repl: Add editor mode support

```js > node > .editor // Entering editor mode (^D to finish, ^C to cancel) function test() { console.log('tested!'); } test(); // ^D tested! undefined > ``` PR-URL: #7275 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Evan Lucas <evanlucas@me.com>

Author: princejwesley

doc/api/repl.md

@@ -38,6 +38,21 @@ The following special commands are supported by all REPL instances:
  `> .save ./file/to/save.js`
 * `.load` - Load a file into the current REPL session.
  `> .load ./file/to/load.js`
+* `.editor` - Enter editor mode (`<ctrl>-D` to finish, `<ctrl>-C` to cancel)
+
+```js
+> .editor
+// Entering editor mode (^D to finish, ^C to cancel)
+function welcome(name) {
+ return `Hello ${name}!`;
+}
+
+welcome('Node.js User');
+
+// ^D
+'Hello Node.js User!'
+>
+```
 
 The following key combinations in the REPL have these special effects:
 

lib/repl.js

@@ -223,6 +223,7 @@ function REPLServer(prompt,
  self.underscoreAssigned = false;
  self.last = undefined;
  self.breakEvalOnSigint = !!breakEvalOnSigint;
+ self.editorMode = false;
 
  self._inTemplateLiteral = false;
 
@@ -394,7 +395,12 @@ function REPLServer(prompt,
  // Figure out which "complete" function to use.
  self.completer = (typeof options.completer === 'function')
  ? options.completer
- : complete;
+ : completer;
+
+ function completer(text, cb) {
+ complete.call(self, text, self.editorMode
+ ? self.completeOnEditorMode(cb) : cb);
+ }
 
  Interface.call(this, {
  input: self.inputStream,
@@ -428,9 +434,11 @@ function REPLServer(prompt,
  });
 
  var sawSIGINT = false;
+ var sawCtrlD = false;
  self.on('SIGINT', function() {
  var empty = self.line.length === 0;
  self.clearLine();
+ self.turnOffEditorMode();
 
  if (!(self.bufferedCommand && self.bufferedCommand.length > 0) && empty) {
  if (sawSIGINT) {
@@ -454,6 +462,11 @@ function REPLServer(prompt,
  debug('line %j', cmd);
  sawSIGINT = false;
 
+ if (self.editorMode) {
+ self.bufferedCommand += cmd + '\n';
+ return;
+ }
+
  // leading whitespaces in template literals should not be trimmed.
  if (self._inTemplateLiteral) {
  self._inTemplateLiteral = false;
@@ -499,7 +512,8 @@ function REPLServer(prompt,
 
  // If error was SyntaxError and not JSON.parse error
  if (e) {
- if (e instanceof Recoverable && !self.lineParser.shouldFail) {
+ if (e instanceof Recoverable && !self.lineParser.shouldFail &&
+ !sawCtrlD) {
  // Start buffering data like that:
  // {
  // ... x: 1
@@ -515,6 +529,7 @@ function REPLServer(prompt,
  // Clear buffer if no SyntaxErrors
  self.lineParser.reset();
  self.bufferedCommand = '';
+ sawCtrlD = false;
 
  // If we got any output - print it (if no error)
  if (!e &&
@@ -555,9 +570,55 @@ function REPLServer(prompt,
  });
 
  self.on('SIGCONT', function() {
- self.displayPrompt(true);
+ if (self.editorMode) {
+ self.outputStream.write(`${self._initialPrompt}.editor\n`);
+ self.outputStream.write(
+ '// Entering editor mode (^D to finish, ^C to cancel)\n');
+ self.outputStream.write(`${self.bufferedCommand}\n`);
+ self.prompt(true);
+ } else {
+ self.displayPrompt(true);
+ }
  });
 
+ // Wrap readline tty to enable editor mode
+ const ttyWrite = self._ttyWrite.bind(self);
+ self._ttyWrite = (d, key) => {
+ if (!self.editorMode || !self.terminal) {
+ ttyWrite(d, key);
+ return;
+ }
+
+ // editor mode
+ if (key.ctrl && !key.shift) {
+ switch (key.name) {
+ case 'd': // End editor mode
+ self.turnOffEditorMode();
+ sawCtrlD = true;
+ ttyWrite(d, { name: 'return' });
+ break;
+ case 'n': // Override next history item
+ case 'p': // Override previous history item
+ break;
+ default:
+ ttyWrite(d, key);
+ }
+ } else {
+ switch (key.name) {
+ case 'up': // Override previous history item
+ case 'down': // Override next history item
+ break;
+ case 'tab':
+ // prevent double tab behavior
+ self._previousKey = null;
+ ttyWrite(d, key);
+ break;
+ default:
+ ttyWrite(d, key);
+ }
+ }
+ };
+
  self.displayPrompt();
 }
