diff --git a/substrate/primitives/runtime/src/lib.rs b/substrate/primitives/runtime/src/lib.rs index 0e1d4c31fd71..ddf92554c830 100644 --- a/substrate/primitives/runtime/src/lib.rs +++ b/substrate/primitives/runtime/src/lib.rs @@ -954,6 +954,32 @@ pub fn print(print: impl traits::Printable) { print.print(); } +/// Utility function to declare string literals backed by an array of length N. +/// +/// The input can be shorter than N, in that case the end of the array is padded with zeros. +/// +/// [`str_array`] is useful when converting strings that end up in the storage as fixed size arrays +/// or in const contexts where static data types have strings that could also end up in the storage. +/// +/// # Example +/// +/// ```rust +/// # use sp_runtime::str_array; +/// const MY_STR: [u8; 6] = str_array("data"); +/// assert_eq!(MY_STR, *b"data\0\0"); +/// ``` +pub const fn str_array(s: &str) -> [u8; N] { + debug_assert!(s.len() <= N, "String literal doesn't fit in array"); + let mut i = 0; + let mut arr = [0; N]; + let s = s.as_bytes(); + while i < s.len() { + arr[i] = s[i]; + i += 1; + } + arr +} + /// Describes on what should happen with a storage transaction. pub enum TransactionOutcome { /// Commit the transaction.