uglify2之transform

全部的节点的transform方法都对应同一个函数:

        node.DEFMETHOD("transform", function(tw, in_list){
            var x, y;
            tw.push(this);
            if (tw.before) x = tw.before(this, descend, in_list);
            if (x === undefined) {
                if (!tw.after) {
                    x = this;
                    descend(x, tw);
                } else {
                    tw.stack[tw.stack.length - 1] = x = this.clone();
                    descend(x, tw);
                    y = tw.after(x, in_list);
                    if (y !== undefined) x = y;
                }
            }
            tw.pop();
            return x;
        });

不一样的是每一个节点能够有不一样的descend方法 

AST_Node的descend方法为一个空函数

如下节点有自定义的descend方法

AST_LabeledStatement,AST_SimpleStatement,AST_Block,AST_DWLoop,AST_For,AST_ForIn,

AST_With,AST_Exit,AST_LoopControl,AST_If,AST_Switch,AST_Case,AST_Try,AST_Catch,

AST_Definitions,AST_VarDef,AST_Lambda,AST_Call,AST_Seq,AST_Dot,AST_Sub,

AST_Unary,AST_Binary,AST_Conditional,AST_Array,AST_Object,AST_ObjectProperty