schala-lang/language/src/ast/mod.rs

@@ -11,8 +11,7 @@ pub use visitor::ASTVisitor;
 pub use walker::walk_ast;
 use crate::tokenizing::Location;
 
-/// An abstract identifier for an AST node. Note that
+/// An abstract identifier for an AST node
-/// the u32 index limits the size of an AST to 2^32 nodes.
 #[derive(Debug, PartialEq, Eq, Hash, Clone, Default)]
 pub struct ItemId {
   idx: u32,
@@ -32,7 +31,13 @@ impl ItemIdStore {
   pub fn new() -> ItemIdStore {
     ItemIdStore { last_idx: 0 }
   }
+  /// Always returns an ItemId with internal value zero
+  #[cfg(test)]
+  pub fn new_id() -> ItemId {
+    ItemId { idx: 0 }
+  }
 
+  /// This limits the size of the AST to 2^32 tree elements
   pub fn fresh(&mut self) -> ItemId {
     let idx = self.last_idx;
     self.last_idx += 1;

schala-lang/language/src/eval/mod.rs

@@ -2,8 +2,10 @@ use std::rc::Rc;
 use std::fmt::Write;
 use std::io;
 
+//use crate::schala::SymbolTableHandle;
 use crate::util::ScopeStack;
 use crate::reduced_ast::{BoundVars, ReducedAST, Stmt, Expr, Lit, Func, Alternative, Subpattern};
+//use crate::symbol_table::{SymbolSpec, Symbol, SymbolTable, FullyQualifiedSymbolName};
 use crate::builtin::Builtin;
 
 mod test;

schala-lang/language/src/eval/test.rs

@@ -1,17 +1,23 @@
 #![cfg(test)]
 
+use std::cell::RefCell;
+use std::rc::Rc;
+
 use crate::symbol_table::SymbolTable;
+use crate::scope_resolution::ScopeResolver;
 use crate::reduced_ast::reduce;
 use crate::eval::State;
 
 fn evaluate_all_outputs(input: &str) -> Vec<Result<String, String>> {
-  let ast = crate::util::quick_ast(input);
+  let mut ast = crate::util::quick_ast(input);
-
+  let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
-  let mut symbol_table = SymbolTable::new();
+  symbol_table.borrow_mut().add_top_level_symbols(&ast).unwrap();
-  symbol_table.process_ast(&ast).unwrap();
+  {
-
+  let mut scope_resolver = ScopeResolver::new(symbol_table.clone());
-  let reduced = reduce(&ast, &symbol_table);
+  let _ = scope_resolver.resolve(&mut ast);
+  }
 
+  let reduced = reduce(&ast, &symbol_table.borrow());
   let mut state = State::new();
   let all_output = state.evaluate(reduced, true);
   all_output

schala-lang/language/src/lib.rs

@@ -25,6 +25,7 @@ mod builtin;
 mod error;
 mod eval;
 mod reduced_ast;
+mod scope_resolution;
 
 mod schala;
 

schala-lang/language/src/parsing/test.rs

@@ -45,7 +45,7 @@ macro_rules! parse_test {
   };
 }
 macro_rules! parse_test_wrap_ast {
-  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: Default::default(), statements: vec![$correct] }) }
+  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: ItemIdStore::new_id(), statements: vec![$correct] }) }
 }
 macro_rules! parse_error {
   ($string:expr) => { assert!(parse($string).is_err()) }
@@ -57,12 +57,12 @@ macro_rules! qname {
     $(
       components.push(rc!($component));
     )*
-    QualifiedName { components, id: Default::default() }
+    QualifiedName { components, id: ItemIdStore::new_id() }
     }
   };
 }
 macro_rules! val {
-  ($var:expr) => { Value(QualifiedName { components: vec![Rc::new($var.to_string())], id: Default::default() }) };
+  ($var:expr) => { Value(QualifiedName { components: vec![Rc::new($var.to_string())], id: ItemIdStore::new_id() }) };
 }
 macro_rules! ty {
   ($name:expr) => { Singleton(tys!($name)) }
@@ -90,8 +90,8 @@ macro_rules! module {
 }
 
 macro_rules! ex {
-  ($expr_type:expr) => { Expression::new(Default::default(), $expr_type) };
+  ($expr_type:expr) => { Expression::new(ItemIdStore::new_id(), $expr_type) };
-  ($expr_type:expr, $type_anno:expr) => { Expression::with_anno(Default::default(), $expr_type, $type_anno) };
+  ($expr_type:expr, $type_anno:expr) => { Expression::with_anno(ItemIdStore::new_id(), $expr_type, $type_anno) };
   (s $expr_text:expr) => {
     {
       let mut parser = make_parser($expr_text);
@@ -105,14 +105,14 @@ macro_rules! inv {
 }
 
 macro_rules! binexp {
-  ($op:expr, $lhs:expr, $rhs:expr) => { BinExp(BinOp::from_sigil($op), bx!(Expression::new(Default::default(), $lhs).into()), bx!(Expression::new(Default::default(), $rhs).into())) }
+  ($op:expr, $lhs:expr, $rhs:expr) => { BinExp(BinOp::from_sigil($op), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into()), bx!(Expression::new(ItemIdStore::new_id(), $rhs).into())) }
 }
 macro_rules! prefexp {
-  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_sigil($op), bx!(Expression::new(Default::default(), $lhs).into())) }
+  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_sigil($op), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into())) }
 }
 macro_rules! exst {
-  ($expr_type:expr) => { make_statement(StatementKind::Expression(Expression::new(Default::default(), $expr_type).into())) };
+  ($expr_type:expr) => { make_statement(StatementKind::Expression(Expression::new(ItemIdStore::new_id(), $expr_type).into())) };
-  ($expr_type:expr, $type_anno:expr) => { make_statement(StatementKind::Expression(Expression::with_anno(Default::default(), $expr_type, $type_anno).into())) };
+  ($expr_type:expr, $type_anno:expr) => { make_statement(StatementKind::Expression(Expression::with_anno(ItemIdStore::new_id(), $expr_type, $type_anno).into())) };
   ($op:expr, $lhs:expr, $rhs:expr) => { make_statement(StatementKind::Expression(ex!(binexp!($op, $lhs, $rhs)))) };
   (s $statement_text:expr) => {
     {
@@ -137,7 +137,7 @@ fn parsing_number_literals_and_binexps() {
 
   parse_test! {"3; 4; 4.3",
     AST {
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       statements: vec![exst!(NatLiteral(3)), exst!(NatLiteral(4)),
       exst!(FloatLiteral(4.3))]
     }
@@ -217,7 +217,7 @@ fn qualified_identifiers() {
   parse_test_wrap_ast! {
     "let q_q = Yolo::Swaggins",
     decl!(Binding { name: rc!(q_q), constant: true, type_anno: None,
-    expr: Expression::new(Default::default(), Value(qname!(Yolo, Swaggins))),
+    expr: Expression::new(ItemIdStore::new_id(), Value(qname!(Yolo, Swaggins))),
     })
   }
 
