Implement block scoping rules

cburgdorf · cburgdorf · commit 05b6f3d74c7a · 2020-11-17T11:37:05.000+01:00
diff --git a/compiler/tests/compile_errors.rs b/compiler/tests/compile_errors.rs
@@ -9,6 +9,14 @@ use std::fs;
 #[rstest(
     fixture_file,
     error,
+    case(
+        "not_in_scope.fe",
+        "[Str(\"semantic error: UndefinedValue { value: \\\"y\\\" }\")]"
+    ),
+    case(
+        "not_in_scope_2.fe",
+        "[Str(\"semantic error: UndefinedValue { value: \\\"y\\\" }\")]"
+    ),
     case("mismatch_return_type.fe", "[Str(\"semantic error: TypeError\")]"),
     case("unexpected_return.fe", "[Str(\"semantic error: TypeError\")]"),
     case("missing_return.fe", "[Str(\"semantic error: MissingReturn\")]"),
diff --git a/compiler/tests/fixtures/compile_errors/not_in_scope.fe b/compiler/tests/fixtures/compile_errors/not_in_scope.fe
@@ -0,0 +1,8 @@
+contract Foo:
+
+    pub def bar() -> u256:
+        if true:
+            y: u256 = 1
+        else:
+            y: u256 = 1
+        return y
diff --git a/compiler/tests/fixtures/compile_errors/not_in_scope_2.fe b/compiler/tests/fixtures/compile_errors/not_in_scope_2.fe
@@ -0,0 +1,8 @@
+contract Foo:
+
+    pub def bar() -> u256:
+        i: u256 = 0
+        while i < 1:
+            i = 1
+            y: u256 = 1
+        return y
diff --git a/compiler/tests/fixtures/if_statement_with_block_declaration.fe b/compiler/tests/fixtures/if_statement_with_block_declaration.fe
@@ -0,0 +1,9 @@
+contract Foo:
+
+    pub def bar() -> u256:
+        if true:
+            y: u256 = 1
+            return y
+        else:
+            y: u256 = 1
+            return y
diff --git a/semantics/src/namespace/scopes.rs b/semantics/src/namespace/scopes.rs
@@ -34,7 +34,7 @@ pub enum ContractDef {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-pub enum FunctionDef {
+pub enum BlockDef {
     Base(Base),
     Array(Array),
 }
@@ -53,25 +53,31 @@ pub struct ContractScope {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-pub struct FunctionScope {
+pub struct BlockScope {
     pub span: Span,
-    pub parent: Shared<ContractScope>,
-    pub defs: HashMap<String, FunctionDef>,
+    pub parent: BlockScopeParent,
+    pub defs: HashMap<String, BlockDef>,
 }
 
 #[allow(dead_code)]
 pub enum Scope {
     Module(Shared<ModuleScope>),
     Contract(Shared<ContractScope>),
-    Function(Shared<FunctionScope>),
+    Block(Shared<BlockScope>),
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub enum BlockScopeParent {
+    Contract(Shared<ContractScope>),
+    Block(Shared<BlockScope>),
 }
 
 impl Scope {
     pub fn module_scope(&self) -> Shared<ModuleScope> {
         match self {
             Scope::Module(scope) => Rc::clone(scope),
             Scope::Contract(scope) => Rc::clone(&scope.borrow().parent),
-            Scope::Function(scope) => Rc::clone(&scope.borrow().parent.borrow().parent),
+            Scope::Block(scope) => Rc::clone(&scope.borrow().contract_scope().borrow().parent),
         }
     }
 }
@@ -136,9 +142,17 @@ impl ContractScope {
     }
 }
 
