template: build.rs dont write file if no change made

2023/Cargo.toml

@@ -13,7 +13,7 @@ members = [
   "day9",
   "day10",
   "day11",
-  # "day12",
+  "day12",
   # "day13",
   # "day14",
   # "day15",

2023/day12/.gitignore

@@ -0,0 +1,19 @@
+input.txt
+flamegraph.svg
+perf.data*
+### Rust
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+

2023/day12/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "day12"
+authors = ["mirsella <[email protected]>"]
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+

2023/day12/build.rs

@@ -0,0 +1,28 @@
+use std::fs::File;
+use std::io::{self, Read};
+use std::path::PathBuf;
+use std::{env, fs};
+
+fn replace_in_file(file_path: &PathBuf, old: &str, new: &str) -> io::Result<()> {
+    let mut contents = String::new();
+    File::open(file_path)?.read_to_string(&mut contents)?;
+    let new_contents = contents.replace(old, new);
+    if contents != new_contents {
+        println!("Updating {}", file_path.display());
+        fs::write(file_path, new_contents)?;
+    }
+    Ok(())
+}
+
+fn main() -> io::Result<()> {
+    let pkg_name = env::var("CARGO_PKG_NAME").unwrap();
+    replace_in_file(
+        &"../Cargo.toml".into(),
+        &format!("# \"{pkg_name}\""),
+        &format!("\"{pkg_name}\""),
+    )?;
+
+    replace_in_file(&"./Cargo.toml".into(), "\n[workspace]", "")?;
+
+    Ok(())
+}

2023/day12/src/main.rs

@@ -0,0 +1,24 @@
+fn part1(input: &str) -> usize {
+    todo!()
+}
+fn part2(input: &str) -> usize {
+    todo!()
+}
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("Part 1: {}", part1(input));
+    println!("Part 2: {}", part2(input));
+}
+
+#[cfg(test)]
+mod tests {
+    const INPUT: &str = "";
+    #[test]
+    fn part1() {
+        assert_eq!(super::part1(INPUT), todo!());
+    }
+    #[test]
+    fn part2() {
+        assert_eq!(super::part2(INPUT), todo!());
+    }
+}

template/build.rs

@@ -7,7 +7,10 @@ fn replace_in_file(file_path: &PathBuf, old: &str, new: &str) -> io::Result<()>
     let mut contents = String::new();
     File::open(file_path)?.read_to_string(&mut contents)?;
     let new_contents = contents.replace(old, new);
-    fs::write(file_path, new_contents)?;
+    if contents != new_contents {
+        println!("Updating {}", file_path.display());
+        fs::write(file_path, new_contents)?;
+    }
     Ok(())
 }