postcard_to_bincode.rs

use std::fs::File;
use std::io::{BufWriter, Read};
use walkdir::WalkDir;
use foo::Foo;

/// Converts postcard `.post` files to bincode `.bin` files assuming they represent `Foo` data
fn main() -> anyhow::Result<()> {
    let root = std::env::current_dir()?.join("data");
    for entry in WalkDir::new(&root).sort_by_file_name().into_iter().filter_map(|e| e.ok()) {
        let path = entry.into_path();

        if !path.is_dir() {
            if let Some(ext) = &path.extension() {
                if ext.eq_ignore_ascii_case("post") {
                    println!("converting {}", path.to_string_lossy());
                    let item: Foo = {
                        let mut file = File::open(&path)?;
                        let mut buf = Vec::new();
                        file.read_to_end(&mut buf)?;
                        postcard::from_bytes(&buf)?
                    };

                    // create destination file
                    let dest = path.with_extension("bin");
                    std::fs::create_dir_all(&dest.parent().unwrap())?;

                    // write data in new format
                    let file = File::create(dest)?;
                    let mut writer = BufWriter::new(file);
                    bincode::serialize_into(&mut writer, &item)?;

                    // delete old file
                    std::fs::remove_file(path)?;
                }
            }
        }
    }

    Ok(())
}