128 lines
5.0 KiB
C#
128 lines
5.0 KiB
C#
// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// software and associated documentation files (the "Software"), to deal in the Software
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// without restriction, including without limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
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// to whom the Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all copies or
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// substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Linq;
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using Unity.CodeEditor.Utils;
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namespace Unity.CodeEditor.Document
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{
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/// <summary>
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/// Provides ITextSourceVersion instances.
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/// </summary>
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internal class TextSourceVersionProvider
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{
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private Version _currentVersion;
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/// <summary>
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/// Creates a new TextSourceVersionProvider instance.
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/// </summary>
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internal TextSourceVersionProvider()
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{
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_currentVersion = new Version(this);
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}
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/// <summary>
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/// Gets the current version.
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/// </summary>
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internal ITextSourceVersion CurrentVersion => _currentVersion;
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/// <summary>
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/// Replaces the current version with a new version.
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/// </summary>
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/// <param name="change">Change from current version to new version</param>
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internal void AppendChange(TextChangeEventArgs change)
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{
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_currentVersion.Change = change ?? throw new ArgumentNullException(nameof(change));
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_currentVersion.Next = new Version(_currentVersion);
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_currentVersion = _currentVersion.Next;
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}
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[DebuggerDisplay("Version #{" + nameof(_id) + "}")]
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private sealed class Version : ITextSourceVersion
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{
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// Reference back to the provider.
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// Used to determine if two checkpoints belong to the same document.
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private readonly TextSourceVersionProvider _provider;
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// ID used for CompareAge()
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private readonly int _id;
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// the change from this version to the next version
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internal TextChangeEventArgs Change;
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public Version Next;
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public Version(TextSourceVersionProvider provider)
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{
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_provider = provider;
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}
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public Version(Version prev)
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{
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_provider = prev._provider;
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_id = unchecked(prev._id + 1);
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}
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public bool BelongsToSameDocumentAs(ITextSourceVersion other)
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{
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var o = other as Version;
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return o != null && _provider == o._provider;
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}
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public int CompareAge(ITextSourceVersion other)
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{
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if (other == null)
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throw new ArgumentNullException(nameof(other));
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var o = other as Version;
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if (o == null || _provider != o._provider)
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throw new ArgumentException("Versions do not belong to the same document.");
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// We will allow overflows, but assume that the maximum distance between checkpoints is 2^31-1.
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// This is guaranteed on x86 because so many checkpoints don't fit into memory.
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return Math.Sign(unchecked(_id - o._id));
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}
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public IEnumerable<TextChangeEventArgs> GetChangesTo(ITextSourceVersion other)
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{
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var result = CompareAge(other);
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var o = (Version)other;
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if (result < 0)
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return GetForwardChanges(o);
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if (result > 0)
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return o.GetForwardChanges(this).Reverse().Select(c => c.Invert());
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return Array.Empty<TextChangeEventArgs>();
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}
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private IEnumerable<TextChangeEventArgs> GetForwardChanges(Version other)
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{
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// Return changes from this(inclusive) to other(exclusive).
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for (var node = this; node != other; node = node.Next)
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{
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yield return node.Change;
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}
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}
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public int MoveOffsetTo(ITextSourceVersion other, int oldOffset, AnchorMovementType movement)
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{
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return GetChangesTo(other)
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.Aggregate(oldOffset, (current, e) => e.GetNewOffset(current, movement));
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}
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}
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}
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}
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