All: Add support for application plugins (#3257)

ReactNativeClient/lib/services/BooleanExpression.ts

@@ -0,0 +1,31 @@
+import { ContextKeyExpr, ContextKeyExpression } from './contextkey/contextkey';
+
+export default class BooleanExpression {
+
+	private expression_:string;
+	private rules_:ContextKeyExpression = null;
+
+	constructor(expression:string) {
+		this.expression_ = expression;
+	}
+
+	private createContext(ctx: any) {
+		return {
+			getValue: (key: string) => {
+				return ctx[key];
+			},
+		};
+	}
+
+	private get rules():ContextKeyExpression {
+		if (!this.rules_) {
+			this.rules_ = ContextKeyExpr.deserialize(this.expression_);
+		}
+		return this.rules_;
+	}
+
+	public evaluate(context:any):boolean {
+		return this.rules.evaluate(this.createContext(context));
+	}
+
+}