feat: additional modules support

- allow module related statements to appear in preprocessor blocks
- export declarations can now appear anywhere other declarations can

grammar.js

@@ -50,6 +50,10 @@ const ASSIGNMENT_OPERATORS = [
   'xor_eq',
 ];
 
+const commaSep = C.commaSep;
+const commaSep1 = C.commaSep1;
+const preprocIf = C.preprocIf;
+
 module.exports = grammar(C, {
   name: 'cpp',
 
@@ -133,8 +137,12 @@ module.exports = grammar(C, {
       alias($.operator_cast_definition, $.function_definition),
       alias($.operator_cast_declaration, $.declaration),
     ),
+
     _block_item: ($, original) => choice(
-      ...original.members.filter((member) => member.content?.name != '_old_style_function_definition'),
+      ...original.members.filter((member) =>
+        member.content?.name != '_old_style_function_definition' &&
+        !member.name.startsWith('preproc_if'),
+      ),
       $.namespace_definition,
       $.concept_definition,
       $.namespace_alias_definition,
@@ -144,11 +152,18 @@ module.exports = grammar(C, {
       $.consteval_block_declaration,
       $.template_declaration,
       $.template_instantiation,
+      $.export_declaration,
+      $.import_declaration,
+      alias($.preproc_if_in_block, $.preproc_if),
+      alias($.preproc_ifdef_in_block, $.preproc_ifdef),
       alias($.constructor_or_destructor_definition, $.function_definition),
       alias($.operator_cast_definition, $.function_definition),
       alias($.operator_cast_declaration, $.declaration),
     ),
 
+    ...preprocIf('', $ => $._top_level_item),
+    ...preprocIf('_in_block', $ => $._block_item),
+
     // Types
 
     placeholder_type_specifier: $ => prec(1, seq(
@@ -371,13 +386,12 @@ module.exports = grammar(C, {
       ';',
     ),
 
-    export_declaration: $ => seq(
+    export_declaration: $ => prec(1, seq(
       'export',
-      choice($._block_item, seq('{', repeat($._block_item), '}')),
-    ),
+      choice($._block_item, $.declaration_list),
+    )),
 
     import_declaration: $ => seq(
-      optional('export'),
       'import',
       choice(
         field('name', $.module_name),
@@ -1587,25 +1601,3 @@ module.exports = grammar(C, {
     _namespace_identifier: $ => alias($.identifier, $.namespace_identifier),
   },
 });
-
-/**
- * Creates a rule to optionally match one or more of the rules separated by a comma
- *
- * @param {Rule} rule
- *
- * @returns {ChoiceRule}
- */
-function commaSep(rule) {
-  return optional(commaSep1(rule));
-}
-
-/**
- * Creates a rule to match one or more of the rules separated by a comma
- *
- * @param {Rule} rule
- *
- * @returns {SeqRule}
- */
-function commaSep1(rule) {
-  return seq(rule, repeat(seq(',', rule)));
-}

test/corpus/modules.txt

@@ -73,9 +73,10 @@ export import mod;
 --------------------------------------------------------------------------------
 
 (translation_unit
-  (import_declaration
-    name: (module_name
-      (identifier))))
+  (export_declaration
+    (import_declaration
+      name: (module_name
+        (identifier)))))
 
 ================================================================================
 import Declaration partition with export
@@ -85,10 +86,11 @@ export import :mod;
 --------------------------------------------------------------------------------
 
 (translation_unit
-  (import_declaration
-    partition: (module_partition
-      (module_name
-        (identifier)))))
+  (export_declaration
+    (import_declaration
+      partition: (module_partition
+        (module_name
+          (identifier))))))
 
 ================================================================================
 import Declaration headerunit with export
@@ -98,8 +100,9 @@ export import ;
 --------------------------------------------------------------------------------
 
 (translation_unit
-  (import_declaration
-    header: (system_lib_string)))
+  (export_declaration
+    (import_declaration
+      header: (system_lib_string))))
 
 ================================================================================
 global module fragment
@@ -171,22 +174,23 @@ char const* french() { return "Salut!"; }
         (string_literal
           (string_content)))))
   (export_declaration
-    (function_definition
-      type: (primitive_type)
-      declarator: (function_declarator
-        declarator: (identifier)
-        parameters: (parameter_list))
-      body: (compound_statement
-        (return_statement
-          (number_literal))))
-    (function_definition
-      type: (primitive_type)
-      declarator: (function_declarator
-        declarator: (identifier)
-        parameters: (parameter_list))
-      body: (compound_statement
-        (return_statement
-          (number_literal)))))
+    (declaration_list
+      (function_definition
+        type: (primitive_type)
+        declarator: (function_declarator
+          declarator: (identifier)
+          parameters: (parameter_list))
+        body: (compound_statement
+          (return_statement
+            (number_literal))))
+      (function_definition
+        type: (primitive_type)
+        declarator: (function_declarator
+          declarator: (identifier)
+          parameters: (parameter_list))
+        body: (compound_statement
+          (return_statement
+            (number_literal))))))
   (export_declaration
     (namespace_definition
       name: (namespace_identifier)
@@ -213,3 +217,51 @@ char const* french() { return "Salut!"; }
             (return_statement
               (string_literal
                 (string_content)))))))))
+
+================================================================================
+Modules in preprocessor sections
+================================================================================
+
+#ifdef USE_MODULES
+module;
+#include <vector>
+export module foo;
+#endif
+
+#if USE_MODULES
+import std;
+#else
+import <vector>;
+#endif
+
+export {
+#ifdef USE_MODULE
+class Foo;
+#endif
+}
+
+--------
+
+(translation_unit
+  (preproc_ifdef
+    (identifier)
+    (global_module_fragment_declaration)
+      (preproc_include
+        (system_lib_string))
+    (module_declaration
+      (module_name
+        (identifier))))
+  (preproc_if
+    (identifier)
+    (import_declaration
+      (module_name
+        (identifier)))
+    (preproc_else
+      (import_declaration
+        (system_lib_string))))
+  (export_declaration
+    (declaration_list
+      (preproc_ifdef
+        (identifier)
+        (class_specifier
+          (type_identifier))))))