Implement named blocks

5 files changed, 72 insertions, 1 deletions

diff --git a/include/elna/boot/ast.h b/include/elna/boot/ast.h
index ffc57de..4eea412 100644
--- a/include/elna/boot/ast.h
+++ b/include/elna/boot/ast.h
@@ -148,6 +148,8 @@ namespace elna::boot
     template<literal_type T>
     class literal;
     class defer_statement;
+    class block_statement;
+    class break_statement;
     class empty_statement;
 
     /**
@@ -171,6 +173,8 @@ namespace elna::boot
         virtual void visit(repeat_statement *) = 0;
         virtual void visit(for_statement *) = 0;
         virtual void visit(defer_statement *) = 0;
+        virtual void visit(block_statement *) = 0;
+        virtual void visit(break_statement *) = 0;
         virtual void visit(case_statement *) = 0;
         virtual void visit(empty_statement *) = 0;
         virtual void visit(unit *) = 0;
@@ -223,6 +227,8 @@ namespace elna::boot
         [[noreturn]] void visit(repeat_statement *) override;
         [[noreturn]] void visit(for_statement *) override;
         [[noreturn]] void visit(defer_statement *) override;
+        [[noreturn]] void visit(block_statement *) override;
+        [[noreturn]] void visit(break_statement *) override;
         [[noreturn]] void visit(empty_statement *) override;
         [[noreturn]] void visit(case_statement *) override;
         [[noreturn]] void visit(procedure_call *) override;
@@ -271,6 +277,8 @@ namespace elna::boot
         void visit(repeat_statement *statement) override;
         void visit(for_statement *statement) override;
         void visit(defer_statement *statement) override;
+        void visit(block_statement *statement) override;
+        void visit(break_statement *) override;
         void visit(empty_statement *) override;
         void visit(case_statement *statement) override;
         void visit(procedure_call *call) override;
@@ -1104,6 +1112,34 @@ namespace elna::boot
         ~defer_statement() override;
     };
 
+    /**
+     * Named block a break-statement can jump out of.
+     */
+    class block_statement : public statement
+    {
+    public:
+        const identifier name;
+        const std::vector<statement *> statements;
+
+        block_statement(const source_position position, identifier&& name,
+                std::vector<statement *>&& statements);
+        void accept(parser_visitor *visitor) override;
+
+        ~block_statement() override;
+    };
+
+    /**
+     * Jump to the end of the named block.
+     */
+    class break_statement : public statement
+    {
+    public:
+        const identifier label;
+
+        break_statement(const source_position position, identifier&& label);
+        void accept(parser_visitor *visitor) override;
+    };
+
     class empty_statement : public statement
     {
     public:
diff --git a/include/elna/boot/name_analysis.h b/include/elna/boot/name_analysis.h
index eff122b..67cd713 100644
--- a/include/elna/boot/name_analysis.h
+++ b/include/elna/boot/name_analysis.h
@@ -43,7 +43,10 @@ namespace elna::boot
             undeclared_type,
             undeclared_trait,
             undeclared_symbol,
-            not_a_type
+            undeclared_label,
+            not_a_type,
+            not_a_label,
+            break_leaves_defer
         };
         struct redefinition
         {
@@ -208,6 +211,8 @@ namespace elna::boot
         symbol_bag& bag;
         evaluator constant_evaluator;
         std::filesystem::path module_file;
+        /// Number of defer bodies the visited statement stands in.
+        std::size_t defer_depth{ 0 };
 
         resolving_visitor(symbol_bag& bag, const target_info& target,
                 const std::filesystem::path& module_path);
@@ -310,6 +315,8 @@ namespace elna::boot
         void visit(while_statement *statement) override;
         void visit(repeat_statement *statement) override;
         void visit(defer_statement *statement) override;
+        void visit(block_statement *statement) override;
+        void visit(break_statement *statement) override;
         void visit(empty_statement *) override;
         void visit(case_statement *statement) override;
 
diff --git a/include/elna/boot/symbol.h b/include/elna/boot/symbol.h
index 08292bc..5bbe2c6 100644
--- a/include/elna/boot/symbol.h
+++ b/include/elna/boot/symbol.h
@@ -271,6 +271,7 @@ namespace elna::boot
     class type_info;
     class procedure_info;
     class variable_info;
+    class label_info;
 
     class info : public std::enable_shared_from_this<info>
     {
@@ -285,6 +286,7 @@ namespace elna::boot
         virtual std::shared_ptr<type_info> is_type();
         virtual std::shared_ptr<procedure_info> is_procedure();
         virtual std::shared_ptr<variable_info> is_variable();
+        virtual std::shared_ptr<label_info> is_label();
     };
 
     /**
@@ -501,6 +503,28 @@ namespace elna::boot
         std::shared_ptr<variable_info> is_variable() override;
     };
 
+    /**
+     * Named block a break-statement can jump to.
+     */
+    class label_info : public info
+    {
+    public:
+        /**
+         * Constructs a label symbol information.
+         *
+         * \param defer_depth Number of defer bodies enclosing the block.
+         */
+        explicit label_info(std::size_t defer_depth);
+
+        std::shared_ptr<label_info> is_label() override;
+
+        /*
+         * A break may not leave the defer body it stands in, so a label
+         * declared outside that body is not a valid target.
+         */
+        const std::size_t defer_depth;
+    };
+
     std::shared_ptr<symbol_table> builtin_symbol_table(const target_info& target);
 
     /**
diff --git a/include/elna/boot/validation.h b/include/elna/boot/validation.h
index 8598ada..87e0b18 100644
--- a/include/elna/boot/validation.h
+++ b/include/elna/boot/validation.h
@@ -65,6 +65,8 @@ namespace elna::boot
         void visit(repeat_statement *statement) override;
         void visit(for_statement *statement) override;
         void visit(defer_statement *statement) override;
+        void visit(block_statement *statement) override;
+        void visit(break_statement *) override;
         void visit(empty_statement *) override;
         void visit(procedure_call *) override;
     };
diff --git a/include/elna/gcc/elna-generic.h b/include/elna/gcc/elna-generic.h
index dde883a..b05a8f9 100644
--- a/include/elna/gcc/elna-generic.h
+++ b/include/elna/gcc/elna-generic.h
@@ -103,6 +103,8 @@ namespace elna::gcc
         void visit(boot::for_statement *statement) override;
         void visit(boot::while_statement *statement) override;
         void visit(boot::defer_statement *statement) override;
+        void visit(boot::block_statement *statement) override;
+        void visit(boot::break_statement *statement) override;
         void visit(boot::empty_statement *) override;
         void visit(boot::case_statement *statement) override;
     };