Function guess_format

src/formats/mod.rs:32–61

(
	ext: &Option<String>,
	reader: &mut CachedReader,
	formats: &'a IndexMap<&'static str, Box<dyn Format>>,
)

#[allow(clippy::borrowed_box)]
pub fn guess_format<'a>(
	ext: &Option<String>,
	reader: &mut CachedReader,
	formats: &'a IndexMap<&'static str, Box<dyn Format>>,
) -> Option<&'a Box<dyn Format>> {
	if let Some(ref ext) = ext {
		for (_, format) in formats {
			for pe in format.get_extensions() {
				if ext == pe {
					return Some(format);
				}
			}
		}
	}

	let mut header = [0; CACHE_LEN];
	if reader.read(&mut header).is_ok() {
		reader.rewind();

		for (_, format) in formats {
			if let Ok(is_header) = format.is_valid_header(&header) {
				if is_header {
					return Some(format);
				}
			}
		}
	}

	None
}