/****************************************************************************
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**
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** Copyright (C) 2022 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the Qt VS Tools.
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**
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** $QT_BEGIN_LICENSE:GPL-EXCEPT$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3 as published by the Free Software
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** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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using System;
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using System.Collections.Concurrent;
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using System.Diagnostics;
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using System.Linq.Expressions;
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using System.Reflection;
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namespace QtVsTools.Common
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{
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public class LazyFactory
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{
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private Lazy<ConcurrentDictionary<PropertyInfo, Lazy<object>>> LazyObjs { get; }
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private ConcurrentDictionary<PropertyInfo, Lazy<object>> Objs => LazyObjs.Value;
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public LazyFactory()
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{
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LazyObjs = new Lazy<ConcurrentDictionary<PropertyInfo, Lazy<object>>>();
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}
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public T Get<T>(Expression<Func<T>> propertyRef, Func<T> initFunc) where T : class
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{
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var lazyPropertyExpr = propertyRef?.Body as MemberExpression;
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var lazyProperty = lazyPropertyExpr?.Member as PropertyInfo;
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if (lazyProperty == null)
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throw new ArgumentException("Invalid property reference", "propertyRef");
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var lazyObj = Objs.GetOrAdd(lazyProperty, (_) => new Lazy<object>(() => initFunc()));
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return lazyObj.Value as T;
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}
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}
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}
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