-impl FunctionScope {
-    pub fn new(span: Span, parent: Shared<ContractScope>) -> Shared<Self> {
-        Rc::new(RefCell::new(FunctionScope {
+impl BlockScope {
+    pub fn from_contract_scope(span: Span, parent: Shared<ContractScope>) -> Shared<Self> {
+        BlockScope::new(span, BlockScopeParent::Contract(parent))
+    }
+
+    pub fn from_block_scope(span: Span, parent: Shared<BlockScope>) -> Shared<Self> {
+        BlockScope::new(span, BlockScopeParent::Block(parent))
+    }
+
+    pub fn new(span: Span, parent: BlockScopeParent) -> Shared<Self> {
+        Rc::new(RefCell::new(BlockScope {
             span,
             parent,
             defs: HashMap::new(),
@@ -147,26 +161,136 @@ impl FunctionScope {
 
     #[allow(dead_code)]
     pub fn module_scope(&self) -> Shared<ModuleScope> {
-        Rc::clone(&self.parent.borrow().parent)
+        Rc::clone(&self.contract_scope().borrow().parent)
     }
 
+    /// Return the contract scope and its immediate block scope child
+    fn find_scope_boundary(&self) -> (Shared<ContractScope>, Shared<BlockScope>) {
+        let mut parent = self.parent.clone();
+        let mut last_block_scope = Rc::new(RefCell::new(self.clone()));
+        loop {
+            parent = match parent {
+                BlockScopeParent::Block(ref scope) => {
+                    last_block_scope = scope.clone();
+                    scope.borrow().parent.clone()
+                }
+                BlockScopeParent::Contract(ref scope) => return (scope.clone(), last_block_scope),
+            }
+        }
+    }
+
+    /// Return the contract scope that the block scope inherits from
     pub fn contract_scope(&self) -> Shared<ContractScope> {
-        Rc::clone(&self.parent)
+        let (contract_scope, _) = self.find_scope_boundary();
+        contract_scope
+    }
+
+    /// Return the block scope that is associated with the function block
+    pub fn function_scope(&self) -> Shared<BlockScope> {
+        let (_, function_scope) = self.find_scope_boundary();
+        function_scope
     }
 
     pub fn contract_def(&self, name: String) -> Option<ContractDef> {
         self.contract_scope().borrow().def(name)
     }
 
-    pub fn def(&self, name: String) -> Option<FunctionDef> {
-        self.defs.get(&name).map(|def| (*def).clone())
+    /// Lookup definition in current or inherited block scope
+    pub fn def(&self, name: String) -> Option<BlockDef> {
+        let block_def = self.defs.get(&name).map(|def| (*def).clone());
+        if block_def.is_none() {
+            if let BlockScopeParent::Block(scope) = &self.parent {
+                scope.borrow().def(name)
+            } else {
+                None
+            }
+        } else {
+            block_def
+        }
     }
 
     pub fn add_array(&mut self, name: String, array: Array) {
-        self.defs.insert(name, FunctionDef::Array(array));
+        self.defs.insert(name, BlockDef::Array(array));
     }
 
