CLeanup, and get domain overlap and mapping adjustment working.

src/mapping/domain.rs

@@ -2,7 +2,7 @@ use serde::{Deserialize, Serialize};
 
 /// Domain, in sectors.
 /// Requires sector_size to be provided elsewhere for conversion to bytes.
-#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq)]
+#[derive(Clone, Copy, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Domain {
     pub start: usize,
     pub end: usize,
@@ -19,6 +19,34 @@ impl Domain {
     pub fn len(self) -> usize {
         self.end - self.start
     }
+
+    /// Returns the type of overlap between this domain and another.
+    pub fn overlap(&self, other: Domain) -> DomainOverlap {
+        if self.end <= other.start || other.end <= self.start {
+            // Cases 7, 8, 12, and 13 of map::tests::test_update
+            DomainOverlap::None
+        } else if other.start >= self.start && other.end <= self.end {
+            // Cases 3, 5, 9, and 11 of map::tests::test_update
+            DomainOverlap::SelfEngulfsOther
+        } else if other.start <= self.start && other.end >= self.end {
+            // Cases 4, 6, and 10 of map::tests::test_update
+            DomainOverlap::OtherEngulfsSelf
+        } else if self.start < other.start {
+            // Case 1 of map::tests::test_update
+            DomainOverlap::OtherOverlapsEnd
+        } else {
+            // Case 2 of map::tests::test_update
+            DomainOverlap::OtherOverlapsStart
+        }
+    }
+}
+
+pub enum DomainOverlap {
+    None,
+    SelfEngulfsOther,
+    OtherEngulfsSelf,
+    OtherOverlapsStart,
+    OtherOverlapsEnd,
 }
 
 #[cfg(test)]