heed 0.23.0

A fully typed LMDB (mdb.master) wrapper with minimum overhead
Documentation 
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use std::error::Error;

use heed::types::*;
use heed::{CommitOrAbort, Database, EnvOpenOptions, PutFlags};

// In this test we are checking that we can append ordered entries in one
// database even if there is multiple databases which already contain entries.
fn main() -> Result<(), Box<dyn Error>> {
    let env_path = tempfile::tempdir()?;

    let env = unsafe {
        EnvOpenOptions::new()
            .map_size(10 * 1024 * 1024) // 10MB
            .max_dbs(3)
            .open(env_path)?
    };

    let wtxn = env.write_txn()?;
    let (first, second) = env
        .create_databases_and_commit(wtxn, |wdo, wtxn| {
            let first: Database<Str, Str> = wdo.create_database(wtxn, Some("first"))?;
            let second: Database<Str, Str> = wdo.create_database(wtxn, Some("second"))?;
            heed::Result::Ok(CommitOrAbort::<_, ()>::Commit((first, second)))
        })?
        .unwrap_commit();

    let mut wtxn = env.write_txn()?;
    // We fill the first database with entries.
    first.put(&mut wtxn, "I am here", "to test things")?;
    first.put(&mut wtxn, "I am here too", "for the same purpose")?;

    // We try to append ordered entries in the second database.
    let mut iter = second.iter_mut(&mut wtxn)?;

    unsafe { iter.put_current_with_options::<Str>(PutFlags::APPEND, "aaaa", "lol")? };
    unsafe { iter.put_current_with_options::<Str>(PutFlags::APPEND, "abcd", "lol")? };
    unsafe { iter.put_current_with_options::<Str>(PutFlags::APPEND, "bcde", "lol")? };

    drop(iter);

    wtxn.commit()?;

    Ok(())
}