6 +1,7 @@
 use std::{
     env::current_exe,
     fmt::{self, Debug, Display},
+    rc::Weak,
 };
 
 use colored::Colorize;
@@ -14,7 +15,8 @@ pub struct Chunk {
     instructions: Vec<(Instruction, Span)>,
     constants: Vec<Value>,
     locals: Vec<Local>,
-    scope_depth: usize,
+    current_scope: Scope,
+    block_count: usize,
 }
 
 impl Chunk {
@@ -24,7 +26,8 @@ impl Chunk {
             instructions: Vec::new(),
             constants: Vec::new(),
             locals: Vec::new(),
-            scope_depth: 0,
+            current_scope: Scope::default(),
+            block_count: 0,
         }
     }
 
@@ -39,7 +42,8 @@ impl Chunk {
             instructions,
             constants,
             locals,
-            scope_depth: 0,
+            current_scope: Scope::default(),
+            block_count: 0,
         }
     }
 
@@ -87,8 +91,8 @@ impl Chunk {
         &mut self.locals
     }
 
-    pub fn scope_depth(&self) -> usize {
-        self.scope_depth
+    pub fn current_scope(&self) -> Scope {
+        self.current_scope
     }
 
     pub fn get_constant(&self, index: u8) -> Option<&Value> {
@@ -118,11 +122,19 @@ impl Chunk {
     }
 
     pub fn begin_scope(&mut self) {
-        self.scope_depth += 1;
+        self.current_scope.depth += 1;
+        self.current_scope.block = self.block_count;
     }
 
     pub fn end_scope(&mut self) {
-        self.scope_depth -= 1;
+        self.current_scope.depth -= 1;
+
+        if self.current_scope.depth == 0 {
+            self.block_count += 1;
+            self.current_scope.block = 0;
+        } else {
+            self.current_scope.block = self.block_count;
+        };
     }
 
     pub fn disassembler(&self) -> ChunkDisassembler {
@@ -163,7 +175,7 @@ pub struct Local {
     pub identifier_index: u8,
     pub r#type: Option<Type>,
     pub is_mutable: bool,
-    pub depth: usize,
+    pub scope: Scope,
     pub register_index: u8,
 }
 
@@ -172,19 +184,39 @@ impl Local {
         identifier_index: u8,
         r#type: Option<Type>,
         mutable: bool,
-        depth: usize,
+        scope: Scope,
         register_index: u8,
     ) -> Self {
         Self {
             identifier_index,
             r#type,
             is_mutable: mutable,
-            depth,
+            scope,
             register_index,
         }
     }
 }
 
+#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Scope {
+    /// The level of block nesting.
+    pub depth: usize,
+    /// The nth top-level block in the chunk.
+    pub block: usize,
+}
+
+impl Scope {
+    pub fn new(depth: usize, block: usize) -> Self {
+        Self { depth, block }
+    }
+}
+
+impl Display for Scope {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({}, {})", self.depth, self.block)
+    }
+}
+
 pub struct ChunkDisassembler<'a> {
     chunk: &'a Chunk,
     source: Option<&'a str>,
@@ -207,7 +239,7 @@ impl<'a> ChunkDisassembler<'a> {
     const LOCAL_HEADER: [&'static str; 4] = [
         "Locals",
         "------",
-        "INDEX IDENTIFIER TYPE     MUTABLE DEPTH REGISTER",
+        "INDEX IDENTIFIER TYPE     MUTABLE SCOPE REGISTER",
         "----- ---------- -------- ------- ----- --------",
     ];
 
@@ -429,7 +461,7 @@ impl<'a> ChunkDisassembler<'a> {
             Local {
                 identifier_index,
                 r#type,
-                depth,
+                scope: depth,
                 register_index,
                 is_mutable: mutable,
             },

dust-lang/src/instruction.rs

@@ -454,7 +454,7 @@ impl Instruction {
                 };
                 let mutable_display = if self.c_as_boolean() { "mut" } else { "" };
 
-                format!("L{local_index} = R{to_register} {mutable_display} {identifier_display}")
+                format!("R{to_register} = L{local_index} {mutable_display} {identifier_display}")
             }
             Operation::GetLocal => {
                 let local_index = self.b();

dust-lang/src/lib.rs

@@ -11,7 +11,7 @@ mod r#type;
 mod value;
 mod vm;
 
