Make modules re-exportable

3 files changed, 18 insertions, 4 deletions

diff --git a/include/elna/boot/ast.h b/include/elna/boot/ast.h
index 6edeb25..06e5d41 100644
--- a/include/elna/boot/ast.h
+++ b/include/elna/boot/ast.h
@@ -1027,13 +1027,19 @@ namespace elna::boot
 
     /**
      * Import statement.
+     *
+     * An asterisk after the module path marks a re-export: the symbols the
+     * imported module exports become visible to the modules importing this
+     * one as well.
      */
     class import_declaration : public node
     {
     public:
         const std::vector<std::string> segments;
+        const bool exported;
 
-        import_declaration(const source_position position, std::vector<std::string>&& segments);
+        import_declaration(const source_position position, std::vector<std::string>&& segments,
+                const bool exported = false);
         void accept(parser_visitor *visitor) override;
     };
 
diff --git a/include/elna/boot/dependency.h b/include/elna/boot/dependency.h
index 7bd3de9..f52bfb1 100644
--- a/include/elna/boot/dependency.h
+++ b/include/elna/boot/dependency.h
@@ -156,6 +156,8 @@ namespace elna::boot
     {
         source_position position;
         std::shared_ptr<symbol_table> symbols;
+        /// Whether the importing module re-exports the symbols.
+        bool reexport = false;
     };
 
     /**
@@ -302,7 +304,8 @@ namespace elna::boot
                 }
                 imports.push_back({
                     .position = sub_tree->position(),
-                    .symbols = this->cache.find(module_path)->second.exported_symbols()
+                    .symbols = this->cache.find(module_path)->second.exported_symbols(),
+                    .reexport = sub_tree->exported
                 });
             }
             result.append(key, std::move(circular));
diff --git a/include/elna/boot/symbol.h b/include/elna/boot/symbol.h
index 07bcf80..bdac269 100644
--- a/include/elna/boot/symbol.h
+++ b/include/elna/boot/symbol.h
@@ -558,6 +558,8 @@ namespace elna::boot
     {
         std::shared_ptr<symbol_table> symbols;
         std::vector<std::shared_ptr<symbol_table>> imports;
+        // The subset of imports that is re-exported by this module.
+        std::vector<std::shared_ptr<symbol_table>> reexports;
         forward_table unresolved;
 
         std::shared_ptr<info> lookup_import(const std::string& name) const;
@@ -643,11 +645,14 @@ namespace elna::boot
          * earlier import keeps its names.
          *
          * \param symbols Exported symbol table of another module.
+         * \param reexport Whether the imported symbols are exported by this
+         *        module as well, so they are visible to its importers.
          *
          * \return Names an earlier import already brought into the scope,
          *         sorted by name.
          */
-        std::vector<import_collision> add_import(const std::shared_ptr<symbol_table>& symbols);
+        std::vector<import_collision> add_import(const std::shared_ptr<symbol_table>& symbols,
+                const bool reexport = false);
 
         /**
          * Tells whether the current scope is the module global scope.
@@ -661,7 +666,7 @@ namespace elna::boot
 
         /**
          * The symbol table containing the exported declarations of the
-         * module, computed lazily. Must be called while the current scope is
+         * module and the symbols of the modules it re-exports, computed lazily. Must be called while the current scope is
          * still the module scope.
          *
          * \return Exported symbols of the module.