repl: Proposal for better repl (implementation)

doc/api/repl.md

@@ -27,11 +27,7 @@ customizable evaluation functions.
 
 The following special commands are supported by all REPL instances:
 
-* `.break` - When in the process of inputting a multi-line expression, entering
-  the `.break` command (or pressing the `<ctrl>-C` key combination) will abort
-  further input or processing of that expression.
-* `.clear` - Resets the REPL `context` to an empty object and clears any
-  multi-line expression currently being input.
+* `.clear` - Resets the local REPL `context` to an empty object.
 * `.exit` - Close the I/O stream, causing the REPL to exit.
 * `.help` - Show this list of special commands.
 * `.save` - Save the current REPL session to a file:
@@ -56,7 +52,7 @@ welcome('Node.js User');
 
 The following key combinations in the REPL have these special effects:
 
-* `<ctrl>-C` - When pressed once, has the same effect as the `.break` command.
+* `<ctrl>-C` - When pressed once, it will break the current command.
   When pressed twice on a blank line, has the same effect as the `.exit`
   command.
 * `<ctrl>-D` - Has the same effect as the `.exit` command.
@@ -178,34 +174,6 @@ function myEval(cmd, context, filename, callback) {
 repl.start({prompt: '> ', eval: myEval});
 ```
 
-#### Recoverable Errors
-
-As a user is typing input into the REPL prompt, pressing the `<enter>` key will
-send the current line of input to the `eval` function. In order to support
-multi-line input, the eval function can return an instance of `repl.Recoverable`
-to the provided callback function:
-
-```js
-function myEval(cmd, context, filename, callback) {
-  let result;
-  try {
-    result = vm.runInThisContext(cmd);
-  } catch (e) {
-    if (isRecoverableError(e)) {
-      return callback(new repl.Recoverable(e));
-    }
-  }
-  callback(null, result);
-}
-
-function isRecoverableError(error) {
-  if (error.name === 'SyntaxError') {
-    return /^(Unexpected end of input|Unexpected token)/.test(error.message);
-  }
-  return false;
-}
-```
-
 ### Customizing REPL Output
 
 By default, `repl.REPLServer` instances format output using the
@@ -420,6 +388,18 @@ changes:
   * `breakEvalOnSigint` - Stop evaluating the current piece of code when
     `SIGINT` is received, i.e. `Ctrl+C` is pressed. This cannot be used together
     with a custom `eval` function. Defaults to `false`.
+  * `executeOnTimeout` {number} If `terminal` is false,`executeOnTimeout`
+     delay is used to determine the end of expression. Defaults to 50ms.
+     `executeOnTimeout` will be coerced to `[100, 2000]` range.
+  * `displayWelcomeMessage` {boolean} If `true`, welcome message will be
+    displayed. Defaults to `false`.
+```js
+> node
+Welcome to Node.js <<version>> (<<vm name>> VM, <<vm version>>)
+Type ^M or enter to execute, ^J to continue, ^C to exit
+Or try .help for help, more at https://nodejs.org/dist/<<version>>/docs/api/repl.html
+>
+```
 
 The `repl.start()` method creates and starts a `repl.REPLServer` instance.
 
@@ -440,11 +420,15 @@ without passing any arguments (or by passing the `-i` argument):
 
 ```js
 $ node
-> const a = [1, 2, 3];
+Welcome to Node.js v6.5.0 (v8 VM, 5.1.281.81)
+Type ^M or enter to execute, ^J to continue, ^C to exit
+Or try .help for help, more at https://nodejs.org/dist/v6.5.0/docs/api/repl.html
+
+> a = [1, 2, 3]; // ^M or ⏎
 [ 1, 2, 3 ]
-> a.forEach((v) => {
-...   console.log(v);
-...   });
+> a.forEach((v) => { // ^J to continue
+   console.log(v);
+  });
 1
 2
 3

lib/_debugger.js

@@ -765,7 +765,8 @@ function Interface(stdin, stdout, args) {
     output: this.stdout,
     eval: (code, ctx, file, cb) => this.controlEval(code, ctx, file, cb),
     useGlobal: false,
-    ignoreUndefined: true
+    ignoreUndefined: true,
+    displayWelcomeMessage: false,
   };
   if (parseInt(process.env['NODE_NO_READLINE'], 10)) {
     opts.terminal = false;

lib/internal/repl.js

@@ -24,7 +24,8 @@ function createRepl(env, opts, cb) {
     ignoreUndefined: false,
     terminal: process.stdout.isTTY,
     useGlobal: true,
-    breakEvalOnSigint: true
+    breakEvalOnSigint: true,
+    displayWelcomeMessage: process.execArgv.indexOf('-i') === -1,
   }, opts);
 
   if (parseInt(env.NODE_NO_READLINE)) {

lib/readline.js

@@ -989,7 +989,7 @@ function emitKeypressEvents(stream, iface) {
         clearTimeout(timeoutId);
 
         if (iface) {
-          iface._sawKeyPress = r.length === 1;
+          iface._sawKeyPress = r.length === 1 || (r[0] === '\x1b');
         }
 
         for (var i = 0; i < r.length; i++) {