90 lines
2.6 KiB
C#
90 lines
2.6 KiB
C#
using System;
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using System.Collections.Generic;
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namespace Umbraco.Core.Migrations
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{
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/// <summary>
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/// Represents a migration plan builder for merges.
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/// </summary>
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public class MergeBuilder
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{
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private readonly MigrationPlan _plan;
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private readonly List<Type> _migrations = new List<Type>();
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private string _withLast;
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private bool _with;
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/// <summary>
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/// Initializes a new instance of the <see cref="MergeBuilder"/> class.
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/// </summary>
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internal MergeBuilder(MigrationPlan plan)
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{
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_plan = plan;
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}
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/// <summary>
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/// Adds a transition to a target state through an empty migration.
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/// </summary>
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public MergeBuilder To(string targetState)
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=> To<NoopMigration>(targetState);
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/// <summary>
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/// Adds a transition to a target state through a migration.
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/// </summary>
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public MergeBuilder To<TMigration>(string targetState)
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where TMigration : IMigration
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=> To(targetState, typeof(TMigration));
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/// <summary>
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/// Adds a transition to a target state through a migration.
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/// </summary>
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public MergeBuilder To(string targetState, Type migration)
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{
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if (_with)
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{
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_withLast = targetState;
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targetState = _plan.CreateRandomState();
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}
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else
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{
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_migrations.Add(migration);
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}
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_plan.To(targetState, migration);
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return this;
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}
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/// <summary>
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/// Begins the second branch of the merge.
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/// </summary>
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public MergeBuilder With()
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{
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if (_with)
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throw new InvalidOperationException("Cannot invoke With() twice.");
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_with = true;
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return this;
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}
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/// <summary>
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/// Completes the merge.
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/// </summary>
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public MigrationPlan As(string targetState)
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{
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if (!_with)
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throw new InvalidOperationException("Cannot invoke As() without invoking With() first.");
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// reach final state
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_plan.To(targetState);
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// restart at former end of branch2
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_plan.From(_withLast);
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// and replay all branch1 migrations
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foreach (var migration in _migrations)
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_plan.To(_plan.CreateRandomState(), migration);
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// reaching final state
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_plan.To(targetState);
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return _plan;
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}
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}
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}
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