Function showCompletionPreview

lib/internal/repl/utils.js:229–288

(line, insertPreview)

  };

  function showCompletionPreview(line, insertPreview) {
    previewCompletionCounter++;

    const count = previewCompletionCounter;

    repl.completer(line, (error, data) => {
      // Tab completion might be async and the result might already be outdated.
      if (count !== previewCompletionCounter) {
        return;
      }

      if (error) {
        debug('Error while generating completion preview', error);
        return;
      }

      // Result and the text that was completed.
      const { 0: rawCompletions, 1: completeOn } = data;

      if (!rawCompletions || rawCompletions.length === 0) {
        return;
      }

      hasCompletions = true;

      // If there is a common prefix to all matches, then apply that portion.
      const completions = ArrayPrototypeFilter(rawCompletions, Boolean);
      const prefix = commonPrefix(completions);

      // No common prefix found.
      if (prefix.length <= completeOn.length) {
        return;
      }

      const suffix = StringPrototypeSlice(prefix, completeOn.length);

      if (insertPreview) {
        repl._insertString(suffix);
        return;
      }

      completionPreview = suffix;

      const result = repl.useColors ?
        `\u001b[90m${suffix}\u001b[39m` :
        ` // ${suffix}`;

      const { cursorPos, displayPos } = getPreviewPos();
      if (repl.line.length !== repl.cursor) {
        cursorTo(repl.output, displayPos.cols);
        moveCursor(repl.output, 0, displayPos.rows - cursorPos.rows);
      }
      repl.output.write(result);
      cursorTo(repl.output, cursorPos.cols);
      const totalLine = `${repl.getPrompt()}${repl.line}${suffix}`;
      const newPos = repl._getDisplayPos(totalLine);
      const rows = newPos.rows - cursorPos.rows - (newPos.cols === 0 ? 1 : 0);
      moveCursor(repl.output, 0, -rows);