101 lines
3.4 KiB
C#
101 lines
3.4 KiB
C#
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using System.Linq.Expressions;
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using System.Collections;
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using Microsoft.EntityFrameworkCore;
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using Microsoft.EntityFrameworkCore.Query;
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#nullable disable
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namespace GiecChallenge.Tests
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{
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public static class ICollectionExtensions
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{
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public static IQueryable<T> AsAsyncQueryable<T>(this ICollection<T> source) =>
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new AsyncQueryable<T>(source.AsQueryable());
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}
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internal class AsyncQueryable<T> : IAsyncEnumerable<T>, IQueryable<T>
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{
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private IQueryable<T> Source;
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public AsyncQueryable(IQueryable<T> source)
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{
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Source = source;
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}
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public Type ElementType => typeof(T);
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public Expression Expression => Source.Expression;
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public IQueryProvider Provider => new AsyncQueryProvider<T>(Source.Provider);
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public IAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToken = default)
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{
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return new AsyncEnumeratorWrapper<T>(Source.GetEnumerator());
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}
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public IEnumerator<T> GetEnumerator() => Source.GetEnumerator();
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IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
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}
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internal class AsyncQueryProvider<T> : IQueryProvider, IAsyncQueryProvider
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{
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private readonly IQueryProvider Source;
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public AsyncQueryProvider(IQueryProvider source)
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{
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Source = source;
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}
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public IQueryable CreateQuery(Expression expression) =>
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Source.CreateQuery(expression);
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public IQueryable<TElement> CreateQuery<TElement>(Expression expression) =>
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new AsyncQueryable<TElement>(Source.CreateQuery<TElement>(expression));
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public object Execute(Expression expression) => Execute<T>(expression);
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public TResult Execute<TResult>(Expression expression) =>
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Source.Execute<TResult>(expression);
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public TResult ExecuteAsync<TResult>(Expression expression, CancellationToken cancellationToken)
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{
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var expectedResultType = typeof(TResult).GetGenericArguments()[0];
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var executionResult = typeof(IQueryProvider)
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.GetMethod(
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name: nameof(IQueryProvider.Execute),
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genericParameterCount: 1,
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types: new[] {typeof(Expression)})
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.MakeGenericMethod(expectedResultType)
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.Invoke(this, new[] {expression});
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return (TResult) typeof(Task).GetMethod(nameof(Task.FromResult))
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?.MakeGenericMethod(expectedResultType)
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.Invoke(null, new[] {executionResult});
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}
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TResult IAsyncQueryProvider.ExecuteAsync<TResult>(Expression expression, CancellationToken cancellationToken) =>
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ExecuteAsync<TResult>(expression, cancellationToken);
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}
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internal class AsyncEnumeratorWrapper<T> : IAsyncEnumerator<T>
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{
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private readonly IEnumerator<T> Source;
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public AsyncEnumeratorWrapper(IEnumerator<T> source)
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{
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Source = source;
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}
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public T Current => Source.Current;
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public ValueTask DisposeAsync()
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{
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return new ValueTask(Task.CompletedTask);
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}
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public ValueTask<bool> MoveNextAsync()
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{
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return new ValueTask<bool>(Source.MoveNext());
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}
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}
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}
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