/****************************************************************************
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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.Collections.Concurrent;
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using System.Text;
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namespace QtVsTools.SyntaxAnalysis
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{
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using static RegExprAssert;
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////////////////////////////////////////////////////////////////////////////////////////////////
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///
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/// RegExprAssert ( -> RegExpr)
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///
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////////////////////////////////////////////////////////////////////////////////////////////////
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/// <summary>
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/// Asserts a pattern on the input string without consuming chars.
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/// </summary>
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///
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public partial class RegExprAssert : RegExpr
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{
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public enum AssertLook { Ahead, Behind }
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public AssertLook Context { get; set; }
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public bool Negative { get; set; }
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public RegExpr Expr { get; set; }
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protected override IEnumerable<RegExpr> OnRender(RegExpr defaultTokenWs, RegExpr parent,
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StringBuilder pattern, ref RenderMode mode, Stack<Token> tokenStack)
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{
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base.OnRender(defaultTokenWs, parent, pattern, ref mode, tokenStack);
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if (mode.HasFlag(RenderMode.Assert))
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throw new NestedAssertException();
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switch (Context) {
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case AssertLook.Ahead:
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if (Negative)
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pattern.Append("(?!");
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else
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pattern.Append("(?=");
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break;
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case AssertLook.Behind:
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if (Negative)
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pattern.Append("(?<!");
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else
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pattern.Append("(?<=");
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break;
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}
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mode |= RenderMode.Assert;
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return Items(Expr);
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}
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protected override void OnRenderEnd(RegExpr defaultTokenWs, RegExpr parent,
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StringBuilder pattern, ref RenderMode mode, Stack<Token> tokenStack)
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{
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base.OnRenderEnd(defaultTokenWs, parent, pattern, ref mode, tokenStack);
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pattern.Append(")");
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mode &= ~RenderMode.Assert;
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}
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}
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public abstract partial class RegExpr
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{
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RegExprAssert AsAssert()
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{
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if (this is RegExprAssert)
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return this as RegExprAssert;
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return new RegExprAssert
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{
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Context = AssertLook.Ahead,
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Negative = false,
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Expr = this
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};
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}
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public static RegExprAssert AssertLookAhead(RegExpr expr)
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{
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var assert = expr.AsAssert();
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return new RegExprAssert
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{
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Context = AssertLook.Ahead,
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Negative = assert.Negative,
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Expr = assert.Expr
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};
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}
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public static RegExprAssert AssertLookBehind(RegExpr expr)
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{
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var assert = expr.AsAssert();
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return new RegExprAssert
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{
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Context = AssertLook.Behind,
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Negative = assert.Negative,
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Expr = assert.Expr
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};
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}
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public static RegExprAssert AssertNegated(RegExpr expr)
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{
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var assert = expr.AsAssert();
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return new RegExprAssert
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{
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Context = assert.Context,
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Negative = !assert.Negative,
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Expr = assert.Expr
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};
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}
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public delegate RegExprAssert AssertTemplate(RegExpr expr);
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public class AssertExprBuilder
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{
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AssertTemplate Template { get; set; }
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public AssertExprBuilder(AssertTemplate template)
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{
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Template = template;
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}
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public class Expr
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{
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public RegExprAssert Assert { get; set; }
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public Expr(RegExprAssert assert) { Assert = assert; }
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public static implicit operator RegExpr(Expr e)
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{
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return e.Assert;
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}
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public static RegExpr operator &(RegExpr rx1, Expr rx2)
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{
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return Concat(rx1, rx2);
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}
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public static RegExpr operator |(RegExpr rx1, Expr rx2)
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{
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return Choice(rx1, rx2);
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}
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}
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public class NegateableExpr : Expr
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{
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public NegateableExpr(RegExprAssert assert) : base(assert) { }
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public static Expr operator !(NegateableExpr x)
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{
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return new Expr(AssertNegated(x.Assert));
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}
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}
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public NegateableExpr this[RegExpr expr]
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{
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get { return new NegateableExpr(Template(expr)); }
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}
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}
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public class NestedAssertException : RegExprException
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{
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public NestedAssertException(string message = null) : base(message) { }
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}
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}
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}
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