Sequence trait

src/sequence.rs

@@ -1,13 +1,33 @@
 use crate::{ParseResult, Parser};
 
-pub fn sequence<I, O1, O2, E>(
+pub fn sequence<S, I, O, E>(sequence: S) -> impl Parser<I, O, E>
+where
+    S: Sequence<I, O, E>,
+{
+    move |input| -> ParseResult<I, O, E> { sequence.parse(input) }
+}
+
+pub fn seq2<I, O1, O2, E>(
     first: impl Parser<I, O1, E>,
     second: impl Parser<I, O2, E>,
 ) -> impl Parser<I, (O1, O2), E> {
-    move |input| -> ParseResult<I, (O1, O2), E> {
-        first.parse(input).and_then(|(result1, rest)| {
-            second
-                .parse(rest)
+    sequence((first, second))
+}
+
+pub trait Sequence<I, O, E> {
+    fn parse(&self, input: I) -> ParseResult<I, O, E>;
+}
+
+impl<P1, P2, I, O1, O2, E> Sequence<I, (O1, O2), E> for (P1, P2)
+where
+    P1: Parser<I, O1, E>,
+    P2: Parser<I, O2, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, (O1, O2), E> {
+        let p1 = &self.0;
+        let p2 = &self.1;
+        p1.parse(input).and_then(|(result1, rest)| {
+            p2.parse(rest)
                 .map(|(result2, rest2)| ((result1, result2), rest2))
         })
     }