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lib/internal/readline/callbacks.js

@@ -0,0 +1,132 @@
+'use strict';
+
+const {
+  NumberIsNaN,
+} = primordials;
+
+const {
+  codes: {
+    ERR_INVALID_ARG_VALUE,
+    ERR_INVALID_CURSOR_POS,
+  },
+} = require('internal/errors');
+
+const {
+  validateFunction,
+} = require('internal/validators');
+const {
+  CSI,
+} = require('internal/readline/utils');
+
+const {
+  kClearLine,
+  kClearScreenDown,
+  kClearToLineBeginning,
+  kClearToLineEnd,
+} = CSI;
+
+
+/**
+ * moves the cursor to the x and y coordinate on the given stream
+ */
+
+function cursorTo(stream, x, y, callback) {
+  if (callback !== undefined) {
+    validateFunction(callback, 'callback');
+  }
+
+  if (typeof y === 'function') {
+    callback = y;
+    y = undefined;
+  }
+
+  if (NumberIsNaN(x)) throw new ERR_INVALID_ARG_VALUE('x', x);
+  if (NumberIsNaN(y)) throw new ERR_INVALID_ARG_VALUE('y', y);
+
+  if (stream == null || (typeof x !== 'number' && typeof y !== 'number')) {
+    if (typeof callback === 'function') process.nextTick(callback, null);
+    return true;
+  }
+
+  if (typeof x !== 'number') throw new ERR_INVALID_CURSOR_POS();
+
+  const data = typeof y !== 'number' ? CSI`${x + 1}G` : CSI`${y + 1};${x + 1}H`;
+  return stream.write(data, callback);
+}
+
+/**
+ * moves the cursor relative to its current location
+ */
+
+function moveCursor(stream, dx, dy, callback) {
+  if (callback !== undefined) {
+    validateFunction(callback, 'callback');
+  }
+
+  if (stream == null || !(dx || dy)) {
+    if (typeof callback === 'function') process.nextTick(callback, null);
+    return true;
+  }
+
+  let data = '';
+
+  if (dx < 0) {
+    data += CSI`${-dx}D`;
+  } else if (dx > 0) {
+    data += CSI`${dx}C`;
+  }
+
+  if (dy < 0) {
+    data += CSI`${-dy}A`;
+  } else if (dy > 0) {
+    data += CSI`${dy}B`;
+  }
+
+  return stream.write(data, callback);
+}
+
+/**
+ * clears the current line the cursor is on:
+ *   -1 for left of the cursor
+ *   +1 for right of the cursor
+ *    0 for the entire line
+ */
+
+function clearLine(stream, dir, callback) {
+  if (callback !== undefined) {
+    validateFunction(callback, 'callback');
+  }
+
+  if (stream === null || stream === undefined) {
+    if (typeof callback === 'function') process.nextTick(callback, null);
+    return true;
+  }
+
+  const type =
+    dir < 0 ? kClearToLineBeginning : dir > 0 ? kClearToLineEnd : kClearLine;
+  return stream.write(type, callback);
+}
+
+/**
+ * clears the screen from the current position of the cursor down
+ */
+
+function clearScreenDown(stream, callback) {
+  if (callback !== undefined) {
+    validateFunction(callback, 'callback');
+  }
+
+  if (stream === null || stream === undefined) {
+    if (typeof callback === 'function') process.nextTick(callback, null);
+    return true;
+  }
+
+  return stream.write(kClearScreenDown, callback);
+}
+
+module.exports = {
+  clearLine,
+  clearScreenDown,
+  cursorTo,
+  moveCursor,
+};

lib/internal/readline/emitKeypressEvents.js

@@ -0,0 +1,99 @@
+'use strict';
+
+const {
+  SafeStringIterator,
+  Symbol,
+} = primordials;
+
+const {
+  charLengthAt,
+  CSI,
+  emitKeys,
+} = require('internal/readline/utils');
+const {
+  kSawKeyPress,
+} = require('internal/readline/interface');
+
+const { clearTimeout, setTimeout } = require('timers');
+const {
+  kEscape,
+} = CSI;
+
+const { StringDecoder } = require('string_decoder');
+
+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;
+
+/**
+ * accepts a readable Stream instance and makes it emit "keypress" events
+ */
+
+function emitKeypressEvents(stream, iface = {}) {
+  if (stream[KEYPRESS_DECODER]) return;
+
+  stream[KEYPRESS_DECODER] = new StringDecoder('utf8');
+
+  stream[ESCAPE_DECODER] = emitKeys(stream);
+  stream[ESCAPE_DECODER].next();
+
+  const triggerEscape = () => stream[ESCAPE_DECODER].next('');
+  const { escapeCodeTimeout = ESCAPE_CODE_TIMEOUT } = iface;
+  let timeoutId;
+
+  function onData(input) {
+    if (stream.listenerCount('keypress') > 0) {
+      const string = stream[KEYPRESS_DECODER].write(input);
+      if (string) {
+        clearTimeout(timeoutId);
+
+        // This supports characters of length 2.
