Bunch of work on name analysis. Reintroduce Rc<RefCell<_>> for symbols.

ast-generator/src/deserialize/struct_spec.rs

@@ -5,6 +5,22 @@ use crate::deserialize::util::{get_as_bool, make_build_fn_name, unwrap_single_me
 use crate::spec::struct_spec::*;
 use yaml_rust2::Yaml;
 
+fn deserialize_field(field_yaml: &Yaml) -> StructField {
+    let (name, props) = unwrap_single_member_hash(field_yaml);
+    let kind = props["kind"].as_str().unwrap();
+    let wrap = if let Some(wrap) = props["wrap"].as_str() {
+        match wrap { 
+            "rc_ref_cell" => {
+                Some(StructFieldWrap::RcRefCell)
+            }
+            _ => panic!()
+        }
+    } else {
+        None
+    };
+    StructField::new(&name, kind, wrap)
+}
+
 fn deserialize_skip_child(props: &Yaml) -> StructChild {
     let rule = props["rule"].as_str().unwrap();
     StructChild::SkipChild(SkipChild::new(rule))
@@ -151,6 +167,18 @@ pub fn deserialize_struct_spec(name: &str, struct_yaml: &Yaml) -> StructSpec {
     } else {
         deserialize_error!("array", "children", name);
     };
+    
+    let fields = if struct_yaml["fields"].is_array() {
+        struct_yaml["fields"].as_vec()
+            .unwrap()
+            .iter()
+            .map(|field| deserialize_field(field))
+            .map(Box::new)
+            .collect()
+    } else {
+        vec![]
+    };
+    
     let derive = if struct_yaml["derive"].is_array() {
         struct_yaml["derive"].as_vec()
             .unwrap()
@@ -161,5 +189,5 @@ pub fn deserialize_struct_spec(name: &str, struct_yaml: &Yaml) -> StructSpec {
         vec![]
     };
     
-    StructSpec::new(name, children, derive)
+    StructSpec::new(name, children, fields, derive)
 }

ast-generator/src/lib.rs

@@ -114,6 +114,9 @@ fn generate_node_file(build_specs: &[BuildSpec]) -> AstGeneratedFile {
         .collect::<Vec<_>>();
     let combined = quote! {
         use std::range::Range;
+        use std::rc::Rc;
+        use std::cell::RefCell;
+        use crate::name_analysis::symbol::use_symbol::UseSymbol;
 
         #(#types)*
     };

ast-generator/src/spec/struct_spec.rs

@@ -1,14 +1,16 @@
 pub struct StructSpec {
     build: String,
     children: Vec<Box<StructChild>>,
+    fields: Vec<Box<StructField>>,
     derive: Vec<String>,
 }
 
 impl StructSpec {
-    pub fn new(build: &str, children: Vec<Box<StructChild>>, derive: Vec<String>) -> Self {
+    pub fn new(build: &str, children: Vec<Box<StructChild>>, fields: Vec<Box<StructField>>, derive: Vec<String>) -> Self {
         Self {
             build: build.to_string(),
             children,
+            fields,
             derive,
         }
     }
@@ -23,6 +25,10 @@ impl StructSpec {
         self.children.iter().map(Box::as_ref)
     }
     
+    pub fn fields(&self) -> impl Iterator<Item = &StructField> {
+        self.fields.iter().map(Box::as_ref)
+    }
+    
     pub fn derive(&self) -> &[String] {
         &self.derive
     }
@@ -266,3 +272,37 @@ pub enum SpecialChildKind {
     FileId,
     Range,
 }
+
+#[derive(Debug)]
+pub struct StructField {
+    name: String,
+    kind: String,
+    wrap: Option<StructFieldWrap>,
+}
+
+impl StructField {
+    pub fn new(name: &str, kind: &str, wrap: Option<StructFieldWrap>) -> Self {
+        Self {
+            name: name.to_string(),
+            kind: kind.to_string(),
+            wrap,
+        }
+    }
+    
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+    
+    pub fn kind(&self) -> &str {
+        &self.kind
+    }
+    
+    pub fn wrap(&self) -> Option<&StructFieldWrap> {
+        self.wrap.as_ref()
+    }
+}
+
+#[derive(Debug)]
+pub enum StructFieldWrap {
+    RcRefCell
+}

ast-generator/src/type_gen/struct_type.rs

@@ -1,10 +1,66 @@
 use crate::spec::struct_spec::{
-    MemberChild, MemberChildBuild, SpecialChild, SpecialChildKind, StructChild, StructSpec,
+    MemberChild, MemberChildBuild, SpecialChild, SpecialChildKind, StructChild, StructField,
-    VecChild, VecChildBuild,
+    StructFieldWrap, StructSpec, VecChild, VecChildBuild,
 };
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
 