 inherits(REPLServer, Interface);
@@ -680,6 +741,12 @@ REPLServer.prototype.setPrompt = function setPrompt(prompt) {
  REPLServer.super_.prototype.setPrompt.call(this, prompt);
 };
 
+REPLServer.prototype.turnOffEditorMode = function() {
+ this.editorMode = false;
+ this.setPrompt(this._initialPrompt);
+};
+
+
 // A stream to push an array into a REPL
 // used in REPLServer.complete
 function ArrayStream() {
@@ -987,6 +1054,39 @@ function complete(line, callback) {
  }
 }
 
+function longestCommonPrefix(arr = []) {
+ const cnt = arr.length;
+ if (cnt === 0) return '';
+ if (cnt === 1) return arr[0];
+
+ const first = arr[0];
+ // complexity: O(m * n)
+ for (let m = 0; m < first.length; m++) {
+ const c = first[m];
+ for (let n = 1; n < cnt; n++) {
+ const entry = arr[n];
+ if (m >= entry.length || c !== entry[m]) {
+ return first.substring(0, m);
+ }
+ }
+ }
+ return first;
+}
+
+REPLServer.prototype.completeOnEditorMode = (callback) => (err, results) => {
+ if (err) return callback(err);
+
+ const [completions, completeOn = ''] = results;
+ const prefixLength = completeOn.length;
+
+ if (prefixLength === 0) return callback(null, [[], completeOn]);
+
+ const isNotEmpty = (v) => v.length > 0;
+ const trimCompleteOnPrefix = (v) => v.substring(prefixLength);
+ const data = completions.filter(isNotEmpty).map(trimCompleteOnPrefix);
+
+ callback(null, [[`${completeOn}${longestCommonPrefix(data)}`], completeOn]);
+};
 
 /**
  * Used to parse and execute the Node REPL commands.
@@ -1189,6 +1289,17 @@ function defineDefaultCommands(repl) {
  this.displayPrompt();
  }
  });
+
+ repl.defineCommand('editor', {
+ help: 'Entering editor mode (^D to finish, ^C to cancel)',
+ action() {
+ if (!this.terminal) return;
+ this.editorMode = true;
+ REPLServer.super_.prototype.setPrompt.call(this, '');
+ this.outputStream.write(
+ '// Entering editor mode (^D to finish, ^C to cancel)\n');
+ }
+ });
 }
 
 function regexpEscape(s) {

test/parallel/test-repl-.editor.js

@@ -0,0 +1,55 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const repl = require('repl');
+
+// \u001b[1G - Moves the cursor to 1st column
+// \u001b[0J - Clear screen
+// \u001b[3G - Moves the cursor to 3rd column
+const terminalCode = '\u001b[1G\u001b[0J> \u001b[3G';
+
+function run(input, output, event) {
+ const stream = new common.ArrayStream();
+ let found = '';
+
+ stream.write = (msg) => found += msg.replace('\r', '');
+
+ const expected = `${terminalCode}.editor\n` +
+ '// Entering editor mode (^D to finish, ^C to cancel)\n' +
+ `${input}${output}\n${terminalCode}`;
+
+ const replServer = repl.start({
+ prompt: '> ',
+ terminal: true,
+ input: stream,
+ output: stream,
+ useColors: false
+ });
+
+ stream.emit('data', '.editor\n');
+ stream.emit('data', input);
+ replServer.write('', event);
+ replServer.close();
+ assert.strictEqual(found, expected);
+}
+
+const tests = [
+ {
+ input: '',
+ output: '\n(To exit, press ^C again or type .exit)',
+ event: {ctrl: true, name: 'c'}
+ },
+ {
+ input: 'var i = 1;',
+ output: '',
+ event: {ctrl: true, name: 'c'}
+ },
+ {
+ input: 'var i = 1;\ni + 3',
+ output: '\n4',
+ event: {ctrl: true, name: 'd'}
+ }
+];
+
+tests.forEach(({input, output, event}) => run(input, output, event));

test/parallel/test-repl-tab-complete.js

@@ -348,3 +348,25 @@ testCustomCompleterAsyncMode.complete('a', common.mustCall((error, data) => {
  'a'
  ]);
 }));
+
+// tab completion in editor mode
+const editorStream = new common.ArrayStream();
+const editor = repl.start({
+ stream: editorStream,
+ terminal: true,
+ useColors: false
+});
+
+editorStream.run(['.clear']);
+editorStream.run(['.editor']);
+
+editor.completer('co', common.mustCall((error, data) => {
+ assert.deepStrictEqual(data, [['con'], 'co']);
+}));
+
+editorStream.run(['.clear']);
+editorStream.run(['.editor']);
+
+editor.completer('var log = console.l', common.mustCall((error, data) => {
+ assert.deepStrictEqual(data, [['console.log'], 'console.l']);
+}));