Added @debug decorator

This decorator's intend is to eliminate debugging functions at compile time. Currently clears the function body, only.

docs/compiled.js

@@ -312,6 +312,7 @@
     this.enclosingClass = null;
     this.currentReturnType = null;
     this.nextGlobalVariableOffset = 0;
+    this.isDebug = false;
     this.boolType = null;
     this.sbyteType = null;
     this.errorType = null;
@@ -426,6 +427,10 @@
             metadata(node, context, decorator);
           }
 
+          else if (decorator.stringValue === "debug") {
+            debug(node, context, decorator);
+          }
+
           else {
             context.log.error(node.range, "There is no such decorator");
           }
@@ -1824,6 +1829,7 @@
       source = source.next;
     }
 
+    this.context.isDebug = this.preprocessor.isDefined("NODEBUG") === false;
     __imports.Profiler_end("parsing");
     __imports.Profiler_begin();
     var global = this.global;
@@ -1905,6 +1911,34 @@
     return builder.append(path).append(extension).finish();
   }
 
+  function debug(node, context, decorator) {
+    __imports.assert(node.kind === 17);
+
+    if (node.functionReturnType().stringValue !== "void") {
+      context.log.error(decorator.range, "This decorator cannot be used with functions specifying a return value");
+
+      return;
+    }
+
+    if (context.isDebug) {
+      return;
+    }
+
+    var body = node.functionBody();
+
+    if (body === null || body.childCount() === 0) {
+      return;
+    }
+
+    var child = body.firstChild;
+
+    while (child !== null) {
+      var next = child.nextSibling;
+      child.remove();
+      child = next;
+    }
+  }
+
   function metadata(node, context, decorator) {
     __imports.assert(node.kind === 17);
     var body = node.functionBody();

src/checker.thin

@@ -6,6 +6,7 @@ class CheckContext {
   enclosingClass: Symbol;
   currentReturnType: Type;
   nextGlobalVariableOffset: int;
+  isDebug: bool;
 
   // Native types
   boolType: Type;
@@ -143,6 +144,7 @@ function initialize(context: CheckContext, node: Node, parentScope: Scope, mode:
       while (decorator != null) {
         var name = decorator.stringValue;
         if (decorator.stringValue == "metadata") metadata(node, context, decorator);
+        else if (decorator.stringValue == "debug") debug(node, context, decorator);
         else context.log.error(node.range, "There is no such decorator");
         decorator = decorator.nextSibling;
       }

src/compiler.thin

@@ -104,6 +104,7 @@ class Compiler {
       }
       source = source.next;
     }
+    this.context.isDebug = this.preprocessor.isDefined("NODEBUG") == false;
 
     Profiler_end("parsing");
     Profiler_begin();

src/decorators/debug.thin

@@ -0,0 +1,27 @@
+// Eliminates functions when compiling with the NODEBUG preprocessor flag.
+// TODO: Add a compiler optimization that removes empty functions and their respective calls.
+
+function debug(node: Node, context: CheckContext, decorator: Node): void {
+  assert(node.kind == NodeKind.FUNCTION);
+
+  // Recover from invalid use
+  if (node.functionReturnType().stringValue != "void") {
+    context.log.error(decorator.range, "This decorator cannot be used with functions specifying a return value");
+    return;
+  }
+
+  if (context.isDebug) return;
+
+  var body = node.functionBody();
+  if (body == null || body.childCount() == 0) { // Import or already empty
+    return;
+  }
+
+  // Clear the body
+  var child = body.firstChild;
+  while (child != null) {
+    var next = child.nextSibling;;
+    child.remove();
+    child = next;
+  }
+}

src/decorators/metadata.thin

@@ -1,12 +1,10 @@
+// Injects basic metadata into the decorated function.
+
 function metadata(node: Node, context: CheckContext, decorator: Node): void {
   assert(node.kind == NodeKind.FUNCTION);
 
-  // This is an example of what decorators could do. However, without a way to extend the
-  // compiler with custom decorators (i.e. imports and function pointers), this feature
-  // won't be of much value, yet.
-
   var body = node.functionBody();
-  if (body == null || body.childCount() == 0) { // No need to instrument empty functions
+  if (body == null || body.childCount() == 0) { // No need to instrument imports or empty functions
     return;
   }