dev: add Context to putility

src/putility/index.js

@@ -23,6 +23,7 @@ module.exports = {
     AdvancedBase,
     libs: {
         promise: require('./src/libs/promise'),
+        context: require('./src/libs/context'),
     },
     concepts: {
         Service,

src/putility/src/libs/context.js

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2024 Puter Technologies Inc.
+ *
+ * This file is part of Puter.
+ *
+ * Puter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+class Context {
+    constructor (values) {
+        for ( const k in values ) this[k] = values[k];
+    }
+    sub (newValues) {
+        if ( newValues === undefined ) newValues = {};
+        const sub = Object.create(this);
+
+        const alreadyApplied = {};
+        for ( const k in sub ) {
+            if ( sub[k] instanceof Context ) {
+                const newValuesForK =
+                    newValues.hasOwnProperty(k)
+                        ? newValues[k] : undefined;
+                sub[k] = sub[k].sub(newValuesForK);
+                alreadyApplied[k] = true;
+            }
+        }
+
+        for ( const k in newValues ) {
+            if ( alreadyApplied[k] ) continue;
+            sub[k] = newValues[k];
+        }
+
+        return sub;
+    }
+}
+
+module.exports = {
+    Context,
+};

src/putility/test/context.test.js

@@ -0,0 +1,18 @@
+const { Context } = require('../src/libs/context');
+const { expect } = require('chai');
+
+describe('context', () => {
+    it('works', () => {
+        const c0 = new Context({
+            a: 1, b: 2,
+        });
+        const c1 = c0.sub({
+            b: 3
+        });
+
+        expect(c0.a).to.equal(1);
+        expect(c0.b).to.equal(2);
+        expect(c1.a).to.equal(1);
+        expect(c1.b).to.equal(3);
+    });
+});