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Contents
/// An ISBN type
#[derive(PartialEq, Eq)]
enum IsbnType {
Isbn10,
Isbn13,
}
/// Checks if an 'X' is valid at the given position for the given ISBN type
#[allow(non_snake_case)]
fn is_X_valid(position: &usize, isbn_type: &IsbnType) -> bool {
(isbn_type == &IsbnType::Isbn10 && position == &9 ) ||
(isbn_type == &IsbnType::Isbn13 && position == &12)
}
/// Checks if a '-' is valid at the given position for the given ISBN type
fn is_dash_valid(position: &usize, isbn_type: &IsbnType) -> bool {
isbn_type == &IsbnType::Isbn13 &&
(position == &1 || position == &5 || position == &11)
}
/// Determines whether the supplied string is a valid ISBN number
pub fn is_valid_isbn(isbn: &str) -> bool {
let isbn_type = match isbn.len() {
10 => IsbnType::Isbn10,
13 => IsbnType::Isbn13,
_ => return false,
};
let mut checksum = 0;
let mut coefficient = 10;
for (position, c) in isbn.char_indices() {
let digit_value = match c {
'0' ... '9' => c.to_digit(10).unwrap(),
'X' if is_X_valid(&position, &isbn_type) => 10,
'-' if is_dash_valid(&position, &isbn_type) => continue,
_ => return false,
};
checksum += coefficient * digit_value;
coefficient -= 1;
}
checksum % 11 == 0
}
Version data entries
118 entries across 118 versions & 1 rubygems