Mike Gerwitz

Activist for User Freedom

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authorMike Gerwitz <gerwitzm@lovullo.com>2016-12-21 11:21:09 -0500
committerMike Gerwitz <gerwitzm@lovullo.com>2017-01-03 09:11:18 -0500
commit29f67bd157c6ab1b617fa680eb647fd8227910f3 (patch)
tree4a7bf4941d0e9cba0e3f38aa8959048a3daafa2c
parentd8d44130e888d43b2b8c47a526f9dc074726d024 (diff)
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Add store.Cascading
* src/store/Cascading.js: Add trait. * test/store/CascadingTest.js: Add test case.
-rw-r--r--src/store/Cascading.js99
-rw-r--r--test/store/CascadingTest.js77
2 files changed, 176 insertions, 0 deletions
diff --git a/src/store/Cascading.js b/src/store/Cascading.js
new file mode 100644
index 0000000..0bf4dfa
--- /dev/null
+++ b/src/store/Cascading.js
@@ -0,0 +1,99 @@
+/**
+ * Recurisvely-clearing key/value store
+ *
+ * Copyright (C) 2016 LoVullo Associates, Inc.
+ *
+ * This file is part of the Liza Data Collection Framework
+ *
+ * Liza is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+var Trait = require( 'easejs' ).Trait,
+ Class = require( 'easejs' ).Class,
+ Store = require( './Store' );
+
+
+/**
+ * Store of stores with cascading clear
+ *
+ * The store `S` into which this trait is mixed will accept only other
+ * Store objects which will each have their `#clear` method called
+ * when `#clear` is invoked on `S`.
+ *
+ * @example
+ * let store_a = Store().add( 'key', value' ),
+ * store_b = Store().add( 'foo', 'bar' );
+ *
+ * store_a.get( 'key' ); // value
+ * store_b.get( 'foo' ); // bar
+ *
+ * Store.use( Cascading )
+ * .add( 'a', store_a )
+ * .add( 'b', store_b )
+ * .clear();
+ *
+ * store_a.get( 'key' ); // undefined
+ * store_b.get( 'foo' ); // undefined
+ *
+ * Store.use( Cascading ).add( 'invalid', 'value' );
+ * // TypeError: Can only add Store to Cascading stores
+ *
+ * Although clear cascades to each `Store`, other methods do not (for
+ * example, `get` will not query all `Store`s); another trait should
+ * be added for such a thing. This behavior allows for, effectively,
+ * namespacing.
+ *
+ * This trait can be used, for example, to implement a centralized
+ * caching system that can trigger a reload of objects realtime
+ * system-wide, allowing for transparent hot code swapping (assuming
+ * that the caller will re-store).
+ */
+module.exports = Trait( 'Cascading' )
+ .implement( Store )
+ .extend(
+{
+ /**
+ * Add item to store under `key` with value `value`
+ *
+ * Only [`Store`]{@link module:store.Store} objects may be attached.
+ *
+ * @param {string} key store key
+ * @param {Store} value Store to attach
+ *
+ * @return {Store} self
+ */
+ 'virtual abstract override public add': function( key, value )
+ {
+ if ( !Class.isA( Store, value ) )
+ {
+ throw TypeError( "Can only add Store to Cascading stores" );
+ }
+
+ return this.__super( key, value );
+ },
+
+
+ /**
+ * Clear all stores in the store
+ *
+ * @return {Store} self
+ */
+ 'virtual abstract override public clear': function()
+ {
+ this.reduce( function( _, store )
+ {
+ store.clear();
+ } );
+ },
+} );
diff --git a/test/store/CascadingTest.js b/test/store/CascadingTest.js
new file mode 100644
index 0000000..51aaca0
--- /dev/null
+++ b/test/store/CascadingTest.js
@@ -0,0 +1,77 @@
+/**
+ * Test case for Cascading store
+ *
+ * Copyright (C) 2016 LoVullo Associates, Inc.
+ *
+ * This file is part of the Liza Data Collection Framework
+ *
+ * Liza is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+var store = require( '../../' ).store,
+ expect = require( 'chai' ).expect,
+ Store = store.MemoryStore,
+ Sut = store.Cascading;
+
+describe( 'store.Cascading', () =>
+{
+ describe( '#add', () =>
+ {
+ it( 'does not allow attaching non-store objects', () =>
+ {
+ expect( () => Store.use( Sut )().add( 'invalid', {} ) )
+ .to.throw( TypeError );
+ } );
+
+
+ it( 'allows attaching Store objects', () =>
+ {
+ expect( () => Store.use( Sut )().add( 'valid', Store() ) )
+ .to.not.throw( TypeError );
+ } );
+ } );
+
+
+ describe( '#clear', () =>
+ {
+ it( 'invokes #clear on all contained stores', () =>
+ {
+ const cleared = [];
+
+ const MockStore = Store.extend(
+ {
+ 'override clear'()
+ {
+ cleared.push( this.__inst );
+ }
+ } );
+
+ const stores = [ 1, 2, 3 ].map( () => MockStore() );
+ const sut = Store.use( Sut )();
+
+ stores.forEach( ( store, i ) => sut.add( i, store ) );
+
+ // should trigger clear on all stores
+ sut.clear();
+
+ expect(
+ stores.every( store =>
+ cleared.some( item => item === store )
+ )
+ ).to.be.true;
+ } );
+ } );
+} ); \ No newline at end of file