+fn make_field_accessors(field: &StructField) -> TokenStream {
+    let field_ident = format_ident!("{}", field.name());
+    let field_type = {
+        let inner = format_ident!("{}", field.kind());
+        if let Some(wrap) = field.wrap() {
+            match wrap {
+                StructFieldWrap::RcRefCell => {
+                    quote! { Rc<RefCell<#inner>> }
+                }
+            }
+        } else {
+            quote! { #inner }
+        }
+    };
+    let set_field_ident = format_ident!("set_{}", field.name());
+    let field_ident_mut = format_ident!("{}_mut", field.name());
+
+    quote! {
+        pub fn #field_ident(&self) -> Option<&#field_type> {
+            self.#field_ident.as_ref()
+        }
+        
+        pub fn #field_ident_mut(&mut self) -> Option<&mut #field_type> {
+            self.#field_ident.as_mut()
+        }
+
+        pub fn #set_field_ident(&mut self, #field_ident: #field_type) {
+            self.#field_ident = Some(#field_ident);
+        }
+    }
+}
+
+fn make_field_initializer(field: &StructField) -> TokenStream {
+    let field_ident = format_ident!("{}", field.name());
+    quote! { #field_ident: None }
+}
+
+fn make_annotated_field(field: &StructField) -> TokenStream {
+    let field_ident = format_ident!("{}", field.name());
+    let field_type = if let Some(wrap) = field.wrap() {
+        match wrap {
+            StructFieldWrap::RcRefCell => {
+                let inner = format_ident!("{}", field.kind());
+                quote! { Rc<RefCell<#inner>> }
+            }
+        }
+    } else {
+        let inner = format_ident!("{}", field.kind());
+        quote! { #inner }
+    };
+
+    quote! {
+        #field_ident: Option<#field_type>
+    }
+}
+
 fn make_vec_child_accessors(vec_child: &VecChild) -> TokenStream {
     let child_ident = format_ident!("{}", vec_child.name());
     match vec_child.build() {
@@ -184,13 +240,18 @@ fn make_annotated_member(child: &StructChild) -> Option<TokenStream> {
 
 pub fn make_struct_type(build_spec: &StructSpec) -> TokenStream {
     let type_ident = format_ident!("{}", build_spec.build());
-    let annotated_members = build_spec
+    let annotated_children_members = build_spec
         .children()
         .map(|child| make_annotated_member(child))
         .filter(Option::is_some)
         .map(Option::unwrap)
         .collect::<Vec<_>>();
 
+    let annotated_fields = build_spec
+        .fields()
+        .map(|field| make_annotated_field(field))
+        .collect::<Vec<_>>();
+
     let member_names = build_spec
         .children()
         .map(|child| make_member_ident(child))
@@ -198,17 +259,28 @@ pub fn make_struct_type(build_spec: &StructSpec) -> TokenStream {
         .map(Option::unwrap)
         .collect::<Vec<_>>();
 
-    let accessors = build_spec
+    let field_initializers = build_spec
+        .fields()
+        .map(|field| make_field_initializer(field))
+        .collect::<Vec<_>>();
+
+    let child_accessors = build_spec
         .children()
         .map(|child| make_accessors(child))
         .filter(Option::is_some)
         .map(Option::unwrap)
         .collect::<Vec<_>>();
 
+    let field_accessors = build_spec
+        .fields()
+        .map(|field| make_field_accessors(field))
+        .collect::<Vec<_>>();
+
     let struct_stream = {
         let base = quote! {
             pub struct #type_ident {
-                #(#annotated_members),*
+                #(#annotated_children_members,)*
+                #(#annotated_fields,)*
             }
         };
         if !build_spec.derive().is_empty() {
@@ -231,13 +303,15 @@ pub fn make_struct_type(build_spec: &StructSpec) -> TokenStream {
         #struct_stream
 
         impl #type_ident {
-            pub fn new(#(#annotated_members),*) -> Self {
+            pub fn new(#(#annotated_children_members),*) -> Self {
                 Self {
-                    #(#member_names),*
+                    #(#member_names,)*
+                    #(#field_initializers,)*
                 }
             }
 
