utils.mjs

// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
// Copyright Joyent, Inc. and other Node contributors.
//
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// copy of this software and associated documentation files (the
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// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

"use strict";

const kUTF16SurrogateThreshold = 0x10000; // 2 ** 16
const kEscape = "\x1b";
export const kSubstringSearch = Symbol("kSubstringSearch");

export 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
export function charLengthLeft(str, i) {
  if (i <= 0) {
    return 0;
  }
  if (
    (i > 1 &&
      str.codePointAt(i - 2) >= kUTF16SurrogateThreshold) ||
    str.codePointAt(i - 1) >= kUTF16SurrogateThreshold
  ) {
    return 2;
  }
  return 1;
}

export 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 str.codePointAt(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
*/
export 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
         *
         * So the generic regexp is like /^\d\d?(;\d)?[~^$]$/
         *
         *
         * 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;
          }
        }

        // 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 = s.slice(cmdStart);
        let match;

        if ((match = cmd.match(/^(\d\d?)(;(\d))?([~^$])$/))) {
          code += match[1] + match[4];
          modifier = (match[3] || 1) - 1;
        } else if (
          (match = cmd.match(/^((\d;)?(\d))?([A-Za-z])$/))
        ) {
          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;

        /* 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 = String.fromCharCode(
        ch.charCodeAt() + "a".charCodeAt() - 1,
      );
      key.ctrl = true;
    } else if (/^[0-9A-Za-z]$/.test(ch)) {
      // Letter, number, shift+letter
      key.name = ch.toLowerCase();
      key.shift = /^[A-Z]$/.test(ch);
      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).
export function commonPrefix(strings) {
  if (strings.length === 1) {
    return strings[0];
  }
  const sorted = strings.slice().sort();
  const min = sorted[0];
  const max = sorted[sorted.length - 1];
  for (let i = 0; i < min.length; i++) {
    if (min[i] !== max[i]) {
      return min.slice(0, i);
    }
  }
  return min;
}

export default {
  CSI,
  charLengthAt,
  charLengthLeft,
  emitKeys,
  commonPrefix,
};