     pub fn add_base(&mut self, name: String, base: Base) {
-        self.defs.insert(name, FunctionDef::Base(base));
+        self.defs.insert(name, BlockDef::Base(base));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::namespace::scopes::{
+        BlockDef,
+        BlockScope,
+        ContractScope,
+        ModuleScope,
+    };
+    use crate::namespace::types::Base;
+    use fe_parser::span::Span;
+
+    #[test]
+    fn test_scope_resolution_on_first_level_block_scope() {
+        let module_scope = ModuleScope::new();
+        let contract_scope = ContractScope::new(module_scope);
+        let block_scope_1 =
+            BlockScope::from_contract_scope(Span::new(0, 0), contract_scope.clone());
+        assert_eq!(block_scope_1, block_scope_1.borrow().function_scope());
+        assert_eq!(contract_scope, block_scope_1.borrow().contract_scope());
+    }
+
+    #[test]
+    fn test_scope_resolution_on_second_level_block_scope() {
+        let module_scope = ModuleScope::new();
+        let contract_scope = ContractScope::new(module_scope);
+        let block_scope_1 =
+            BlockScope::from_contract_scope(Span::new(0, 0), contract_scope.clone());
+        let block_scope_2 = BlockScope::from_block_scope(Span::new(0, 0), block_scope_1.clone());
+        assert_eq!(block_scope_1, block_scope_2.borrow().function_scope());
+        assert_eq!(contract_scope, block_scope_2.borrow().contract_scope());
+    }
+
+    #[test]
+    fn test_1st_level_def_lookup_on_1st_level_block_scope() {
+        let module_scope = ModuleScope::new();
+        let contract_scope = ContractScope::new(module_scope);
+        let block_scope_1 =
+            BlockScope::from_contract_scope(Span::new(0, 0), contract_scope.clone());
+        block_scope_1
+            .borrow_mut()
+            .add_base("some_thing".to_string(), Base::Bool);
+        assert_eq!(
+            Some(BlockDef::Base(Base::Bool)),
+            block_scope_1.borrow().def("some_thing".to_string())
+        );
+    }
+
+    #[test]
+    fn test_1st_level_def_lookup_on_2nd_level_block_scope() {
+        let module_scope = ModuleScope::new();
+        let contract_scope = ContractScope::new(module_scope);
+        let block_scope_1 =
+            BlockScope::from_contract_scope(Span::new(0, 0), contract_scope.clone());
+        let block_scope_2 = BlockScope::from_block_scope(Span::new(0, 0), block_scope_1.clone());
+        block_scope_1
+            .borrow_mut()
+            .add_base("some_thing".to_string(), Base::Bool);
+        assert_eq!(
+            Some(BlockDef::Base(Base::Bool)),
+            block_scope_2.borrow().def("some_thing".to_string())
+        );
+    }
+
+    #[test]
+    fn test_2nd_level_def_lookup_on_1nd_level_block_scope_fails() {
+        let module_scope = ModuleScope::new();
+        let contract_scope = ContractScope::new(module_scope);
+        let block_scope_1 =
+            BlockScope::from_contract_scope(Span::new(0, 0), contract_scope.clone());
+        let block_scope_2 = BlockScope::from_block_scope(Span::new(0, 0), block_scope_1.clone());
+        block_scope_2
+            .borrow_mut()
+            .add_base("some_thing".to_string(), Base::Bool);
+        assert_eq!(None, block_scope_1.borrow().def("some_thing".to_string()));
     }
 }
diff --git a/semantics/src/traversal/assignments.rs b/semantics/src/traversal/assignments.rs
@@ -1,7 +1,7 @@
 use crate::errors::SemanticError;
 use crate::namespace::operations;
 use crate::namespace::scopes::{
-    FunctionScope,
+    BlockScope,
     Shared,
 };
 use crate::traversal::expressions;
@@ -14,7 +14,7 @@ use std::rc::Rc;
 ///
 /// e.g. `foo[42] = "bar"`, `self.foo[42] = "bar"`, `foo = 42`
 pub fn assign(
-    scope: Shared<FunctionScope>,
+    scope: Shared<BlockScope>,
     context: Shared<Context>,
     stmt: &Spanned<fe::FuncStmt>,
 ) -> Result<(), SemanticError> {
@@ -44,7 +44,7 @@ pub fn assign(
 ///
 /// e.g. `foo[42] = "bar"`, `self.foo[42] = "bar"`
 fn assign_subscript(
-    scope: Shared<FunctionScope>,
+    scope: Shared<BlockScope>,
     context: Shared<Context>,
     target: &Spanned<fe::Expr>,
     value: &Spanned<fe::Expr>,
@@ -74,7 +74,7 @@ fn assign_subscript(
 ///
 /// e.g. `foo = 42`
 fn assign_name(
-    scope: Shared<FunctionScope>,
+    scope: Shared<BlockScope>,
     context: Shared<Context>,
     target: &Spanned<fe::Expr>,
     value: &Spanned<fe::Expr>,
@@ -93,8 +93,8 @@ fn assign_name(
 mod tests {
     use crate::errors::SemanticError;
     use crate::namespace::scopes::{
+        BlockScope,
         ContractScope,
-        FunctionScope,
         ModuleScope,
         Shared,
     };
@@ -115,7 +115,7 @@ mod tests {
     // - self.foobar: Map<u256, u256>
     // - foo: u256
     // - bar: u256[100]
-    fn scope() -> Shared<FunctionScope> {
+    fn scope() -> Shared<BlockScope> {
         let module_scope = ModuleScope::new();
         let contract_scope = ContractScope::new(module_scope);
         contract_scope.borrow_mut().add_map(
@@ -125,7 +125,7 @@ mod tests {
                 value: Box::new(Type::Base(Base::U256)),
             },
         );
-        let function_scope = FunctionScope::new(Span::new(0, 0), contract_scope);
+        let function_scope = BlockScope::from_contract_scope(Span::new(0, 0), contract_scope);
         function_scope
             .borrow_mut()
             .add_base("foo".to_string(), Base::U256);
@@ -139,7 +139,7 @@ mod tests {
         function_scope
     }
 