+        iface[kSawKeyPress] = charLengthAt(string, 0) === string.length;
+        iface.isCompletionEnabled = false;
+
+        let length = 0;
+        for (const character of new SafeStringIterator(string)) {
+          length += character.length;
+          if (length === string.length) {
+            iface.isCompletionEnabled = true;
+          }
+
+          try {
+            stream[ESCAPE_DECODER].next(character);
+            // Escape letter at the tail position
+            if (length === string.length && character === kEscape) {
+              timeoutId = setTimeout(triggerEscape, escapeCodeTimeout);
+            }
+          } catch (err) {
+            // If the generator throws (it could happen in the `keypress`
+            // event), we need to restart it.
+            stream[ESCAPE_DECODER] = emitKeys(stream);
+            stream[ESCAPE_DECODER].next();
+            throw err;
+          }
+        }
+      }
+    } else {
+      // Nobody's watching anyway
+      stream.removeListener('data', onData);
+      stream.on('newListener', onNewListener);
+    }
+  }
+
+  function onNewListener(event) {
+    if (event === 'keypress') {
+      stream.on('data', onData);
+      stream.removeListener('newListener', onNewListener);
+    }
+  }
+
+  if (stream.listenerCount('keypress') > 0) {
+    stream.on('data', onData);
+  } else {
+    stream.on('newListener', onNewListener);
+  }
+}
+
+module.exports = emitKeypressEvents;

lib/internal/readline/promises.js

@@ -0,0 +1,144 @@
+'use strict';
+
+const {
+  ArrayPrototypeJoin,
+  ArrayPrototypePush,
+  Promise,
+} = primordials;
+
+const { CSI } = require('internal/readline/utils');
+const { validateBoolean, validateInteger } = require('internal/validators');
+const { isWritable } = require('internal/streams/utils');
+const { codes: {
+  ERR_INVALID_ARG_TYPE,
+} } = require('internal/errors');
+
+const {
+  kClearToLineBeginning,
+  kClearToLineEnd,
+  kClearLine,
+  kClearScreenDown,
+} = CSI;
+
+class Readline {
+  #autoCommit = false;
+  #stream;
+  #todo = [];
+
+  constructor(stream, options = undefined) {
+    if (!isWritable(stream))
+      throw new ERR_INVALID_ARG_TYPE('stream', 'Writable', stream);
+    this.#stream = stream;
+    if (options?.autoCommit != null) {
+      validateBoolean(options.autoCommit, 'options.autoCommit');
+      this.#autoCommit = options.autoCommit;
+    }
+  }
+
+  /**
+   * Moves the cursor to the x and y coordinate on the given stream.
+   * @param {integer} x
+   * @param {integer} [y]
+   * @returns {Readline} this
+   */
+  cursorTo(x, y = undefined) {
+    validateInteger(x, 'x');
+    if (y != null) validateInteger(y, 'y');
+
+    const data = y == null ? CSI`${x + 1}G` : CSI`${y + 1};${x + 1}H`;
+    if (this.#autoCommit) process.nextTick(() => this.#stream.write(data));
+    else ArrayPrototypePush(this.#todo, data);
+
+    return this;
+  }
+
+  /**
+   * Moves the cursor relative to its current location.