-            #(#accessors)*
+            #(#child_accessors)*
+            #(#field_accessors)*
         }
     }
 }

src/name_analysis/first_pass.rs

@@ -1,12 +1,14 @@
-use crate::ast::node::{CompilationUnit, UseStatement, UseStatementSuffix};
+use std::cell::RefCell;
+use crate::ast::node::{CompilationUnit, Identifier, UseStatement, UseStatementSuffix};
 use crate::diagnostic::DmDiagnostic;
 use crate::name_analysis::fqn_context::FqnContext;
 use crate::name_analysis::symbol::source_definition::SourceDefinition;
-use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol};
+use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol, UseSymbol};
 use crate::name_analysis::symbol_table::{SymbolInsertError, SymbolTable};
 use crate::name_analysis::util::use_statement_base_fqn;
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use std::range::Range;
+use std::rc::Rc;
 
 fn handle_insert_error(
     err: SymbolInsertError,
@@ -69,7 +71,7 @@ macro_rules! insert_concrete_use_symbol {
     };
 }
 
-pub fn np1_compilation_unit(
+pub fn nap1_compilation_unit(
     file_name: &str,
     compilation_unit: &mut CompilationUnit,
     symbol_table: &mut SymbolTable,
@@ -85,13 +87,42 @@ pub fn np1_compilation_unit(
     }
 
     for use_statement in compilation_unit.use_statements_mut() {
-        np1_use_statement(use_statement, symbol_table, diagnostics);
+        nap1_use_statement(use_statement, symbol_table, diagnostics);
     }
 
     symbol_table.pop_scope();
 }
 
-fn np1_use_statement(
+fn handle_concrete_use_statement(
+    use_statement: &mut UseStatement,
+    identifier: &Identifier,
+    symbol_table: &mut SymbolTable,
+    diagnostics: &mut Vec<DmDiagnostic>,
+) {
+    let base_fqn = use_statement_base_fqn(use_statement);
+    let to_insert = ConcreteUseSymbol::new(
+        &base_fqn,
+        identifier.name(),
+        Some(SourceDefinition::from_identifier(identifier))
+    );
+    match symbol_table.insert_concrete_use_symbol(to_insert) {
+        Ok(inserted) => {
+            use_statement.set_use_symbol(Rc::new(RefCell::new(UseSymbol::Concrete(inserted))));
+        }
+        Err(insert_error) => {
+            handle_insert_error(
+                insert_error,
+                identifier.name(),
+                identifier.file_id(),
+                identifier.range(),
+                "Use Symbol",
+                diagnostics
+            );
+        }
+    }
+}
+
+fn nap1_use_statement(
     use_statement: &mut UseStatement,
     symbol_table: &mut SymbolTable,
     diagnostics: &mut Vec<DmDiagnostic>,

src/name_analysis/mod.rs

@@ -23,14 +23,13 @@ The resolve phase has one main responsibility: resolve all references based on t
 use crate::ast::ast_node::AstNode;
 use crate::ast::node::CompilationUnit;
 use crate::diagnostic::DmDiagnostic;
-use crate::name_analysis::first_pass::np1_compilation_unit;
+use crate::name_analysis::first_pass::nap1_compilation_unit;
+use crate::name_analysis::second_pass::nap2_compilation_unit;
 use crate::name_analysis::symbol_table::SymbolTable;
 use codespan_reporting::files::Files;
 use std::hash::Hash;
-use crate::name_analysis::second_pass::nap2_compilation_unit;
 
 pub(self) mod fqn_context;
-mod gather;
 // mod resolve;
 mod first_pass;
 mod scope_table;
@@ -49,7 +48,7 @@ pub fn analyze_names<'a, F: Files<'a, FileId = usize, Name = String>>(
     // gather symbols
     for compilation_unit in compilation_units.iter_mut() {
         let file_name = files.name(compilation_unit.file_id()).unwrap();
-        np1_compilation_unit(&file_name, compilation_unit, symbol_table, &mut diagnostics);
+        nap1_compilation_unit(&file_name, compilation_unit, symbol_table, &mut diagnostics);
     }
 
     // resolve symbols

src/name_analysis/second_pass.rs

@@ -1,5 +1,6 @@
 use crate::ast::node::{CompilationUnit, Identifier, UseStatement, UseStatementSuffix};
 use crate::diagnostic::DmDiagnostic;
+use crate::name_analysis::symbol::use_symbol::UseSymbol;
 use crate::name_analysis::symbol_table::{SymbolLookupError, SymbolTable};
 use crate::name_analysis::util::use_statement_base_fqn;
 use codespan_reporting::diagnostic::{Diagnostic, Label};
@@ -50,9 +51,18 @@ fn nap2_use_statement(
 
