From 265e6d6a27eebbcafbd73f0da76e516a139f21d1 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 4 Jul 2026 22:29:49 +0200
Subject: Allow empty statements

---
 boot/ast.cc      | 15 +++++++++++++++
 boot/parser.yy   | 28 +++++++++++++---------------
 boot/semantic.cc |  8 ++++++++
 3 files changed, 36 insertions(+), 15 deletions(-)

(limited to 'boot')

diff --git a/boot/ast.cc b/boot/ast.cc
index e4c46a4..91b46a4 100644
--- a/boot/ast.cc
+++ b/boot/ast.cc
@@ -114,6 +114,11 @@ namespace elna::boot
         not_implemented();
     }
 
+    void empty_visitor::visit(empty_statement *)
+    {
+        not_implemented();
+    }
+
     void empty_visitor::visit(case_statement *)
     {
         not_implemented();
@@ -702,6 +707,16 @@ namespace elna::boot
         }
     }
 
+    void empty_statement::accept(parser_visitor *visitor)
+    {
+        visitor->visit(this);
+    }
+
+    empty_statement::empty_statement(const struct position position)
+        : node(position)
+    {
+    }
+
     designator_expression::~designator_expression()
     {
     }
diff --git a/boot/parser.yy b/boot/parser.yy
index 1a5364b..4d4f038 100644
--- a/boot/parser.yy
+++ b/boot/parser.yy
@@ -140,7 +140,7 @@ along with GCC; see the file COPYING3.  If not see
 %type <elna::boot::procedure_call*> call_expression;
 %type <elna::boot::return_statement *> return_statement;
 %type <elna::boot::statement *> statement;
-%type <std::vector<elna::boot::statement *>> required_statements optional_statements;
+%type <std::vector<elna::boot::statement *>> statements;
 %type <std::unique_ptr<std::vector<elna::boot::statement *>>> statement_part;
 %type <elna::boot::procedure_declaration *> procedure_declaration;
 %type <std::pair<std::vector<std::string>, elna::boot::procedure_type_expression *>> procedure_heading;
@@ -193,12 +193,12 @@ block: constant_part variable_part statement_part "end"
         }
 statement_part:
     /* no statements */ {}
-    | "begin" required_statements { $$ = std::make_unique<std::vector<boot::statement *>>(std::move($2));; }
+    | "begin" statements { $$ = std::make_unique<std::vector<boot::statement *>>(std::move($2));; }
     | return_statement
         {
             $$ = std::make_unique<std::vector<boot::statement *>>(std::vector<boot::statement *>{ $1 });
         }
-    | "begin" required_statements ";" return_statement
+    | "begin" statements ";" return_statement
         {
             $$ = std::make_unique<std::vector<boot::statement *>>(std::move($2));
             $$->push_back($4);
@@ -253,7 +253,7 @@ call_expression: designator_expression actual_parameter_list
 cast_expression: "cast" "(" expression ":" type_expression ")"
         { $$ = new boot::cast_expression(boot::make_position(@1), $5, $3); }
 elsif_do_statements:
-    "elsif" expression "do" optional_statements elsif_do_statements
+    "elsif" expression "do" statements elsif_do_statements
         {
             boot::conditional_statements *branch = new boot::conditional_statements($2, std::move($4));
             std::swap($5, $$);
@@ -261,10 +261,10 @@ elsif_do_statements:
         }
     | {}
 else_statements:
-    "else" optional_statements { $$ = new std::vector<boot::statement *>(std::move($2)); }
+    "else" statements { $$ = new std::vector<boot::statement *>(std::move($2)); }
     | { $$ = nullptr; }
 elsif_then_statements:
-    "elsif" expression "then" optional_statements elsif_then_statements
+    "elsif" expression "then" statements elsif_then_statements
         {
             boot::conditional_statements *branch = new boot::conditional_statements($2, std::move($4));
             std::swap($5, $$);
@@ -406,22 +406,23 @@ designator_expression:
 statement:
     designator_expression ":=" expression
         { $$ = new boot::assign_statement(boot::make_position(@1), $1, $3); }
-    | "while" expression "do" optional_statements elsif_do_statements "end"
+    | "while" expression "do" statements elsif_do_statements "end"
         {
             boot::conditional_statements *body = new boot::conditional_statements($2, std::move($4));
             $$ = new boot::while_statement(boot::make_position(@1), body, std::move($5));
         }
-    | "if" expression "then" optional_statements elsif_then_statements else_statements "end"
+    | "if" expression "then" statements elsif_then_statements else_statements "end"
         {
             boot::conditional_statements *then = new boot::conditional_statements($2, std::move($4));
             $$ = new boot::if_statement(boot::make_position(@1), then, std::move($5), $6);
         }
     | call_expression { $$ = $1; }
-    | "defer" optional_statements "end"
+    | "defer" statements "end"
         { $$ = new boot::defer_statement(boot::make_position(@1), std::move($2)); }
     | "case" expression "of" switch_cases else_statements "end"
         { $$ = new boot::case_statement(boot::make_position(@1), $2, std::move($4), $5); }
-switch_case: case_labels ":" optional_statements
+	| { $$ = new boot::empty_statement(boot::make_position(@$)); }
+switch_case: case_labels ":" statements
         { $$ = { .labels = std::move($1), .statements = std::move($3) }; }
 switch_cases:
     switch_case "|" switch_cases
@@ -437,16 +438,13 @@ case_labels:
             $$.emplace($$.cbegin(), $1);
         }
     | expression { $$.push_back($1); }
-required_statements:
-    required_statements ";" statement
+statements:
+    statements ";" statement
         {
             std::swap($$, $1);
             $$.insert($$.cend(), $3);
         }
     | statement { $$.push_back($1); }
-optional_statements:
-    required_statements { std::swap($$, $1); }
-    | /* no statements */ {}
 field_declaration:
     IDENTIFIER ":" type_expression { $$ = std::make_pair($1, $3); }
 required_fields:
diff --git a/boot/semantic.cc b/boot/semantic.cc
index 3ccc81b..300c91d 100644
--- a/boot/semantic.cc
+++ b/boot/semantic.cc
@@ -139,6 +139,10 @@ namespace elna::boot
     {
     }
 
+    void type_analysis_visitor::visit(empty_statement *)
+    {
+    }
+
     void type_analysis_visitor::visit(case_statement *)
     {
     }
@@ -463,6 +467,10 @@ namespace elna::boot
         }
     }
 
+    void name_analysis_visitor::visit(empty_statement *)
+    {
+    }
+
     void name_analysis_visitor::visit(case_statement *statement)
     {
         statement->condition().accept(this);
-- 
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