blog.erl

-module(blog).
-compile(export_all).

transform(Forms) ->
	Tree = erl_syntax:form_list(Forms),
	ModifiedTree = postorder(Fun, Tree),
	erl_syntax:revert_forms(ModifiedTree).

parse_transform(Forms, Options) ->
	TransFun =
		case lists:keysearch(trans_fun, 1, Options) of
			{value, {trans_fun, Fun}} ->
				Fun;
			false ->
				fun blog:replaceSend/1
		end,			
	transform(Forms, Fun).

replaceSend(Node) ->
	case erl_syntax:type(Node) of
		infix_expr ->
			OpNode = erl_syntax:infix_expr_operator(Node),
			case erl_syntax:operator_name(OpNode) of
				'!' ->
					erl_syntax:block_expr([
						erl_syntax:application(
							erl_syntax:module_qualifier(erl_syntax:atom(io), erl_syntax:atom(format)),[erl_syntax:string("About to send:~n")]),
						Node
					]);
				_ ->
					Node
			end;
		_ ->
			Node
	end.
	
postorder(F, Tree) ->
         F(case erl_syntax:subtrees(Tree) of
             [] -> Tree;
             List -> erl_syntax:update_tree(Tree,
                                 [[postorder(F, Subtree)
                                   || Subtree <- Group]
                                  || Group <- List])
           end).