Ancient Cursor

Abstract container of data synchronization.

Install

npm i --save ancient-cursor

About

In most popular realisations of pubsub next abstractions (query, content, transport, source, storage) are stirred or combined, what, for example, makes dependence from current environment or makes schemes for data required.

• Query may be in any form.
• No need for schemes in content. Use it as desired.
• Cursor knows nothing about transport. It have events with data, which should be tracked, and something will make decisions about transporting. (we recommend ancient-channels and ancient-peer)
• No dependency from source of data. It may be database-client or query-lang executor (like GraphQL). (we recommend ancient-asket)
• Use any database as storage. (we recommend ancient-tracker)

Path

We use this term around all the package. It may be like this

• _.get path syntax: 'a[1].c' or ['a', 1, 'c']
• _.get + _.match syntax: ['a', { b:2 }, 'c'].

Bundle

"Box" for data-changings with functions and parsers to work with it.

Example

import {
  bundleParsers,
} from 'ancient-cursor/lib/bundle';

const container = { data: { a:[{ b:3, c:4 }] } };
bundleParsers.extend(container, {
  type: 'extend',
  path: 'a.0',
  value: { d: 6 },
});
container.data; // { a:[{ b:3, c:4, d:6 }] }

More bundles

Cursor

Simple capsule to actualize remote data. With cursor.exec() you can send query to remote data source. All changes apply using bundles as external stand-alone instructions what and where to change, when called cursor.apply () function. cursor.apply() emits 'changed' event, where you can use watch() to listen changes by specified path.

Example

import {
  Cursor,
  watch,
} from '../lib/cursor';

let changed = false;
let watched = false;
const cursor = new Cursor(); 

cursor.on('exec', ({ cursor }) => {
  // Here is transportation logic and after executing cursor.query by remote data-source may be called cursor.apply();
  cursor.apply({
    type: 'set',
    path: '',
    value: { a: [{ b: { c: 'd' } }] },
  });
});
cursor.exec('some query');

cursor.on('changed', ({ bundleChanges }) => {
  changed = true;
  watch(bundleChanges, 'b', () => {
    watched = true;
  });
});

cursor.data // { a: [{ b: { c: 'd' } }] }
cursor.apply({
  type: 'set',
  path: 'a.0',
  value: { d: { e: 'f' } },
});
cursor.data // { a: [{ d: { e: 'f' } }] }
triggered; // true;
watched; // false

cursor.apply({
  type: 'extend',
  path: '',
  value: { b: 123 },
});
cursor.data // { a: [{ d: { e: 'f' } }], b: 123 }
watched; // true

Stackable-cursor

Extends Cursor with queue funcionality.

Example

import {
  StackableCursor,
} from '../lib/stackable-cursor';

  const cursor = new StackableCursor();
  cursor.exec(undefined, { a: [{ b: { c: 123 } }] });

  cursor.apply({ indexInStack: 2, type: 'extend', path: 'a.0.b', value: {d: 234} });
  cursor.bundlesStack.length; // 1
  cursor.nextBundleIndex; // 0
  cursor.data; // { a: [{ b: { c: 123 } }] }

  cursor.apply({ indexInStack: 0, type: 'set', path: 'a.0.b.c', value: 456 });
  cursor.bundlesStack.length; // 1
  cursor.nextBundleIndex; // 1
  cursor.data; // { a: [{ b: { c: 456 } }] }

  cursor.apply({ indexInStack: 1, type: 'set', path: 'a.0.b.c', value: 345 });
  cursor.bundlesStack.length; // 0
  cursor.nextBundleIndex; // 3
  cursor.data; // { a: [{ b: { c: 345, d: 234 } }] }