impl split_at_checked equivalent to respect MSRV

src/bsl/out_point.rs

@@ -1,4 +1,4 @@
-use crate::{Error, Parse, ParseResult, SResult};
+use crate::{slice::split_at_checked, Error, Parse, ParseResult, SResult};
 
 /// The out point of a transaction input, identifying the previous output being spent
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -15,7 +15,7 @@ impl<'a> AsRef<[u8]> for OutPoint<'a> {
 impl<'a> Parse<'a> for OutPoint<'a> {
     /// Parse the out point from the given slice
     fn parse(slice: &'a [u8]) -> SResult<Self> {
-        let (slice, remaining) = slice.split_at_checked(36).ok_or(Error::MoreBytesNeeded)?;
+        let (slice, remaining) = split_at_checked(slice, 36)?;
         Ok(ParseResult::new(remaining, OutPoint { slice }))
     }
 }

src/bsl/script.rs

@@ -1,5 +1,5 @@
 use super::scan_len;
-use crate::{Error, Parse, ParseResult, SResult};
+use crate::{slice::split_at_checked, Error, Parse, ParseResult, SResult};
 
 /// The Script, this type could be found in transaction outputs as `script_pubkey` or in transaction
 /// inputs as `script_sig`.
@@ -17,9 +17,7 @@ impl<'a> Parse<'a> for Script<'a> {
     fn parse(slice: &'a [u8]) -> SResult<Self> {
         let mut consumed = 0;
         let n = scan_len(slice, &mut consumed)? as usize;
-        let (script_bytes, remaining) = slice
-            .split_at_checked(consumed + n)
-            .ok_or(Error::MoreBytesNeeded)?;
+        let (script_bytes, remaining) = split_at_checked(slice, consumed + n)?;
         Ok(ParseResult::new(
             remaining,
             Script {

src/slice.rs

@@ -13,6 +13,17 @@ pub fn read_slice(from: &[u8], len: usize) -> SResult<&[u8]> {
     }
 }
 
+/// Split the slice at the given length, returning the remaining slice and the parsed slice.
+/// Replace with std split_at_checked when MSRV >= 1.80.0
+#[inline(always)]
+pub(crate) fn split_at_checked(from: &[u8], len: usize) -> Result<(&[u8], &[u8]), Error> {
+    if from.len() < len {
+        Err(Error::MoreBytesNeeded)
+    } else {
+        Ok(from.split_at(len))
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::{Error, ParseResult};