     let mut handle_concrete_use_symbol = |identifier: &Identifier| {
         let fqn = format!("{}::{}", base_fqn, identifier.name());
-        if let Err(error) = symbol_table.resolve_usable_by_fqn(&fqn) {
+        match symbol_table.resolve_concrete_usable_by_fqn(&fqn) {
+            Ok(resolved_symbol) => match *use_statement.use_symbol().unwrap().borrow() {
+                UseSymbol::Concrete(ref concrete_use_symbol) => {
+                    concrete_use_symbol
+                        .borrow_mut()
+                        .set_resolved_symbol(resolved_symbol);
+                }
+                _ => panic!("Unexpected symbol type"),
+            },
+            Err(lookup_error) => {
                 handle_lookup_error(
-                error,
+                    lookup_error,
                     &fqn,
                     use_statement.file_id(),
                     use_statement.range(),
@@ -60,6 +70,7 @@ fn nap2_use_statement(
                     diagnostics,
                 );
             }
+        }
     };
 
     match use_statement.suffix() {

src/name_analysis/symbol/mod.rs

@@ -4,26 +4,30 @@ pub(crate) mod module_symbol;
 pub(crate) mod parameter_symbol;
 pub(crate) mod source_definition;
 pub(crate) mod type_symbol;
+pub(crate) mod usable_symbol;
 pub(crate) mod use_symbol;
 pub(crate) mod variable_symbol;
 
-use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol};
+use crate::name_analysis::symbol::type_symbol::ConcreteTypeSymbol;
+use crate::name_analysis::symbol::use_symbol::UseSymbol;
 use class_member_symbol::ClassMemberSymbol;
 use function_symbol::FunctionSymbol;
 use module_symbol::ModuleSymbol;
 use parameter_symbol::ParameterSymbol;
 use source_definition::SourceDefinition;
+use std::cell::RefCell;
 use std::fmt::{Debug, Display};
 use std::ops::Deref;
+use std::rc::Rc;
 use type_symbol::TypeSymbol;
 use variable_symbol::VariableSymbol;
 
 #[derive(Debug, Clone)]
 pub enum Symbol {
-    ConcreteUse(ConcreteUseSymbol),
+    Use(UseSymbol),
-    StarUse(StarUseSymbol),
     Module(ModuleSymbol),
     Type(TypeSymbol),
+    ConcreteType(Rc<RefCell<ConcreteTypeSymbol>>),
     Function(FunctionSymbol),
     Parameter(ParameterSymbol),
     Variable(VariableSymbol),
@@ -31,16 +35,18 @@ pub enum Symbol {
 }
 
 impl Symbol {
-    pub fn definition(&self) -> Option<&SourceDefinition> {
+    pub fn definition(&self) -> Option<SourceDefinition> {
         match self {
-            Symbol::ConcreteUse(concrete) => concrete.source_definition(),
+            Symbol::Use(use_symbol) => use_symbol.source_definition(),
-            Symbol::StarUse(star) => star.source_definition(),
+            Symbol::Module(module) => module.source_definition().cloned(),
-            Symbol::Module(module) => module.source_definition(),
+            Symbol::Type(type_symbol) => type_symbol.source_definition().cloned(),
-            Symbol::Type(type_symbol) => type_symbol.source_definition(),
+            Symbol::ConcreteType(concrete_type_symbol) => concrete_type_symbol.borrow().source_definition().cloned(),
-            Symbol::Function(function_symbol) => function_symbol.source_definition(),
+            Symbol::Function(function_symbol) => function_symbol.source_definition().cloned(),
-            Symbol::Parameter(parameter_symbol) => parameter_symbol.source_definition(),
+            Symbol::Parameter(parameter_symbol) => parameter_symbol.source_definition().cloned(),
-            Symbol::Variable(variable_symbol) => variable_symbol.source_definition(),
+            Symbol::Variable(variable_symbol) => variable_symbol.source_definition().cloned(),
-            Symbol::ClassMember(class_member_symbol) => class_member_symbol.source_definition(),
+            Symbol::ClassMember(class_member_symbol) => {
+                class_member_symbol.source_definition().cloned()
+            }
         }
     }
 }

src/name_analysis/symbol/usable_symbol.rs

@@ -0,0 +1,10 @@
+use crate::name_analysis::symbol::function_symbol::FunctionSymbol;
+use crate::name_analysis::symbol::type_symbol::{ConcreteTypeSymbol, TypeSymbol};
+use std::cell::RefCell;
+use std::rc::Rc;
+
+#[derive(Clone, Debug)]
+pub enum ConcreteUsableSymbol {
+    Type(Rc<RefCell<ConcreteTypeSymbol>>),
+    Function(Rc<RefCell<FunctionSymbol>>),
+}

src/name_analysis/symbol/use_symbol.rs

@@ -1,11 +1,30 @@
 use crate::name_analysis::symbol::source_definition::SourceDefinition;
+use crate::name_analysis::symbol::usable_symbol::ConcreteUsableSymbol;
+use std::cell::RefCell;
 use std::fmt::{Debug, Formatter};
+use std::rc::Rc;
+
+#[derive(Debug, Clone)]
+pub enum UseSymbol {
+    Concrete(Rc<RefCell<ConcreteUseSymbol>>),
+    Star(StarUseSymbol),
+}
+
+impl UseSymbol {
+    pub fn source_definition(&self) -> Option<SourceDefinition> {
+        match self {
+            UseSymbol::Concrete(concrete) => concrete.borrow().source_definition().cloned(),
+            UseSymbol::Star(star) => star.source_definition().cloned(),
+        }
+    }
+}
 
