fn make_box()

in mp4parse/src/tests.rs [29:71]

• 39 lines of code
• 2 McCabe index (conditional complexity)

fn make_box<F>(size: BoxSize, name: &[u8; 4], func: F) -> Cursor<Vec<u8>>
where
    F: Fn(Section) -> Section,
{
    let mut section = Section::new();
    let box_size = Label::new();
    section = match size {
        BoxSize::Short(size) | BoxSize::UncheckedShort(size) => section.B32(size),
        BoxSize::Long(_) | BoxSize::UncheckedLong(_) => section.B32(1),
        BoxSize::Auto => section.B32(&box_size),
    };
    section = section.append_bytes(name);
    section = match size {
        // The spec allows the 32-bit size to be 0 to indicate unknown
        // length streams.  It's not clear if this is valid when using a
        // 64-bit size, so prohibit it for now.
        BoxSize::Long(size) => {
            assert!(size > 0);
            section.B64(size)
        }
        BoxSize::UncheckedLong(size) => section.B64(size),
        _ => section,
    };
    section = func(section);
    match size {
        BoxSize::Short(size) => {
            if size > 0 {
                assert_eq!(u64::from(size), section.size())
            }
        }
        BoxSize::Long(size) => assert_eq!(size, section.size()),
        BoxSize::Auto => {
            assert!(
                section.size() <= u64::from(u32::MAX),
                "Tried to use a long box with BoxSize::Auto"
            );
            box_size.set_const(section.size());
        }
        // Skip checking BoxSize::Unchecked* cases.
        _ => (),
    }
    Cursor::new(section.get_contents().unwrap())
}