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using System;
using System.Collections.Generic;
using LibGit2Sharp.Core.Compat;
namespace LibGit2Sharp.Core
{
internal abstract class LazyGroup<T>
{
private readonly IList<IEvaluator<T>> evaluators = new List<IEvaluator<T>>();
private readonly object @lock = new object();
private bool evaluated;
protected readonly Repository repo;
protected LazyGroup(Repository repo)
{
this.repo = repo;
}
public ILazy<TResult> AddLazy<TResult>(Func<T, TResult> func)
{
var prop = new Dependent<T, TResult>(func, this);
evaluators.Add(prop);
return prop;
}
public void Evaluate()
{
if (evaluated)
return;
lock (@lock)
{
if (evaluated)
return;
EvaluateInternal(input =>
{
foreach (var e in evaluators)
e.Evaluate(input);
});
evaluated = true;
}
}
protected abstract void EvaluateInternal(Action<T> evaluator);
protected static ILazy<TResult> Singleton<TResult>(Func<TResult> resultSelector)
{
return new LazyWrapper<TResult>(resultSelector);
}
private interface IEvaluator<TInput>
{
void Evaluate(TInput input);
}
private class Dependent<TInput, TOutput> : ILazy<TOutput>, IEvaluator<TInput>
{
private readonly Func<TInput, TOutput> valueFactory;
private readonly LazyGroup<TInput> lazyGroup;
private TOutput value;
private bool hasBeenEvaluated;
public Dependent(Func<TInput, TOutput> valueFactory, LazyGroup<TInput> lazyGroup)
{
this.valueFactory = valueFactory;
this.lazyGroup = lazyGroup;
}
public TOutput Value
{
get { return Evaluate(); }
}
private TOutput Evaluate()
{
if (!hasBeenEvaluated)
{
lazyGroup.Evaluate();
}
return value;
}
void IEvaluator<TInput>.Evaluate(TInput input)
{
value = valueFactory(input);
hasBeenEvaluated = true;
}
}
protected class LazyWrapper<TType> : Lazy<TType>, ILazy<TType>
{
public LazyWrapper(Func<TType> evaluator)
: base(evaluator)
{
}
}
}
}
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