func()

in src/ulsp/internal/protocol/mapper.go [58:99]

• 35 lines of code
• 11 McCabe index (conditional complexity)

func (m *TextOffsetMapper) PositionOffset(p protocol.Position) (int, error) {
	m.initLines()

	// Validate line number.
	if p.Line > uint32(len(m.lineStart)) {
		return 0, fmt.Errorf("line number %d out of range 0-%d", p.Line, len(m.lineStart))
	} else if p.Line == uint32(len(m.lineStart)) {
		if p.Character == 0 {
			return len(m.Content), nil // EOF
		}
		return 0, fmt.Errorf("column is beyond end of file")
	}

	offset := m.lineStart[p.Line]
	content := m.Content[offset:] // rest of file from start of enclosing line

	// Advance bytes up to the required number of UTF-16 codes.
	col8 := 0
	for col16 := 0; col16 < int(p.Character); col16++ {
		r, sz := utf8.DecodeRune(content)
		if sz == 0 {
			return 0, fmt.Errorf("column is beyond end of file")
		}
		if r == '\n' {
			return 0, fmt.Errorf("column is beyond end of line")
		}
		if sz == 1 && r == utf8.RuneError {
			return 0, fmt.Errorf("buffer contains invalid UTF-8 text")
		}
		content = content[sz:]

		if r >= 0x10000 {
			col16++ // rune was encoded by a pair of surrogate UTF-16 codes

			if col16 == int(p.Character) {
				break // requested position is in the middle of a rune
			}
		}
		col8 += sz
	}
	return offset + col8, nil
}