+   * @param {integer} dx
+   * @param {integer} dy
+   * @returns {Readline} this
+   */
+  moveCursor(dx, dy) {
+    if (dx || dy) {
+      validateInteger(dx, 'dx');
+      validateInteger(dy, 'dy');
+
+      let data = '';
+
+      if (dx < 0) {
+        data += CSI`${-dx}D`;
+      } else if (dx > 0) {
+        data += CSI`${dx}C`;
+      }
+
+      if (dy < 0) {
+        data += CSI`${-dy}A`;
+      } else if (dy > 0) {
+        data += CSI`${dy}B`;
+      }
+      if (this.#autoCommit) process.nextTick(() => this.#stream.write(data));
+      else ArrayPrototypePush(this.#todo, data);
+    }
+    return this;
+  }
+
+  /**
+   * Clears the current line the cursor is on.
+   * @param {-1|0|1} dir Direction to clear:
+   *   -1 for left of the cursor
+   *   +1 for right of the cursor
+   *    0 for the entire line
+   * @returns {Readline} this
+   */
+  clearLine(dir) {
+    validateInteger(dir, 'dir', -1, 1);
+
+    const data =
+      dir < 0 ? kClearToLineBeginning :
+        dir > 0 ? kClearToLineEnd :
+          kClearLine;
+    if (this.#autoCommit) process.nextTick(() => this.#stream.write(data));
+    else ArrayPrototypePush(this.#todo, data);
+    return this;
+  }
+
+  /**
+   * Clears the screen from the current position of the cursor down.
+   * @returns {Readline} this
+   */
+  clearScreenDown() {
+    if (this.#autoCommit) {
+      process.nextTick(() => this.#stream.write(kClearScreenDown));
+    } else {
+      ArrayPrototypePush(this.#todo, kClearScreenDown);
+    }
+    return this;
+  }
+
+  /**
+   * Sends all the pending actions to the associated `stream` and clears the
+   * internal list of pending actions.
+   * @returns {Promise<void>} Resolves when all pending actions have been
+   * flushed to the associated `stream`.
+   */
+  commit() {
+    return new Promise((resolve) => {
+      this.#stream.write(ArrayPrototypeJoin(this.#todo, ''), resolve);
+      this.#todo = [];
+    });
+  }
+
+  /**
+   * Clears the internal list of pending actions without sending it to the
+   * associated `stream`.
+   * @returns {Readline} this
+   */
+  rollback() {
+    this.#todo = [];
+    return this;
+  }
+}
+
+module.exports = {
+  Readline,
+};

lib/internal/readline/utils.js

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+'use strict';
+
+const {
+  ArrayPrototypeToSorted,
+  RegExpPrototypeExec,
+  StringFromCharCode,
+  StringPrototypeCharCodeAt,
+  StringPrototypeCodePointAt,
+  StringPrototypeSlice,
+  StringPrototypeSplit,
+  StringPrototypeToLowerCase,
+  Symbol,
+} = primordials;
+
+const kUTF16SurrogateThreshold = 0x10000; // 2 ** 16
+const kEscape = '\x1b';
+const kSubstringSearch = Symbol('kSubstringSearch');
+
+function CSI(strings, ...args) {
+  let ret = `${kEscape}[`;
+  for (let n = 0; n < strings.length; n++) {
+    ret += strings[n];
+    if (n < args.length)
+      ret += args[n];
+  }
+  return ret;
+}
+
+CSI.kEscape = kEscape;
+CSI.kClearToLineBeginning = CSI`1K`;
+CSI.kClearToLineEnd = CSI`0K`;
+CSI.kClearLine = CSI`2K`;
+CSI.kClearScreenDown = CSI`0J`;
+
+// TODO(BridgeAR): Treat combined characters as single character, i.e,
+// 'a\u0301' and '\u0301a' (both have the same visual output).
+// Check Canonical_Combining_Class in
+// http://userguide.icu-project.org/strings/properties
+function charLengthLeft(str, i) {
+  if (i <= 0)
+    return 0;
+  if ((i > 1 &&
+      StringPrototypeCodePointAt(str, i - 2) >= kUTF16SurrogateThreshold) ||
+      StringPrototypeCodePointAt(str, i - 1) >= kUTF16SurrogateThreshold) {
+    return 2;
+  }
+  return 1;
+}
+
+function charLengthAt(str, i) {
+  if (str.length <= i) {
+    // Pretend to move to the right. This is necessary to autocomplete while
+    // moving to the right.
