Struct Chain 

pub struct Chain<P: Chained> { /* private fields */ }

A chain of records the app keeps beside its own, held for a view or surface. See the module docs.

Implementations

impl<P: Chained> Chain<P>

pub fn id(&self) -> &str

The address the chain is published under: what an agent or a script invokes its actions on.

pub fn parts(&self) -> Vec<(u64, Rc<P::State>)>

Every part this window holds, oldest first, as it stands now.

pub fn head(&self) -> Option<u64>

The number of the chain’s head: the newest part held. None while nothing was written to the chain.

pub fn revision(&self) -> u64

Increases whenever a held part changed or a newer head arrived.

pub fn hold(&self, index: u64) -> Result<(), String>

Hold the earlier part index too: read it from this device, or ask the workspace for it when this device has none of it. Its history merges in as it arrives (Self::revision moves, the window is woken); Self::waiting says where it stands until then.

pub fn waiting(&self, index: u64) -> Option<PartArrival>

Where part index, asked for and not read here yet, stands: on its way (a view shows it loading, not empty), or unavailable (a view says so, with nothing spinning). None once it is read.

pub fn waited(&self) -> Vec<(u64, PartArrival)>

Every part asked for and not read here yet, oldest first.

pub fn apply(&self, action: &P::Action) -> Result<u64, ActionError>

Apply action now, as the window’s person, to the part it changes. The part’s number.

Errors

As the door refuses it: the person may not, the app’s record or the part refused it.

pub fn invoke(&self, invoke: &Invoke<P>) -> Result<u64, ActionError>

Apply what invoke names now, as Self::apply.

Errors

As Self::apply, or the arguments do not build the action.

pub fn undo_in(&self, index: u64) -> Result<(), ActionError>

Take back the window’s person’s last step in part index, through the part’s history as the undo verb the chain publishes on it does: the way back a surface offers for a step it took at the person’s own gesture (Undo beside a message they deleted).

A refusal is reported through the dispatcher’s refused, as the door’s are.

Errors

As the door refuses it: the person may not change the part’s history, the part is not here, or they have no step in it to take back.

pub fn stage_as( &self, invoke: &Invoke<P>, author: &str, ) -> Result<u64, ActionError>

Apply what invoke names as author wrote it: a screenshot scenario staging what other people wrote, or a test acting as someone else. Checked and recorded as Self::apply is, attributed to author.

Errors

As Self::invoke.

pub fn stage_at( &self, invoke: &Invoke<P>, author: &str, now_ms: i64, ) -> Result<u64, ActionError>

Self::stage_as at now_ms, the action’s time: what someone wrote at another time.

Errors

As Self::invoke.

pub fn write_start(&self, index: u64, state: &P::State) -> Result<(), String>

where P::State: Fields,

Write state into part index directly, as what the part starts with: a capture’s or a test’s fixture (items under fixed ids, written by several people) in fields the parts keep to their own actions (#[model(readonly)]), which refuse every generic edit. Not an action: nothing checks who may, nobody is its author, and it is committed as the part’s genesis, so only a fixture writes it.

pub fn takes_changes(&self) -> bool

Whether the chain takes a change now: not while a frame reads the app’s records (a view’s sync), when Self::stage_as waits for a later pass (an event, a settle pass).

pub fn dispatcher(&self) -> Dispatcher<P>

The chain’s dispatcher: what it submits goes through the host’s door as a click on a control does (a destructive verb asks first), and apply_now applies at once.

pub fn detached( app_id: &'static str, me: &str, base: impl Fn() -> Rc<<P::Base as Resource>::State> + 'static, ) -> Option<Self>

A chain outside any host, for a tool or a test that holds the app’s records without a window: held in a store of its own, edited as me (or whoever Self::stage_as names), who may do anything, its actions reading the app’s record from base. None when P does not read as a part.

pub fn detached_in( store: RecordStore, app_id: &'static str, me: &str, base: impl Fn() -> Rc<<P::Base as Resource>::State> + 'static, ) -> Option<Self>

Self::detached, held in store: one device’s records of the app in a workspace, for a test of what reaches that device’s store from another one.

pub fn as_reader(&self, me: &str) -> Self

The same detached chain edited as me: another person’s window over it, in a test.

pub fn part_bytes(&self, index: u64) -> Option<Vec<u8>>

Part index as a document’s bytes, for a tool that carries it to another device itself; None when the chain holds no such part.

Trait Implementations

impl<P: Chained> Clone for Chain<P>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.