started support for generating source maps (WIP)

plugged in @fitzgen's source-map library

lib/output.js

@@ -53,7 +53,8 @@ function OutputStream(options) {
         width         : 80,
         max_line_len  : 32000,
         ie_proof      : true,
-        beautify      : true
+        beautify      : true,
+        source_map    : null
     });
 
     var indentation = 0;
@@ -152,12 +153,12 @@ function OutputStream(options) {
             might_need_space = false;
             maybe_newline();
         }
-        var a = str.split(/\r?\n/), n = a.length;
+        var a = str.split(/\r?\n/), n = a.length - 1;
         current_line += n;
-        if (n == 1) {
-            current_col += a[n - 1].length;
+        if (n == 0) {
+            current_col += a[n].length;
         } else {
-            current_col = a[n - 1].length;
+            current_col = a[n].length;
         }
         current_pos += str.length;
         last = str;
@@ -243,9 +244,22 @@ function OutputStream(options) {
         if (options.space_colon) space();
     };
 
+    var add_mapping = options.source_map ? function(token, name) {
+        options.source_map.add(
+            current_line, current_col,
+            token.line, token.col,
+            (!name && token.type == "name") ? token.value : name
+        );
+    } : noop;
+
+    function get() {
+        return OUTPUT;
+    };
+
     var stack = [];
     return {
-        get             : function() { return OUTPUT },
+        get             : get,
+        toString        : get,
         indent          : indent,
         newline         : newline,
         print           : print,
@@ -261,6 +275,7 @@ function OutputStream(options) {
         with_block      : with_block,
         with_parens     : with_parens,
         with_square     : with_square,
+        add_mapping     : add_mapping,
         option          : function(opt) { return options[opt] },
         line            : function() { return current_line },
         col             : function() { return current_col },
@@ -287,9 +302,11 @@ function OutputStream(options) {
             stream.push_node(self);
             if (self.needs_parens(stream)) {
                 stream.with_parens(function(){
+                    self.add_source_map(stream);
                     generator(self, stream);
                 });
             } else {
+                self.add_source_map(stream);
                 generator(self, stream);
             }
             stream.pop_node();
@@ -868,11 +885,7 @@ function OutputStream(options) {
     });
     DEFPRINT(AST_SymbolRef, function(self, output){
         var def = self.symbol;
-        if (def) {
-            def.print(output);
-        } else {
-            output.print_name(self.name);
-        }
+        output.print_name(def ? def.mangled_name || def.name : self.name);
     });
     DEFPRINT(AST_This, function(self, output){
         output.print("this");
@@ -973,4 +986,32 @@ function OutputStream(options) {
         });
     };
 
+    /* -----[ source map generators ]----- */
+
+    function DEFMAP(nodetype, generator) {
+        nodetype.DEFMETHOD("add_source_map", function(stream){
+            generator(this, stream);
+        });
+    };
+
+    // We could easily add info for ALL nodes, but it seems to me that
+    // would be quite wasteful, hence this noop in the base class.
+    DEFMAP(AST_Node, noop);
+
+    function basic_sourcemap_gen(self, output) {
+        output.add_mapping(self.start);
+    };
+
+    // XXX: I'm not exactly sure if we need it for all of these nodes,
+    // or if we should add even more.
+
+    DEFMAP(AST_Directive, basic_sourcemap_gen);
+    DEFMAP(AST_Debugger, basic_sourcemap_gen);
+    DEFMAP(AST_Symbol, basic_sourcemap_gen);
+    DEFMAP(AST_Jump, basic_sourcemap_gen);
+    DEFMAP(AST_PropAccess, basic_sourcemap_gen);
+    DEFMAP(AST_ObjectProperty, function(self, output){
+        output.add_mapping(self.start, self.key);
+    });
+
 })();