From e697b8ed21c176370985d702bc662cf3ee24ad96 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg@everydayimshuflin.com>
Date: Fri, 26 Jan 2024 09:39:46 -0800
Subject: [PATCH] Sequence trait

---
 src/lib.rs      | 10 +++++-----
 src/sequence.rs | 30 +++++++++++++++++++++++++-----
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index ad50a6b..41eb741 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -39,7 +39,7 @@ mod tests {
 
     #[test]
     fn test_sequence() {
-        let parser = sequence(literal("bongo"), sequence(literal(" "), literal("jonzzz")));
+        let parser = seq2(literal("bongo"), seq2(literal(" "), literal("jonzzz")));
         let output = parser.parse("bongo jonzzz").unwrap();
         assert_eq!(output.0 .0, "bongo");
         assert_eq!(output.0 .1, (" ", "jonzzz"));
@@ -61,7 +61,7 @@ mod tests {
     #[test]
     fn test_map() {
         let parser = map(
-            sequence(literal("a"), literal("b")),
+            seq2(literal("a"), literal("b")),
             |(_a, _b): (&str, &str)| 59,
         );
         let output = parser.parse("abcd").unwrap();
@@ -70,16 +70,16 @@ mod tests {
 
     #[test]
     fn test_combinators() {
-        let parser = sequence(map(repeated(literal_char('a')), |_| 10), literal_char('b'));
+        let parser = seq2(map(repeated(literal_char('a')), |_| 10), literal_char('b'));
         let output = parser.parse("aaaaaaaabcd").unwrap();
         assert_eq! {((10, 'b'), "cd"), output};
     }
 
     #[test]
     fn test_optional() {
-        let parser = sequence(
+        let parser = seq2(
             optional(literal("alpha")),
-            sequence(repeated(literal(" ")), literal("beta")),
+            seq2(repeated(literal(" ")), literal("beta")),
         );
 
         let output1 = parser.parse("   beta").unwrap();
diff --git a/src/sequence.rs b/src/sequence.rs
index 87229e1..23f44df 100644
--- a/src/sequence.rs
+++ b/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))
         })
     }