@@ -583,7 +583,7 @@ fn more_advanced_lambdas() {
     r#"fn wahoo() { let a = 10; \(x) { x + a } };
     wahoo()(3) "#,
     AST {
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       statements: vec![
         exst!(s r"fn wahoo() { let a = 10; \(x) { x + a } }"),
         exst! {
@@ -746,7 +746,7 @@ fn imports() {
   parse_test_wrap_ast! {
     "import harbinger::draughts::Norgleheim",
     import!(ImportSpecifier { 
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       path_components: vec![rc!(harbinger), rc!(draughts), rc!(Norgleheim)],
       imported_names: ImportedNames::LastOfPath
     })
@@ -758,7 +758,7 @@ fn imports_2() {
   parse_test_wrap_ast! {
     "import harbinger::draughts::{Norgleheim, Xraksenlaigar}",
     import!(ImportSpecifier { 
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       path_components: vec![rc!(harbinger), rc!(draughts)],
       imported_names: ImportedNames::List(vec![
         rc!(Norgleheim),
@@ -773,7 +773,7 @@ fn imports_3() {
   parse_test_wrap_ast! {
     "import bespouri::{}",
     import!(ImportSpecifier { 
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       path_components: vec![rc!(bespouri)],
       imported_names: ImportedNames::List(vec![])
     })
@@ -786,7 +786,7 @@ fn imports_4() {
   parse_test_wrap_ast! {
     "import bespouri::*",
     import!(ImportSpecifier {
-      id: Default::default(),
+      id: ItemIdStore::new_id(),
       path_components: vec![rc!(bespouri)],
       imported_names: ImportedNames::All
     })

schala-lang/language/src/reduced_ast.rs

@@ -17,7 +17,7 @@ use std::str::FromStr;
 use std::convert::TryFrom;
 
 use crate::ast::*;
-use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable};
+use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable, FullyQualifiedSymbolName};
 use crate::builtin::Builtin;
 use crate::util::deref_optional_box;
 
@@ -129,12 +129,12 @@ impl<'a> Reducer<'a> {
 
   fn statement(&mut self, stmt: &Statement) -> Stmt {
     match &stmt.kind {
-      StatementKind::Expression(expr) => Stmt::Expr(self.expression(expr)),
+      StatementKind::Expression(expr) => Stmt::Expr(self.expression(&expr)),
-      StatementKind::Declaration(decl) => self.declaration(decl),
+      StatementKind::Declaration(decl) => self.declaration(&decl),
       StatementKind::Import(_) => Stmt::Noop,
       StatementKind::Module(modspec) => {
         for statement in modspec.contents.iter() {
-          self.statement(statement);
+          self.statement(&statement);
         }
         Stmt::Noop
       }
@@ -156,7 +156,7 @@ impl<'a> Reducer<'a> {
 
   fn expression(&mut self, expr: &Expression) -> Expr {
     use crate::ast::ExpressionKind::*;
-    let input = &expr.kind;
+    let ref input = expr.kind;
     match input {
       NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
       FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
@@ -178,26 +178,34 @@ impl<'a> Reducer<'a> {
   }
 
   fn value(&mut self, qualified_name: &QualifiedName) -> Expr {
-    let Symbol { local_name, spec, .. } = match self.symbol_table.lookup_symbol(&qualified_name.id) {
+    let symbol_table = self.symbol_table;
+    let ref id = qualified_name.id;
+    let ref sym_name = match symbol_table.get_fqsn_from_id(id) {
+      Some(fqsn) => fqsn,
+      None => return Expr::ReductionError(format!("FQSN lookup for Value {:?} failed", qualified_name)),
+    };
+
+    //TODO this probably needs to change
+    let FullyQualifiedSymbolName(ref v) = sym_name;
+    let name = v.last().unwrap().name.clone();
+
+    let Symbol { local_name, spec, .. } = match symbol_table.lookup_by_fqsn(&sym_name) {
       Some(s) => s,
-      //TODO this causes several evaluation tests to fail, figure out what's going on here
       //None => return Expr::ReductionError(format!("Symbol {:?} not found", sym_name)),
-      None => {
+      None => return Expr::Sym(name.clone())
-        let name = qualified_name.components.last().unwrap().clone();
-        return Expr::Sym(name)
-      }
     };
 
     match spec {
       SymbolSpec::RecordConstructor { .. } => Expr::ReductionError(format!("AST reducer doesn't expect a RecordConstructor here")),
       SymbolSpec::DataConstructor { index, type_args, type_name } => Expr::Constructor {
         type_name: type_name.clone(),
-        name: local_name.clone(),
+        name: name.clone(),
         tag: index.clone(),
         arity: type_args.len(),
       },
       SymbolSpec::Func(_) => Expr::Sym(local_name.clone()),
       SymbolSpec::Binding => Expr::Sym(local_name.clone()), //TODO not sure if this is right, probably needs to eventually be fqsn
+      SymbolSpec::Type { .. } => Expr::ReductionError("AST reducer doesnt expect a type here".to_string())
     }
   }
 
@@ -210,16 +218,18 @@ impl<'a> Reducer<'a> {
   }
 
   fn reduce_named_struct(&mut self, name: &QualifiedName, fields: &Vec<(Rc<String>, Expression)>) -> Expr {
-    let symbol = match self.symbol_table.lookup_symbol(&name.id) {
+    let symbol_table = self.symbol_table;
+    let ref sym_name = match symbol_table.get_fqsn_from_id(&name.id) {
       Some(fqsn) => fqsn,
       None => return Expr::ReductionError(format!("FQSN lookup for name {:?} failed", name)),
     };
 
-    let (type_name, index, members_from_table) = match &symbol.spec {
+    let FullyQualifiedSymbolName(ref v) = sym_name;
-      SymbolSpec::RecordConstructor { members, type_name, index } => (type_name.clone(), index, members),
+    let ref name = v.last().unwrap().name;
+    let (type_name, index, members_from_table) = match symbol_table.lookup_by_fqsn(&sym_name) {
+      Some(Symbol { spec: SymbolSpec::RecordConstructor { members, type_name, index },  .. }) => (type_name.clone(), index, members),
       _ => return Expr::ReductionError("Not a record constructor".to_string()),
     };
-
     let arity = members_from_table.len();
 
     let mut args: Vec<(Rc<String>, Expr)> = fields.iter()
@@ -232,7 +242,7 @@ impl<'a> Reducer<'a> {
     let args = args.into_iter().map(|(_, expr)| expr).collect();
 
     //TODO make sure this sorting actually works
-    let f = box Expr::Constructor { type_name, name: symbol.local_name.clone(), tag: *index, arity, };
+    let f = box Expr::Constructor { type_name, name: name.clone(), tag: *index, arity, };
     Expr::Call { f, args }
   }
 
@@ -244,6 +254,7 @@ impl<'a> Reducer<'a> {
   }
 
   fn reduce_if_expression(&mut self, discriminator: Option<&Expression>, body: &IfExpressionBody) -> Expr {
+    let symbol_table = self.symbol_table;
     let cond = Box::new(match discriminator {
       Some(expr) => self.expression(expr),
       None => return Expr::ReductionError(format!("blank cond if-expr not supported")),
@@ -266,7 +277,7 @@ impl<'a> Reducer<'a> {
         };
 
         let alternatives = vec![
-          pattern.to_alternative(then_clause, self.symbol_table),
+          pattern.to_alternative(then_clause, symbol_table),
           Alternative {
             matchable: Subpattern {
               tag: None,
@@ -292,7 +303,7 @@ impl<'a> Reducer<'a> {
             },
             Condition::Pattern(ref p) =>  {
               let item = self.block(&arm.body);
-              let alt = p.to_alternative(item, self.symbol_table);
+              let alt = p.to_alternative(item, symbol_table);
               alternatives.push(alt);
             },
             Condition::TruncatedOp(_, _) => {
@@ -308,7 +319,7 @@ impl<'a> Reducer<'a> {
     }
   }
 
