From cbb30d3e9f253a736348431fe77b9770fbdbe4df Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg@everydayimshuflin.com>
Date: Fri, 26 Jan 2024 00:07:52 -0800
Subject: [PATCH] Modules

---
 src/choice.rs     | 21 ++++++++++++++++
 src/lib.rs        | 61 ++++++++++++++++-------------------------------
 src/primitives.rs | 26 ++++++++++++++++++++
 src/sequence.rs   | 14 +++++++++++
 4 files changed, 81 insertions(+), 41 deletions(-)
 create mode 100644 src/choice.rs
 create mode 100644 src/primitives.rs
 create mode 100644 src/sequence.rs

diff --git a/src/choice.rs b/src/choice.rs
new file mode 100644
index 0000000..f037cfb
--- /dev/null
+++ b/src/choice.rs
@@ -0,0 +1,21 @@
+use crate::Parser;
+
+pub fn choice<'a, I, O, E>(parsers: &'a [&'a dyn Parser<I, O, E>]) -> impl Parser<I, O, E> + 'a
+where
+    I: Clone,
+{
+    move |input: I| {
+        //TODO need a more principled way to return an error when no choices work
+        let mut err = None;
+
+        for parser in parsers.iter() {
+            match parser.parse(input.clone()) {
+                Ok(res) => return Ok(res),
+                Err(e) => {
+                    err = Some(e);
+                }
+            }
+        }
+        Err(err.unwrap())
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index b955260..245f314 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,15 @@
 #![allow(dead_code)] //TODO eventually turn this off
+mod choice;
+mod primitives;
+mod sequence;
+
+pub use choice::*;
+pub use primitives::*;
+pub use sequence::*;
 
 type ParseResult<I, O, E> = Result<(O, I), E>;
 
-trait Parser<I, O, E> {
+pub trait Parser<I, O, E> {
     fn parse(&self, input: I) -> ParseResult<I, O, E>;
 }
 
@@ -15,46 +22,6 @@ where
     }
 }
 
-fn literal(expected: &'static str) -> impl Fn(&str) -> ParseResult<&str, &str, &str> {
-    move |input| match input.get(0..expected.len()) {
-        Some(next) if next == expected => Ok((next, &input[expected.len()..])),
-        _ => Err(input),
-    }
-}
-
-fn sequence<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)
-                .map(|(result2, rest2)| ((result1, result2), rest2))
-        })
-    }
-}
-
-fn choice<'a, I, O, E>(parsers: &'a [&'a dyn Parser<I, O, E>]) -> impl Parser<I, O, E> + 'a
-where
-    I: Clone,
-{
-    move |input: I| {
-        //TODO need a more principled way to return an error when no choices work
-        let mut err = None;
-
-        for parser in parsers.iter() {
-            match parser.parse(input.clone()) {
-                Ok(res) => return Ok(res),
-                Err(e) => {
-                    err = Some(e);
-                }
-            }
-        }
-        Err(err.unwrap())
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -74,4 +41,16 @@ mod tests {
         assert_eq!(output.0 .1, (" ", "jonzzz"));
         assert_eq!(output.1, "");
     }
+
+    #[test]
+    fn test_choice() {
+        let a = literal("bongo");
+        let b = literal("sucy");
+        let c = literal("ara");
+        let inputs = [&a as &dyn Parser<&str, &str, &str>, &b, &c];
+        let parser = choice(&inputs);
+
+        let output = parser.parse("ara hajimete").unwrap();
+        assert_eq!(("ara", " hajimete"), output);
+    }
 }
diff --git a/src/primitives.rs b/src/primitives.rs
new file mode 100644
index 0000000..c5e1622
--- /dev/null
+++ b/src/primitives.rs
@@ -0,0 +1,26 @@
+use crate::{ParseResult, Parser};
+
+pub fn literal(expected: &'static str) -> impl Fn(&str) -> ParseResult<&str, &str, &str> {
+    move |input| match input.get(0..expected.len()) {
+        Some(next) if next == expected => Ok((next, &input[expected.len()..])),
+        _ => Err(input),
+    }
+}
+
+pub fn literal_char<'a>(expected: char) -> impl Parser<&'a str, char, &'a str> {
+    move |input: &'a str| match input.chars().next() {
+        Some(ch) if ch == expected => Ok((expected, &input[ch.len_utf8()..])),
+        _ => Err(input),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn literals() {
+        let parser = literal_char('f');
+        assert_eq!(Ok(('f', "unky")), parser.parse("funky"));
+    }
+}
diff --git a/src/sequence.rs b/src/sequence.rs
new file mode 100644
index 0000000..87229e1
--- /dev/null
+++ b/src/sequence.rs
@@ -0,0 +1,14 @@
+use crate::{ParseResult, Parser};
+
+pub fn sequence<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)
+                .map(|(result2, rest2)| ((result1, result2), rest2))
+        })
+    }
+}