Merge #174: Add CheckedHrpstring::fe32_iter function

319d9e3 Remove generics from AsciiToFe32Iter (Tobin C. Harding)
931b80f Add CheckedHrpstring::fe32_iter function (Tobin C. Harding)

Pull request description:

  Simplify the `AsciiToFe32Iter`, make it public, and add a function to create it.

ACKs for top commit:
  apoelstra:
    ACK 319d9e3

Tree-SHA512: 5ea007de59dafb59f2b209e4660367306f279c1ceac3dad52744a7298f99d6bc294dabae6c6fa7899f9223c4249e74dd68f54a03131f929812cf2039a820e34c

Author: apoelstra

src/primitives/decode.rs

@@ -373,6 +373,14 @@ impl<'s> CheckedHrpstring<'s> {
     #[inline]
     pub fn data_part_ascii_no_checksum(&self) -> &'s [u8] { self.ascii }
 
+    /// Returns an iterator that yields the data part of the parsed bech32 encoded string as [`Fe32`]s.
+    ///
+    /// Converts the ASCII bytes representing field elements to the respective field elements.
+    #[inline]
+    pub fn fe32_iter<I: Iterator<Item = u8>>(&self) -> AsciiToFe32Iter {
+        AsciiToFe32Iter { iter: self.ascii.iter().copied() }
+    }
+
     /// Returns an iterator that yields the data part of the parsed bech32 encoded string.
     ///
     /// Converts the ASCII bytes representing field elements to the respective field elements, then
@@ -631,7 +639,7 @@ fn check_characters(s: &str) -> Result<usize, CharError> {
 
 /// An iterator over a parsed HRP string data as bytes.
 pub struct ByteIter<'s> {
-    iter: FesToBytes<AsciiToFe32Iter<iter::Copied<slice::Iter<'s, u8>>>>,
+    iter: FesToBytes<AsciiToFe32Iter<'s>>,
 }
 
 impl<'s> Iterator for ByteIter<'s> {
@@ -649,7 +657,7 @@ impl<'s> ExactSizeIterator for ByteIter<'s> {
 
 /// An iterator over a parsed HRP string data as field elements.
 pub struct Fe32Iter<'s> {
-    iter: AsciiToFe32Iter<iter::Copied<slice::Iter<'s, u8>>>,
+    iter: AsciiToFe32Iter<'s>,
 }
 
 impl<'s> Iterator for Fe32Iter<'s> {
@@ -660,21 +668,18 @@ impl<'s> Iterator for Fe32Iter<'s> {
     fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
 }
 
-/// Helper iterator adaptor that maps an iterator of valid bech32 character ASCII bytes to an
+/// Iterator adaptor that maps an iterator of valid bech32 character ASCII bytes to an
 /// iterator of field elements.
 ///
 /// # Panics
 ///
 /// If any `u8` in the input iterator is out of range for an [`Fe32`]. Should only be used on data
 /// that has already been checked for validity (eg, by using `check_characters`).
-struct AsciiToFe32Iter<I: Iterator<Item = u8>> {
-    iter: I,
+pub struct AsciiToFe32Iter<'s> {
+    iter: iter::Copied<slice::Iter<'s, u8>>,
 }
 
-impl<I> Iterator for AsciiToFe32Iter<I>
-where
-    I: Iterator<Item = u8>,
-{
+impl<'s> Iterator for AsciiToFe32Iter<'s> {
     type Item = Fe32;
     #[inline]
     fn next(&mut self) -> Option<Fe32> { self.iter.next().map(Fe32::from_char_unchecked) }
@@ -685,10 +690,7 @@ where
     }
 }
 
-impl<I> ExactSizeIterator for AsciiToFe32Iter<I>
-where
-    I: Iterator<Item = u8> + ExactSizeIterator,
-{
+impl<'s> ExactSizeIterator for AsciiToFe32Iter<'s> {
     #[inline]
     fn len(&self) -> usize { self.iter.len() }
 }