-  fn binop(&mut self, binop: &BinOp, lhs: &Expression, rhs: &Expression) -> Expr {
+  fn binop(&mut self, binop: &BinOp, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
     let operation = Builtin::from_str(binop.sigil()).ok();
     match operation {
       Some(Builtin::Assignment) => Expr::Assign {
@@ -326,7 +337,7 @@ impl<'a> Reducer<'a> {
     }
   }
 
-  fn prefix(&mut self, prefix: &PrefixOp, arg: &Expression) -> Expr {
+  fn prefix(&mut self, prefix: &PrefixOp, arg: &Box<Expression>) -> Expr {
     let builtin: Option<Builtin> = TryFrom::try_from(prefix).ok();
     match builtin {
       Some(op) => {
@@ -348,7 +359,7 @@ impl<'a> Reducer<'a> {
         func: Func::UserDefined {
           name: Some(name.clone()),
           params: params.iter().map(|param| param.name.clone()).collect(),
-          body: self.block(statements),
+          body: self.block(&statements),
         }
       },
       TypeDecl { .. } => Stmt::Noop,
@@ -371,12 +382,13 @@ impl<'a> Reducer<'a> {
 fn handle_symbol(symbol: Option<&Symbol>, inner_patterns: &Vec<Pattern>, symbol_table: &SymbolTable) -> Subpattern {
   use self::Pattern::*;
   let tag = symbol.map(|symbol| match symbol.spec {
-    SymbolSpec::DataConstructor { index, .. } => index,
+    SymbolSpec::DataConstructor { index, .. } => index.clone(),
     _ => panic!("Symbol is not a data constructor - this should've been caught in type-checking"),
   });
   let bound_vars = inner_patterns.iter().map(|p| match p {
     VarOrName(qualified_name) => {
-      let symbol_exists = symbol_table.lookup_symbol(&qualified_name.id).is_some();
+      let fqsn = symbol_table.get_fqsn_from_id(&qualified_name.id);
+      let symbol_exists = fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)).is_some();
       if symbol_exists {
         None
       } else {
@@ -436,9 +448,12 @@ impl Pattern {
     use self::Pattern::*;
     match self {
       TupleStruct(QualifiedName{ components, id }, inner_patterns) => {
-        match symbol_table.lookup_symbol(id) {
+        let fqsn = symbol_table.get_fqsn_from_id(&id);
+        match fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)) {
           Some(symbol) => handle_symbol(Some(symbol), inner_patterns, symbol_table),
-          None => panic!("Symbol {:?} not found", components)
+          None => {
+            panic!("Symbol {:?} not found", components);
+          }
         }
       },
       TuplePattern(inner_patterns) => handle_symbol(None, inner_patterns, symbol_table),
@@ -448,12 +463,12 @@ impl Pattern {
       Ignored => Subpattern { tag: None, subpatterns: vec![], guard: None, bound_vars: vec![] },
       Literal(lit) => lit.to_subpattern(symbol_table),
       VarOrName(QualifiedName { components, id  }) => {
-        // if symbol is Some, treat this as a symbol pattern. If it's None, treat it
+        // if fqsn is Some, treat this as a symbol pattern. If it's None, treat it
         // as a variable.
-        match symbol_table.lookup_symbol(id) {
+        let fqsn = symbol_table.get_fqsn_from_id(&id);
+        match fqsn.and_then(|fqsn| symbol_table.lookup_by_fqsn(&fqsn)) {
           Some(symbol) => handle_symbol(Some(symbol), &vec![], symbol_table),
           None => {
-            println!("Components: {:?}", components);
             let name = if components.len() == 1 {
               components[0].clone()
             } else {
@@ -463,7 +478,7 @@ impl Pattern {
               tag: None,
               subpatterns: vec![],
               guard: None,
-              bound_vars: vec![Some(name)],
+              bound_vars: vec![Some(name.clone())],
             }
           }
         }

schala-lang/language/src/schala.rs

@@ -20,6 +20,7 @@ pub struct Schala {
   state: eval::State<'static>,
   /// Keeps track of symbols and scopes
   symbol_table: SymbolTableHandle,
+  resolver: crate::scope_resolution::ScopeResolver<'static>,
   /// Contains information for type-checking
   type_context: typechecking::TypeContext<'static>,
   /// Schala Parser
@@ -44,6 +45,7 @@ impl Schala {
     Schala {
       source_reference: SourceReference::new(),
       symbol_table: symbols.clone(),
+      resolver: crate::scope_resolution::ScopeResolver::new(symbols.clone()),
       state: eval::State::new(),
       type_context: typechecking::TypeContext::new(),
       active_parser: parsing::Parser::new()
@@ -76,13 +78,17 @@ impl Schala {
 
     //2nd stage - parsing
     self.active_parser.add_new_tokens(tokens);
-    let ast = self.active_parser.parse()
+    let mut ast = self.active_parser.parse()
       .map_err(|err| SchalaError::from_parse_error(err, &self.source_reference))?;
 
-    //Perform all symbol table work
+    // Symbol table
-    self.symbol_table.borrow_mut().process_ast(&ast)
+    self.symbol_table.borrow_mut().add_top_level_symbols(&ast)
       .map_err(|err| SchalaError::from_string(err, Stage::Symbols))?;
 
+    // Scope resolution - requires mutating AST
+    self.resolver.resolve(&mut ast)
+      .map_err(|err| SchalaError::from_string(err, Stage::ScopeResolution))?;
+
     // Typechecking
     // TODO typechecking not working
     let _overall_type = self.type_context.typecheck(&ast)

schala-lang/language/src/symbol_table/mod.rs

@@ -4,83 +4,55 @@ use std::rc::Rc;
 use std::fmt;
 use std::fmt::Write;
 
-use crate::tokenizing::Location;
+use crate::tokenizing::LineNumber;
 use crate::ast;
-use crate::ast::{ItemId, TypeBody, Variant, TypeSingletonName, Declaration, Statement, StatementKind, ModuleSpecifier};
+use crate::ast::{ItemId, TypeBody, TypeSingletonName, Signature, Statement, StatementKind, ModuleSpecifier};
 use crate::typechecking::TypeName;
 
-mod resolver;
+
+#[allow(unused_macros)]
+macro_rules! fqsn {
+  ( $( $name:expr ; $kind:tt),* ) => {
+    {
+      let mut vec = vec![];
+      $(
+        vec.push(crate::symbol_table::ScopeSegment::new(std::rc::Rc::new($name.to_string())));
+      )*
+      FullyQualifiedSymbolName(vec)
+    }
+  };
+}
+
 mod tables;
+use tables::DeclLocations;
 mod symbol_trie;
 use symbol_trie::SymbolTrie;
 mod test;
 
-/// Fully-qualified symbol name
+/// Keeps track of what names were used in a given namespace. Call try_register to add a name to
-#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
+/// the table, or report an error if a name already exists.
-pub struct FQSN {
+struct DuplicateNameTrackTable {
-  //TODO FQSN's need to be cheaply cloneable
+  table: HashMap<Rc<String>, LineNumber>,
-  scopes: Vec<Scope>, //TODO rename to ScopeSegment
 }
 
