From 0c5dcca9e3cef6b2f456fccefd9f6c5e43444053 Mon Sep 17 00:00:00 2001
From: Daniel Olano <me@olanod.com>
Date: Sat, 11 Nov 2023 20:34:08 +0100
Subject: [PATCH] Add `s` utility function to frame support (#2275)
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A utility function I consider quite useful to declare string literals
that are backed by an array.
---------
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Davide Galassi <davxy@datawok.net>
---
substrate/primitives/runtime/src/lib.rs | 26 +++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/substrate/primitives/runtime/src/lib.rs b/substrate/primitives/runtime/src/lib.rs
index 0e1d4c31fd7..ddf92554c83 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<const N: usize>(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<R> {
/// Commit the transaction.
--
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