Add --fix-to-stdout

README.md

@@ -58,6 +58,8 @@ along with an access token in `~/.eslint_d`.
 
 ## Editor integration
 
+### Linting
+
 - __Sublime__: Check out [SublimeLinter-contrib-eslint\_d][SublimeLinter].
 - __Vim__: Install the [syntastic][] plugin, then make sure this is in your
   `.vimrc`:
@@ -82,6 +84,42 @@ along with an access token in `~/.eslint_d`.
 
 If you're using `eslint_d` in any other editor, please tell me!
 
+### Automatic Fixing
+
+`eslint_d` has an additional flag that `eslint` does not have, `--fix-to-stdout`
+which prints the fixed file to stdout. This allows editors to add before save
+hooks to automatically fix a file prior to saving. It must be used with
+`--stdin`.
+
+- __Emacs__: Add this to your `init.el`, be sure to add hooks for the actual
+  major modes you use:
+
+    ```elisp
+    (defun eslint-fix ()
+      (interactive)
+      (setq temp-point (point))
+      (shell-command-on-region
+       ;; Region
+       (point-min)
+       (point-max)
+       ;; Command
+       "eslint_d --stdin --fix-to-stdout"
+       ;; Output to current buffer
+       t
+       ;; Replace buffer
+       t
+       ;; Error buffer name
+       "*eslint-fix error*"
+       ;; Display error buffer
+       t)
+      ;; Refresh syntax highlighting
+      (font-lock-fontify-buffer)
+      (goto-char temp-point))
+
+    (add-hook 'js-mode-hook
+              (lambda () (add-hook 'before-save-hook #'eslint-fix)))
+    ```
+
 ## Moar speed
 
 If you're really into performance and want the lowest possible latency, talk to

lib/linter.js

@@ -21,7 +21,7 @@ function translateOptions(cliOptions, cwd) {
     cache: cliOptions.cache,
     cacheFile: cliOptions.cacheFile,
     cacheLocation: cliOptions.cacheLocation,
-    fix: cliOptions.fix,
+    fix: cliOptions.fix || cliOptions.fixToStdout,
     allowInlineConfig: cliOptions.inlineConfig,
     printConfig: cliOptions.printConfig,
     cwd: cwd
@@ -49,7 +49,12 @@ module.exports = function (cwd, args, text) {
       }))
     };
   }
-  var currentOptions = options.parse([0, 0].concat(args));
+  var currentOptions;
+  try {
+    currentOptions = options.parse([0, 0].concat(args));
+  } catch (e) {
+    return e.message + '\n# exit 1';
+  }
   cwdDeps.chalk.enabled = currentOptions.color;
   var files = currentOptions._;
   var stdin = currentOptions.stdin;
@@ -74,12 +79,19 @@ module.exports = function (cwd, args, text) {
 
     return JSON.stringify(fileConfig, null, '  ');
   }
+  if (currentOptions.fixToStdout && !stdin) {
+    return 'The --fix-to-stdout option must be used with --stdin.'
+      + '\n# exit 1';
+  }
   var report;
-  if (stdin && text) {
+  if (stdin) {
     report = engine.executeOnText(text, currentOptions.stdinFilename);
   } else {
     report = engine.executeOnFiles(files);
   }
+  if (currentOptions.fixToStdout) {
+    return report.results[0].output || text;
+  }
   if (currentOptions.fix) {
     cwdDeps.eslint.CLIEngine.outputFixes(report);
   }

lib/options.js

@@ -158,6 +158,12 @@ module.exports = optionator({
       default: false,
       description: 'Automatically fix problems'
     },
+    {
+      option: 'fix-to-stdout',
+      type: 'Boolean',
+      description: 'Print the fix results to stdout instead of regular output, '
+        + 'must be used with --stdin'
+    },
     {
       option: 'debug',
       type: 'Boolean',