Use generics instead of trait objects; improve declaration

2 files changed, 19 insertions, 12 deletions

diff --git a/src/delta.rs b/src/delta.rs
index 4f3552e7..425f87b7 100644
--- a/src/delta.rs
+++ b/src/delta.rs
@@ -44,12 +44,15 @@ impl State {
 // | HunkMinus  | flush, emit | flush, emit | flush, emit | flush, emit | push        | push     |
 // | HunkPlus   | flush, emit | flush, emit | flush, emit | flush, emit | flush, push | push     |
 
-pub fn delta(
-    lines: impl Iterator<Item = String>,
+pub fn delta<I>(
+    lines: I,
     config: &Config,
     assets: &HighlightingAssets,
     writer: &mut Write,
-) -> std::io::Result<()> {
+) -> std::io::Result<()>
+where
+    I: Iterator<Item = String>,
+{
     // TODO: Painter::new(config)
     let mut painter = Painter {
         minus_lines: Vec::new(),
diff --git a/src/edits.rs b/src/edits.rs
index 18addb08..b3eb43fd 100644
--- a/src/edits.rs
+++ b/src/edits.rs
@@ -328,10 +328,11 @@ mod string_pair {
             }
         }
 
-        fn common_prefix_length(
-            s0: impl Iterator<Item = char>,
-            s1: impl Iterator<Item = char>,
-        ) -> usize {
+        fn common_prefix_length<I>(s0: I, s1: I) -> usize
+        where
+            I: Iterator,
+            I::Item: PartialEq,
+        {
             let mut i = 0;
             for (c0, c1) in s0.zip(s1) {
                 if c0 != c1 {
@@ -344,10 +345,10 @@ mod string_pair {
         }
 
         /// Return common suffix length and number of trailing whitespace characters on each string.
-        fn suffix_data(
-            s0: impl DoubleEndedIterator<Item = char>,
-            s1: impl DoubleEndedIterator<Item = char>,
-        ) -> (usize, [usize; 2]) {
+        fn suffix_data<I>(s0: I, s1: I) -> (usize, [usize; 2])
+        where
+            I: DoubleEndedIterator<Item = char>,
+        {
             let mut s0 = s0.rev().peekable();
             let mut s1 = s1.rev().peekable();
             let n0 = StringPair::consume_whitespace(&mut s0);
@@ -357,7 +358,10 @@ mod string_pair {
         }
 
         /// Consume leading whitespace; return number of characters consumed.
-        fn consume_whitespace(s: &mut Peekable<impl Iterator<Item = char>>) -> usize {
+        fn consume_whitespace<I>(s: &mut Peekable<I>) -> usize
+        where
+            I: Iterator<Item = char>,
+        {
             let mut i = 0;
             loop {
                 match s.peek() {