+    return 1;
+  }
+  return StringPrototypeCodePointAt(str, i) >= kUTF16SurrogateThreshold ? 2 : 1;
+}
+
+/*
+  Some patterns seen in terminal key escape codes, derived from combos seen
+  at http://www.midnight-commander.org/browser/lib/tty/key.c
+
+  ESC letter
+  ESC [ letter
+  ESC [ modifier letter
+  ESC [ 1 ; modifier letter
+  ESC [ num char
+  ESC [ num ; modifier char
+  ESC O letter
+  ESC O modifier letter
+  ESC O 1 ; modifier letter
+  ESC N letter
+  ESC [ [ num ; modifier char
+  ESC [ [ 1 ; modifier letter
+  ESC ESC [ num char
+  ESC ESC O letter
+
+  - char is usually ~ but $ and ^ also happen with rxvt
+  - modifier is 1 +
+                (shift     * 1) +
+                (left_alt  * 2) +
+                (ctrl      * 4) +
+                (right_alt * 8)
+  - two leading ESCs apparently mean the same as one leading ESC
+*/
+function* emitKeys(stream) {
+  while (true) {
+    let ch = yield;
+    let s = ch;
+    let escaped = false;
+    const key = {
+      sequence: null,
+      name: undefined,
+      ctrl: false,
+      meta: false,
+      shift: false,
+    };
+
+    if (ch === kEscape) {
+      escaped = true;
+      s += (ch = yield);
+
+      if (ch === kEscape) {
+        s += (ch = yield);
+      }
+    }
+
+    if (escaped && (ch === 'O' || ch === '[')) {
+      // ANSI escape sequence
+      let code = ch;
+      let modifier = 0;
+
+      if (ch === 'O') {
+        // ESC O letter
+        // ESC O modifier letter
+        s += (ch = yield);
+
+        if (ch >= '0' && ch <= '9') {
+          modifier = (ch >> 0) - 1;
+          s += (ch = yield);
+        }
+
+        code += ch;
+      } else if (ch === '[') {
+        // ESC [ letter
+        // ESC [ modifier letter
+        // ESC [ [ modifier letter
+        // ESC [ [ num char
+        s += (ch = yield);
+
+        if (ch === '[') {
+          // \x1b[[A
+          //      ^--- escape codes might have a second bracket
+          code += ch;
+          s += (ch = yield);
+        }
+
+        /*
+         * Here and later we try to buffer just enough data to get
+         * a complete ascii sequence.
+         *
+         * We have basically two classes of ascii characters to process:
+         *
+         *
+         * 1. `\x1b[24;5~` should be parsed as { code: '[24~', modifier: 5 }
+         *
+         * This particular example is featuring Ctrl+F12 in xterm.
+         *
+         *  - `;5` part is optional, e.g. it could be `\x1b[24~`
+         *  - first part can contain one or two digits
+         *  - there is also special case when there can be 3 digits
+         *    but without modifier. They are the case of paste bracket mode
+         *
+         * So the generic regexp is like /^(?:\d\d?(;\d)?[~^$]|\d{3}~)$/
+         *
+         *
+         * 2. `\x1b[1;5H` should be parsed as { code: '[H', modifier: 5 }
+         *
+         * This particular example is featuring Ctrl+Home in xterm.
+         *
+         *  - `1;5` part is optional, e.g. it could be `\x1b[H`
+         *  - `1;` part is optional, e.g. it could be `\x1b[5H`
+         *
+         * So the generic regexp is like /^((\d;)?\d)?[A-Za-z]$/
+         *
+         */
+        const cmdStart = s.length - 1;
+
+        // Skip one or two leading digits
+        if (ch >= '0' && ch <= '9') {
+          s += (ch = yield);
+
+          if (ch >= '0' && ch <= '9') {
+            s += (ch = yield);
+
+            if (ch >= '0' && ch <= '9') {
+              s += (ch = yield);
+            }
+          }
+        }
+
+        // skip modifier
+        if (ch === ';') {
+          s += (ch = yield);
+
+          if (ch >= '0' && ch <= '9') {
+            s += yield;
+          }
+        }
+
+        /*
+         * We buffered enough data, now trying to extract code
+         * and modifier from it
+         */
+        const cmd = StringPrototypeSlice(s, cmdStart);
+        let match;
+
