Add parsing for conditionals (cont.)

Signed-off-by: Marcel Müller <neikos@neikos.email>

src/input.rs

@@ -22,11 +22,20 @@ impl NomoInput {
     pub fn into_parts(self) -> (Arc<str>, Range<usize>) {
         (self.backing, self.range)
     }
+
+    pub fn get_range(&self) -> Range<usize> {
+        self.range.clone()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct NomoInputCheckpoint {
+    range: Range<usize>,
 }
 
 impl std::fmt::Debug for NomoInput {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "\"{}\"", self.as_str())
+        write!(f, "{:?} ({:?})", self.as_str(), self.range)
     }
 }
 
@@ -74,6 +83,18 @@ impl NomoInput {
     }
 }
 
+impl Offset for NomoInputCheckpoint {
+    fn offset_from(&self, start: &Self) -> usize {
+        self.range.start - start.range.start
+    }
+}
+
+impl Offset<NomoInputCheckpoint> for NomoInput {
+    fn offset_from(&self, start: &NomoInputCheckpoint) -> usize {
+        self.range.start - start.range.start
+    }
+}
+
 impl Offset for NomoInput {
     fn offset_from(&self, start: &Self) -> usize {
         self.as_str().offset_from(&start.as_str())
@@ -116,7 +137,7 @@ impl Stream for NomoInput {
 
     type IterOffsets = NomoInputIter;
 
-    type Checkpoint = NomoInput;
+    type Checkpoint = NomoInputCheckpoint;
 
     fn iter_offsets(&self) -> Self::IterOffsets {
         NomoInputIter {
@@ -167,7 +188,9 @@ impl Stream for NomoInput {
     }
 
     fn checkpoint(&self) -> Self::Checkpoint {
-        self.clone()
+        NomoInputCheckpoint {
+            range: self.get_range(),
+        }
     }
 
     fn reset(&mut self, checkpoint: &Self::Checkpoint) {