readline: refactor readline module

lib/internal/readline.js

@@ -7,23 +7,38 @@
 const ansi =
   /[\u001b\u009b][[()#;?]*(?:[0-9]{1,4}(?:;[0-9]{0,4})*)?[0-9A-ORZcf-nqry=><]/g;
 
+const kEscape = '\x1b';
 
-module.exports = {
-  emitKeys,
-  stripVTControlCharacters
-};
+var getStringWidth;
+var isFullWidthCodePoint;
+
+function CSI(strings, ...args) {
+  let ret = `${kEscape}[`;
+  for (var n = 0; n < strings.length; n++) {
+    ret += strings[n];
+    if (n < args.length)
+      ret += args[n];
+  }
+  return ret;
+}
+
+CSI.kEscape = kEscape;
+CSI.kClearToBeginning = CSI`1K`;
+CSI.kClearToEnd = CSI`0K`;
+CSI.kClearLine = CSI`2K`;
+CSI.kClearScreenDown = CSI`0J`;
 
 if (process.binding('config').hasIntl) {
   const icu = process.binding('icu');
-  module.exports.getStringWidth = function getStringWidth(str, options) {
+  getStringWidth = function getStringWidth(str, options) {
     options = options || {};
     if (!Number.isInteger(str))
       str = stripVTControlCharacters(String(str));
     return icu.getStringWidth(str,
                               Boolean(options.ambiguousAsFullWidth),
                               Boolean(options.expandEmojiSequence));
   };
-  module.exports.isFullWidthCodePoint =
+  isFullWidthCodePoint =
     function isFullWidthCodePoint(code, options) {
       if (typeof code !== 'number')
         return false;
@@ -33,9 +48,9 @@ if (process.binding('config').hasIntl) {
   /**
    * Returns the number of columns required to display the given string.
    */
-  module.exports.getStringWidth = function getStringWidth(str) {
+  getStringWidth = function getStringWidth(str) {
     if (Number.isInteger(str))
-      return module.exports.isFullWidthCodePoint(str) ? 2 : 1;
+      return isFullWidthCodePoint(str) ? 2 : 1;
 
     let width = 0;
 
@@ -48,7 +63,7 @@ if (process.binding('config').hasIntl) {
         i++;
       }
 
-      if (module.exports.isFullWidthCodePoint(code)) {
+      if (isFullWidthCodePoint(code)) {
         width += 2;
       } else {
         width++;
@@ -62,7 +77,7 @@ if (process.binding('config').hasIntl) {
    * Returns true if the character represented by a given
    * Unicode code point is full-width. Otherwise returns false.
    */
-  module.exports.isFullWidthCodePoint = function isFullWidthCodePoint(code) {
+  isFullWidthCodePoint = function isFullWidthCodePoint(code) {
     if (!Number.isInteger(code)) {
       return false;
     }
@@ -154,11 +169,11 @@ function* emitKeys(stream) {
       shift: false
     };
 
-    if (ch === '\x1b') {
+    if (ch === kEscape) {
       escaped = true;
       s += (ch = yield);
 
-      if (ch === '\x1b') {
+      if (ch === kEscape) {
         s += (ch = yield);
       }
     }
@@ -373,7 +388,7 @@ function* emitKeys(stream) {
       // backspace or ctrl+h
       key.name = 'backspace';
       key.meta = escaped;
-    } else if (ch === '\x1b') {
+    } else if (ch === kEscape) {
       // escape key
       key.name = 'escape';
       key.meta = escaped;
@@ -407,3 +422,11 @@ function* emitKeys(stream) {
     /* Unrecognized or broken escape sequence, don't emit anything */
   }
 }
+
+module.exports = {
+  emitKeys,
+  getStringWidth,
+  isFullWidthCodePoint,
+  stripVTControlCharacters,
+  CSI
+};

lib/readline.js

@@ -27,25 +27,41 @@
 
 'use strict';
 
