public translateBufferLineToString()

in src/Buffer.ts [237:296]
43 lines of code
13 McCabe index (conditional complexity)

  public translateBufferLineToString(lineIndex: number, trimRight: boolean, startCol: number = 0, endCol: number = null): string {
    // Get full line
    let lineString = '';
    const line = this.lines.get(lineIndex);
    if (!line) {
      return '';
    }

    // Initialize column and index values. Column values represent the actual
    // cell column, indexes represent the index in the string. Indexes are
    // needed here because some chars are 0 characters long (eg. after wide
    // chars) and some chars are longer than 1 characters long (eg. emojis).
    let startIndex = startCol;
    // Only set endCol to the line length when it is null. 0 is a valid column.
    if (endCol === null) {
      endCol = line.length;
    }
    let endIndex = endCol;

    for (let i = 0; i < line.length; i++) {
      const char = line.get(i);
      lineString += char[CHAR_DATA_CHAR_INDEX];
      // Adjust start and end cols for wide characters if they affect their
      // column indexes
      if (char[CHAR_DATA_WIDTH_INDEX] === 0) {
        if (startCol >= i) {
          startIndex--;
        }
        if (endCol > i) {
          endIndex--;
        }
      } else {
        // Adjust the columns to take glyphs that are represented by multiple
        // code points into account.
        if (char[CHAR_DATA_CHAR_INDEX].length > 1) {
          if (startCol > i) {
            startIndex += char[CHAR_DATA_CHAR_INDEX].length - 1;
          }
          if (endCol > i) {
            endIndex += char[CHAR_DATA_CHAR_INDEX].length - 1;
          }
        }
      }
    }

    // Calculate the final end col by trimming whitespace on the right of the
    // line if needed.
    if (trimRight) {
      const rightWhitespaceIndex = lineString.search(/\s+$/);
      if (rightWhitespaceIndex !== -1) {
        endIndex = Math.min(endIndex, rightWhitespaceIndex);
      }
      // Return the empty string if only trimmed whitespace is selected
      if (endIndex <= startIndex) {
        return '';
      }
    }

    return lineString.substring(startIndex, endIndex);
  }