Function setupPreview

lib/internal/repl/utils.js:147–522

(repl, contextSymbol, bufferSymbol, active)

}

function setupPreview(repl, contextSymbol, bufferSymbol, active) {
  // Simple terminals can't handle previews.
  if (process.env.TERM === 'dumb' || !active) {
    return { showPreview() {}, clearPreview() {} };
  }

  let inputPreview = null;

  let previewCompletionCounter = 0;
  let completionPreview = null;

  let hasCompletions = false;

  let wrapped = false;

  let escaped = null;

  function getPreviewPos() {
    const displayPos = repl._getDisplayPos(`${repl.getPrompt()}${repl.line}`);
    const cursorPos = repl.line.length !== repl.cursor ?
      repl.getCursorPos() :
      displayPos;
    return { displayPos, cursorPos };
  }

  function isCursorAtInputEnd() {
    const { cursorPos, displayPos } = getPreviewPos();
    return cursorPos.rows === displayPos.rows &&
           cursorPos.cols === displayPos.cols;
  }

  const clearPreview = (key) => {
    if (inputPreview !== null) {
      const { displayPos, cursorPos } = getPreviewPos();
      const rows = displayPos.rows - cursorPos.rows + 1;
      moveCursor(repl.output, 0, rows);
      clearLine(repl.output);
      moveCursor(repl.output, 0, -rows);
      inputPreview = null;
    }
    if (completionPreview !== null) {
      // Prevent cursor moves if not necessary!
      const move = repl.line.length !== repl.cursor;
      let pos, rows;
      if (move) {
        pos = getPreviewPos();
        cursorTo(repl.output, pos.displayPos.cols);
        rows = pos.displayPos.rows - pos.cursorPos.rows;
        moveCursor(repl.output, 0, rows);
      }
      const totalLine = `${repl.getPrompt()}${repl.line}${completionPreview}`;
      const newPos = repl._getDisplayPos(totalLine);
      // Minimize work for the terminal. It is enough to clear the right part of
      // the current line in case the preview is visible on a single line.
      if (newPos.rows === 0 || (pos && pos.displayPos.rows === newPos.rows)) {
        clearLine(repl.output, 1);
      } else {
        clearScreenDown(repl.output);