Document symbol bag class and methods

boot/semantic.cc

@@ -205,18 +205,16 @@ namespace elna::boot
     void name_analysis_visitor::visit(type_declaration *definition)
     {
         definition->body().accept(this);
-        auto unresolved_declaration = this->bag.unresolved.at(definition->identifier.identifier);
+        this->bag.resolve(definition->identifier.identifier, this->current_type);
-
-        unresolved_declaration->reference = this->current_type;
     }
 
     void name_analysis_visitor::visit(named_type_expression *type_expression)
     {
-        auto unresolved_alias = this->bag.unresolved.find(type_expression->name);
+        auto unresolved_alias = this->bag.declared(type_expression->name);
 
-        if (unresolved_alias != this->bag.unresolved.end())
+        if (unresolved_alias != nullptr)
         {
-            this->current_type = type(unresolved_alias->second);
+            this->current_type = type(unresolved_alias);
         }
         else if (auto from_symbol_table = this->bag.lookup(type_expression->name))
         {
@@ -301,7 +299,11 @@ namespace elna::boot
 
         for (const auto& variable_identifier : declaration->identifiers)
         {
-            this->bag.enter(variable_identifier.identifier, std::make_shared<variable_info>(this->current_type));
+            if (!this->bag.enter(variable_identifier.identifier, std::make_shared<variable_info>(this->current_type)))
+            {
+                add_error<already_declared_error>(variable_identifier.identifier, this->input_file,
+                        declaration->position());
+            }
         }
     }
 
@@ -441,17 +443,17 @@ namespace elna::boot
     }
 
     bool name_analysis_visitor::check_unresolved_symbol(std::shared_ptr<alias_type> alias,
-            std::vector<std::string>& path)
+            std::vector<std::string>& alias_path)
     {
-        if (std::find(std::cbegin(path), std::cend(path), alias->name) != std::cend(path))
+        if (std::find(std::cbegin(alias_path), std::cend(alias_path), alias->name) != std::cend(alias_path))
         {
             return false;
         }
-        path.push_back(alias->name);
+        alias_path.push_back(alias->name);
 
         if (auto another_alias = alias->reference.get<alias_type>())
         {
-            return check_unresolved_symbol(another_alias, path);
+            return check_unresolved_symbol(another_alias, alias_path);
         }
         return true;
     }
@@ -462,18 +464,18 @@ namespace elna::boot
         {
             type->accept(this);
         }
-        for (auto& unresolved : this->bag.unresolved)
+        for (auto& unresolved : this->bag)
         {
-            std::vector<std::string> path;
+            std::vector<std::string> alias_path;
 
-            if (check_unresolved_symbol(unresolved.second, path))
+            if (check_unresolved_symbol(unresolved.second, alias_path))
             {
                 auto info = std::make_shared<type_info>(type_info(type(unresolved.second)));
                 this->bag.enter(unresolved.first, info);
             }
             else
             {
-                add_error<cyclic_declaration_error>(path, this->input_file, position{ 0, 0 });
+                add_error<cyclic_declaration_error>(alias_path, this->input_file, position{ 0, 0 });
             }
         }
         for (variable_declaration *const variable : unit->variables)

boot/symbol.cc

@@ -358,14 +358,20 @@ namespace elna::boot
         return result;
     }
 
-    symbol_bag::symbol_bag()
+    symbol_bag::symbol_bag(forward_table&& unresolved, std::shared_ptr<symbol_table> global_table)
+        : unresolved(unresolved)
     {
-        this->symbols = std::make_shared<symbol_table>();
+        this->symbols = std::make_shared<symbol_table>(global_table);
     }
 
-    symbol_bag::symbol_bag(forward_table&& unresolved, std::shared_ptr<symbol_table> symbols)
+    forward_table::const_iterator symbol_bag::begin()
-        : symbols(symbols), unresolved(unresolved)
     {
+        return unresolved.cbegin();
+    }
+
+    forward_table::const_iterator symbol_bag::end()
+    {
+        return unresolved.cend();
     }
 
     std::shared_ptr<info> symbol_bag::lookup(const std::string& name)
@@ -396,18 +402,31 @@ namespace elna::boot
         this->symbols = child;
     }
 
-    void symbol_bag::leave()
+    std::shared_ptr<symbol_table> symbol_bag::leave()
     {
-        this->symbols = this->symbols->scope();
+        std::shared_ptr<symbol_table> result = this->symbols;
+
+        this->symbols = result->scope();
+        return result;
     }
 
-    void symbol_bag::add_import(std::shared_ptr<symbol_table> table)
+    std::shared_ptr<alias_type> symbol_bag::declared(const std::string& symbol_name)
     {
-        this->imports.push_front(table);
+        auto unresolved_alias = this->unresolved.find(symbol_name);
+
+        return unresolved_alias == this->unresolved.end() ? std::shared_ptr<alias_type>() : unresolved_alias->second;
+    }
+
+    std::shared_ptr<alias_type> symbol_bag::resolve(const std::string& symbol_name, type& resolution)
+    {
+        auto unresolved_declaration = this->unresolved.at(symbol_name);
+
+        unresolved_declaration->reference = resolution;
+        return unresolved_declaration;
     }
 
     void symbol_bag::add_import(const symbol_bag& bag)
     {
-        add_import(bag.symbols);
+        this->imports.push_front(bag.symbols);
     }
 }

gcc/elna-builtins.cc

@@ -238,6 +238,17 @@ namespace elna::gcc
         DECL_EXTERNAL(fndecl) = info.symbols == nullptr;
     }
 
