/****************************************************************************
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**
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** Copyright (C) 2019 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.Generic;
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using System.Linq;
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namespace QtVsTools.SyntaxAnalysis
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{
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public abstract partial class RegExpr
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{
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const string MetaChars = @"[]\/#^$.|?*+(){}-";
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protected static string Escape(string s)
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{
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return new string(s.SelectMany(c =>
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MetaChars.Contains(c) ? Items('\\', c) :
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(c == ' ') ? "\\x20".Cast<char>() :
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(c == '\t') ? "\\t".Cast<char>() :
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(c == '\r') ? "\\r".Cast<char>() :
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(c == '\n') ? "\\n".Cast<char>() :
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Items(c)).ToArray());
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}
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public static bool NeedsGroup(string literal)
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{
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if (literal.Length == 1)
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return false;
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if (literal.Length == 2 && literal.StartsWith(@"\"))
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return false;
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if (literal.Length == 3 && literal.StartsWith(@"\c"))
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return false;
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if (literal.Length == 4 && literal.StartsWith(@"\x"))
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return false;
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if (literal.Length == 6 && literal.StartsWith(@"\u"))
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return false;
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return true;
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}
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internal T As<T>()
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where T : RegExpr
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{
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if (this is T)
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return this as T;
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else
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throw new InvalidCastException();
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}
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internal static IEnumerable<T> Empty<T>()
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{
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return new T[] { };
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}
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internal static IEnumerable<T> Items<T>(params T[] items)
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{
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return items;
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}
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public sealed class Void { }
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}
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public static class RegExprExtensions
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{
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public static void ReverseTop<T>(this Stack<T> stack, int count = 2)
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{
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if (count < 2 || stack.Count < count)
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return;
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var items = Enumerable.Repeat(stack, count).Select(s => s.Pop()).ToList();
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items.ForEach(item => stack.Push(item));
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}
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}
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}
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