Add implementation of dependency tree

Author: lukeapage

bin/lessc

@@ -163,7 +163,10 @@ var ensureDirectory = function (filepath) {
 };
 
 if (options.depends) {
-    // output the target filename, needs to be specified on the command line (no stdout)
+    if (!outputbase) {
+        sys.print("option --depends requires an output path to be specified");
+        return;
+    }
     sys.print(outputbase + ": ");
 }
 
@@ -184,8 +187,10 @@ var parseLessFile = function (e, data) {
             currentErrorcode = 1;
             return;
         } else if (options.depends) {
-            // todo - loop through the imports
-            // sys.print(path.resolve(path.dirname(env.parentPath),importname)
+            for(var file in parser.imports.files) {
+                sys.print(file + " ")
+            }
+            sys.print("\n");
         } else if(!options.lint) {
             try {
                 var css = tree.toCSS({

lib/less/lessc_helper.js

@@ -30,6 +30,7 @@ var lessc_helper = {
         sys.puts("options:");
         sys.puts("  -h, --help              Print help (this message) and exit.");
         sys.puts("  --include-path          Set include paths. Separated by `:'. Use `;' on Windows.");
+        sys.puts("  -M, --depends           Output a makefile import dependency list to stdout");
         sys.puts("  --no-color              Disable colorized output.");
         sys.puts("  --no-ie-compat          Disable IE compatibility checks.");
         sys.puts("  -l, --lint              Syntax check only (lint).");