From 9f55bef23818c54aa4ca53ec7481ea5bdb5734b3 Mon Sep 17 00:00:00 2001
From: Lewis Dale <lewis.dale@fortacode.co.uk>
Date: Mon, 2 Jan 2023 18:46:20 +0000
Subject: [PATCH] Parse escape characters properly

---
 src/basic.rs | 56 ++++++++++++++++++++++++++++++----------------------
 src/main.rs  |  2 +-
 2 files changed, 33 insertions(+), 25 deletions(-)

diff --git a/src/basic.rs b/src/basic.rs
index 23bb8d6..04d8555 100644
--- a/src/basic.rs
+++ b/src/basic.rs
@@ -1,26 +1,34 @@
 use nom::{
-    bytes::complete::{tag, take_until, escaped},
-    character::{complete::{u32 as ccu32, one_of}, streaming::none_of},
-    combinator::map,
+    branch::alt,
+    bytes::complete::{escaped_transform, tag, take_until},
+    character::{
+        complete::{u32 as ccu32},
+        streaming::none_of,
+    },
+    combinator::{map, value},
     sequence::{delimited, terminated, tuple},
     IResult,
 };
 
-pub type Line<'a> = (u32, Command<'a>);
+pub type Line = (u32, Command);
 
 #[derive(Debug, PartialEq, Eq)]
-pub enum Command<'a> {
-    Print(&'a str),
+pub enum Command {
+    Print(String),
     None,
 }
 
-fn read_string(i: &str) -> IResult<&str, &str> {
+fn read_string(i: &str) -> IResult<&str, String> {
     // take_until("\"")(i)
-	delimited(
-		tag("\""),
-		escaped(none_of("\\\""), '\\', one_of("\"\\")),
-		tag("\"")
-	)(i)
+    delimited(
+        tag("\""),
+        escaped_transform(
+            none_of("\\\""),
+            '\\',
+            alt((value("\\", tag("\\")), value("\"", tag("\"")))),
+        ),
+        tag("\""),
+    )(i)
 }
 
 fn parse_command(i: &str) -> IResult<&str, Command> {
@@ -45,25 +53,25 @@ mod tests {
     #[test]
     fn it_parses_a_print_command() {
         let input = "10 PRINT \"Hello, world\"";
-        let expected = (10, super::Command::Print("Hello, world"));
+        let expected = (10, super::Command::Print(String::from("Hello, world")));
 
         let (_, result) = super::parse_line(input).unwrap();
         assert_eq!(expected, result);
     }
 
-	#[test]
-	fn it_reads_a_string() {
-		let input = r#""Hello, \"World\"""#;
-		let (_, output) = super::read_string(input).unwrap();
-		assert_eq!(r#"Hello, \"World\""#, output);
-	}
+    #[test]
+    fn it_reads_a_string() {
+        let input = r#""Hello, \"World\"""#;
+        let (_, output) = super::read_string(input).unwrap();
+        assert_eq!(r#"Hello, "World""#, output);
+    }
 
-	#[test]
-	fn it_parses_a_print_command_with_escaped_quotes() {
-		let input = r#"10 PRINT "Hello, \"world\"""#;
-        let expected = (10, super::Command::Print(r#"Hello, \"world\""#));
+    #[test]
+    fn it_parses_a_print_command_with_escaped_quotes() {
+        let input = r#"10 PRINT "Hello, \"world\"""#;
+        let expected = (10, super::Command::Print(String::from(r#"Hello, "world""#)));
 
         let (_, result) = super::parse_line(input).unwrap();
         assert_eq!(expected, result);
-	}
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index c6cd6e9..6afda37 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,7 +8,7 @@ fn main() {
     let (_, (_, command)) = basic::parse_line(lines).unwrap();
     match command {
         basic::Command::Print(input) => {
-            println!("{}", input.replace("\\", ""));
+            println!("{}", input);
         }
         _ => {
             panic!("Command not recognised");