 #[derive(Clone)]
 pub struct ConcreteUseSymbol {
     base_fqn: String,
     declared_name: String,
     source_definition: Option<SourceDefinition>,
+    resolved_symbol: Option<ConcreteUsableSymbol>,
 }
 
 impl ConcreteUseSymbol {
@@ -18,6 +37,7 @@ impl ConcreteUseSymbol {
             base_fqn: base_fqn.to_string(),
             declared_name: declared_name.to_string(),
             source_definition,
+            resolved_symbol: None,
         }
     }
 
@@ -32,6 +52,14 @@ impl ConcreteUseSymbol {
     pub fn source_definition(&self) -> Option<&SourceDefinition> {
         self.source_definition.as_ref()
     }
+
+    pub fn resolved_symbol(&self) -> Option<&ConcreteUsableSymbol> {
+        self.resolved_symbol.as_ref()
+    }
+
+    pub fn set_resolved_symbol(&mut self, symbol: ConcreteUsableSymbol) {
+        self.resolved_symbol = Some(symbol);
+    }
 }
 
 impl Debug for ConcreteUseSymbol {

src/name_analysis/symbol_table/mod.rs

@@ -2,15 +2,19 @@ use crate::name_analysis::symbol::class_member_symbol::ClassMemberSymbol;
 use crate::name_analysis::symbol::function_symbol::FunctionSymbol;
 use crate::name_analysis::symbol::module_symbol::ModuleSymbol;
 use crate::name_analysis::symbol::parameter_symbol::ParameterSymbol;
-use crate::name_analysis::symbol::type_symbol::TypeSymbol;
+use crate::name_analysis::symbol::type_symbol::ConcreteTypeSymbol;
-use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol};
+use crate::name_analysis::symbol::usable_symbol::ConcreteUsableSymbol;
+use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol, UseSymbol};
 use crate::name_analysis::symbol::variable_symbol::VariableSymbol;
 use crate::name_analysis::symbol::*;
 use crate::name_analysis::symbol_table::SymbolInsertError::SymbolAlreadyDefined;
 use crate::name_analysis::symbol_table::SymbolLookupError::NoDefinition;
 use scope::Scope;
+use std::cell::RefCell;
+use std::collections::VecDeque;
 use std::fmt::Display;
 use std::ops::Deref;
+use std::rc::Rc;
 
 mod scope;
 
@@ -44,13 +48,14 @@ impl SymbolTable {
     }
 
     pub fn push_scope(&mut self, debug_name: &str) {
-        let id = self.scopes.len();
+        let id_to_push = self.scopes.len();
         self.scopes.push(Scope::new(
             Some(self.current_scope_id),
-            id,
+            id_to_push,
             debug_name.to_string(),
         ));
-        self.current_scope_id = id;
+        self.current_scope_mut().add_child(id_to_push);
+        self.current_scope_id = id_to_push;
     }
 
     pub fn pop_scope(&mut self) {
@@ -70,20 +75,17 @@ impl SymbolTable {
     fn find_current_scope_concrete_use_symbol(
         &self,
         declared_name: &str,
-    ) -> Option<&ConcreteUseSymbol> {
+    ) -> Option<Rc<RefCell<ConcreteUseSymbol>>> {
         self.current_scope()
             .concrete_use_symbols()
             .get(declared_name)
+            .cloned()
     }
 
     fn find_current_scope_star_use_symbol(&self, base_fqn: &str) -> Option<&StarUseSymbol> {
         self.current_scope().star_use_symbols().get(base_fqn)
     }
 
