Parser finished.

src/prob5.rs

@@ -1,19 +1,116 @@
-fn parser(content: &str) {
-    let output = content
-        .lines()
-        .filter(|item| !item.starts_with("move"))
-        .flat_map(|line| {
-            let splitted = line
-                .trim()
-                .split(' ')
-                .enumerate()
-                .filter(|item| !item.1.contains(' '))
-                .filter(|item| !item.1.is_empty())
-                .collect::<Vec<(usize, &str)>>();
-            println!("{splitted:?}");
-            splitted
+use nom::{
+    branch::alt,
+    bytes::complete::{tag, take, take_while1},
+    combinator::{all_consuming, map, map_res, opt},
+    sequence::{delimited, preceded, tuple},
+    Finish, IResult,
+};
+
+#[derive(Debug)]
+struct Instruction {
+    quantity: usize,
+    src: usize,
+    dst: usize,
+}
+
+/// Used to parse a crate
+///
+/// # Arguments
+///
+/// * `i`:
+///
+/// returns: Result<(&str, char), Err<Error<I>>>
+///
+fn parse_crate(i: &str) -> IResult<&str, char> {
+    let first_char = |s: &str| s.chars().next().unwrap();
+    let f = delimited(tag("["), take(1_usize), tag("]"));
+    map(f, first_char)(i)
+}
+
+fn parse_hole(i: &str) -> IResult<&str, ()> {
+    // `drop` takes a value and returns nothing, which is
+    // perfect for our case
+    map(tag("   "), drop)(i)
+}
+
+fn parse_crate_or_hole(i: &str) -> IResult<&str, Option<char>> {
+    alt((map(parse_crate, Some), map(parse_hole, |_| None)))(i)
+}
+
+fn parse_crate_line(i: &str) -> IResult<&str, Vec<Option<char>>> {
+    let (mut i, c) = parse_crate_or_hole(i)?;
+    let mut v = vec![c];
+
+    loop {
+        let (next_i, maybe_c) = opt(preceded(tag(" "), parse_crate_or_hole))(i)?;
+        match maybe_c {
+            Some(c) => v.push(c),
+            None => break,
+        }
+        i = next_i;
+    }
+
+    Ok((i, v))
+}
+
+fn transpose_rev<T>(v: Vec<Vec<Option<T>>>) -> Vec<Vec<T>> {
+    assert!(!v.is_empty());
+    let len = v[0].len();
+    let mut iters: Vec<_> = v.into_iter().map(|n| n.into_iter()).collect();
+    (0..len)
+        .map(|_| {
+            iters
+                .iter_mut()
+                .filter_map(|n| n.next().unwrap())
+                .collect::<Vec<T>>()
         })
-        .collect::<Vec<(usize, &str)>>();
+        .collect()
+}
+
+fn parse_number(i: &str) -> IResult<&str, usize> {
+    map_res(take_while1(|c: char| c.is_ascii_digit()), |s: &str| {
+        s.parse::<usize>()
+    })(i)
+}
+
+fn parse_pile_number(i: &str) -> IResult<&str, usize> {
+    map(parse_number, |i| i - 1)(i)
+}
+
+fn parse_instruction(i: &str) -> IResult<&str, Instruction> {
+    map(
+        tuple((
+            preceded(tag("move "), parse_number),
+            preceded(tag(" from "), parse_pile_number),
+            preceded(tag(" to "), parse_pile_number),
+        )),
+        |(quantity, src, dst)| Instruction { quantity, src, dst },
+    )(i)
+}
+
+fn parser(content: &str) {
+    let mut lines = content.lines();
+    let crate_lines = (&mut lines)
+        .map_while(|line| {
+            all_consuming(parse_crate_line)(line)
+                .finish()
+                .ok()
+                .map(|(_, line)| line)
+        })
+        .collect();
+
+    let crate_columns = transpose_rev(crate_lines);
+
+    crate_columns.iter().for_each(|item| println!("{item:?}"));
+
+    assert!(lines.next().unwrap().is_empty());
+
+    let instructions: Vec<_> = lines
+        .map(|line| all_consuming(parse_instruction)(line).finish().unwrap().1)
+        .collect();
+    for ins in &instructions {
+        println!("{ins:?}");
+    }
 }
 
 pub fn solve(file_path: &str) -> i32 {