readline: treat bare \r as a line ending

Fixes #3305

Author: isaacs

lib/readline.js

@@ -49,6 +49,8 @@ function Interface(input, output, completer, terminal) {
     return new Interface(input, output, completer, terminal);
   }
 
+  this._sawReturn = false;
+
   EventEmitter.call(this);
 
   if (arguments.length === 1) {
@@ -292,18 +294,27 @@ Interface.prototype.write = function(d, key) {
   this.terminal ? this._ttyWrite(d, key) : this._normalWrite(d);
 };
 
+// \r\n, \n, or \r followed by something other than \n
+var lineEnding = /\r?\n|\r(?!\n)/;
 Interface.prototype._normalWrite = function(b) {
   if (b === undefined) {
     return;
   }
   var string = this._decoder.write(b);
+  if (this._sawReturn) {
+    string = string.replace(/^\n/, '');
+    this._sawReturn = false;
+  }
+
   if (this._line_buffer) {
     string = this._line_buffer + string;
     this._line_buffer = null;
   }
-  if (string.indexOf('\n') !== -1) {
+  if (lineEnding.test(string)) {
+    this._sawReturn = /\r$/.test(string);
+
     // got one or more newlines; process into "line" events
-    var lines = string.split(/\r?\n/);
+    var lines = string.split(lineEnding);
     // either '' or (concievably) the unfinished portion of the next line
     string = lines.pop();
     this._line_buffer = string;
@@ -733,11 +744,23 @@ Interface.prototype._ttyWrite = function(s, key) {
   } else {
     /* No modifier keys used */
 
+    // \r bookkeeping is only relevant if a \n comes right after.
+    if (this._sawReturn && key.name !== 'enter')
+      this._sawReturn = false;
+
     switch (key.name) {
-      case 'enter':
+      case 'return':  // carriage return, i.e. \r
+        this._sawReturn = true;
         this._line();
         break;
 
+      case 'enter':
+        if (this._sawReturn)
+          this._sawReturn = false
+        else
+          this._line();
+        break;
+
       case 'backspace':
         this._deleteLeft();
         break;
@@ -758,7 +781,6 @@ Interface.prototype._ttyWrite = function(s, key) {
         this._moveCursor(+1);
         break;
 
-      case 'return':  // carriage return, i.e. \r
       case 'home':
         this._moveCursor(-Infinity);
         break;

test/simple/test-readline-interface.js

@@ -126,6 +126,36 @@ FakeInput.prototype.end = function() {};
   assert.equal(callCount, expectedLines.length - 1);
   rli.close();
 
+  // \r\n should emit one line event when split across multiple writes.
+  fi = new FakeInput();
+  rli = new readline.Interface({ input: fi, output: fi, terminal: terminal });
+  expectedLines = ['foo', 'bar', 'baz', 'bat'];
+  callCount = 0;
+  rli.on('line', function(line) {
+    assert.equal(line, expectedLines[callCount]);
+    callCount++;
+  });
+  expectedLines.forEach(function(line) {
+    fi.emit('data', line + '\r');
+    fi.emit('data', '\n');
+  });
+  assert.equal(callCount, expectedLines.length);
+  rli.close();
+
+  // \r should behave like \n when alone
+  fi = new FakeInput();
+  rli = new readline.Interface({ input: fi, output: fi, terminal: true });
+  expectedLines = ['foo', 'bar', 'baz', 'bat'];
+  callCount = 0;
+  rli.on('line', function(line) {
+    assert.equal(line, expectedLines[callCount]);
+    callCount++;
+  });
+  fi.emit('data', expectedLines.join('\r'));
+  assert.equal(callCount, expectedLines.length - 1);
+  rli.close();
+
+
   // sending a multi-byte utf8 char over multiple writes
   var buf = Buffer('☮', 'utf8');
   fi = new FakeInput();