Extract utils

backend/reconcile/src/utils/common_prefix_len.rs

@@ -0,0 +1,46 @@
+use std::ops::{Index, Range};
+
+/// Given two lookups and ranges calculates the length of the common prefix.
+/// Copied from https://github.com/mitsuhiko/similar/blob/7e15c44de11a1cd61e1149189929e189ef977fd8/src/algorithms/utils.rs
+pub fn common_prefix_len<Old, New>(
+    old: &Old,
+    old_range: Range<usize>,
+    new: &New,
+    new_range: Range<usize>,
+) -> usize
+where
+    Old: Index<usize> + ?Sized,
+    New: Index<usize> + ?Sized,
+    New::Output: PartialEq<Old::Output>,
+{
+    new_range
+        .zip(old_range)
+        .take_while(|x| new[x.0] == old[x.1])
+        .count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn test_common_prefix_len() {
+        assert_eq!(
+            common_prefix_len("".as_bytes(), 0..0, "".as_bytes(), 0..0),
+            0
+        );
+        assert_eq!(
+            common_prefix_len("foobarbaz".as_bytes(), 0..9, "foobarblah".as_bytes(), 0..10),
+            7
+        );
+        assert_eq!(
+            common_prefix_len("foobarbaz".as_bytes(), 0..9, "blablabla".as_bytes(), 0..9),
+            0
+        );
+        assert_eq!(
+            common_prefix_len("foobarbaz".as_bytes(), 3..9, "foobarblah".as_bytes(), 3..10),
+            4
+        );
+    }
+}

backend/reconcile/src/utils/common_suffix_len.rs

@@ -0,0 +1,47 @@
+use std::ops::{Index, Range};
+
+/// Given two lookups and ranges calculates the length of common suffix.
+/// Copied from https://github.com/mitsuhiko/similar/blob/7e15c44de11a1cd61e1149189929e189ef977fd8/src/algorithms/utils.rs
+pub fn common_suffix_len<Old, New>(
+    old: &Old,
+    old_range: Range<usize>,
+    new: &New,
+    new_range: Range<usize>,
+) -> usize
+where
+    Old: Index<usize> + ?Sized,
+    New: Index<usize> + ?Sized,
+    New::Output: PartialEq<Old::Output>,
+{
+    new_range
+        .rev()
+        .zip(old_range.rev())
+        .take_while(|x| new[x.0] == old[x.1])
+        .count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn test_common_suffix_len() {
+        assert_eq!(
+            common_suffix_len("".as_bytes(), 0..0, "".as_bytes(), 0..0),
+            0
+        );
+        assert_eq!(
+            common_suffix_len("1234".as_bytes(), 0..4, "X0001234".as_bytes(), 0..8),
+            4
+        );
+        assert_eq!(
+            common_suffix_len("1234".as_bytes(), 0..4, "Xxxx".as_bytes(), 0..4),
+            0
+        );
+        assert_eq!(
+            common_suffix_len("1234".as_bytes(), 2..4, "01234".as_bytes(), 2..5),
+            2
+        );
+    }
+}

backend/reconcile/src/utils/merge_iters.rs

@@ -0,0 +1,87 @@
+use std::cmp::Ordering;
+use std::iter::Peekable;
+
+pub struct MergeAscending<L, R, F, O>
+where
+    L: Iterator<Item = R::Item>,
+    R: Iterator,
+    F: Fn(&R::Item) -> O,
+    O: PartialOrd,
+{
+    left: Peekable<L>,
+    right: Peekable<R>,
+    get_key: F,
+}
+
+impl<L, R, F, O> MergeAscending<L, R, F, O>
+where
+    L: Iterator<Item = R::Item>,
+    R: Iterator,
+    F: Fn(&R::Item) -> O,
+    O: PartialOrd,
+{
+    fn new(left: L, right: R, get_key: F) -> Self {
+        MergeAscending {
+            left: left.peekable(),
+            right: right.peekable(),
+            get_key,
+        }
+    }
+}
+
+impl<L, R, F, O> Iterator for MergeAscending<L, R, F, O>
+where
+    L: Iterator<Item = R::Item>,
+    R: Iterator,
+    F: Fn(&R::Item) -> O,
+    O: PartialOrd,
+{
+    type Item = L::Item;
+
+    fn next(&mut self) -> Option<L::Item> {
+        let order = match (self.left.peek(), self.right.peek()) {
+            (Some(l), Some(r)) => (self.get_key)(l).partial_cmp(&(self.get_key)(r)),
+            (Some(_), None) => Some(Ordering::Less),
+            (None, Some(_)) => Some(Ordering::Greater),
+            (None, None) => return None,
+        };
+
+        match order {
+            Some(Ordering::Less) | None => self.left.next(),
+            Some(Ordering::Equal) => self.left.next(),
+            Some(Ordering::Greater) => self.right.next(),
+        }
+    }
+}
+
+pub trait MergeSorted: Iterator {
+    fn merge_sorted_by_key<R, F, O>(self, other: R, get_key: F) -> MergeAscending<Self, R, F, O>
+    where
+        Self: Sized,
+        R: Iterator<Item = Self::Item>,
+        F: Fn(&Self::Item) -> O,
+        O: PartialOrd,
+    {
+        MergeAscending::new(self, other, get_key)
+    }
+}
+
+impl<T: ?Sized> MergeSorted for T where T: Iterator {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn test_merge_sorted_by_key() {
+        let left = [9, 7, 5, 3, 1];
+        let right = [7, 6, 5, 4, 3];
+
+        let result: Vec<i32> = left
+            .into_iter()
+            .merge_sorted_by_key(right.into_iter(), |x| -1 * x)
+            .collect();
+        assert_eq!(result, vec![9, 7, 7, 6, 5, 5, 4, 3, 3, 1]);
+    }
+}

backend/reconcile/src/utils/mod.rs

@@ -0,0 +1,5 @@
+pub mod common_prefix_len;
+pub mod common_suffix_len;
+pub mod merge_iters;
+pub mod ordered_operation;
+pub mod side;

backend/reconcile/src/utils/ordered_operation.rs

@@ -0,0 +1,11 @@
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use crate::operations::Operation;
+
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct OrderedOperation {
+    pub order: usize,
+    pub operation: Operation,
+}

backend/reconcile/src/utils/side.rs

@@ -0,0 +1,4 @@
+pub enum Side {
+    Left,
+    Right,
+}