Check opposite eq

nickdrozd · Oct 29, 2024 · dc095bf · dc095bf
1 parent 2594f79
commit dc095bf
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Showing 2 changed files with 24 additions and 2 deletions.
diff --git a/src/reason.rs b/src/reason.rs
@@ -467,6 +467,14 @@ impl Alignment for Backstepper {
         self.rspan.len()
     }
 
+    fn l_eq(&self, prev: &Self) -> bool {
+        self.lspan == prev.lspan
+    }
+
+    fn r_eq(&self, prev: &Self) -> bool {
+        self.rspan == prev.rspan
+    }
+
     fn get_slice(&self, start: Pos, ltr: bool) -> TapeSlice {
         let (lspan, rspan, diff) = if ltr {
             (&self.lspan, &self.rspan, self.head() - start)

diff --git a/src/tape.rs b/src/tape.rs
@@ -431,13 +431,16 @@ impl HeadTape {
     }
 }
 
-pub trait Alignment: Eq {
+pub trait Alignment {
     fn head(&self) -> Pos;
     fn scan(&self) -> Color;
 
     fn l_len(&self) -> usize;
     fn r_len(&self) -> usize;
 
+    fn l_eq(&self, prev: &Self) -> bool;
+    fn r_eq(&self, prev: &Self) -> bool;
+
     fn get_slice(&self, start: Pos, ltr: bool) -> TapeSlice;
 
     fn get_ltr(&self, start: Pos) -> TapeSlice {
@@ -464,17 +467,20 @@ pub trait Alignment: Eq {
         if 0 < diff {
             self.r_len() == prev.r_len()
                 && self.l_len() >= prev.l_len()
+                && self.r_eq(prev)
                 && prev.get_ltr(leftmost)
                     == self.get_ltr(leftmost + diff)
         } else if diff < 0 {
             self.l_len() == prev.l_len()
                 && self.r_len() >= prev.r_len()
+                && self.l_eq(prev)
                 && prev.get_rtl(rightmost)
                     == self.get_rtl(rightmost + diff)
         } else {
             self.l_len() == prev.l_len()
                 && self.r_len() == prev.r_len()
-                && self == prev
+                && self.l_eq(prev)
+                && self.r_eq(prev)
         }
     }
 }
@@ -496,6 +502,14 @@ impl Alignment for HeadTape {
         self.tape.rspan.len()
     }
 
+    fn l_eq(&self, prev: &Self) -> bool {
+        self.tape.lspan == prev.tape.lspan
+    }
+
+    fn r_eq(&self, prev: &Self) -> bool {
+        self.tape.rspan == prev.tape.rspan
+    }
+
     fn get_slice(&self, start: Pos, ltr: bool) -> TapeSlice {
         let (lspan, rspan, diff) = if ltr {
             (&self.tape.lspan, &self.tape.rspan, self.head() - start)