-pub use chunk::{Chunk, ChunkDisassembler, Local};
+pub use chunk::{Chunk, ChunkDisassembler, Local, Scope};
 pub use dust_error::{AnnotatedError, DustError};
 pub use formatter::{format, Formatter};
 pub use instruction::Instruction;

dust-lang/src/parser.rs

@@ -10,7 +10,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::{
     AnnotatedError, Chunk, DustError, FunctionType, Instruction, LexError, Lexer, Local,
-    NativeFunction, Operation, Span, Token, TokenKind, TokenOwned, Type, Value,
+    NativeFunction, Operation, Scope, Span, Token, TokenKind, TokenOwned, Type, Value,
 };
 
 pub fn parse(source: &str) -> Result<Chunk, DustError> {
@@ -149,11 +149,11 @@ impl<'src> Parser<'src> {
         identifier: &str,
         r#type: Option<Type>,
         is_mutable: bool,
+        scope: Scope,
         register_index: u8,
     ) -> (u8, u8) {
         log::debug!("Declare local {identifier}");
 
-        let scope_depth = self.chunk.scope_depth();
         let identifier = Value::string(identifier);
         let identifier_index = self.chunk.push_or_get_constant(identifier);
 
@@ -161,7 +161,7 @@ impl<'src> Parser<'src> {
             identifier_index,
             r#type,
             is_mutable,
-            scope_depth,
+            scope,
             register_index,
         ));
 
@@ -823,9 +823,10 @@ impl<'src> Parser<'src> {
             } else if let Some(name) = self.chunk.name() {
                 if name.as_str() == text {
                     let register = self.next_register();
+                    let scope = self.chunk.current_scope();
 
                     self.emit_instruction(Instruction::load_self(register), start_position);
-                    self.declare_local(text, None, false, register);
+                    self.declare_local(text, None, false, scope, register);
 
                     self.current_is_expression = true;
 
@@ -1317,6 +1318,7 @@ impl<'src> Parser<'src> {
 
         self.advance()?;
 
+        let scope = self.chunk.current_scope();
         let is_mutable = self.allow(Token::Mut)?;
         let position = self.current_position;
         let identifier = if let Token::Identifier(text) = self.current_token {
@@ -1344,7 +1346,7 @@ impl<'src> Parser<'src> {
         self.expect(Token::Equal)?;
         self.parse_expression()?;
 
-        let (local_index, _) = self.declare_local(identifier, r#type, is_mutable, register);
+        let (local_index, _) = self.declare_local(identifier, r#type, is_mutable, scope, register);
         let register = self.next_register().saturating_sub(1);
 
         self.emit_instruction(
@@ -1403,10 +1405,12 @@ impl<'src> Parser<'src> {
                 .as_ref()
                 .map(|values| values.len() as u8)
                 .unwrap_or(0);
+            let scope = function_parser.chunk.current_scope();
             let (_, identifier_index) = function_parser.declare_local(
                 parameter,
                 Some(r#type.clone()),
                 is_mutable,
+                scope,
                 register,
             );
 
@@ -1456,10 +1460,12 @@ impl<'src> Parser<'src> {
 
         if let Some((identifier, identifier_position)) = identifier {
             let register = self.next_register();
+            let scope = self.chunk.current_scope();
             let (local_index, _) = self.declare_local(
                 identifier,
                 Some(Type::Function(function_type)),
                 false,
+                scope,
                 register,
             );
 

dust-lang/tests/control_flow.rs

@@ -23,7 +23,7 @@ fn equality_assignment_long() {
                 (Instruction::r#return(true), Span(44, 44)),
             ],
             vec![Value::integer(4), Value::string("a")],
-            vec![Local::new(1, None, false, 0, 0)]
+            vec![Local::new(1, None, false, Scope { depth: 0, block: 0 }, 0)]
         )),
     );
 
@@ -53,7 +53,7 @@ fn equality_assignment_short() {
                 (Instruction::r#return(true), Span(16, 16)),
             ],
             vec![Value::integer(4), Value::string("a")],
-            vec![Local::new(1, None, false, 0, 0)]
+            vec![Local::new(1, None, false, Scope::default(), 0)]
         )),
     );
 
