checkpoint (refactoring, WIP)

lib/ast.js

@@ -709,5 +709,39 @@ TreeWalker.prototype = {
     },
     parent: function(n) {
         return this.stack[this.stack.length - 2 - (n || 0)];
-    }
+    },
+    push: function (node) {
+        this.stack.push(node);
+    },
+    pop: function() {
+        return this.stack.pop();
+    },
+    self: function() {
+        return this.stack[this.stack.length - 1];
+    },
+    find_parent: function(type) {
+        var stack = this.stack;
+        for (var i = stack.length; --i >= 0;) {
+            var x = stack[i];
+            if (x instanceof type) return x;
+        }
+    },
+    in_boolean_context: function() {
+        var stack = this.stack;
+        var i = stack.length, self = stack[--i];
+        while (i > 0) {
+            var p = stack[--i];
+            if ((p instanceof AST_If           && p.condition === self) ||
+                (p instanceof AST_Conditional  && p.condition === self) ||
+                (p instanceof AST_DWLoop       && p.condition === self) ||
+                (p instanceof AST_For          && p.condition === self) ||
+                (p instanceof AST_UnaryPrefix  && p.operator == "!" && p.expression === self))
+            {
+                return true;
+            }
+            if (!(p instanceof AST_Binary && (p.operator == "&&" || p.operator == "||")))
+                return false;
+            self = p;
+        }
+    },
 };