-impl FQSN {
+impl DuplicateNameTrackTable {
-  fn from_scope_stack(scopes: &[Scope], new_name: String) -> Self {
+  fn new() -> DuplicateNameTrackTable {
-    let mut v = Vec::new();
+    DuplicateNameTrackTable { table: HashMap::new() }
-    for s in scopes {
-      v.push(s.clone());
-    }
-    v.push(Scope::Name(new_name));
-    FQSN { scopes: v }
-  }
-}
-
-//TODO eventually this should use ItemId's to avoid String-cloning
-/// One segment within a scope.
-#[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
-enum Scope {
-  Name(String)
-}
-
-#[allow(dead_code)]
-#[derive(Debug, Clone)]
-struct DuplicateName {
-  prev_name: FQSN,
-  location: Location
-}
-
-#[allow(dead_code)]
-#[derive(Debug)]
-struct NameSpec<K> {
-  location: Location,
-  kind: K
-}
-
-#[derive(Debug)]
-enum NameKind {
-  Module,
-  Function,
-  Binding,
-}
-
-#[derive(Debug)]
-struct TypeKind;
-
-/// Keeps track of what names were used in a given namespace.
-struct NameTable<K> {
-  table: HashMap<FQSN, NameSpec<K>>
-}
-
-impl<K> NameTable<K> {
-  fn new() -> Self {
-    Self { table: HashMap::new() }
   }
 
-  fn register(&mut self, name: FQSN, spec: NameSpec<K>) -> Result<(), DuplicateName> {
+  fn try_register(&mut self, name: &Rc<String>, id: &ItemId, decl_locations: &DeclLocations) -> Result<(), LineNumber> {
     match self.table.entry(name.clone()) {
       Entry::Occupied(o) => {
-        Err(DuplicateName { prev_name: name, location: o.get().location })
+        let line_number = o.get();
+        Err(*line_number)
       },
       Entry::Vacant(v) => {
-        v.insert(spec);
+        let line_number = if let Some(loc) = decl_locations.lookup(id) {
+          loc.line_num
+        } else {
+          0
+        };
+        v.insert(line_number);
         Ok(())
       }
     }
@@ -119,54 +91,48 @@ impl ScopeSegment {
   }
 }
 
+
 //cf. p. 150 or so of Language Implementation Patterns
 pub struct SymbolTable {
+  decl_locations: DeclLocations,
   symbol_path_to_symbol: HashMap<FullyQualifiedSymbolName, Symbol>,
-
+  id_to_fqsn: HashMap<ItemId, FullyQualifiedSymbolName>,
-
-  /// Used for import resolution.
   symbol_trie: SymbolTrie,
-
-  /// These tables are responsible for preventing duplicate names.
-  fq_names: NameTable<NameKind>, //Note that presence of two tables implies that a type and other binding with the same name can co-exist
-  types: NameTable<TypeKind>,
-
-  /// A map of the `ItemId`s of instances of use of names to their fully-canonicalized FQSN form.
-  /// Updated by the item id resolver.
-  id_to_fqsn: HashMap<ItemId, FQSN>,
-
-  /// A map of the FQSN of an AST definition to a Symbol data structure, which contains
-  /// some basic information about what that symbol is and (ideally) references to other tables
-  /// (e.g. typechecking tables) with more information about that symbol.
-  fqsn_to_symbol: HashMap<FQSN, Symbol>,
 }
 
 impl SymbolTable {
   pub fn new() -> SymbolTable {
     SymbolTable {
+      decl_locations: DeclLocations::new(),
       symbol_path_to_symbol: HashMap::new(),
-      symbol_trie: SymbolTrie::new(),
-
-      fq_names: NameTable::new(),
-      types: NameTable::new(),
       id_to_fqsn: HashMap::new(),
-      fqsn_to_symbol: HashMap::new(),
+      symbol_trie: SymbolTrie::new()
     }
   }
 
-  /// The main entry point into the symbol table. This will traverse the AST in several
+  pub fn map_id_to_fqsn(&mut self, id: &ItemId, fqsn: FullyQualifiedSymbolName) {
-  /// different ways and populate subtables with information that will be used further in the
+    self.id_to_fqsn.insert(id.clone(), fqsn);
-  /// compilation process.
-  pub fn process_ast(&mut self, ast: &ast::AST) -> Result<(), String> {
-
-    self.populate_name_tables(ast)?;
-    self.resolve_symbol_ids(ast)?;
-    Ok(())
   }
 
-  pub fn lookup_symbol(&self, id: &ItemId) -> Option<&Symbol> {
+  pub fn get_fqsn_from_id(&self, id: &ItemId) -> Option<FullyQualifiedSymbolName> {
-    let fqsn = self.id_to_fqsn.get(id);
+    self.id_to_fqsn.get(&id).cloned()
-    fqsn.and_then(|fqsn| self.fqsn_to_symbol.get(fqsn))
+  }
+
+  fn add_new_symbol(&mut self, local_name: &Rc<String>, scope_path: &Vec<ScopeSegment>, spec: SymbolSpec) {
+    let mut vec: Vec<ScopeSegment> = scope_path.clone();
+    vec.push(ScopeSegment { name: local_name.clone() });
+    let fully_qualified_name = FullyQualifiedSymbolName(vec);
+    let symbol = Symbol { local_name: local_name.clone(), fully_qualified_name: fully_qualified_name.clone(), spec };
+    self.symbol_trie.insert(&fully_qualified_name);
+    self.symbol_path_to_symbol.insert(fully_qualified_name, symbol);
+  }
+
+  pub fn lookup_by_fqsn(&self, fully_qualified_path: &FullyQualifiedSymbolName) -> Option<&Symbol> {
+    self.symbol_path_to_symbol.get(fully_qualified_path)
+  }
+
+  pub fn lookup_children_of_fqsn(&self, path: &FullyQualifiedSymbolName) -> Vec<FullyQualifiedSymbolName> {
+    self.symbol_trie.get_children(path)
   }
 }
 
@@ -174,7 +140,7 @@ impl SymbolTable {
 #[derive(Debug)]
 pub struct Symbol {
   pub local_name: Rc<String>,
-  //fully_qualified_name: FullyQualifiedSymbolName,
+  fully_qualified_name: FullyQualifiedSymbolName,
   pub spec: SymbolSpec,
 }
 
@@ -189,8 +155,8 @@ pub enum SymbolSpec {
   Func(Vec<TypeName>),
   DataConstructor {
     index: usize,
-    type_name: TypeName, //TODO this eventually needs to be some kind of ID
+    type_name: TypeName,
-    type_args: Vec<Rc<String>>, //TODO this should be a lookup table into type information, it's not the concern of the symbol table
+    type_args: Vec<Rc<String>>,
   },
   RecordConstructor {
     index: usize,
@@ -198,6 +164,9 @@ pub enum SymbolSpec {
     type_name: TypeName,
   },
   Binding,
+  Type {
+    name: TypeName
+  },
 }
 
 impl fmt::Display for SymbolSpec {
@@ -208,159 +177,137 @@ impl fmt::Display for SymbolSpec {
       DataConstructor { index, type_name, type_args } => write!(f, "DataConstructor(idx: {})({:?} -> {})", index, type_args, type_name),
       RecordConstructor { type_name, index, ..} => write!(f, "RecordConstructor(idx: {})(<members> -> {})", index, type_name),
       Binding => write!(f, "Binding"),
+      Type { name } => write!(f, "Type <{}>", name),
     }
   }
 }
 
