Method sliceString

lib/lines.ts:553–613

(
    start: Pos = this.firstPos(),
    end: Pos = this.lastPos(),
    options?: Options,
  )

  }

  sliceString(
    start: Pos = this.firstPos(),
    end: Pos = this.lastPos(),
    options?: Options,
  ) {
    const { tabWidth, useTabs, reuseWhitespace, lineTerminator } =
      normalizeOptions(options);

    const parts = [];

    for (let line = start.line; line <= end.line; ++line) {
      let info = this.infos[line - 1];

      if (line === start.line) {
        if (line === end.line) {
          info = sliceInfo(info, start.column, end.column);
        } else {
          info = sliceInfo(info, start.column);
        }
      } else if (line === end.line) {
        info = sliceInfo(info, 0, end.column);
      }

      const indent = Math.max(info.indent, 0);

      const before = info.line.slice(0, info.sliceStart);
      if (
        reuseWhitespace &&
        isOnlyWhitespace(before) &&
        countSpaces(before, tabWidth) === indent
      ) {
        // Reuse original spaces if the indentation is correct.
        parts.push(info.line.slice(0, info.sliceEnd));
        continue;
      }

      let tabs = 0;
      let spaces = indent;

      if (useTabs) {
        tabs = Math.floor(indent / tabWidth);
        spaces -= tabs * tabWidth;
      }

      let result = "";

      if (tabs > 0) {
        result += new Array(tabs + 1).join("\t");
      }

      if (spaces > 0) {
        result += new Array(spaces + 1).join(" ");
      }

      result += info.line.slice(info.sliceStart, info.sliceEnd);

      parts.push(result);
    }