-    fn find_current_scope_type_symbol(&self, declared_name: &str) -> Option<&TypeSymbol> {
-        self.current_scope().type_symbols().get(declared_name)
-    }
-
     fn find_current_scope_module_symbol(&self, declared_name: &str) -> Option<&ModuleSymbol> {
         self.current_scope().module_symbols().get(declared_name)
     }
@@ -119,11 +121,13 @@ impl SymbolTable {
 
     fn find_current_scope_usable_symbol(&self, declared_name: &str) -> Option<Symbol> {
         self.find_current_scope_concrete_use_symbol(declared_name)
-            .map(|concrete_use_symbol| Symbol::ConcreteUse(concrete_use_symbol.clone()))
+            .map(|concrete_use_symbol| {
-            .or_else(|| {
+                Symbol::Use(UseSymbol::Concrete(concrete_use_symbol.clone()))
-                self.find_current_scope_type_symbol(declared_name)
-                    .map(|type_symbol| Symbol::Type(type_symbol.clone()))
             })
+            // .or_else(|| {
+            //     self.find_current_scope_type_symbol(declared_name)
+            //         .map(|type_symbol| Symbol::Type(type_symbol.clone()))
+            // })
             .or_else(|| {
                 self.find_current_scope_module_symbol(declared_name)
                     .map(|module_symbol| Symbol::Module(module_symbol.clone()))
@@ -133,17 +137,22 @@ impl SymbolTable {
     pub fn insert_concrete_use_symbol(
         &mut self,
         concrete_use_symbol: ConcreteUseSymbol,
-    ) -> Result<(), SymbolInsertError> {
+    ) -> Result<Rc<RefCell<ConcreteUseSymbol>>, SymbolInsertError> {
         if let Some(defined_symbol) =
             self.find_current_scope_usable_symbol(concrete_use_symbol.declared_name())
         {
             Err(SymbolAlreadyDefined(defined_symbol))
         } else {
-            self.current_scope_mut().concrete_use_symbols_mut().insert(
+            let name = concrete_use_symbol.declared_name().to_string();
-                concrete_use_symbol.declared_name().to_string(),
+            self.current_scope_mut()
-                concrete_use_symbol,
+                .concrete_use_symbols_mut()
-            );
+                .insert(name.clone(), Rc::new(RefCell::new(concrete_use_symbol)));
-            Ok(())
+            Ok(self
+                .current_scope()
+                .concrete_use_symbols()
+                .get(&name)
+                .cloned()
+                .unwrap())
         }
     }
 
@@ -154,9 +163,9 @@ impl SymbolTable {
         if let Some(defined_symbol) =
             self.find_current_scope_star_use_symbol(star_use_symbol.base_fqn())
         {
-            Err(SymbolAlreadyDefined(Symbol::StarUse(
+            Err(SymbolAlreadyDefined(Symbol::Use(UseSymbol::Star(
                 defined_symbol.clone(),
-            )))
+            ))))
         } else {
             self.current_scope_mut()
                 .star_use_symbols_mut()
@@ -181,15 +190,23 @@ impl SymbolTable {
         }
     }
 
-    pub fn insert_type_symbol(&mut self, type_symbol: TypeSymbol) -> Result<(), SymbolInsertError> {
+    fn find_current_scope_concrete_type_symbol(
-        if let Some(defined_symbol) =
+        &self,
-            self.find_current_scope_usable_symbol(type_symbol.declared_name())
+        declared_name: &str,
+    ) -> Option<Rc<RefCell<ConcreteTypeSymbol>>> {
+        self.current_scope().get_concrete_type_symbol(declared_name)
+    }
+
+    pub fn insert_concrete_type_symbol(
+        &mut self,
+        symbol: ConcreteTypeSymbol,
+    ) -> Result<(), SymbolInsertError> {
+        if let Some(defined_type) =
+            self.find_current_scope_concrete_type_symbol(symbol.declared_name())
         {
-            Err(SymbolAlreadyDefined(defined_symbol))
+            Err(SymbolAlreadyDefined(Symbol::ConcreteType(defined_type)))
         } else {
-            self.current_scope_mut()
+            self.current_scope_mut().insert_concrete_type_symbol(symbol);
-                .type_symbols_mut()
-                .insert(type_symbol.declared_name().to_string(), type_symbol);
             Ok(())
         }
     }
@@ -264,66 +281,6 @@ impl SymbolTable {
         }
     }
 
