Crate databoard 

databoard

Implementation of a hierarchical key-value-store with the possibility to do a remapping from a level up to its parent level.

The following restrictions apply:

• Each level can have exactly one parent.
• There is no remapping down the hierarchy.
• The remapping is evaluated recursively up the levels.

You can do the remapping either

• fully automatic,
• fully manual or
• do an automatic remapping with manual overrides.

For controlling the access in the hierarchy there are two kinds of special keys:

• keys prefixed with an @ redirect to the top level databoard of the hierarchy.
• keys prefixed with an _ restrict the access to the current databoard.

Usage

A standalone databoard:

use databoard::Databoard;

// instantiation of a default Databoard
let databoard = Databoard::new();
// setting a value returns a `Result` of the previous content, in this case a `None`. 
let old = databoard.set("test", 42).unwrap();
// getting the value may fail, so it returns a `Result`,
let value = databoard.get::<i32>("test").unwrap();
// deleting the value returns a `Result` of the previous content, in this case `42`.
let value = databoard.delete::<i32>("test").unwrap();

Hierarchical usage:

use databoard::{Databoard, RemappingList};

let top_level = Databoard::new();
// this creates a databoard with automatic remapping to parent
let level1 = Databoard::with_parent(top_level.clone());
// some remapping rules
let mut remappings = RemappingList::default();
remappings.add("test", "{test}");
remappings.add("other_test", "{test}");
// this creates a databoard with manual remapping to parent using the defined remapping rules
let level2 = Databoard::with(Some(level1.clone()), Some(remappings), false);

// sets the value in the top `databoard`
top_level.set("test", 42).unwrap();
// but it can also be accessed from the two other levels
let value1: i32 = level1.get("test").unwrap();
let value2: i32 = level2.get("other_test").unwrap();

License

Licensed with the fair use “NGMC” license, see license file

Contribution

Any contribution intentionally submitted for inclusion in the work by you, shall be licensed with the same “NGMC” license, without any additional terms or conditions.

Structs

Databoard

A thread safe data board.

EntryReadGuard

Read-Locked entry guard. Until this value is dropped, a read lock is held on the entry.

EntryWriteGuard

Write-Locked entry guard. Until this value is dropped, a write lock is held on the entry.

RemappingList

A mutable remapping list.

Enums

Error

Things that may go wrong using the Databoard.

RemappingTarget

Target of a remapping entry

Functions

check_board_pointer

Returns the literal of the Databoard pointer if it is one.

check_local_key

Returns the literal of the current/local Databoard key if it is one.

check_local_pointer

Returns the literal of the current/local Databoard pointer if it is one.

check_top_level_key

Returns the literal of the top level Databoard key if it is one.

check_top_level_pointer

Returns the literal of the top level Databoard pointer if it is one.

is_board_pointer

Checks whether the given key is a pointer into a Databoard.

is_const_assignment

Returns true if a key is not a board pointer but a constant assignment , otherwise false

is_local_pointer

Checks whether the given key is a pointer into current/local Databoard.

is_top_level_pointer

Checks whether the given key is a pointer into top level Databoard.

strip_board_pointer

Returns Some(literal) of the Databoard pointer if it is one, otherwise None.

strip_local_pointer

Returns Some(literal) of the current/local Databoard pointer if it is one, otherwise None. The leading _ is removed from the literal.

strip_top_level_pointer

Returns Some(literal) of the top level Databoard pointer if it is one, otherwise None. The leading @ is removed from the literal.