deps(filename) {
    var opts = utils.merge({ cache: false }, this.options);
    if (filename) opts.filename = filename;

    var DepsResolver = require('./visitor/deps-resolver')
      , parser = new Parser(this.str, opts);

    try {
      nodes.filename = opts.filename;
      // parse
      var ast = parser.parse()
        , resolver = new DepsResolver(ast, opts);

      // resolve dependencies
      return resolver.resolve();
    } catch (err) {
      var options = {};
      options.input = err.input || this.str;
      options.filename = err.filename || opts.filename;
      options.lineno = err.lineno || parser.lexer.lineno;
      options.column = err.column || parser.lexer.column;
      throw utils.formatException(err, options);
    }
  }
Get dependencies of the compiled file.

@param {String} [filename]
@return {Array}
@api public