New debugging span (using range). #1123 (#1148)

* New debugging span (using range). #1123

* elide lifetime

Author: re-masashi

pest/src/iterators/pairs.rs

@@ -608,10 +608,10 @@ mod tests {
         assert_eq!(
             format!("{:?}", pairs),
             "[\
-                Pair { rule: a, span: Span { str: \"abc\", start: 0, end: 3 }, inner: [\
-                    Pair { rule: b, span: Span { str: \"b\", start: 1, end: 2 }, inner: [] }\
+                Pair { rule: a, span: Span { str: \"abc\", range: 0..3 }, inner: [\
+                    Pair { rule: b, span: Span { str: \"b\", range: 1..2 }, inner: [] }\
                 ] }, \
-                Pair { rule: c, span: Span { str: \"e\", start: 4, end: 5 }, inner: [] }\
+                Pair { rule: c, span: Span { str: \"e\", range: 4..5 }, inner: [] }\
             ]"
             .to_owned()
         );

pest/src/span.rs

@@ -272,10 +272,10 @@ impl<'i> Span<'i> {
 
 impl fmt::Debug for Span<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let range = self.start..self.end;
         f.debug_struct("Span")
             .field("str", &self.as_str())
-            .field("start", &self.start)
-            .field("end", &self.end)
+            .field("range", &range)
             .finish()
     }
 }