Crate macrodb

MacroDB

This crate exports a macro that can be used to turn an appropriate Rust struct into an in-memory database that guarantees consistency and supports indices. The Rust struct needs to be written by hand, the macro only generates a safe interface for using the in-memory database.

Example

Here is a full example of building a user database. An error type is defined, that is used by the database methods to return information failures. A struct for the record type that is to be stored is defined (the User struct). Finally, a struct for the database is defined that contains two indices. The table macro generates methods for inserting, updating and deleting rows.

use std::collections::{BTreeMap, BTreeSet};
use macrodb::table;

/// Error type for database interactions.
pub enum Error {
    UserIdExists,
    UserEmailExists,
    UserNotFound,
}

type UserId = u64;

/// Record type for a user (a row in the database).
#[derive(Clone)]
pub struct User {
    id: UserId,
    name: String,
    email: String,
}

/// Database definition.
pub struct Database {
    /// Users table.
    users: BTreeMap<UserId, User>,
    /// Unique index of users by email.
    user_by_email: BTreeMap<String, UserId>,
}

// The table macro will autogenerate the users_insert(), users_update() and users_delete()
// methods.
impl Database {
    table!(
        users: User,
        id: UserId,
        missing Error => Error::UserNotFound,
        primary users id => Error::UserIdExists,
        unique user_by_email email => Error::UserEmailExists
    );
}

See the documentation on table for more information.

Macros

paste

Re-expport of paste, which is used internally.

table

Table Macro