+const { debug, inherits } = require('util');
+const Buffer = require('buffer').Buffer;
+const EventEmitter = require('events');
+const {
+  CSI,
+  emitKeys,
+  getStringWidth,
+  isFullWidthCodePoint,
+  stripVTControlCharacters
+} = require('internal/readline');
+
+const {
+  kEscape,
+  kClearToBeginning,
+  kClearToEnd,
+  kClearLine,
+  kClearScreenDown
+} = CSI;
+
 const kHistorySize = 30;
 const kMincrlfDelay = 100;
 const kMaxcrlfDelay = 2000;
+// \r\n, \n, or \r followed by something other than \n
+const lineEnding = /\r?\n|\r(?!\n)/;
 
-const util = require('util');
-const debug = util.debuglog('readline');
-const inherits = util.inherits;
-const Buffer = require('buffer').Buffer;
-const EventEmitter = require('events');
-const internalReadline = require('internal/readline');
-const emitKeys = internalReadline.emitKeys;
-const getStringWidth = internalReadline.getStringWidth;
-const isFullWidthCodePoint = internalReadline.isFullWidthCodePoint;
-const stripVTControlCharacters = internalReadline.stripVTControlCharacters;
+const KEYPRESS_DECODER = Symbol('keypress-decoder');
+const ESCAPE_DECODER = Symbol('escape-decoder');
+
+// GNU readline library - keyseq-timeout is 500ms (default)
+const ESCAPE_CODE_TIMEOUT = 500;
 
 
-exports.createInterface = function(input, output, completer, terminal) {
+function createInterface(input, output, completer, terminal) {
   return new Interface(input, output, completer, terminal);
-};
+}
 
 
 function Interface(input, output, completer, terminal) {
@@ -311,13 +327,13 @@ Interface.prototype._refreshLine = function() {
   // first move to the bottom of the current line, based on cursor pos
   var prevRows = this.prevRows || 0;
   if (prevRows > 0) {
-    exports.moveCursor(this.output, 0, -prevRows);
+    moveCursor(this.output, 0, -prevRows);
   }
 
   // Cursor to left edge.
-  exports.cursorTo(this.output, 0);
+  cursorTo(this.output, 0);
   // erase data
-  exports.clearScreenDown(this.output);
+  clearScreenDown(this.output);
 
   // Write the prompt and the current buffer content.
   this._writeToOutput(line);
@@ -328,11 +344,11 @@ Interface.prototype._refreshLine = function() {
   }
 
   // Move cursor to original position.
-  exports.cursorTo(this.output, cursorPos.cols);
+  cursorTo(this.output, cursorPos.cols);
 
   var diff = lineRows - cursorPos.rows;
   if (diff > 0) {
-    exports.moveCursor(this.output, 0, -diff);
+    moveCursor(this.output, 0, -diff);
   }
 
   this.prevRows = cursorPos.rows;
@@ -373,8 +389,6 @@ 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
-const lineEnding = /\r?\n|\r(?!\n)/;
 Interface.prototype._normalWrite = function(b) {
   if (b === undefined) {
     return;
@@ -716,7 +730,7 @@ Interface.prototype._moveCursor = function(dx) {
           this.line.substring(this.cursor, oldcursor)
           );
     }
-    exports.moveCursor(this.output, diffWidth, 0);
+    moveCursor(this.output, diffWidth, 0);
     this.prevRows = newPos.rows;
   } else {
     this._refreshLine();
@@ -798,8 +812,8 @@ Interface.prototype._ttyWrite = function(s, key) {
         break;
 
       case 'l': // clear the whole screen
-        exports.cursorTo(this.output, 0, 0);
-        exports.clearScreenDown(this.output);
+        cursorTo(this.output, 0, 0);
+        clearScreenDown(this.output);
         this._refreshLine();
         break;
 
