From 567ea606427bfa44c2338c660713151b027cfa49 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Wed, 19 Oct 2022 19:42:29 -0700
Subject: [PATCH] repeated combinator

---
 src/choice.rs      |  7 +++--
 src/combinators.rs | 77 ++++++++++++++++++++++++++++++++++++++++++++--
 src/parser.rs      |  2 +-
 3 files changed, 80 insertions(+), 6 deletions(-)

diff --git a/src/choice.rs b/src/choice.rs
index 18c953d..ec01c0d 100644
--- a/src/choice.rs
+++ b/src/choice.rs
@@ -147,12 +147,15 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::combinators::one_or_more;
+    use crate::combinators::repeated;
     use crate::primitives::literal;
 
     #[test]
     fn test_choice() {
-        let p = choice2(literal("gnostika").to(1), one_or_more(literal(" ")).to(2));
+        let p = choice2(
+            literal("gnostika").to(1),
+            repeated(literal(" ")).at_least(1).to(2),
+        );
         assert_eq!(p.parse("gnostika twentynine"), Ok((1, " twentynine")));
     }
 }
diff --git a/src/combinators.rs b/src/combinators.rs
index 4b3ef25..38d0efb 100644
--- a/src/combinators.rs
+++ b/src/combinators.rs
@@ -1,4 +1,4 @@
-use crate::parser::Parser;
+use crate::parser::{BoxedParser, ParseResult, Parser};
 
 pub fn optional<P, I, O, E>(parser: P) -> impl Parser<I, Option<O>, E>
 where
@@ -23,6 +23,78 @@ where
     }
 }
 
+pub struct Repeated<'a, I, O>
+where
+    I: Clone,
+{
+    inner_parser: BoxedParser<'a, I, O, I>,
+    at_least: Option<u16>,
+    at_most: Option<u16>,
+}
+
+impl<'a, I, O> Repeated<'a, I, O>
+where
+    I: Clone,
+{
+    pub fn at_least(self, n: u16) -> Self {
+        Self {
+            at_least: Some(n),
+            ..self
+        }
+    }
+    pub fn at_most(self, n: u16) -> Self {
+        Self {
+            at_most: Some(n),
+            ..self
+        }
+    }
+}
+
+impl<'a, I, O> Parser<I, Vec<O>, I> for Repeated<'a, I, O>
+where
+    I: Clone + 'a,
+{
+    fn parse(&self, input: I) -> ParseResult<I, Vec<O>, I> {
+        let mut results = Vec::new();
+        let mut count: u16 = 0;
+
+        let at_least = self.at_least.unwrap_or(0);
+        let at_most = self.at_most.unwrap_or(u16::MAX);
+
+        if at_most == 0 {
+            return Ok((results, input));
+        }
+
+        let mut further_input = input.clone();
+
+        while let Ok((item, rest)) = self.inner_parser.parse(further_input.clone()) {
+            results.push(item);
+            further_input = rest;
+            count += 1;
+            if count >= at_most {
+                break;
+            }
+        }
+        if count < at_least {
+            return Err(input);
+        }
+
+        Ok((results, further_input))
+    }
+}
+
+pub fn repeated<'a, P, I, O>(parser: P) -> Repeated<'a, I, O>
+where
+    P: Parser<I, O, I> + 'static,
+    I: Clone + 'static,
+{
+    Repeated {
+        inner_parser: BoxedParser::new(parser),
+        at_least: None,
+        at_most: None,
+    }
+}
+
 pub fn zero_or_more<P, I, O>(parser: P) -> impl Parser<I, Vec<O>, I>
 where
     P: Parser<I, O, I>,
@@ -60,7 +132,6 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::combinators::one_or_more;
     use crate::primitives::literal;
 
     #[test]
@@ -72,7 +143,7 @@ mod tests {
 
     #[test]
     fn test_one_or_more() {
-        let p = one_or_more(literal("bongo "));
+        let p = repeated(literal("bongo ")).at_least(1);
         let input = "bongo bongo bongo bongo bongo ";
 
         let (output, rest) = p.parse(input).unwrap();
diff --git a/src/parser.rs b/src/parser.rs
index ff64f07..86c9908 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -60,7 +60,7 @@ pub struct BoxedParser<'a, I, O, E> {
 }
 
 impl<'a, I, O, E> BoxedParser<'a, I, O, E> {
-    fn new<P>(inner: P) -> Self
+    pub(crate) fn new<P>(inner: P) -> Self
     where
         P: Parser<I, O, E> + 'a,
     {