-    fn lookup_type_in_scope_by_declared_name<'a>(
-        scope: &'a Scope,
-        declared_name: &str,
-    ) -> Option<&'a TypeSymbol> {
-        scope.type_symbols().get(declared_name)
-    }
-
-    pub fn lookup_type_by_declared_name(
-        &self,
-        declared_name: &str,
-        scope_id: usize,
-    ) -> Result<&TypeSymbol, SymbolLookupError> {
-        let mut scope_opt = Some(&self.scopes[scope_id]);
-        while let Some(scope) = scope_opt {
-            if let Some(symbol) = Self::lookup_type_in_scope_by_declared_name(scope, declared_name)
-            {
-                return Ok(symbol);
-            }
-            scope_opt = if let Some(parent_id) = scope.parent() {
-                Some(&self.scopes[parent_id])
-            } else {
-                None
-            }
-        }
-        Err(NoDefinition)
-    }
-
-    fn lookup_type_in_scope_by_fqn<'a>(scope: &'a Scope, fqn: &str) -> Option<&'a TypeSymbol> {
-        for type_symbol in scope.type_symbols().values() {
-            match type_symbol {
-                TypeSymbol::Concrete(concrete_type_symbol) => {
-                    if concrete_type_symbol.fqn() == fqn {
-                        return Some(type_symbol);
-                    }
-                }
-                TypeSymbol::Generic(_) => {}
-            }
-        }
-        None
-    }
-
-    pub fn lookup_type_by_fqn(
-        &self,
-        fqn: &str,
-        scope_id: usize,
-    ) -> Result<&TypeSymbol, SymbolLookupError> {
-        let mut scope_opt = Some(&self.scopes[scope_id]);
-        while let Some(scope) = scope_opt {
-            if let Some(type_symbol) = Self::lookup_type_in_scope_by_fqn(scope, fqn) {
-                return Ok(type_symbol);
-            }
-            scope_opt = if let Some(parent_id) = scope.parent() {
-                Some(&self.scopes[parent_id])
-            } else {
-                None
-            };
-        }
-        Err(NoDefinition)
-    }
-
     fn lookup_addressable_in_scope_by_identifier(
         scope: &Scope,
         identifier: &str,
@@ -350,12 +307,12 @@ impl SymbolTable {
                     .get(identifier)
                     .map(|function_symbol| Symbol::Function(function_symbol.clone()))
             })
-            .or_else(|| {
+        // .or_else(|| {
-                scope
+        //     scope
-                    .type_symbols()
+        //         .type_symbols()
-                    .get(identifier)
+        //         .get(identifier)
-                    .map(|type_symbol| Symbol::Type(type_symbol.clone()))
+        //         .map(|type_symbol| Symbol::Type(type_symbol.clone()))
-            })
+        // })
     }
 
     pub fn lookup_addressable_by_identifier(
@@ -378,17 +335,36 @@ impl SymbolTable {
         Err(NoDefinition)
     }
 
-    pub fn resolve_usable_by_fqn(
+    pub fn resolve_concrete_usable_by_fqn(
         &self,
-        fqn: &str
+        fqn: &str,
-    ) -> Result<Symbol, SymbolLookupError> {
+    ) -> Result<ConcreteUsableSymbol, SymbolLookupError> {
-        todo!()
+        // breadth-first search, use a queue
+        let mut search_stack: VecDeque<usize> = VecDeque::new();
+        search_stack.push_back(0); // global scope
+
+        while let Some(scope_id) = search_stack.pop_front() {
+            let scope = &self.scopes[scope_id];
+            for child_id in scope.children() {
+                search_stack.push_back(child_id);
             }
 
-    pub fn resolve_usable_star(
+            if let Some(concrete_type_symbol) = scope.get_concrete_type_symbol_by_fqn(fqn) {
-        &self,
+                return Ok(ConcreteUsableSymbol::Type(concrete_type_symbol));
-        base_fqn: &str,
+            }
-    ) -> Result<(), SymbolLookupError> {
+
+            // TODO: this is inefficient. Use a (cached) hash table of Fqn => Rc<RefCell<symbol>>
+            for function_symbol in scope.function_symbols().values() {
+                if function_symbol.fqn() == fqn {
+                    return Ok(ConcreteUsableSymbol::Function(todo!()));
+                }
+            }
+        }
+
+        Err(NoDefinition)
+    }
+
+    pub fn resolve_usable_star(&self, base_fqn: &str) -> Result<(), SymbolLookupError> {
         todo!()
     }
 }

src/name_analysis/symbol_table/scope.rs

@@ -2,20 +2,24 @@ use crate::name_analysis::symbol::class_member_symbol::ClassMemberSymbol;
 use crate::name_analysis::symbol::function_symbol::FunctionSymbol;
 use crate::name_analysis::symbol::module_symbol::ModuleSymbol;
 use crate::name_analysis::symbol::parameter_symbol::ParameterSymbol;
-use crate::name_analysis::symbol::type_symbol::TypeSymbol;
+use crate::name_analysis::symbol::type_symbol::{ConcreteTypeSymbol, TypeSymbol};
 use crate::name_analysis::symbol::use_symbol::{ConcreteUseSymbol, StarUseSymbol};
 use crate::name_analysis::symbol::variable_symbol::VariableSymbol;
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt::{Display, Formatter};
+use std::rc::Rc;
 