+        if ((match = RegExpPrototypeExec(/^(?:(\d\d?)(?:;(\d))?([~^$])|(\d{3}~))$/, cmd))) {
+          if (match[4]) {
+            code += match[4];
+          } else {
+            code += match[1] + match[3];
+            modifier = (match[2] || 1) - 1;
+          }
+        } else if (
+          (match = RegExpPrototypeExec(/^((\d;)?(\d))?([A-Za-z])$/, cmd))
+        ) {
+          code += match[4];
+          modifier = (match[3] || 1) - 1;
+        } else {
+          code += cmd;
+        }
+      }
+
+      // Parse the key modifier
+      key.ctrl = !!(modifier & 4);
+      key.meta = !!(modifier & 10);
+      key.shift = !!(modifier & 1);
+      key.code = code;
+
+      // Parse the key itself
+      switch (code) {
+        /* xterm/gnome ESC [ letter (with modifier) */
+        case '[P': key.name = 'f1'; break;
+        case '[Q': key.name = 'f2'; break;
+        case '[R': key.name = 'f3'; break;
+        case '[S': key.name = 'f4'; break;
+
+        /* xterm/gnome ESC O letter (without modifier) */
+        case 'OP': key.name = 'f1'; break;
+        case 'OQ': key.name = 'f2'; break;
+        case 'OR': key.name = 'f3'; break;
+        case 'OS': key.name = 'f4'; break;
+
+        /* xterm/rxvt ESC [ number ~ */
+        case '[11~': key.name = 'f1'; break;
+        case '[12~': key.name = 'f2'; break;
+        case '[13~': key.name = 'f3'; break;
+        case '[14~': key.name = 'f4'; break;
+
+        /* paste bracket mode */
+        case '[200~': key.name = 'paste-start'; break;
+        case '[201~': key.name = 'paste-end'; break;
+
+        /* from Cygwin and used in libuv */
+        case '[[A': key.name = 'f1'; break;
+        case '[[B': key.name = 'f2'; break;
+        case '[[C': key.name = 'f3'; break;
+        case '[[D': key.name = 'f4'; break;
+        case '[[E': key.name = 'f5'; break;
+
+        /* common */
+        case '[15~': key.name = 'f5'; break;
+        case '[17~': key.name = 'f6'; break;
+        case '[18~': key.name = 'f7'; break;
+        case '[19~': key.name = 'f8'; break;
+        case '[20~': key.name = 'f9'; break;
+        case '[21~': key.name = 'f10'; break;
+        case '[23~': key.name = 'f11'; break;
+        case '[24~': key.name = 'f12'; break;
+
+        /* xterm ESC [ letter */
+        case '[A': key.name = 'up'; break;
+        case '[B': key.name = 'down'; break;
+        case '[C': key.name = 'right'; break;
+        case '[D': key.name = 'left'; break;
+        case '[E': key.name = 'clear'; break;
+        case '[F': key.name = 'end'; break;
+        case '[H': key.name = 'home'; break;
+
+        /* xterm/gnome ESC O letter */
+        case 'OA': key.name = 'up'; break;
+        case 'OB': key.name = 'down'; break;
+        case 'OC': key.name = 'right'; break;
+        case 'OD': key.name = 'left'; break;
+        case 'OE': key.name = 'clear'; break;
+        case 'OF': key.name = 'end'; break;
+        case 'OH': key.name = 'home'; break;
+
+        /* xterm/rxvt ESC [ number ~ */
+        case '[1~': key.name = 'home'; break;
+        case '[2~': key.name = 'insert'; break;
+        case '[3~': key.name = 'delete'; break;
+        case '[4~': key.name = 'end'; break;
+        case '[5~': key.name = 'pageup'; break;
+        case '[6~': key.name = 'pagedown'; break;
+
+        /* putty */
+        case '[[5~': key.name = 'pageup'; break;
+        case '[[6~': key.name = 'pagedown'; break;
+
+        /* rxvt */
+        case '[7~': key.name = 'home'; break;
+        case '[8~': key.name = 'end'; break;
+
+        /* rxvt keys with modifiers */
+        case '[a': key.name = 'up'; key.shift = true; break;
+        case '[b': key.name = 'down'; key.shift = true; break;
+        case '[c': key.name = 'right'; key.shift = true; break;
+        case '[d': key.name = 'left'; key.shift = true; break;
+        case '[e': key.name = 'clear'; key.shift = true; break;
+
