feat: Introduce a Measured trait

containing:

* len
* remaining

src/lib.rs

@@ -52,6 +52,11 @@ pub trait Peekable<O> {
     fn peek_next(&self) -> Option<O>;
 }
 
+pub trait Measured {
+    fn len(&self) -> usize;
+    fn remaining(&self) -> usize;
+}
+
 /// SpanRange encompasses the valid Ops::Range types for use with the Span trait.
 pub enum SpanRange {
     Range(std::ops::Range<usize>),
@@ -317,3 +322,25 @@ impl<'a> Peekable<&'a u8> for StrCursor<'a> {
         self.source.as_bytes().get(self.offset)
     }
 }
+
+impl<'a> Measured for StrCursor<'a> {
+    fn len(&self) -> usize {
+        self.source.len()
+    }
+
+    fn remaining(&self) -> usize {
+        self.source[self.offset..].len()
+    }
+}
+
+impl<'a, O> Measured for SliceCursor<'a, O>
+    where O: Debug
+{
+    fn len(&self) -> usize {
+        self.source.len()
+    }
+
+    fn remaining(&self) -> usize {
+        self.source[self.offset..].len()
+    }
+}

src/test.rs

@@ -14,7 +14,7 @@
 
 use super::{
     SliceCursor, StrCursor,
-    Cursor, Offsetable, Span
+    Cursor, Offsetable, Span, Measured
 };
 
 #[test]
@@ -87,8 +87,11 @@ fn test_str_span() {
 
     let mut iter = StrCursor::new(input_str);
     assert_eq!(0, iter.get_offset());
+    assert_eq!(12, iter.len());
+    assert_eq!(12, iter.remaining());
     assert_eq!("foo", iter.span(0..3));
     iter.next();
+    assert_eq!(11, iter.remaining());
     assert_eq!("oo", iter.span(0..2));
 }
 
@@ -98,7 +101,10 @@ fn test_slice_span() {
 
     let mut iter = SliceCursor::new(input_str.as_bytes());
     assert_eq!(0, iter.get_offset());
+    assert_eq!(12, iter.len());
+    assert_eq!(12, iter.remaining());
     assert_eq!("foo".as_bytes(), iter.span(0..3));
     iter.next();
+    assert_eq!(11, iter.remaining());
     assert_eq!("oo".as_bytes(), iter.span(0..2));
 }