IQuerySource.cs

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using System.Linq.Expressions;
using Fauna.Types;
 
namespace Fauna.Linq;
 
public interface IQuerySource
{
    // TODO(matt) use an API-specific exception in-line with what other LINQ
    // libraries do.
    internal static Exception Fail(Expression? expr) =>
        Fail($"Unsupported {expr?.NodeType} expression: {expr}");
 
    internal static Exception Fail(string op, string msg) =>
        Fail($"Unsupported method call `{op}`: {msg}");
 
    internal static Exception Fail(string msg) => new NotSupportedException(msg);
}
 
public interface IQuerySource<T> : IQuerySource
{
    // Core execution
 
    public IAsyncEnumerable<Page<T>> PaginateAsync(QueryOptions? queryOptions = null, CancellationToken cancel = default);
    public IAsyncEnumerable<T> ToAsyncEnumerable(CancellationToken cancel = default);
    public IEnumerable<T> ToEnumerable();
 
    // Composition methods
 
    public IQuerySource<T> Distinct();
    public IQuerySource<T> Order();
    public IQuerySource<T> OrderBy<K>(Expression<Func<T, K>> keySelector);
    public IQuerySource<T> OrderDescending();
    public IQuerySource<T> OrderByDescending<K>(Expression<Func<T, K>> keySelector);
    public IQuerySource<T> Reverse();
    public IQuerySource<R> Select<R>(Expression<Func<T, R>> selector);
    // public IQuerySource<R> SelectMany<R>(Expression<Func<T, IQuerySource<R>>> selector);
    public IQuerySource<T> Skip(int count);
    public IQuerySource<T> Take(int count);
    public IQuerySource<T> Where(Expression<Func<T, bool>> predicate);
 
    // Terminal result methods
 
    // public R Aggregate<A, R>(A seed, Expression<Func<A, T, A>> accum, Func<A, R> selector);
    // public Task<R> AggregateAsync<A, R>(A seed, Expression<Func<A, T, A>> accum, Func<A, R> selector);
 
    // // not IQueryable
    // public R Fold<R>(R seed, Expression<Func<R, T, R>> accum);
    // public Task<R> FoldAsync<R>(R seed, Expression<Func<R, T, R>> accum);
 
    public bool All(Expression<Func<T, bool>> predicate);
    public Task<bool> AllAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public bool Any();
    public Task<bool> AnyAsync(CancellationToken cancel = default);
 
    public bool Any(Expression<Func<T, bool>> predicate);
    public Task<bool> AnyAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public int Count();
    public Task<int> CountAsync(CancellationToken cancel = default);
 
    public int Count(Expression<Func<T, bool>> predicate);
    public Task<int> CountAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T First();
    public Task<T> FirstAsync(CancellationToken cancel = default);
 
    public T First(Expression<Func<T, bool>> predicate);
    public Task<T> FirstAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T? FirstOrDefault();
    public Task<T?> FirstOrDefaultAsync(CancellationToken cancel = default);
 
    public T? FirstOrDefault(Expression<Func<T, bool>> predicate);
    public Task<T?> FirstOrDefaultAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T Last();
    public Task<T> LastAsync(CancellationToken cancel = default);
 
    public T Last(Expression<Func<T, bool>> predicate);
    public Task<T> LastAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T? LastOrDefault();
    public Task<T?> LastOrDefaultAsync(CancellationToken cancel = default);
 
    public T? LastOrDefault(Expression<Func<T, bool>> predicate);
    public Task<T?> LastOrDefaultAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public long LongCount();
    public Task<long> LongCountAsync(CancellationToken cancel = default);
 
    public long LongCount(Expression<Func<T, bool>> predicate);
    public Task<long> LongCountAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T Max();
    public Task<T> MaxAsync(CancellationToken cancel = default);
 
    public R Max<R>(Expression<Func<T, R>> selector);
    public Task<R> MaxAsync<R>(Expression<Func<T, R>> selector, CancellationToken cancel = default);
 
    // public T MaxBy<K>(Expression<Func<T, K>> selector);
    // public Task<K> MaxByAsync<K>(Expression<Func<T, K>> selector, CancellationToken cancel = default);
 
    public T Min();
    public Task<T> MinAsync(CancellationToken cancel = default);
 
    // public T MinBy<K>(Expression<Func<T, K>> selector);
    // public Task<K> MinByAsync<K>(Expression<Func<T, K>> selector, CancellationToken cancel = default);
 
    public R Min<R>(Expression<Func<T, R>> selector);
    public Task<R> MinAsync<R>(Expression<Func<T, R>> selector, CancellationToken cancel = default);
 
    public T Single();
    public Task<T> SingleAsync(CancellationToken cancel = default);
 
    public T Single(Expression<Func<T, bool>> predicate);
    public Task<T> SingleAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public T SingleOrDefault();
    public Task<T> SingleOrDefaultAsync(CancellationToken cancel = default);
 
    public T SingleOrDefault(Expression<Func<T, bool>> predicate);
    public Task<T> SingleOrDefaultAsync(Expression<Func<T, bool>> predicate, CancellationToken cancel = default);
 
    public int Sum(Expression<Func<T, int>> selector);
    public Task<int> SumAsync(Expression<Func<T, int>> selector, CancellationToken cancel = default);
 
    public long Sum(Expression<Func<T, long>> selector);
    public Task<long> SumAsync(Expression<Func<T, long>> selector, CancellationToken cancel = default);
 
    // public float Sum(Expression<Func<T, float>> selector);
    // public Task<float> SumAsync(Expression<Func<T, float>> selector, CancellationToken cancel = default);
 
    public double Sum(Expression<Func<T, double>> selector);
    public Task<double> SumAsync(Expression<Func<T, double>> selector, CancellationToken cancel = default);
 
    public double Average(Expression<Func<T, double>> selector);
    public Task<double> AverageAsync(Expression<Func<T, double>> selector, CancellationToken cancel = default);
 
    // Collection result methods
 
    public List<T> ToList();
    public Task<List<T>> ToListAsync(CancellationToken cancel = default);
 
    public T[] ToArray();
    public Task<T[]> ToArrayAsync(CancellationToken cancel = default);
 
    public HashSet<T> ToHashSet();
    public Task<HashSet<T>> ToHashSetAsync(CancellationToken cancel = default);
 
    public HashSet<T> ToHashSet(IEqualityComparer<T>? comparer);
    public Task<HashSet<T>> ToHashSetAsync(IEqualityComparer<T>? comparer, CancellationToken cancel = default);
 
    public Dictionary<K, V> ToDictionary<K, V>(Func<T, K> getKey, Func<T, V> getValue) where K : notnull;
    public Task<Dictionary<K, V>> ToDictionaryAsync<K, V>(Func<T, K> getKey, Func<T, V> getValue, CancellationToken cancel = default) where K : notnull;
 
    public Dictionary<K, V> ToDictionary<K, V>(Func<T, K> getKey, Func<T, V> getValue, IEqualityComparer<K>? comparer) where K : notnull;
    public Task<Dictionary<K, V>> ToDictionaryAsync<K, V>(Func<T, K> getKey, Func<T, V> getValue, IEqualityComparer<K>? comparer, CancellationToken cancel = default) where K : notnull;
}