-
 impl SymbolTable {
   /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem
    * later */
 
-  /// Walks the AST, matching the ID of an identifier used in some expression to
+  pub fn add_top_level_symbols(&mut self, ast: &ast::AST) -> Result<(), String> {
-  /// the corresponding Symbol.
+    let mut scope_name_stack = Vec::new();
-  fn resolve_symbol_ids(&mut self, ast: &ast::AST) -> Result<(), String> {
+    self.add_symbols_from_scope(&ast.statements, &mut scope_name_stack)
-    let mut resolver = resolver::Resolver::new(self);
-    resolver.resolve(ast)?;
-    Ok(())
   }
 
-  /// This function traverses the AST and adds symbol table entries for
+  fn add_symbols_from_scope<'a>(&'a mut self, statements: &Vec<Statement>, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
-  /// constants, functions, types, and modules defined within. This simultaneously
+    use self::ast::Declaration::*;
-  /// checks for dupicate definitions (and returns errors if discovered), and sets
+
-  /// up name tables that will be used by further parts of the compiler
+    let mut seen_identifiers = DuplicateNameTrackTable::new();
-  fn populate_name_tables(&mut self, ast: &ast::AST) -> Result<(), String> {
+    let mut seen_modules = DuplicateNameTrackTable::new();
-    let mut scope_stack = vec![];
+
-    self.add_from_scope(ast.statements.as_ref(), &mut scope_stack)
+    for statement in statements.iter() {
-      .map_err(|err| format!("{:?}", err))?;
+      match statement {
-    Ok(())
+        Statement { kind: StatementKind::Declaration(decl), id, location, } => {
+          self.decl_locations.add_location(id, *location);
+
+          match decl {
+            FuncSig(ref signature) => {
+              seen_identifiers.try_register(&signature.name, id, &self.decl_locations)
+                .map_err(|line| format!("Duplicate function definition: {}. It's already defined at {}", signature.name, line))?;
+              self.add_function_signature(signature, scope_name_stack)?
             }
-
+            FuncDecl(ref signature, ref body) => {
-  fn add_symbol(&mut self, fqsn: FQSN, symbol: Symbol) {
+              seen_identifiers.try_register(&signature.name, id, &self.decl_locations)
-    self.symbol_trie.insert(&fqsn);
+                .map_err(|line| format!("Duplicate function definition: {}. It's already defined at {}", signature.name, line))?;
-    self.fqsn_to_symbol.insert(fqsn, symbol);
+              self.add_function_signature(signature, scope_name_stack)?;
-
+              scope_name_stack.push(ScopeSegment{
-  }
+                name: signature.name.clone(),
-
-  //TODO this should probably return a vector of duplicate name errors
-  fn add_from_scope<'a>(&'a mut self, statements: &[Statement], scope_stack: &mut Vec<Scope>) -> Result<(), DuplicateName> {
-    for statement in statements {
-      //TODO I'm not sure if I need to do anything with this ID
-      let Statement { id: _, kind, location } = statement;
-      let location = *location;
-      match kind {
-        StatementKind::Declaration(Declaration::FuncSig(signature)) => {
-          let fn_name: String = signature.name.as_str().to_owned();
-          let fq_function = FQSN::from_scope_stack(scope_stack.as_ref(), fn_name);
-          self.fq_names.register(fq_function.clone(), NameSpec { location, kind: NameKind::Function })?;
-          self.types.register(fq_function.clone(), NameSpec { location, kind: TypeKind } )?;
-
-          self.add_symbol(fq_function, Symbol {
-            local_name: signature.name.clone(),
-            spec: SymbolSpec::Func(vec![]), //TODO does this inner vec need to exist at all?
               });
-        }
+              let output = self.add_symbols_from_scope(body, scope_name_stack);
-        StatementKind::Declaration(Declaration::FuncDecl(signature, body)) => {
+              scope_name_stack.pop();
-          let fn_name: String = signature.name.as_str().to_owned();
-          let new_scope = Scope::Name(fn_name.clone());
-          let fq_function = FQSN::from_scope_stack(scope_stack.as_ref(), fn_name);
-          self.fq_names.register(fq_function.clone(), NameSpec { location, kind: NameKind::Function })?;
-          self.types.register(fq_function.clone(), NameSpec { location, kind: TypeKind } )?;
-
-          self.add_symbol(fq_function, Symbol {
-            local_name: signature.name.clone(),
-            spec: SymbolSpec::Func(vec![]), //TODO does this inner vec need to exist at all?
-          });
-
-          scope_stack.push(new_scope);
-          let output = self.add_from_scope(body.as_ref(), scope_stack);
-          scope_stack.pop();
               output?
             },
-        StatementKind::Declaration(Declaration::TypeDecl { name, body, mutable }) => {
+            TypeDecl { name, body, mutable } => {
-          let fq_type = FQSN::from_scope_stack(scope_stack.as_ref(), name.name.as_ref().to_owned());
+              seen_identifiers.try_register(&name.name, &id, &self.decl_locations)
-          self.types.register(fq_type, NameSpec { location, kind: TypeKind } )?;
+                .map_err(|line| format!("Duplicate type definition: {}. It's already defined at {}", name.name, line))?;
-          if let Err(errors) = self.add_type_members(name, body, mutable, location, scope_stack) {
+              self.add_type_decl(name, body, mutable, scope_name_stack)?
-            return Err(errors[0].clone());
+            },
+            Binding { name, .. } => {
+              seen_identifiers.try_register(&name, &id, &self.decl_locations)
+                .map_err(|line| format!("Duplicate variable definition: {}. It's already defined at {}", name, line))?;
+              self.add_new_symbol(name, scope_name_stack, SymbolSpec::Binding);
+            }
+            _ => ()
           }
         },
-        StatementKind::Declaration(Declaration::Binding { name, .. }) => {
+        Statement { kind: StatementKind::Module(ModuleSpecifier { name, contents}), id, location } => {
-          let fq_binding = FQSN::from_scope_stack(scope_stack.as_ref(), name.as_str().to_owned());
+          self.decl_locations.add_location(id, *location);
-          self.fq_names.register(fq_binding.clone(), NameSpec { location, kind: NameKind::Binding })?;
+          seen_modules.try_register(name, id, &self.decl_locations)
-          self.add_symbol(fq_binding, Symbol {
+            .map_err(|line| format!("Duplicate module definition: {}. It's already defined at {}", name, line))?;
-            local_name: name.clone(),
+          scope_name_stack.push(ScopeSegment { name: name.clone() });
-            spec: SymbolSpec::Binding,
+          let output = self.add_symbols_from_scope(contents, scope_name_stack);
-          });
+          scope_name_stack.pop();
-        }
-        StatementKind::Module(ModuleSpecifier { name, contents }) => {
-          let mod_name = name.as_str().to_owned();
-          let fq_module = FQSN::from_scope_stack(scope_stack.as_ref(), mod_name.clone());
-          let new_scope = Scope::Name(mod_name);
-          self.fq_names.register(fq_module, NameSpec { location, kind: NameKind::Module })?;
-          scope_stack.push(new_scope);
-          let output = self.add_from_scope(contents.as_ref(), scope_stack);
-          scope_stack.pop();
           output?
         },
-        _ => (),
+        _ => ()
       }
     }
     Ok(())
   }
+  #[allow(dead_code)]
+  pub fn debug_symbol_table(&self) -> String {
+    let mut output = "Symbol table\n".to_string();
+    let mut sorted_symbols: Vec<(&FullyQualifiedSymbolName, &Symbol)> = self.symbol_path_to_symbol.iter().collect();
+    sorted_symbols.sort_by(|(fqsn, _), (other_fqsn, _)| fqsn.cmp(other_fqsn));
+    for (name, sym) in sorted_symbols.iter() {
+      write!(output, "{} -> {}\n", name, sym).unwrap();
+    }
+    output
+  }
 
