From a9cee17a286bc243cd76ccb552d3d4bcf30636d6 Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <me@sijmenschoon.nl>
Date: Sat, 19 Dec 2020 16:04:37 +0100
Subject: [PATCH] rust(day19): Part 1

---
 rust/src/main.rs | 127 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

diff --git a/rust/src/main.rs b/rust/src/main.rs
index 28fe4d0..a6f65b6 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -669,6 +669,130 @@ mod day16 {
     }
 }
 
+mod day17 {
+    use std::time::Duration;
+
+    pub fn run(_print: bool) -> Duration {
+        Duration::new(0, 0)
+    }
+}
+
+mod day18 {
+    use std::time::Duration;
+
+    pub fn run(_print: bool) -> Duration {
+        Duration::new(0, 0)
+    }
+}
+
+mod day19 {
+    use std::collections::BTreeMap as HashMap;
+    use std::time::Duration;
+
+    #[derive(Debug)]
+    enum Rhs {
+        Terminal(char),
+        Variables(Vec<Vec<usize>>),
+    }
+
+    type Rules = HashMap<usize, Rhs>;
+
+    fn parse(input: &str) -> Option<(Rules, Vec<&str>)> {
+        let mut rules = HashMap::new();
+        let mut messages = Vec::new();
+        let mut parsing_rules = true;
+        for line in input.lines() {
+            let trim = line.trim();
+            if trim.is_empty() {
+                parsing_rules = false;
+                continue;
+            }
+
+            if parsing_rules {
+                let mut split = trim.split(": ");
+                let lhs: usize = split.next()?.parse().ok()?;
+
+                let terms = split.next()?;
+                let rhs = if terms.starts_with('"') {
+                    Rhs::Terminal(terms.chars().nth(1)?)
+                } else {
+                    Rhs::Variables(
+                        terms
+                            .split(" | ")
+                            .map(|t| t.split(" ").flat_map(str::parse).collect())
+                            .collect(),
+                    )
+                };
+
+                rules.insert(lhs, rhs);
+            } else {
+                messages.push(trim);
+            }
+        }
+
+        Some((rules, messages))
+    }
+
+    pub fn run(_print: bool) -> Duration {
+        let input = std::fs::read_to_string("../inputs/19").unwrap();
+
+        println!("from typing import Tuple");
+        println!();
+
+        let (rules, messages) = parse(&input).unwrap();
+
+        for (i, rule) in rules.iter() {
+            println!("def rule_{}(s: str) -> Tuple[bool, str]:", i);
+            match rule {
+                Rhs::Terminal(terminal) => {
+                    println!("    if s[0] == '{}':", terminal);
+                    println!("        return True, s[1:]");
+                    println!("    return False, s");
+                }
+
+                Rhs::Variables(variables) => {
+                    for term in variables {
+                        println!("    r = s");
+                        for (j, variable) in term.iter().enumerate() {
+                            println!("    valid_{}, r = rule_{}(r)", j, variable);
+                        }
+                        println!("    if all((");
+                        for j in 0..term.len() {
+                            println!("        valid_{}, ", j);
+                        }
+                        println!("    )):");
+                        println!("        return True, r");
+                        println!();
+                    }
+                    println!("    return False, s");
+                }
+            }
+
+            println!();
+            println!();
+        }
+        println!("def validate(s):");
+        for i in 0..rules.len() {
+            println!("    if rule_{}(s) == (True, ''):", i);
+            println!("        return True");
+        }
+        println!("    return False");
+
+        println!();
+        println!("if __name__ == '__main__':");
+        println!("    part1 = 0");
+        for message in messages {
+            println!("    if (result := validate('{}')):", message);
+            println!("        part1 += 1");
+            println!("    print('{}:', result)", message);
+            println!();
+        }
+        println!("    print('Part 1:', part1)");
+
+        Duration::new(0, 0)
+    }
+}
+
 fn main() {
     let days = [
         day01::run,
@@ -687,6 +811,9 @@ fn main() {
         day14::run,
         day15::run,
         day16::run,
+        day17::run,
+        day18::run,
+        day19::run,
     ];
 
     if let Some(day) = std::env::args().nth(1) {