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 <[email protected]> Reviewed-By: Evan Lucas <[email protected]>

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)
+functionwelcome(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=(typeofoptions.completer==='function')
  ? options.completer
- : complete;
+ : completer;
+
+functioncompleter(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,
 });
 
 varsawSIGINT=false;
+varsawCtrlD=false;
 self.on('SIGINT',function(){
 varempty=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(einstanceofRecoverable&&!self.lineParser.shouldFail){
+if(einstanceofRecoverable&&!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
+constttyWrite=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
 functionArrayStream(){
@@ -987,6 +1054,39 @@ function complete(line, callback){
 }
 }
 
+functionlongestCommonPrefix(arr=[]){
+constcnt=arr.length;
+if(cnt===0)return'';
+if(cnt===1)returnarr[0];
+
+constfirst=arr[0];
+// complexity: O(m * n)
+for(letm=0;m<first.length;m++){
+constc=first[m];
+for(letn=1;n<cnt;n++){
+constentry=arr[n];
+if(m>=entry.length||c!==entry[m]){
+returnfirst.substring(0,m);
+}
+}
+}
+returnfirst;
+}
+
+REPLServer.prototype.completeOnEditorMode=(callback)=>(err,results)=>{
+if(err)returncallback(err);
+
+const[completions,completeOn='']=results;
+constprefixLength=completeOn.length;
+
+if(prefixLength===0)returncallback(null,[[],completeOn]);
+
+constisNotEmpty=(v)=>v.length>0;
+consttrimCompleteOnPrefix=(v)=>v.substring(prefixLength);
+constdata=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');
+}
+});
 }
 
 functionregexpEscape(s){

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

@@ -0,0 +1,55 @@
+'use strict';
+
+constcommon=require('../common');
+constassert=require('assert');
+constrepl=require('repl');
+
+// \u001b[1G - Moves the cursor to 1st column
+// \u001b[0J - Clear screen
+// \u001b[3G - Moves the cursor to 3rd column
+constterminalCode='\u001b[1G\u001b[0J> \u001b[3G';
+
+functionrun(input,output,event){
+conststream=newcommon.ArrayStream();
+letfound='';
+
+stream.write=(msg)=>found+=msg.replace('\r','');
+
+constexpected=`${terminalCode}.editor\n`+
+'// Entering editor mode (^D to finish, ^C to cancel)\n'+
+`${input}${output}\n${terminalCode}`;
+
+constreplServer=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);
+}
+
+consttests=[
+{
+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
+consteditorStream=newcommon.ArrayStream();
+consteditor=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']);
+}));