FEATURE: a text token convenience macro.

src/macros.rs

@@ -1,5 +1,31 @@
 //! Contains the helper macros for abortable-parser.
 
+/// Convenience macro for looking for a specific text token in a byte input stream.
+macro_rules! text_token {
+    ($i:expr, $e:expr) => {{
+        use $crate::Error;
+        use $crate::Result;
+        let mut _i = $i.clone();
+        let mut count = 0;
+        for expected in $e.bytes() {
+            let item = match _i.next() {
+                Some(item) => item,
+                None => break,
+            };
+            if item == &expected {
+                count += 1;
+            }
+        }
+        if count == $e.len() {
+            Result::Complete(_i.clone(), $e)
+        } else {
+            Result::Fail(Error::new(format!("Expected {} but didn't get it.", $e), $i))
+        }
+    }};
+}
+
+// FIXME(jwall): We need until!, not! and peek!.
+
 /// Converts a function indentifier into a macro call. Useful when writing your own macro combinator.
 #[macro_export]
 macro_rules! run {
@@ -25,6 +51,8 @@ macro_rules! must {
     };
 }
 
+/// Wraps any Error return from a subparser in another error. Stores the position at
+/// this point in the parse tree allowing you to associate context with wrapped errors.
 #[macro_export]
 macro_rules! wrap_err {
     ($i:expr, $f:ident!( $( $args:tt )* ), $e:expr) => {{

src/test.rs

@@ -66,6 +66,26 @@ fn parse_three(i: SliceIter<u8>) -> Result<SliceIter<u8>, String, String> {
     }
 }
 
+#[test]
+fn test_text_token() {
+    let input_str = "foo bar";
+    let iter = SliceIter::new(input_str.as_bytes());
+    let result = text_token!(&iter, "foo");
+    assert!(result.is_complete());
+    if let Result::Complete(i, o) = result {
+        assert_eq!(i.get_offset(), 3);
+        assert_eq!(o, "foo");
+    }
+}
+
+#[test]
+fn test_text_token_fails() {
+    let input_str = "foo bar";
+    let iter = SliceIter::new(input_str.as_bytes());
+    let result = text_token!(&iter, "bar");
+    assert!(result.is_fail());
+}
+
 #[test]
 fn test_wrap_err_fail() {
     let input_str = "foo";