-    fn analyze(scope: Shared<FunctionScope>, src: &str) -> Result<Context, SemanticError> {
+    fn analyze(scope: Shared<BlockScope>, src: &str) -> Result<Context, SemanticError> {
         let context = Context::new_shared();
         let tokens = parser::get_parse_tokens(src).expect("Couldn't parse expression");
         let assignment = &parser::parsers::assign_stmt(&tokens[..])
diff --git a/semantics/src/traversal/declarations.rs b/semantics/src/traversal/declarations.rs
@@ -1,6 +1,6 @@
 use crate::errors::SemanticError;
 use crate::namespace::scopes::{
-    FunctionScope,
+    BlockScope,
     Scope,
     Shared,
 };
@@ -16,13 +16,13 @@ use std::rc::Rc;
 
 /// Gather context information for var declarations and check for type errors.
 pub fn var_decl(
-    scope: Shared<FunctionScope>,
+    scope: Shared<BlockScope>,
     context: Shared<Context>,
     stmt: &Spanned<fe::FuncStmt>,
 ) -> Result<(), SemanticError> {
     if let fe::FuncStmt::VarDecl { target, typ, value } = &stmt.node {
         let name = expressions::expr_name_string(target)?;
-        let declared_type = types::type_desc_fixed_size(Scope::Function(Rc::clone(&scope)), typ)?;
+        let declared_type = types::type_desc_fixed_size(Scope::Block(Rc::clone(&scope)), typ)?;
         if let Some(value) = value {
             let value_attributes =
                 expressions::expr(Rc::clone(&scope), Rc::clone(&context), value)?;
@@ -48,9 +48,9 @@ pub fn var_decl(
 mod tests {
     use crate::errors::SemanticError;
     use crate::namespace::scopes::{
+        BlockDef,
+        BlockScope,
         ContractScope,
-        FunctionDef,
-        FunctionScope,
         ModuleScope,
         Shared,
     };
@@ -61,13 +61,13 @@ mod tests {
     use fe_parser::span::Span;
     use std::rc::Rc;
 
-    fn scope() -> Shared<FunctionScope> {
+    fn scope() -> Shared<BlockScope> {
         let module_scope = ModuleScope::new();
         let contract_scope = ContractScope::new(module_scope);
-        FunctionScope::new(Span::new(0, 0), contract_scope)
+        BlockScope::from_contract_scope(Span::new(0, 0), contract_scope)
     }
 
-    fn analyze(scope: Shared<FunctionScope>, src: &str) -> Result<Context, SemanticError> {
+    fn analyze(scope: Shared<BlockScope>, src: &str) -> Result<Context, SemanticError> {
         let context = Context::new_shared();
         let tokens = parser::get_parse_tokens(src).expect("Couldn't parse expression");
         let statement = &parser::parsers::vardecl_stmt(&tokens[..])
@@ -89,7 +89,7 @@ mod tests {
         assert_eq!(context.expressions.len(), 3);
         assert_eq!(
             scope.borrow().def("foo".to_string()),
-            Some(FunctionDef::Base(Base::U256))
+            Some(BlockDef::Base(Base::U256))
         );
     }
 
diff --git a/semantics/src/traversal/expressions.rs b/semantics/src/traversal/expressions.rs
diff --git a/semantics/src/traversal/functions.rs b/semantics/src/traversal/functions.rs