@@ -112,7 +112,7 @@ fn if_else_assigment() {
                 Value::integer(42),
                 Value::string("a")
             ],
-            vec![Local::new(5, None, false, 0, 0)]
+            vec![Local::new(5, None, false, Scope::default(), 0)]
         )),
     );
 

dust-lang/tests/expressions.rs

@@ -41,7 +41,7 @@ fn add_assign() {
                 (Instruction::r#return(true), Span(24, 24))
             ],
             vec![Value::integer(1), Value::string("a"), Value::integer(2)],
-            vec![Local::new(1, None, true, 0, 0)]
+            vec![Local::new(1, None, true, Scope::default(), 0)]
         ))
     );
 
@@ -82,7 +82,7 @@ fn define_local() {
                 (Instruction::r#return(false), Span(11, 11))
             ],
             vec![Value::integer(42), Value::string("x")],
-            vec![Local::new(1, None, false, 0, 0)]
+            vec![Local::new(1, None, false, Scope::default(), 0)]
         )),
     );
 
@@ -133,7 +133,7 @@ fn divide_assign() {
                 (Instruction::r#return(true), Span(24, 24))
             ],
             vec![Value::integer(2), Value::string("a")],
-            vec![Local::new(1, None, true, 0, 0)]
+            vec![Local::new(1, None, true, Scope::default(), 0)]
         ))
     );
 
@@ -359,7 +359,7 @@ fn multiply_assign() {
                 (Instruction::r#return(true), Span(23, 23))
             ],
             vec![Value::integer(2), Value::string("a"), Value::integer(3)],
-            vec![Local::new(1, None, true, 0, 0),]
+            vec![Local::new(1, None, true, Scope::default(), 0),]
         ))
     );
 
@@ -453,7 +453,7 @@ fn set_local() {
                 (Instruction::r#return(true), Span(25, 25)),
             ],
             vec![Value::integer(41), Value::string("x"), Value::integer(42)],
-            vec![Local::new(1, None, true, 0, 0)]
+            vec![Local::new(1, None, true, Scope::default(), 0)]
         )),
     );
 
@@ -504,7 +504,7 @@ fn subtract_assign() {
                 (Instruction::r#return(true), Span(25, 25)),
             ],
             vec![Value::integer(42), Value::string("x"), Value::integer(2)],
-            vec![Local::new(1, None, true, 0, 0)]
+            vec![Local::new(1, None, true, Scope::default(), 0)]
         )),
     );
 
@@ -532,8 +532,8 @@ fn variable_and() {
             ],
             vec![Value::string("a"), Value::string("b"),],
             vec![
-                Local::new(0, None, false, 0, 0),
-                Local::new(1, None, false, 0, 1),
+                Local::new(0, None, false, Scope::default(), 0),
+                Local::new(1, None, false, Scope::default(), 1),
             ]
         ))
     );
@@ -568,7 +568,7 @@ fn r#while() {
                 Value::integer(5),
                 Value::integer(1),
             ],
-            vec![Local::new(1, None, true, 0, 0),]
+            vec![Local::new(1, None, true, Scope::default(), 0),]
         )),
     );
 

dust-lang/tests/functions.rs

@@ -15,8 +15,8 @@ fn function() {
                 ],
                 vec![Value::string("a"), Value::string("b"),],
                 vec![
-                    Local::new(0, Some(Type::Integer), false, 0, 0),
-                    Local::new(1, Some(Type::Integer), false, 0, 1)
+                    Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                    Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
                 ]
             ),
             FunctionType {
@@ -53,8 +53,8 @@ fn function_call() {
                         ],
                         vec![Value::string("a"), Value::string("b"),],
                         vec![
-                            Local::new(0, Some(Type::Integer), false, 0, 0),
-                            Local::new(1, Some(Type::Integer), false, 0, 1)
+                            Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                            Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
                         ]
                     ),
                     FunctionType {
@@ -97,8 +97,8 @@ fn function_declaration() {
                         ],
                         vec![Value::string("a"), Value::string("b")],
                         vec![
-                            Local::new(0, Some(Type::Integer), false, 0, 0),
-                            Local::new(1, Some(Type::Integer), false, 0, 1)
+                            Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                            Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
                         ]
                     ),
                     FunctionType {
@@ -116,7 +116,7 @@ fn function_declaration() {
                     return_type: Some(Box::new(Type::Integer)),
                 })),
                 false,
-                0,
+                Scope::default(),
                 0
             ),],
         )),