+        case '[2$': key.name = 'insert'; key.shift = true; break;
+        case '[3$': key.name = 'delete'; key.shift = true; break;
+        case '[5$': key.name = 'pageup'; key.shift = true; break;
+        case '[6$': key.name = 'pagedown'; key.shift = true; break;
+        case '[7$': key.name = 'home'; key.shift = true; break;
+        case '[8$': key.name = 'end'; key.shift = true; break;
+
+        case 'Oa': key.name = 'up'; key.ctrl = true; break;
+        case 'Ob': key.name = 'down'; key.ctrl = true; break;
+        case 'Oc': key.name = 'right'; key.ctrl = true; break;
+        case 'Od': key.name = 'left'; key.ctrl = true; break;
+        case 'Oe': key.name = 'clear'; key.ctrl = true; break;
+
+        case '[2^': key.name = 'insert'; key.ctrl = true; break;
+        case '[3^': key.name = 'delete'; key.ctrl = true; break;
+        case '[5^': key.name = 'pageup'; key.ctrl = true; break;
+        case '[6^': key.name = 'pagedown'; key.ctrl = true; break;
+        case '[7^': key.name = 'home'; key.ctrl = true; break;
+        case '[8^': key.name = 'end'; key.ctrl = true; break;
+
+        /* misc. */
+        case '[Z': key.name = 'tab'; key.shift = true; break;
+        default: key.name = 'undefined'; break;
+      }
+    } else if (ch === '\r') {
+      // carriage return
+      key.name = 'return';
+      key.meta = escaped;
+    } else if (ch === '\n') {
+      // Enter, should have been called linefeed
+      key.name = 'enter';
+      key.meta = escaped;
+    } else if (ch === '\t') {
+      // tab
+      key.name = 'tab';
+      key.meta = escaped;
+    } else if (ch === '\b' || ch === '\x7f') {
+      // backspace or ctrl+h
+      key.name = 'backspace';
+      key.meta = escaped;
+    } else if (ch === kEscape) {
+      // escape key
+      key.name = 'escape';
+      key.meta = escaped;
+    } else if (ch === ' ') {
+      key.name = 'space';
+      key.meta = escaped;
+    } else if (!escaped && ch <= '\x1a') {
+      // ctrl+letter
+      key.name = StringFromCharCode(
+        StringPrototypeCharCodeAt(ch) + StringPrototypeCharCodeAt('a') - 1,
+      );
+      key.ctrl = true;
+    } else if (RegExpPrototypeExec(/^[0-9A-Za-z]$/, ch) !== null) {
+      // Letter, number, shift+letter
+      key.name = StringPrototypeToLowerCase(ch);
+      key.shift = RegExpPrototypeExec(/^[A-Z]$/, ch) !== null;
+      key.meta = escaped;
+    } else if (escaped) {
+      // Escape sequence timeout
+      key.name = ch.length ? undefined : 'escape';
+      key.meta = true;
+    }
+
+    key.sequence = s;
+
+    if (s.length !== 0 && (key.name !== undefined || escaped)) {
+      /* Named character or sequence */
+      stream.emit('keypress', escaped ? undefined : s, key);
+    } else if (charLengthAt(s, 0) === s.length) {
+      /* Single unnamed character, e.g. "." */
+      stream.emit('keypress', s, key);
+    }
+    /* Unrecognized or broken escape sequence, don't emit anything */
+  }
+}
+
+// This runs in O(n log n).
+function commonPrefix(strings) {
+  if (strings.length === 0) {
+    return '';
+  }
+  if (strings.length === 1) {
+    return strings[0];
+  }
+  const sorted = ArrayPrototypeToSorted(strings);
+  const min = sorted[0];
+  const max = sorted[sorted.length - 1];
+  for (let i = 0; i < min.length; i++) {
+    if (min[i] !== max[i]) {
+      return StringPrototypeSlice(min, 0, i);
+    }
+  }
+  return min;
+}
+
+function reverseString(line, from = '\r', to = '\r') {
+  const parts = StringPrototypeSplit(line, from);
+
+  // This implementation should be faster than
+  // ArrayPrototypeJoin(ArrayPrototypeReverse(StringPrototypeSplit(line, from)), to);
+  let result = '';
+  for (let i = parts.length - 1; i > 0; i--) {
+    result += parts[i] + to;
+  }
+  result += parts[0];
+
+  return result;
+}
+
+module.exports = {
+  charLengthAt,
+  charLengthLeft,
+  commonPrefix,
+  emitKeys,
+  reverseString,
+  kSubstringSearch,
+  CSI,
+};