Derive macro for defining storable documents

This derive macro helps to define documents which can be managed using persistent storages like LEDB.

The LEDB is an attempt to implement simple but efficient, lightweight but powerful document storage.

The abbreviation LEDB may be treated as an Lightweight Embedded DB, also Low End DB, also Literium Engine DB, also LitE DB, and so on.

Links

• ledb-types Crate on crates.io
• ledb-types API Docs on docs.rs
• ledb-derive Crate on crates.io
• ledb-derive API Docs on docs.rs
• ledb Crate on crates.io
• ledb API Docs on docs.rs

Usage example

extern crate serde;
#[macro_use]
extern crate serde_derive;

extern crate ledb_types;
#[macro_use]
extern crate ledb_derive;

#[derive(Serialize, Deserialize, Document)]
struct MyDoc {
    // define optional primary key field
    #[document(primary)]
    id: Option<Primary>,
    // define unique key field
    #[document(unique)]
    title: String,
    // define index fields
    #[document(index)]
    tag: Vec<String>,
    #[document(unique)]
    timestamp: u32,
    // define nested document
    #[document(nested)]
    meta: MetaData,
}

#[derive(Serialize, Deserialize, Document)]
#[document(nested)]
struct MetaData {
    // define index field
    #[document(index)]
    keywords: Vec<String>,
    // define other fields
    description: String,
}

This automatically generate Document traits like so:

impl Document for MyDoc {
    // declare primary key field name
    fn primary_field() -> Identifier {
        "id".into()
    }
    
    // declare other key fields for index
    fn key_fields() -> KeyFields {
        KeyFields::new()
            // add key fields of document
            .with_field(("title", String::key_type(), IndexKind::Unique))
            .with_field(("tag", String::key_type(), IndexKind::Index))
            .with_field(("timestamp", u32::key_type(), IndexKind::Unique))
            // add key fields from nested document
            .with_fields(MetaData::key_fields().with_parent("meta"))
    }
}

impl Document for MetaData {
    // declare key fields for index
    fn key_fields() -> KeyFields {
        KeyFields::new()
            // add key fields of document
            .with_field(("keywords", KeyType::String, IndexKind::Index))
    }
}