From e6ce2cf34d78405b0a756a24091b0602fd4a7660 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Wed, 19 Oct 2022 22:23:52 -0700
Subject: [PATCH] then_ignore, ignore_then

---
 src/lib.rs    | 26 +++++++++++++-------------
 src/parser.rs | 26 ++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 3069a71..f995968 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -52,21 +52,21 @@ mod tests {
         let digit = || one_of("1234567890");
         assert_eq!(digit().parse("3"), Ok(("3", "")));
 
+        let digits = || repeated(digit()).at_least(1);
+
         let json_number_inner = choice((
-            seq((
-                repeated(digit()).at_least(1),
-                literal(".").then(repeated(digit())).optional(),
-            ))
-            .map(|(mut digits, maybe_more)| {
-                if let Some((point, more)) = maybe_more {
-                    digits.push(point);
-                    digits.extend(more.into_iter());
-                }
-                digits.into_iter().collect::<String>()
-            }),
-            seq((literal("."), repeated(digit()).at_least(1))).map(|(_point, digits)| {
+            seq((digits(), literal(".").ignore_then(digits()).optional())).map(
+                |(mut digits, maybe_decimal)| {
+                    if let Some(decimal_digits) = maybe_decimal {
+                        digits.push(".");
+                        digits.extend(decimal_digits.into_iter());
+                    }
+                    digits.into_iter().collect::<String>()
+                },
+            ),
+            literal(".").ignore_then(digits()).map(|decimal_digits| {
                 let mut d = vec!["."];
-                d.extend(digits.into_iter());
+                d.extend(decimal_digits.into_iter());
                 d.into_iter().collect::<String>()
             }),
         ))
diff --git a/src/parser.rs b/src/parser.rs
index 86c9908..e069cc4 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -44,6 +44,32 @@ pub trait Parser<I, O, E> {
         BoxedParser::new(crate::sequence::tuple2(self, next_parser))
     }
 
+    fn ignore_then<'a, P, O2>(self, next_parser: P) -> BoxedParser<'a, I, O2, E>
+    where
+        Self: Sized + 'a,
+        I: 'a,
+        O: 'a,
+        O2: 'a,
+        E: 'a,
+        P: Parser<I, O2, E> + 'a,
+    {
+        BoxedParser::new(crate::sequence::tuple2(self, next_parser))
+            .map(|(_, next_output)| next_output)
+    }
+
+    fn then_ignore<'a, P, O2>(self, next_parser: P) -> BoxedParser<'a, I, O, E>
+    where
+        Self: Sized + 'a,
+        I: 'a,
+        O: 'a,
+        O2: 'a,
+        E: 'a,
+        P: Parser<I, O, E> + 'a,
+    {
+        BoxedParser::new(crate::sequence::tuple2(self, next_parser))
+            .map(|(this_output, _)| this_output)
+    }
+
     fn optional<'a>(self) -> BoxedParser<'a, I, Option<O>, E>
     where
         I: Clone + 'a,