Implement defer

gcc/elna-tree.cc

@@ -60,6 +60,11 @@ namespace gcc
         TREE_CHAIN(this->last) = t;
     }
 
+    void block_chain::chain(tree t)
+    {
+        BLOCK_CHAIN(this->last) = t;
+    }
+
     tree_symbol_mapping::tree_symbol_mapping(tree bind_expression, tree block)
         : m_bind_expression(bind_expression), m_block(block)
     {
@@ -75,6 +80,47 @@ namespace gcc
         return m_block;
     }
 
+    block_scope::block_scope()
+        : m_statement_list(alloc_stmt_list())
+    {
+    }
+
+    void block_scope::append_statement(tree statement_tree)
+    {
+        if (!defers.empty())
+        {
+            append_to_statement_list(statement_tree, &this->defers.front().second);
+        }
+        else
+        {
+            append_to_statement_list(statement_tree, &this->m_statement_list);
+        }
+    }
+
+    void block_scope::defer(tree statement_tree)
+    {
+        defers.push_front({ statement_tree, alloc_stmt_list() });
+    }
+
+    tree block_scope::chain_defer()
+    {
+        if (this->defers.empty())
+        {
+            return m_statement_list;
+        }
+        std::forward_list<std::pair<tree, tree>>::iterator defer_iterator =
+            this->defers.begin();
+        tree defer_tree = build2(TRY_FINALLY_EXPR, void_type_node, defer_iterator->second, defer_iterator->first);
+
+        ++defer_iterator;
+        for (; defer_iterator != this->defers.end(); ++defer_iterator)
+        {
+            append_to_statement_list(defer_tree, &defer_iterator->second);
+            defer_tree = build2(TRY_FINALLY_EXPR, void_type_node, defer_iterator->second, defer_iterator->first);
+        }
+        return build2(COMPOUND_EXPR, TREE_TYPE(defer_tree), m_statement_list, defer_tree);
+    }
+
     std::shared_ptr<boot::symbol_table<tree>> builtin_symbol_table()
     {
         std::shared_ptr<boot::symbol_table<tree>> initial_table =