seq for tuples of lengths 2 - 5

src/sequence.rs

@@ -1,11 +1,37 @@
-use crate::Parser;
+use crate::{ParseResult, Parser};
 
 pub fn tuple2<P1, P2, I, O1, O2, E>(parser1: P1, parser2: P2) -> impl Parser<I, (O1, O2), E>
 where
     P1: Parser<I, O1, E>,
     P2: Parser<I, O2, E>,
 {
-    move |input| {
+    seq((parser1, parser2))
+}
+
+pub fn seq<T, I, O, E>(sequence: T) -> impl Parser<I, O, E>
+where
+    T: Sequence<I, O, E>,
+{
+    move |input| sequence.parse(input)
+}
+
+/* TODO - eventually rewrite this parser combinator in Schala. Seeing what this
+ * code that makes heavy use of type variables and abstraction over types looks like
+ * in Schala's type system should be educational
+ */
+
+pub trait Sequence<I, O, E> {
+    fn parse(&self, input: I) -> ParseResult<I, O, E>;
+}
+
+impl<I, O1, O2, E, P1, P2> 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 parser1 = &self.0;
+        let parser2 = &self.1;
         parser1.parse(input).and_then(|(result1, rest1)| {
             parser2
                 .parse(rest1)
@@ -14,10 +40,77 @@ where
     }
 }
 
+impl<I, O1, O2, O3, E, P1, P2, P3> Sequence<I, (O1, O2, O3), E> for (P1, P2, P3)
+where
+    P1: Parser<I, O1, E>,
+    P2: Parser<I, O2, E>,
+    P3: Parser<I, O3, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, (O1, O2, O3), E> {
+        let parser1 = &self.0;
+        let parser2 = &self.1;
+        let parser3 = &self.2;
+
+        let (result1, rest1) = parser1.parse(input)?;
+        let (result2, rest2) = parser2.parse(rest1)?;
+        let (result3, rest3) = parser3.parse(rest2)?;
+
+        Ok(((result1, result2, result3), rest3))
+    }
+}
+
+impl<I, O1, O2, O3, O4, E, P1, P2, P3, P4> Sequence<I, (O1, O2, O3, O4), E> for (P1, P2, P3, P4)
+where
+    P1: Parser<I, O1, E>,
+    P2: Parser<I, O2, E>,
+    P3: Parser<I, O3, E>,
+    P4: Parser<I, O4, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, (O1, O2, O3, O4), E> {
+        let parser1 = &self.0;
+        let parser2 = &self.1;
+        let parser3 = &self.2;
+        let parser4 = &self.3;
+
+        let (result1, rest1) = parser1.parse(input)?;
+        let (result2, rest2) = parser2.parse(rest1)?;
+        let (result3, rest3) = parser3.parse(rest2)?;
+        let (result4, rest4) = parser4.parse(rest3)?;
+
+        Ok(((result1, result2, result3, result4), rest4))
+    }
+}
+
+impl<I, O1, O2, O3, O4, O5, E, P1, P2, P3, P4, P5> Sequence<I, (O1, O2, O3, O4, O5), E>
+    for (P1, P2, P3, P4, P5)
+where
+    P1: Parser<I, O1, E>,
+    P2: Parser<I, O2, E>,
+    P3: Parser<I, O3, E>,
+    P4: Parser<I, O4, E>,
+    P5: Parser<I, O5, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, (O1, O2, O3, O4, O5), E> {
+        let parser1 = &self.0;
+        let parser2 = &self.1;
+        let parser3 = &self.2;
+        let parser4 = &self.3;
+        let parser5 = &self.4;
+
+        let (result1, rest1) = parser1.parse(input)?;
+        let (result2, rest2) = parser2.parse(rest1)?;
+        let (result3, rest3) = parser3.parse(rest2)?;
+        let (result4, rest4) = parser4.parse(rest3)?;
+        let (result5, rest5) = parser5.parse(rest4)?;
+
+        Ok(((result1, result2, result3, result4, result5), rest5))
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
-    use crate::{identifier, literal};
+    use crate::{identifier, literal, zero_or_more};
     use std::assert_matches::assert_matches;
 
     #[test]
@@ -28,4 +121,26 @@ mod test {
         let p = identifier.then(literal(" ")).then(literal("ruts"));
         assert_matches!(p.parse("fort1 ruts"), Ok((r, "")) if r.0.0 == "fort1" && r.0.1== " " && r.1 == "ruts");
     }
+
+    #[test]
+    fn test_seq() {
+        let p = seq((
+            literal("bong").to(10),
+            zero_or_more(literal(" ")).to(()),
+            literal("hits").to(20),
+        ));
+        assert_eq!(p.parse("bong        hits").unwrap(), ((10, (), 20), ""));
+
+        let p = seq((
+            literal("alpha").to(10),
+            zero_or_more(literal(" ")).to(()),
+            zero_or_more(literal("-")).to(()),
+            zero_or_more(literal(" ")),
+            literal("beta"),
+        ));
+        assert_eq!(
+            p.parse("alpha      ------   beta gamma").unwrap(),
+            ((10, (), (), vec![" ", " ", " "], "beta"), " gamma")
+        );
+    }
 }