Add support for #else and #elif preprocessor directives

.github/agents/midl-dev.agent.md

@@ -103,7 +103,8 @@ npm run test:parser      # Run parser tests
 - Open any `.idl` file to test language features
 
 ### Publishing
-- Update version: `npm version patch`
+- **Always bump the package version** in `package.json` when making changes that will be published
+- Use semantic versioning: patch (0.0.X) for bug fixes, minor (0.X.0) for features, major (X.0.0) for breaking changes
 - Publishing happens automatically via GitHub Actions on push to main
 
 ## Common Development Tasks
@@ -168,6 +169,7 @@ When working on this repository:
 6. **Document**: Update README or comments if making significant changes
 7. **Security**: Check for vulnerabilities, especially in dependencies
 8. **Validate**: Test language features in a real VSCode instance when possible
+9. **Version Bumping**: Always bump the package version in `package.json` for any PR that will be merged (use patch version for bug fixes, minor for features)
 
 ## Example Tasks
 

package.json

@@ -5,7 +5,7 @@
 	"icon": "images/midl3.png",
 	"author": "Microsoft Corporation",
 	"license": "MIT",
-	"version": "0.0.32",
+	"version": "0.0.33",
 	"repository": {
 		"type": "git",
 		"url": "https://github.com/asklar/midl-langserv"

server/src/midl.pegjs

@@ -52,7 +52,9 @@ importKeyword = "import" { return emit('keyword'); }
   ( includeKW _ includeReference ) /
   ( ifdefKW _ preprocessorExpression ) /
   ( ifndefKW _ preprocessorExpression ) /
+  ( elifKW _ preprocessorExpression ) /
   ( ifKW _ preprocessorExpression) /
+  ( elseKW ) /
   ( endifKW ) /
   ( defineKW _ identifier preprocessorExpression ) /
   ( undefKW _ identifier )
@@ -61,7 +63,9 @@ importKeyword = "import" { return emit('keyword'); }
 includeKW = "#include" { emit('preProcessor'); }
 ifdefKW = "#ifdef" { emit('preProcessor'); }
 ifndefKW = "#ifndef" { emit('preProcessor'); }
+elifKW = "#elif" { emit('preProcessor'); }
 ifKW = "#if" { emit('preProcessor'); }
+elseKW = "#else" { emit('preProcessor'); }
 endifKW = "#endif" { emit('preProcessor'); }
 defineKW = "#define" { emit('preProcessor'); }
 undefKW = "#undef" { emit('preProcessor'); }

server/src/test/assets/preprocessor.idl

@@ -0,0 +1,24 @@
+#ifndef FOO
+#define FOO 1
+
+namespace TestNamespace
+{
+    runtimeclass TestClass
+    {
+        TestClass();
+        Int32 TestProperty{ get; };
+    }
+}
+
+#else
+
+namespace AlternateNamespace
+{
+    runtimeclass AlternateClass
+    {
+        AlternateClass();
+        String AlternateProperty{ get; };
+    }
+}
+
+#endif

server/src/test/assets/preprocessor_elif.idl

@@ -0,0 +1,38 @@
+#ifndef VERSION
+#define VERSION 3
+#endif
+
+#if VERSION == 1
+
+namespace Version1
+{
+    runtimeclass MyClass
+    {
+        MyClass();
+        Int32 Property1{ get; };
+    }
+}
+
+#elif VERSION == 2
+
+namespace Version2
+{
+    runtimeclass MyClass
+    {
+        MyClass();
+        String Property2{ get; };
+    }
+}
+
+#else
+
+namespace DefaultVersion
+{
+    runtimeclass MyClass
+    {
+        MyClass();
+        Boolean Property3{ get; };
+    }
+}
+
+#endif

syntaxes/midl3.tmGrammar.json

@@ -18,7 +18,7 @@
 		},
 		"preprocessor": {
 			"name": "keyword.other",
-			"match": "#(include|define|ifdef|ifndef|if|else|endif|pragma)"
+			"match": "#(include|define|ifdef|ifndef|if|elif|else|endif|pragma)"
 		},
 		"comment": {
 			"patterns": [