Implements #168

README.md

@@ -19,7 +19,7 @@ NilScript was formerly known as oj.
   - [Behind the Scenes](#class-compiler)
 - [The Built-in Base Class](#base-class)
 - [Methods](#method)
-  - [Falsy Messaging](#method-falsy)
+  - [Nullish Messaging](#method-nullish)
   - [Behind the Scenes](#method-compiler)
 - [Properties and Instance Variables](#property)
   - [Synthesis](#property-synthesis) 
@@ -196,15 +196,17 @@ Old-school bare method declarations may also be used:
 @end
 ```
 
-### <a name="method-falsy"></a>Falsy Messaging
+### <a name="method-nullish"></a>Nullish Messaging
 
-Just as Objective-C supports messaging `nil`, NilScript supports the concept of "Falsy Messaging".
+Just as Objective-C supports messaging `nil`, NilScript supports the concept of "Nullish Messaging".
 
-Any message to a falsy JavaScript value (false / undefined / null / 0 / "" / NaN ) will return that value.  
+Any message to a nullish JavaScript value (`undefined` or `null`) will return `null`.
 
 ```
-let foo = null;
-let result = [foo doSomething];  // result is null
+let foo1 = null;
+let foo2 = undefined;
+let result1 = [foo1 doSomething];  // result1 is null
+let result2 = [foo2 doSomething];  // result2 is also null
 ```
 
 ### <a name="method-compiler"></a>Behind the Scenes (Methods)

src/Builder.js

@@ -34,8 +34,9 @@ build()
 
     let traverser = new Traverser(nsFile.ast);
 
-    let currentClass, currentMethod;
+    let currentClass, currentMethod, currentMethodNode;
     let currentProtocol;
+    let functionCount = 0;
 
     let usedSelectorMap   = { };
 
@@ -159,6 +160,8 @@ build()
         let method = makeNSMethodNode(node);
         currentClass.addMethod(method);
         currentMethod = method;
+        currentMethodNode = node;
+        functionCount = 0;
     }
 
     function handleNSMethodDeclaration(node)
@@ -406,8 +409,25 @@ build()
         let name = node.name;
         let transformable = isIdentifierTransformable(node);
 
-        if (transformable && (name[0] == "_") && (name.length > 0) && currentMethod && currentClass) {
-            currentClass.markUsedIvar(name);
+        if (currentMethod && currentClass) {
+            if (transformable && (name[0] == "_") && (name.length > 0)) {
+                if (functionCount > 0) {
+                    currentMethodNode.ns_needs_var_self = true;
+                }
+
+                currentClass.markUsedIvar(name);
+
+            } else if (name == "self") {
+                if (functionCount > 0) {
+                    currentMethodNode.ns_needs_var_self = true;
+                }
+
+                let parent = node.ns_parent;
+
+                if (parent.type == Syntax.AssignmentExpression && parent.left == node) {
+                    currentMethodNode.ns_needs_var_self = true;
+                }
+            }
         }
 
         node.ns_transformable = transformable;
@@ -475,9 +495,14 @@ build()
                 handleVariableDeclarator(node);
 
             } else if (type === Syntax.FunctionDeclaration || type === Syntax.FunctionExpression) {
+                functionCount++;
                 handleFunctionDeclarationOrExpression(node);
 
             } else if (type === Syntax.NSMessageExpression) {
+                if (node.selectorName == "alloc") {
+                    node.ns_nonnull = true;
+                }
+
                 usedSelectorMap[node.selectorName] = true;
 
             } else if (type === Syntax.NSSelectorDirective) {
@@ -505,12 +530,17 @@ build()
         if (type === Syntax.NSClassImplementation) {
             currentClass  = null;
             currentMethod = null;
+            currentMethodNode = null;
 
         } else if (type === Syntax.NSProtocolDefinition) {
             currentProtocol = null;
 
         } else if (type === Syntax.NSMethodDefinition) {
             currentMethod = null;
+            currentMethodNode = null;
+
+        } else if (type === Syntax.FunctionDeclaration || type === Syntax.FunctionExpression) {
+            functionCount--;
         }
     });