dust-lang/tests/scopes.rs

@@ -55,11 +55,11 @@ fn block_scope() {
                 Value::string("e"),
             ],
             vec![
-                Local::new(1, None, false, 0, 0),
-                Local::new(3, None, false, 1, 1),
-                Local::new(5, None, false, 2, 2),
-                Local::new(7, None, false, 1, 3),
-                Local::new(8, None, false, 0, 4),
+                Local::new(1, None, false, Scope::new(0, 0), 0),
+                Local::new(3, None, false, Scope::new(1, 0), 1),
+                Local::new(5, None, false, Scope::new(2, 0), 2),
+                Local::new(7, None, false, Scope::new(1, 0), 3),
+                Local::new(8, None, false, Scope::new(0, 0), 4),
             ]
         )),
     );
@@ -67,6 +67,81 @@ fn block_scope() {
     assert_eq!(run(source), Ok(None));
 }
 
+#[test]
+fn multiple_block_scopes() {
+    let source = "
+        let a = 0;
+        {
+            let b = 42;
+            {
+                let c = 1;
+            }
+            let d = 2;
+        }
+        let q = 42;
+        {
+            let b = 42;
+            {
+                let c = 1;
+            }
+            let d = 2;
+        }
+        let e = 1;
+    ";
+
+    assert_eq!(
+        parse(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(17, 18)),
+                (Instruction::define_local(0, 0, false), Span(13, 14)),
+                (Instruction::load_constant(1, 2, false), Span(50, 52)),
+                (Instruction::define_local(1, 1, false), Span(46, 47)),
+                (Instruction::load_constant(2, 4, false), Span(92, 93)),
+                (Instruction::define_local(2, 2, false), Span(88, 89)),
+                (Instruction::load_constant(3, 6, false), Span(129, 130)),
+                (Instruction::define_local(3, 3, false), Span(125, 126)),
+                (Instruction::load_constant(4, 2, false), Span(158, 160)),
+                (Instruction::define_local(4, 4, false), Span(154, 155)),
+                (Instruction::load_constant(5, 2, false), Span(192, 194)),
+                (Instruction::define_local(5, 5, false), Span(188, 189)),
+                (Instruction::load_constant(6, 4, false), Span(234, 235)),
+                (Instruction::define_local(6, 6, false), Span(230, 231)),
+                (Instruction::load_constant(7, 6, false), Span(271, 272)),
+                (Instruction::define_local(7, 7, false), Span(267, 268)),
+                (Instruction::load_constant(8, 4, false), Span(300, 301)),
+                (Instruction::define_local(8, 8, false), Span(296, 297)),
+                (Instruction::r#return(false), Span(307, 307))
+            ],
+            vec![
+                Value::integer(0),
+                Value::string("a"),
+                Value::integer(42),
+                Value::string("b"),
+                Value::integer(1),
+                Value::string("c"),
+                Value::integer(2),
+                Value::string("d"),
+                Value::string("q"),
+                Value::string("e"),
+            ],
+            vec![
+                Local::new(1, None, false, Scope::new(0, 0), 0),
+                Local::new(3, None, false, Scope::new(1, 0), 1),
+                Local::new(5, None, false, Scope::new(2, 0), 2),
+                Local::new(7, None, false, Scope::new(1, 0), 3),
+                Local::new(8, None, false, Scope::new(0, 0), 4),
+                Local::new(3, None, false, Scope::new(1, 1), 5),
+                Local::new(5, None, false, Scope::new(2, 1), 6),
+                Local::new(7, None, false, Scope::new(1, 1), 7),
+                Local::new(9, None, false, Scope::new(0, 0), 8),
+            ]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
 // #[test]
 // fn disallow_access_to_child_scope() {
 //     let source = r#"