-  fn add_type_members(&mut self, type_name: &TypeSingletonName, type_body: &TypeBody, _mutable: &bool, location: Location, scope_stack: &mut Vec<Scope>) -> Result<(), Vec<DuplicateName>> {
+  fn add_function_signature(&mut self, signature: &Signature, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
-    let mut errors = vec![];
+    let mut local_type_context = LocalTypeContext::new();
+    let types = signature.params.iter().map(|param| match param.anno {
+      Some(ref type_identifier) => Rc::new(format!("{:?}", type_identifier)),
+      None => local_type_context.new_universal_type()
+    }).collect();
+    self.add_new_symbol(&signature.name, scope_name_stack, SymbolSpec::Func(types));
+    Ok(())
+  }
 
-    let mut register = |fqsn: FQSN, spec: SymbolSpec| {
+  //TODO handle type mutability
-      let name_spec = NameSpec { location, kind: TypeKind };
+  fn add_type_decl(&mut self, type_name: &TypeSingletonName, body: &TypeBody, _mutable: &bool, scope_name_stack: &mut Vec<ScopeSegment>) -> Result<(), String> {
-      if let Err(err) = self.types.register(fqsn.clone(), name_spec) {
+    use crate::ast::{TypeIdentifier, Variant};
-        errors.push(err);
+    let TypeBody(variants) = body;
-      } else {
+    let ref type_name = type_name.name;
-        let local_name = match spec {
+
-          SymbolSpec::DataConstructor { ref type_name, ..} | SymbolSpec::RecordConstructor { ref type_name, .. } => type_name.clone(),
+
-          _ => panic!("This should never happen"),
+    let type_spec = SymbolSpec::Type {
-        };
+      name: type_name.clone(),
-        let symbol = Symbol { local_name, spec };
-        self.add_symbol(fqsn, symbol);
-      };
     };
+    self.add_new_symbol(type_name, &scope_name_stack, type_spec);
 
-    let TypeBody(variants) = type_body;
+    scope_name_stack.push(ScopeSegment{
-    let new_scope = Scope::Name(type_name.name.as_ref().to_owned());
+      name: type_name.clone(),
-    scope_stack.push(new_scope);
+    });
-
+    //TODO figure out why _params isn't being used here
-    for (index, variant) in variants.iter().enumerate() {
+    for (index, var) in variants.iter().enumerate() {
-      match variant {
+      match var {
-        Variant::UnitStruct(name) => {
+        Variant::UnitStruct(variant_name) => {
-          let fq_name = FQSN::from_scope_stack(scope_stack.as_ref(), name.as_ref().to_owned());
           let spec = SymbolSpec::DataConstructor {
             index,
-            type_name: name.clone(),
+            type_name: type_name.clone(),
             type_args: vec![],
           };
-          register(fq_name, spec);
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
         },
-        Variant::TupleStruct(name, items) => {
+        Variant::TupleStruct(variant_name, tuple_members) => {
-          let fq_name = FQSN::from_scope_stack(scope_stack.as_ref(), name.as_ref().to_owned());
+          //TODO fix the notion of a tuple type
+          let type_args = tuple_members.iter().map(|type_name| match type_name {
+            TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(),
+            TypeIdentifier::Tuple(_) => unimplemented!(),
+          }).collect();
           let spec = SymbolSpec::DataConstructor {
             index,
-            type_name: name.clone(),
+            type_name: type_name.clone(),
-            type_args: items.iter().map(|_| Rc::new("DUMMY_TYPE_ID".to_string())).collect()
+            type_args
           };
-          register(fq_name, spec);
+          self.add_new_symbol(variant_name, scope_name_stack, spec);
         },
-        Variant::Record { name, members } => {
+        Variant::Record { name, members: defined_members } => {
-          let fq_name = FQSN::from_scope_stack(scope_stack.as_ref(), name.as_ref().to_owned());
+          let mut members = HashMap::new();
-          let spec = SymbolSpec::RecordConstructor {
-            index,
-            type_name: name.clone(),
-            members: members.iter()
-              .map(|(_, _)| (Rc::new("DUMMY_FIELD".to_string()), Rc::new("DUMMY_TYPE_ID".to_string()))).collect()
-          };
-          register(fq_name, spec);
-          //TODO check for duplicates among struct member definitions
-          /*
-
           let mut duplicate_member_definitions = Vec::new();
           for (member_name, member_type) in defined_members {
             match members.entry(member_name.clone()) {
@@ -376,28 +323,28 @@ impl SymbolTable {
           if duplicate_member_definitions.len() != 0 {
             return Err(format!("Duplicate member(s) in definition of type {}: {:?}", type_name, duplicate_member_definitions));
           }
-          */
+          let spec = SymbolSpec::RecordConstructor { index, type_name: type_name.clone(), members };
+          self.add_new_symbol(name, scope_name_stack, spec);
+        },
       }
     }
-    }
+    scope_name_stack.pop();
-
-    scope_stack.pop();
-
-    if errors.is_empty() {
     Ok(())
-    } else {
-      Err(errors)
-    }
-  }
-
-  #[allow(dead_code)]
-  pub fn debug_symbol_table(&self) -> String {
-    let mut output = "Symbol table\n".to_string();
-    let mut sorted_symbols: Vec<(&FullyQualifiedSymbolName, &Symbol)> = self.symbol_path_to_symbol.iter().collect();
-    sorted_symbols.sort_by(|(fqsn, _), (other_fqsn, _)| fqsn.cmp(other_fqsn));
-    for (name, sym) in sorted_symbols.iter() {
-      write!(output, "{} -> {}\n", name, sym).unwrap();
-    }
-    output
   }
 }
+
+struct LocalTypeContext {
+  state: u8
+}
+impl LocalTypeContext {
+  fn new() -> LocalTypeContext {
+    LocalTypeContext { state: 0 }
+  }
+
+  fn new_universal_type(&mut self) -> TypeName {
+    let n = self.state;
+    self.state += 1;
+    Rc::new(format!("{}", (('a' as u8) + n) as char))
+  }
+}
+

schala-lang/language/src/symbol_table/resolver.rs

@@ -1,110 +0,0 @@
-use std::rc::Rc;
-
-use crate::symbol_table::{SymbolTable, FQSN, Scope};
-use crate::ast::*;
-use crate::util::ScopeStack;
-
-type FQSNPrefix = Vec<Scope>;
-
-pub struct Resolver<'a> {
-  symbol_table: &'a mut super::SymbolTable,
-  name_scope_stack: ScopeStack<'a, Rc<String>, FQSNPrefix>,
-}
-
-impl<'a> Resolver<'a> {
-  pub fn new(symbol_table: &'a mut SymbolTable) -> Self {
-    let name_scope_stack: ScopeStack<'a, Rc<String>, FQSNPrefix> = ScopeStack::new(None);
-    Self { symbol_table, name_scope_stack }
-  }
-  pub fn resolve(&mut self, ast: &AST) -> Result<(), String> {
-    walk_ast(self, ast);
-    Ok(())
-  }
-
-  fn lookup_name_in_scope(&self, sym_name: &QualifiedName) -> FQSN {
-    let QualifiedName { components, .. } = sym_name;
-    let first_component = &components[0];
-    match self.name_scope_stack.lookup(first_component) {
-      None => {
-        FQSN {
-          scopes: components.iter()
-            .map(|name| Scope::Name(name.as_ref().to_owned()))
-            .collect()
-        }
-      },
-      Some(fqsn_prefix) => {
-        let mut full_name = fqsn_prefix.clone();
-        let rest_of_name: FQSNPrefix = components[1..].iter().map(|name| Scope::Name(name.as_ref().to_owned())).collect();
-        full_name.extend_from_slice(&rest_of_name);
-
-        FQSN {
-          scopes: full_name
-        }
-      }
-    }
-  }
-
-  // This might be a variable or a pattern, depending on whether this symbol
-  // already exists in the table.
-  fn qualified_name_in_pattern(&mut self, qualified_name: &QualifiedName) {
-    let fqsn = self.lookup_name_in_scope(qualified_name);
-    if self.symbol_table.fqsn_to_symbol.get(&fqsn).is_some() {
-      self.symbol_table.id_to_fqsn.insert(qualified_name.id.clone(), fqsn); //TODO maybe set this to an explicit value if none?
-    }
-  }
-}
-
-impl<'a> ASTVisitor for Resolver<'a> {
-  //TODO need to un-insert these - maybe need to rethink visitor
-  fn import(&mut self, import_spec: &ImportSpecifier) {
-    let ImportSpecifier { ref path_components, ref imported_names, .. } = &import_spec;
-    match imported_names {
-      ImportedNames::All => {
-        let prefix = FQSN {
-          scopes: path_components.iter().map(|c| Scope::Name(c.as_ref().to_owned())).collect()
-        };
-        let members = self.symbol_table.symbol_trie.get_children(&prefix);
-        for member in members.into_iter() {
-          let Scope::Name(n) = member.scopes.last().unwrap();
-          let local_name = Rc::new(n.clone());
-          self.name_scope_stack.insert(local_name, member.scopes);
-        }
-      },
-      ImportedNames::LastOfPath => {
-        let name = path_components.last().unwrap(); //TODO handle better
-        let fqsn_prefix = path_components.iter()
-          .map(|c| Scope::Name(c.as_ref().to_owned()))
-          .collect();
-        self.name_scope_stack.insert(name.clone(), fqsn_prefix);
-      }
-      ImportedNames::List(ref names) => {
-        let fqsn_prefix: FQSNPrefix = path_components.iter()
-          .map(|c| Scope::Name(c.as_ref().to_owned()))
-          .collect();
-        for name in names.iter() {
-          self.name_scope_stack.insert(name.clone(), fqsn_prefix.clone());
-        }
-      }
-    };
-  }
-
-  fn qualified_name(&mut self, qualified_name: &QualifiedName) {
-    let fqsn = self.lookup_name_in_scope(&qualified_name);
-    self.symbol_table.id_to_fqsn.insert(qualified_name.id.clone(), fqsn);
-  }
-
-  fn named_struct(&mut self, qualified_name: &QualifiedName, _fields: &Vec<(Rc<String>, Expression)>) {
-    let fqsn = self.lookup_name_in_scope(&qualified_name);
-    self.symbol_table.id_to_fqsn.insert(qualified_name.id.clone(), fqsn);
-  }
-
-  fn pattern(&mut self, pat: &Pattern) {
-    use Pattern::*;
-    match pat {
-      //TODO I think not handling TuplePattern is an oversight
-      TuplePattern(_) => (),
-      Literal(_) | Ignored => (),
-      TupleStruct(name, _) | Record(name, _) | VarOrName(name) => self.qualified_name_in_pattern(name),
-    };
-  }
-}

schala-lang/language/src/symbol_table/symbol_trie.rs

@@ -1,18 +1,18 @@
 use radix_trie::{Trie, TrieCommon, TrieKey};
-use super::{Scope, FQSN};
+use super::FullyQualifiedSymbolName;
 use std::hash::{Hasher, Hash};
 use std::collections::hash_map::DefaultHasher;
 
 #[derive(Debug)]
-pub struct SymbolTrie(Trie<FQSN, ()>);
+pub struct SymbolTrie(Trie<FullyQualifiedSymbolName, ()>);
 
-impl TrieKey for FQSN {
+impl TrieKey for FullyQualifiedSymbolName {
   fn encode_bytes(&self) -> Vec<u8> {
     let mut hasher = DefaultHasher::new();
     let mut output = vec![];
-    for segment in self.scopes.iter() {
+    let FullyQualifiedSymbolName(scopes) = self;
-      let Scope::Name(s) = segment;
+    for segment in scopes.iter() {
-      s.as_bytes().hash(&mut hasher);
+      segment.name.as_bytes().hash(&mut hasher);
       output.extend_from_slice(&hasher.finish().to_be_bytes());
     }
     output
@@ -24,44 +24,28 @@ impl SymbolTrie {
     SymbolTrie(Trie::new())
   }
 
-  pub fn insert(&mut self, fqsn: &FQSN) {
+  pub fn insert(&mut self, fqsn: &FullyQualifiedSymbolName) {
     self.0.insert(fqsn.clone(), ());
   }
 
-  pub fn get_children(&self, fqsn: &FQSN) -> Vec<FQSN> {
+  pub fn get_children(&self, fqsn: &FullyQualifiedSymbolName) -> Vec<FullyQualifiedSymbolName> {
     let subtrie = match self.0.subtrie(fqsn) {
       Some(s) => s,
       None => return vec![]
     };
-    let output: Vec<FQSN> = subtrie.keys().filter(|cur_key| **cur_key != *fqsn).map(|fqsn| fqsn.clone()).collect();
+    let output: Vec<FullyQualifiedSymbolName> = subtrie.keys().filter(|cur_key| **cur_key != *fqsn).map(|fqsn| fqsn.clone()).collect();
     output
   }
 }
 
-#[cfg(test)]
-mod test {
-  use super::*;
-  use crate::symbol_table::{Scope, FQSN};
-
-  fn make_fqsn(strs: &[&str]) -> FQSN {
-    let mut scopes = vec![];
-    for s in strs {
-      scopes.push(Scope::Name(s.to_string()));
-    }
-    FQSN {
-      scopes
-    }
-  }
-
 #[test]
-  fn test_trie_insertion() {
+fn test_trie_insertion() {
   let mut trie = SymbolTrie::new();
 
-    trie.insert(&make_fqsn(&["unrelated","thing"]));
+  trie.insert(&fqsn!("unrelated"; ty, "thing"; tr));
-    trie.insert(&make_fqsn(&["outer","inner"]));
+  trie.insert(&fqsn!("outer"; ty, "inner"; tr));
-    trie.insert(&make_fqsn(&["outer","inner", "still_inner"]));
+  trie.insert(&fqsn!("outer"; ty, "inner"; ty, "still_inner"; tr));
 
-    let children = trie.get_children(&make_fqsn(&["outer", "inner"]));
+  let children = trie.get_children(&fqsn!("outer"; ty, "inner"; tr));
   assert_eq!(children.len(), 1);
-  }
 }

schala-lang/language/src/symbol_table/tables.rs

@@ -0,0 +1,28 @@
+use std::collections::HashMap;
+
+use crate::ast::ItemId;
+use crate::tokenizing::Location;
+
+
+/// Maps top-level declarations to Locations in source code, to detect
+/// multiply-defined top level items.
+pub struct DeclLocations {
+  map: HashMap<ItemId, Location>
+}
+
+impl DeclLocations {
+  pub fn new() -> Self {
+    Self { map: HashMap::new() }
+  }
+
+  pub(crate) fn add_location(&mut self, id: &ItemId, loc: Location) {
+    self.map.insert(id.clone(), loc);
+  }
+
+  pub(crate) fn lookup(&self, id: &ItemId) -> Option<Location> {
+    match self.map.get(id) {
+      Some(loc) => Some(loc.clone()),
+      None => None
+    }
+  }
+}

schala-lang/language/src/symbol_table/test.rs

@@ -2,37 +2,37 @@
 use super::*;
 use crate::util::quick_ast;
 
-fn add_symbols(src: &str) -> (SymbolTable, Result<(), String>) {
+fn add_symbols_from_source(src: &str) -> (SymbolTable, Result<(), String>) {
   let ast = quick_ast(src);
   let mut symbol_table = SymbolTable::new();
-  let result = symbol_table.process_ast(&ast);
+  let result = symbol_table.add_top_level_symbols(&ast);
   (symbol_table, result)
 }
 
-fn make_fqsn(strs: &[&str]) -> FQSN {
+macro_rules! values_in_table {
-  let mut scopes = vec![];
+  ($source:expr, $single_value:expr) => {
-  for s in strs {
+    values_in_table!($source => $single_value);
-    scopes.push(Scope::Name(s.to_string()));
+  };
-  }
+  ($source:expr => $( $value:expr ),* ) => {
-  FQSN {
+    {
-    scopes
+    let (symbol_table, _) = add_symbols_from_source($source);
+    $(
+      match symbol_table.lookup_by_fqsn($value) {
+        Some(_spec) => (),
+        None => panic!(),
+      };
+    )*
     }
+  };
 }
 
-
 #[test]
 fn basic_symbol_table() {
-  let src = "let a = 10; fn b() { 20 }";
+  values_in_table! { "let a = 10; fn b() { 20 }", &fqsn!("b"; tr) };
-  let (symbols, _) = add_symbols(src);
+  values_in_table! { "type Option<T> = Some(T) | None" =>
-
+    &fqsn!("Option"; tr),
-  symbols.fq_names.table.get(&make_fqsn(&["b"])).unwrap();
+    &fqsn!("Option"; ty, "Some"; tr),
-
+    &fqsn!("Option"; ty, "None"; tr) };
-  let src = "type Option<T> = Some(T) | None";
-  let (symbols, _) = add_symbols(src);
-
-  symbols.types.table.get(&make_fqsn(&["Option"])).unwrap();
-  symbols.types.table.get(&make_fqsn(&["Option", "Some"])).unwrap();
-  symbols.types.table.get(&make_fqsn(&["Option", "None"])).unwrap();
 }
 
 #[test]
@@ -42,9 +42,8 @@ fn no_function_definition_duplicates() {
   fn b() { 2 }
   fn a() { 3 }
   "#;
-  let (_, output) = add_symbols(source);
+  let (_, output) = add_symbols_from_source(source);
-  //TODO test for right type of error
+  assert!(output.unwrap_err().contains("Duplicate function definition: a"))
-  output.unwrap_err();
 }
 
 #[test]
@@ -55,12 +54,10 @@ fn no_variable_definition_duplicates() {
   let q = 39
   let a = 30
   "#;
-  let (_, output) = add_symbols(source);
+  let (_, output) = add_symbols_from_source(source);
-  let _output = output.unwrap_err();
+  let output = output.unwrap_err();
-  /*
   assert!(output.contains("Duplicate variable definition: a"));
   assert!(output.contains("already defined at 2"));
-  */
 }
 
 #[test]
@@ -78,9 +75,8 @@ fn no_variable_definition_duplicates_in_function() {
     let x = 33
   }
   "#;
-  let (_, output) = add_symbols(source);
+  let (_, output) = add_symbols_from_source(source);
-  let _err = output.unwrap_err();
+  assert!(output.unwrap_err().contains("Duplicate variable definition: x"))
-  //assert!(output.unwrap_err().contains("Duplicate variable definition: x"))
 }
 
 #[test]
@@ -93,10 +89,9 @@ fn dont_falsely_detect_duplicates() {
   }
   let q = 39;
   "#;
-  let (symbols, _) = add_symbols(source);
+  let (symbol_table, _) = add_symbols_from_source(source);
-
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!["a"; tr]).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["a"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!["some_func"; fn, "a";tr]).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["some_func", "a"])).is_some());
 }
 
 #[test]
@@ -108,9 +103,9 @@ fn inner_func(arg) {
 }
 x + inner_func(x)
 }"#;
-  let (symbols, _) = add_symbols(source);
+  let (symbol_table, _) = add_symbols_from_source(source);
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; tr)).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "inner_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "inner_func"; tr)).is_some());
 }
 
 #[test]
@@ -128,11 +123,11 @@ fn second_inner_func() {
 
 inner_func(x)
 }"#;
-  let (symbols, _) = add_symbols(source);
+  let (symbol_table, _) = add_symbols_from_source(source);
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; tr)).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "inner_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "inner_func"; tr)).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "second_inner_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "second_inner_func"; tr)).is_some());
-  assert!(symbols.fq_names.table.get(&make_fqsn(&["outer_func", "second_inner_func", "another_inner_func"])).is_some());
+  assert!(symbol_table.lookup_by_fqsn(&fqsn!("outer_func"; fn, "second_inner_func"; fn, "another_inner_func"; tr)).is_some());
 }
 
 #[test]
@@ -152,8 +147,8 @@ fn second_inner_func() {
 
 inner_func(x)
 }"#;
-  let (_, output) = add_symbols(source);
+  let (_, output) = add_symbols_from_source(source);
-  let _err = output.unwrap_err();
+  assert!(output.unwrap_err().contains("Duplicate"))
 }
 
 #[test]
@@ -166,11 +161,10 @@ module stuff {
 
 fn item()
 "#;
-
+  values_in_table! { source  =>
-  let (symbols, _) = add_symbols(source);
+    &fqsn!("item"; tr),
-  symbols.fq_names.table.get(&make_fqsn(&["stuff"])).unwrap();
+    &fqsn!("stuff"; tr, "item"; tr)
-  symbols.fq_names.table.get(&make_fqsn(&["item"])).unwrap();
+  };
-  symbols.fq_names.table.get(&make_fqsn(&["stuff", "item"])).unwrap();
 }
 
 #[test]
@@ -188,6 +182,8 @@ fn duplicate_modules() {
       fn foo() { 256.1 }
     }
     "#;
-  let (_, output) = add_symbols(source);
+  let (_, output) = add_symbols_from_source(source);
-  let _output = output.unwrap_err();
+  let output = output.unwrap_err();
+  assert!(output.contains("Duplicate module"));
+  assert!(output.contains("already defined at 5"));
 }