@@ -957,20 +971,10 @@ Interface.prototype._ttyWrite = function(s, key) {
   }
 };
 
-
-exports.Interface = Interface;
-
-
 /**
  * accepts a readable Stream instance and makes it emit "keypress" events
  */
 
-const KEYPRESS_DECODER = Symbol('keypress-decoder');
-const ESCAPE_DECODER = Symbol('escape-decoder');
-
-// GNU readline library - keyseq-timeout is 500ms (default)
-const ESCAPE_CODE_TIMEOUT = 500;
-
 function emitKeypressEvents(stream, iface) {
   if (stream[KEYPRESS_DECODER]) return;
   var StringDecoder = require('string_decoder').StringDecoder; // lazy load
@@ -1000,7 +1004,7 @@ function emitKeypressEvents(stream, iface) {
           try {
             stream[ESCAPE_DECODER].next(r[i]);
             // Escape letter at the tail position
-            if (r[i] === '\x1b' && i + 1 === r.length) {
+            if (r[i] === kEscape && i + 1 === r.length) {
               timeoutId = setTimeout(escapeCodeTimeout, ESCAPE_CODE_TIMEOUT);
             }
           } catch (err) {
@@ -1036,8 +1040,6 @@ function emitKeypressEvents(stream, iface) {
     stream.on('newListener', onNewListener);
   }
 }
-exports.emitKeypressEvents = emitKeypressEvents;
-
 
 /**
  * moves the cursor to the x and y coordinate on the given stream
@@ -1054,13 +1056,11 @@ function cursorTo(stream, x, y) {
     throw new Error('Can\'t set cursor row without also setting it\'s column');
 
   if (typeof y !== 'number') {
-    stream.write('\x1b[' + (x + 1) + 'G');
+    stream.write(CSI`${x + 1}G`);
   } else {
-    stream.write('\x1b[' + (y + 1) + ';' + (x + 1) + 'H');
+    stream.write(CSI`${y + 1};${x + 1}H`);
   }
 }
-exports.cursorTo = cursorTo;
-
 
 /**
  * moves the cursor relative to its current location
@@ -1071,19 +1071,17 @@ function moveCursor(stream, dx, dy) {
     return;
 
   if (dx < 0) {
-    stream.write('\x1b[' + (-dx) + 'D');
+    stream.write(CSI`${-dx}D`);
   } else if (dx > 0) {
-    stream.write('\x1b[' + dx + 'C');
+    stream.write(CSI`${dx}C`);
   }
 
   if (dy < 0) {
-    stream.write('\x1b[' + (-dy) + 'A');
+    stream.write(CSI`${-dy}A`);
   } else if (dy > 0) {
-    stream.write('\x1b[' + dy + 'B');
+    stream.write(CSI`${dy}B`);
   }
 }
-exports.moveCursor = moveCursor;
-
 
 /**
  * clears the current line the cursor is on:
@@ -1098,17 +1096,15 @@ function clearLine(stream, dir) {
 
   if (dir < 0) {
     // to the beginning
-    stream.write('\x1b[1K');
+    stream.write(kClearToBeginning);
   } else if (dir > 0) {
     // to the end
-    stream.write('\x1b[0K');
+    stream.write(kClearToEnd);
   } else {
     // entire line
-    stream.write('\x1b[2K');
+    stream.write(kClearLine);
   }
 }
-exports.clearLine = clearLine;
-
 
 /**
  * clears the screen from the current position of the cursor down
@@ -1118,6 +1114,15 @@ function clearScreenDown(stream) {
   if (stream === null || stream === undefined)
     return;
 
-  stream.write('\x1b[0J');
+  stream.write(kClearScreenDown);
 }
-exports.clearScreenDown = clearScreenDown;
+
+module.exports = {
+  Interface,
+  clearLine,
+  clearScreenDown,
+  createInterface,
+  cursorTo,
+  emitKeypressEvents,
+  moveCursor
+};