+    tree declare_variable(const std::string& name, const boot::variable_info& info,
+            std::shared_ptr<symbol_table> symbols)
+    {
+        auto variable_type = get_inner_alias(info.symbol, symbols);
+        tree declaration_tree = build_decl(UNKNOWN_LOCATION, VAR_DECL, get_identifier(name.c_str()), variable_type);
+
+        symbols->enter(name, declaration_tree);
+
+        return declaration_tree;
+    }
+
     void rewrite_symbol_table(std::shared_ptr<boot::symbol_table> info_table, std::shared_ptr<symbol_table> symbols)
     {
         for (auto& [symbol_name, symbol_info] : *info_table)
@@ -250,6 +261,10 @@ namespace elna::gcc
                     handle_symbol(symbol_name, alias_type, symbols);
                 }
             }
+            else if (auto variable_info = symbol_info->is_variable())
+            {
+                declare_variable(symbol_name, *variable_info, symbols);
+            }
             else if (auto procedure_info = symbol_info->is_procedure())
             {
                 declare_procedure(symbol_name, *procedure_info, symbols);

gcc/elna-generic.cc

@@ -747,15 +747,15 @@ namespace elna::gcc
     {
         for (const auto& variable_identifier : declaration->identifiers)
         {
-            this->current_expression = get_inner_alias(
-                    this->bag.lookup(variable_identifier.identifier)->is_variable()->symbol,
-                    this->symbols);
-
             location_t declaration_location = get_location(&declaration->position());
-            tree declaration_tree = build_decl(declaration_location, VAR_DECL,
+            tree declaration_tree = this->symbols->lookup(variable_identifier.identifier);
-                    get_identifier(variable_identifier.identifier.c_str()), this->current_expression);
-            bool result = this->symbols->enter(variable_identifier.identifier, declaration_tree);
 
+            if (declaration_tree == NULL_TREE)
+            {
+                auto variable_symbol = this->bag.lookup(variable_identifier.identifier)->is_variable();
+
+                declaration_tree = declare_variable(variable_identifier.identifier, *variable_symbol, this->symbols);
+            }
             // Set initializer if given.
             if (declaration->body != nullptr)
             {
@@ -771,19 +771,18 @@ namespace elna::gcc
                             print_type(TREE_TYPE(this->current_expression)).c_str());
                 }
             }
-            else if (POINTER_TYPE_P(this->current_expression))
+            else if (declaration->is_extern)
+            {
+                DECL_EXTERNAL(declaration_tree) = declaration->is_extern;
+            }
+            else if (POINTER_TYPE_P(TREE_TYPE(declaration_tree)))
             {
                 DECL_INITIAL(declaration_tree) = elna_pointer_nil_node;
             }
-            DECL_EXTERNAL(declaration_tree) = declaration->is_extern;
             TREE_PUBLIC(declaration_tree) = variable_identifier.exported;
             this->current_expression = NULL_TREE;
-            if (!result)
+
-            {
+            if (lang_hooks.decls.global_bindings_p())
-                error_at(declaration_location, "Variable '%s' already declared in this scope",
-                        variable_identifier.identifier.c_str());
-            }
-            else if (lang_hooks.decls.global_bindings_p())
             {
                 TREE_STATIC(declaration_tree) = 1;
                 varpool_node::get_create(declaration_tree);

gcc/elna1.cc

@@ -66,7 +66,6 @@ using dependency_state = elna::boot::dependency_state<std::shared_ptr<elna::gcc:
 
 static elna::boot::dependency elna_parse_file(dependency_state& state, const char *filename)
 {
-    auto module_table = std::make_shared<elna::boot::symbol_table>(state.globals);
     std::ifstream entry_point{ filename, std::ios::in };
 
     if (!entry_point)
@@ -80,7 +79,7 @@ static elna::boot::dependency elna_parse_file(dependency_state& state, const cha
     {
         elna::gcc::report_errors(outcome.errors());
     }
-    elna::boot::symbol_bag outcome_bag = elna::boot::symbol_bag{ std::move(outcome.unresolved), module_table };
+    elna::boot::symbol_bag outcome_bag = elna::boot::symbol_bag{ std::move(outcome.unresolved), state.globals };
 
     for (const auto& sub_tree : outcome.tree->imports)
     {
@@ -102,7 +101,7 @@ static elna::boot::dependency elna_parse_file(dependency_state& state, const cha
         elna::gcc::report_errors(semantic_errors);
     }
     state.cache.insert({ filename, outcome_bag });
-    elna::gcc::rewrite_symbol_table(module_table, state.custom);
+    elna::gcc::rewrite_symbol_table(outcome_bag.leave(), state.custom);
     linemap_add(line_table, LC_LEAVE, 0, NULL, 0);
 