 #[derive(Debug)]
 pub struct Scope {
     parent: Option<usize>,
     id: usize,
-    concrete_use_symbols: HashMap<String, ConcreteUseSymbol>,
+    children: Vec<usize>,
+    concrete_use_symbols: HashMap<String, Rc<RefCell<ConcreteUseSymbol>>>,
     star_use_symbols: HashMap<String, StarUseSymbol>,
     module_symbols: HashMap<String, ModuleSymbol>,
-    type_symbols: HashMap<String, TypeSymbol>,
+    concrete_type_symbols: HashMap<String, Rc<RefCell<ConcreteTypeSymbol>>>,
+    concrete_type_symbols_by_fqn: HashMap<String, Rc<RefCell<ConcreteTypeSymbol>>>,
     function_symbols: HashMap<String, FunctionSymbol>,
     parameter_symbols: HashMap<String, ParameterSymbol>,
     variable_symbols: HashMap<String, VariableSymbol>,
@@ -28,10 +32,12 @@ impl Scope {
         Self {
             parent,
             id,
+            children: vec![],
             concrete_use_symbols: HashMap::new(),
             star_use_symbols: HashMap::new(),
             module_symbols: HashMap::new(),
-            type_symbols: HashMap::new(),
+            concrete_type_symbols: HashMap::new(),
+            concrete_type_symbols_by_fqn: HashMap::new(),
             function_symbols: HashMap::new(),
             parameter_symbols: HashMap::new(),
             variable_symbols: HashMap::new(),
@@ -48,11 +54,21 @@ impl Scope {
         self.id
     }
 
-    pub fn concrete_use_symbols(&self) -> &HashMap<String, ConcreteUseSymbol> {
+    pub fn add_child(&mut self, child_id: usize) {
+        self.children.push(child_id);
+    }
+
+    pub fn children(&self) -> Vec<usize> {
+        self.children.clone()
+    }
+
+    pub fn concrete_use_symbols(&self) -> &HashMap<String, Rc<RefCell<ConcreteUseSymbol>>> {
         &self.concrete_use_symbols
     }
 
-    pub fn concrete_use_symbols_mut(&mut self) -> &mut HashMap<String, ConcreteUseSymbol> {
+    pub fn concrete_use_symbols_mut(
+        &mut self,
+    ) -> &mut HashMap<String, Rc<RefCell<ConcreteUseSymbol>>> {
         &mut self.concrete_use_symbols
     }
 
@@ -72,12 +88,24 @@ impl Scope {
         &mut self.module_symbols
     }
 
-    pub fn type_symbols(&self) -> &HashMap<String, TypeSymbol> {
+    pub fn insert_concrete_type_symbol(&mut self, symbol: ConcreteTypeSymbol) {
-        &self.type_symbols
+        let as_rc = Rc::new(RefCell::new(symbol));
+        self.concrete_type_symbols.insert(
+            as_rc.borrow().declared_name().to_string(),
+            as_rc.clone(),
+        );
+        self.concrete_type_symbols_by_fqn.insert(
+            as_rc.borrow().fqn().to_string(),
+            as_rc.clone(),
+        );
     }
     
-    pub fn type_symbols_mut(&mut self) -> &mut HashMap<String, TypeSymbol> {
+    pub fn get_concrete_type_symbol(&self, declared_name: &str) -> Option<Rc<RefCell<ConcreteTypeSymbol>>> {
-        &mut self.type_symbols
+        self.concrete_type_symbols.get(declared_name).cloned()
+    }
+    
+    pub fn get_concrete_type_symbol_by_fqn(&self, fqn: &str) -> Option<Rc<RefCell<ConcreteTypeSymbol>>> {
+        self.concrete_type_symbols_by_fqn.get(fqn).cloned()
     }
 
     pub fn function_symbols(&self) -> &HashMap<String, FunctionSymbol> {
@@ -131,13 +159,15 @@ impl Display for Scope {
             f,
             "----Scope {} (p: {}) {}----",
             self.id(),
-            self.parent().map(|parent_id| format!("{}", parent_id)).unwrap_or_else(|| "None".to_string()),
+            self.parent()
+                .map(|parent_id| format!("{}", parent_id))
+                .unwrap_or_else(|| "None".to_string()),
             self.debug_name()
         )?;
         write_symbols!(f, self.concrete_use_symbols());
         write_symbols!(f, self.star_use_symbols());
         write_symbols!(f, self.module_symbols());
-        write_symbols!(f, self.type_symbols());
+        todo!("self.concrete_type_symbols");
         write_symbols!(f, self.function_symbols());
         write_symbols!(f, self.parameter_symbols());
         write_symbols!(f, self.variable_symbols());

src/parser/ast.yaml

@@ -248,6 +248,10 @@ UseStatement:
       - range:
           special:
             kind: range
+    fields:
+      - use_symbol:
+          kind: UseSymbol
+          wrap: rc_ref_cell
 UseStatementPrefix:
   struct:
     children: