From e584668efc915f6ded73fb46baba22005721748d Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Sun, 16 Oct 2022 19:16:21 -0700
Subject: [PATCH] combinators module

---
 src/combinators.rs | 75 +++++++++++++++++++++++++++++++++++++++
 src/lib.rs         | 87 ++--------------------------------------------
 src/parser.rs      |  2 +-
 src/sequence.rs    |  2 +-
 4 files changed, 79 insertions(+), 87 deletions(-)
 create mode 100644 src/combinators.rs

diff --git a/src/combinators.rs b/src/combinators.rs
new file mode 100644
index 0000000..ec0cc5d
--- /dev/null
+++ b/src/combinators.rs
@@ -0,0 +1,75 @@
+use crate::parser::Parser;
+
+pub fn map<P, F, I, O1, O2, E>(parser: P, map_fn: F) -> impl Parser<I, O2, E>
+where
+    P: Parser<I, O1, E>,
+    F: Fn(O1) -> O2,
+{
+    move |input| {
+        parser
+            .parse(input)
+            .map(|(result, rest)| (map_fn(result), rest))
+    }
+}
+
+pub fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
+where
+    P: Parser<I, O, I>,
+    I: Copy,
+{
+    move |mut input| {
+        let mut results = Vec::new();
+
+        while let Ok((item, rest)) = parser.parse(input) {
+            results.push(item);
+            input = rest;
+        }
+
+        Ok((results, input))
+    }
+}
+
+pub fn one_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
+where
+    P: Parser<I, O, I> + 'static,
+    I: Copy + 'static,
+    O: 'static,
+{
+    let parser = std::rc::Rc::new(parser);
+    parser
+        .clone()
+        .then(zero_or_more(parser))
+        .map(|(first, rest)| {
+            let mut output = vec![first];
+            output.extend(rest.into_iter());
+            output
+        })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::combinators::one_or_more;
+    use crate::primitives::literal;
+
+    #[test]
+    fn test_map() {
+        let lit_a = literal("a");
+        let output = lit_a.map(|s| s.to_uppercase()).parse("a yolo");
+        assert_eq!(output.unwrap(), ("A".to_string(), " yolo"));
+    }
+
+    #[test]
+    fn test_one_or_more() {
+        let p = one_or_more(literal("bongo "));
+        let input = "bongo bongo bongo bongo bongo ";
+
+        let (output, rest) = p.parse(input).unwrap();
+        assert_eq!(rest, "");
+        assert_eq!(output.len(), 5);
+
+        let (output, rest) = p.parse("bongo ecks").unwrap();
+        assert_eq!(output.len(), 1);
+        assert_eq!(rest, "ecks");
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index cf5a928..138ffdf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,81 +1,13 @@
 #![feature(assert_matches)]
 #![allow(dead_code)] //TODO eventually turn this off
 mod bnf;
+mod combinators;
 mod parser;
 mod primitives;
 mod sequence;
 
 use parser::{ParseResult, Parser};
 
-fn map<P, F, I, O1, O2, E>(parser: P, map_fn: F) -> impl Parser<I, O2, E>
-where
-    P: Parser<I, O1, E>,
-    F: Fn(O1) -> O2,
-{
-    move |input| {
-        parser
-            .parse(input)
-            .map(|(result, rest)| (map_fn(result), rest))
-    }
-}
-
-fn pred<P, F, I, O>(parser: P, pred_fn: F) -> impl Parser<I, O, I>
-where
-    P: Parser<I, O, I>,
-    F: Fn(&O) -> bool,
-{
-    move |input| {
-        parser.parse(input).and_then(|(result, rest)| {
-            if pred_fn(&result) {
-                Ok((result, rest))
-            } else {
-                Err(rest)
-            }
-        })
-    }
-}
-
-fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
-where
-    P: Parser<I, O, I>,
-    I: Copy,
-{
-    move |mut input| {
-        let mut results = Vec::new();
-
-        while let Ok((item, rest)) = parser.parse(input) {
-            results.push(item);
-            input = rest;
-        }
-
-        Ok((results, input))
-    }
-}
-
-fn one_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
-where
-    P: Parser<I, O, I> + 'static,
-    I: Copy + 'static,
-    O: 'static,
-{
-    let parser = std::rc::Rc::new(parser);
-    parser
-        .clone()
-        .then(zero_or_more(parser))
-        .map(|(first, rest)| {
-            let mut output = vec![first];
-            output.extend(rest.into_iter());
-            output
-        })
-}
-
-fn any_char(input: &str) -> ParseResult<&str, char, &str> {
-    match input.chars().next() {
-        Some(ch) => Ok((ch, &input[ch.len_utf8()..])),
-        None => Err(input),
-    }
-}
-
 fn choice<P1, P2, I, O, E>(parser1: P1, parser2: P2) -> impl Parser<I, O, E>
 where
     P1: Parser<I, O, E>,
@@ -91,6 +23,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::combinators::one_or_more;
     use crate::primitives::literal;
     use std::assert_matches::assert_matches;
     use std::collections::HashMap;
@@ -101,22 +34,6 @@ mod tests {
         assert_matches!(output.unwrap(), ("a", " yolo"));
     }
 
-    #[test]
-    fn test_map() {
-        let lit_a = literal("a");
-        let output = lit_a.map(|s| s.to_uppercase()).parse("a yolo");
-        assert_matches!(output.unwrap(), (s, " yolo") if s == "A");
-    }
-
-    #[test]
-    fn test_one_or_more() {
-        let p = one_or_more(literal("bongo "));
-        let input = "bongo bongo bongo bongo bongo ";
-        assert_matches!(p.parse(input), Ok((v, "")) if v.len() == 5);
-        let input = "bongo ecks";
-        assert_matches!(p.parse(input), Ok((v, "ecks")) if v.len() == 1);
-    }
-
     #[test]
     fn test_choice() {
         let p = choice(literal("gnostika").to(1), one_or_more(literal(" ")).to(2));
diff --git a/src/parser.rs b/src/parser.rs
index 87d0bad..475f577 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -18,7 +18,7 @@ pub trait Parser<I, O, E> {
         O2: 'a,
         F: Fn(O) -> O2 + 'a,
     {
-        BoxedParser::new(crate::map(self, map_fn))
+        BoxedParser::new(crate::combinators::map(self, map_fn))
     }
 
     fn to<'a, O2>(self, item: O2) -> BoxedParser<'a, I, O2, E>
diff --git a/src/sequence.rs b/src/sequence.rs
index 8b75a6f..809726c 100644
--- a/src/sequence.rs
+++ b/src/sequence.rs
@@ -110,8 +110,8 @@ where
 #[cfg(test)]
 mod test {
     use super::*;
+    use crate::combinators::zero_or_more;
     use crate::primitives::{identifier, literal};
-    use crate::zero_or_more;
     use std::assert_matches::assert_matches;
 
     #[test]