denoland-deno/ext/node/polyfills/internal/readline/emitKeypressEvents.mjs

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// 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.

// TODO(petamoriken): enable prefer-primordials for node polyfills
// deno-lint-ignore-file prefer-primordials

import { charLengthAt, CSI, emitKeys } from "ext:deno_node/internal/readline/utils.mjs";
import { kSawKeyPress } from "ext:deno_node/internal/readline/symbols.mjs";
import { clearTimeout, setTimeout } from "node:timers";

const {
  kEscape,
} = CSI;

import { StringDecoder } from "node: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
 */

export 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 string[Symbol.iterator]()) {
          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);
  }
}