Switch day3b to a nom parser

2024/Cargo.lock

@@ -15,6 +15,7 @@ dependencies = [
 name = "aoc-2024"
 version = "0.1.0"
 dependencies = [
+ "nom",
  "regex",
 ]
 
@@ -24,6 +25,22 @@ version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
+
 [[package]]
 name = "regex"
 version = "1.11.1"

2024/Cargo.toml

@@ -4,4 +4,5 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+nom = "7.1.3"
 regex = "1.11.1"

2024/src/day3.rs

@@ -1,3 +1,6 @@
+use nom::{
+    branch::alt, bytes::complete::{tag, take_while}, character::{complete::anychar, is_digit}, combinator::eof, multi::{many1, many_till}, Err, Finish, IResult
+};
 use regex::Regex;
 
 const INPUT: &'static str = include_str!("../data/day3.txt");
@@ -17,7 +20,10 @@ struct State {
 
 impl Default for State {
     fn default() -> Self {
-        Self{ mult_enabled: true, value: 0 }
+        Self {
+            mult_enabled: true,
+            value: 0,
+        }
     }
 }
 
@@ -25,7 +31,7 @@ impl Default for State {
 enum Operation {
     Do,
     Dont,
-    Mult(Multiplication)
+    Mult(Multiplication),
 }
 
 impl Operation {
@@ -39,7 +45,7 @@ impl Operation {
                 state.mult_enabled = false;
                 state
             }
-            Operation::Mult(mul) => mul.run(state)
+            Operation::Mult(mul) => mul.run(state),
         }
     }
 }
@@ -61,28 +67,13 @@ impl Multiplication {
 
 fn parse_input_a(input: &str) -> Vec<Operation> {
     let re = Regex::new(r"mul\(([0-9]{1,3}),([0-9]{1,3})\)").unwrap();
-    re.captures_iter(input).map(|capture| {
+    re.captures_iter(input)
+        .map(|capture| {
             let x = capture.get(1).unwrap().as_str().parse::<i32>().unwrap();
             let y = capture.get(2).unwrap().as_str().parse::<i32>().unwrap();
             Operation::Mult(Multiplication { x, y })
-    }).collect::<Vec<Operation>>()
-}
-
-fn parse_input_b(input: &str) -> Vec<Operation> {
-    let operation_re = Regex::new(r"do\(\)|don't\(\)|mul\(([0-9]{1,3}),([0-9]{1,3})\)").unwrap();
-
-    operation_re.captures_iter(input).map(|capture| {
-        match capture.get(0).unwrap().as_str()[0..4].as_ref() {
-            "do()" => Operation::Do,
-            "don'" => Operation::Dont,
-            "mul(" => {
-                let x = capture.get(1).unwrap().as_str().parse::<i32>().unwrap();
-                let y = capture.get(2).unwrap().as_str().parse::<i32>().unwrap();
-                Operation::Mult(Multiplication{ x, y })
-            }
-            _ => unimplemented!()
-        }
-    }).collect::<Vec<Operation>>()
+        })
+        .collect::<Vec<Operation>>()
 }
 
 fn calculate_part(lst: Vec<Operation>) -> i32 {
@@ -95,12 +86,53 @@ fn calculate_part(lst: Vec<Operation>) -> i32 {
     state.value
 }
 
+fn parse_input_b(input: &str) -> Vec<Operation> {
+    match many1(next_operation)(input).finish() {
+        Ok((_, operations)) => operations,
+        v => panic!("something went wrong: {:?}", v),
+    }
+}
+
+fn next_operation(input: &str) -> IResult<&str, Operation> {
+    let (rest, (_discard, operation)) = many_till(anychar, match_operation)(input)?;
+    Ok((rest, operation))
+}
+
+fn match_operation(input: &str) -> IResult<&str, Operation> {
+    alt((match_do, match_dont, match_mult))(input)
+}
+
+fn match_do(input: &str) -> IResult<&str, Operation> {
+    let (rest, _) = tag("do()")(input)?;
+    Ok((rest, Operation::Do))
+}
+
+fn match_dont(input: &str) -> IResult<&str, Operation> {
+    let (rest, _) = tag("don't()")(input)?;
+    Ok((rest, Operation::Dont))
+}
+
+fn match_mult(input: &str) -> IResult<&str, Operation> {
+    let (rest, _) = tag("mul(")(input)?;
+    let (rest, x) = take_while(|c| is_digit(c as u8))(rest)?;
+    let (rest, _) = tag(",")(rest)?;
+    let (rest, y) = take_while(|c| is_digit(c as u8))(rest)?;
+    let (rest, _) = tag(")")(rest)?;
+
+    Ok((rest, Operation::Mult(Multiplication {
+        x: x.parse::<i32>().unwrap(),
+        y: y.parse::<i32>().unwrap(),
+    })))
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
 
-    const TEST_INPUT_A: &'static str = "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
-    const TEST_INPUT_B: &'static str = "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
+    const TEST_INPUT_A: &'static str =
+        "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))";
+    const TEST_INPUT_B: &'static str =
+        "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))";
 
     #[test]
     fn it_solves_parta() {