     return outcome;

include/elna/boot/dependency.h

@@ -21,6 +21,7 @@ along with GCC; see the file COPYING3.  If not see
 #include <fstream>
 #include "elna/boot/result.h"
 #include "elna/boot/ast.h"
+#include "elna/boot/symbol.h"
 
 namespace elna::boot
 {

include/elna/boot/semantic.h

@@ -175,7 +175,7 @@ namespace elna::boot
     class declaration_visitor final : public empty_visitor, public error_container
     {
     public:
-        std::unordered_map<std::string, std::shared_ptr<alias_type>> unresolved;
+        forward_table unresolved;
 
         explicit declaration_visitor(const char *path);
 

include/elna/boot/symbol.h

@@ -231,6 +231,7 @@ namespace elna::boot
          * can not be found.
          *
          * \param name Symbol name.
+         *
          * \return Symbol from the table if found.
          */
         symbol_ptr lookup(const std::string& name)
@@ -250,6 +251,7 @@ namespace elna::boot
 
         /**
          * \param name Symbol name.
+         *
          * \return Whether the table contains a symbol with the given name.
          */
         bool contains(const std::string& name)
@@ -328,24 +330,101 @@ namespace elna::boot
 
     std::shared_ptr<symbol_table> builtin_symbol_table();
 
+    /**
+     * Symbol bag contains:
+     *
+     * - the symbol table of a module itself
+     * - symbol tables of imported modules
+     * - forward declarations
+     */
     class symbol_bag
     {
         std::shared_ptr<symbol_table> symbols;
         std::forward_list<std::shared_ptr<symbol_table>> imports;
-
-    public:
         forward_table unresolved;
 
-        symbol_bag();
+    public:
-        symbol_bag(forward_table&& unresolved, std::shared_ptr<symbol_table> symbols);
 
+        /**
+         * \param unresolved Forward declarations collected in the previous step.
+         * \param global_table Global symbols.
+         */
+        symbol_bag(forward_table&& unresolved, std::shared_ptr<symbol_table> global_table);
+
+        /**
+         * \return Iterator pointing to the first forward declaration.
+         */
+        forward_table::const_iterator begin();
+
+        /**
+         * \return Iterator pointing past the last forward declaration.
+         */
+        forward_table::const_iterator end();
+
+        /**
+         * Looks up a symbol in the current and imported modules.
+         *
+         * \param name Symbol name to look up.
+         *
+         * \return Symbol from one of the symbol tables if found.
+         */
         std::shared_ptr<info> lookup(const std::string& name);
-        bool enter(const std::string& name, std::shared_ptr<info> entry);
-        std::shared_ptr<symbol_table> enter();
-        void enter(std::shared_ptr<symbol_table> child);
-        void leave();
 
-        void add_import(std::shared_ptr<symbol_table> table);
+        /**
+         * Inserts a symbol into the current scope.
+         *
+         * \param name Symbol name.
+         * \param entry Symbol info.
+         *
+         * \return Whether the insertion took place.
+         */
+        bool enter(const std::string& name, std::shared_ptr<info> entry);
+
+        /**
+         * Enters a new scope.
+         *
+         * \return Reference to the allocated scope.
+         */
+        std::shared_ptr<symbol_table> enter();
+
+        /**
+         * Sets the current scope to \a child.
+         *
+         * \param child New scope.
+         */
+        void enter(std::shared_ptr<symbol_table> child);
+
+        /**
+         * Leave the current scope.
+         *
+         * \return Left scope.
+         */
+        std::shared_ptr<symbol_table> leave();
+
+        /**
+         * Checks whether there is a forward declaration \a symbol_name and
+         * returns it if so.
+         *
+         * \param symbol_name Type name to look up.
+         * \return Forward declaration or `nullptr` if the symbol is not declared.
+         */
+        std::shared_ptr<alias_type> declared(const std::string& symbol_name);
+
+        /**
+         * Completes the forward-declared type \a symbol_name and defines it to
+         * be \a resolution.
+         *
+         * \param symbol_name Type name.
+         * \param resolution Type definition.
+         * \return Alias to the defined type.
+         */
+        std::shared_ptr<alias_type> resolve(const std::string& symbol_name, type& resolution);
+
+        /**
+         * Add imported symbols to the scope.
+         *
+         * \param bag Symbol bag of another module.
+         */
         void add_import(const symbol_bag& bag);
     };
 }

include/elna/gcc/elna-builtins.h

@@ -36,4 +36,6 @@ namespace elna::gcc
     tree get_inner_alias(const boot::type& type, std::shared_ptr<symbol_table> symbols);
     void declare_procedure(const std::string& name, const boot::procedure_info& info,
             std::shared_ptr<symbol_table> symbols);
+    tree declare_variable(const std::string& name, const boot::variable_info& info,
+            std::shared_ptr<symbol_table> symbols);
 }