Page.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

using System.Collections.Generic;
using System.ComponentModel;

namespace Azure
{
    /// <summary>
    /// A single <see cref="Page{T}"/> of values from a request that may return
    /// zero or more <see cref="Page{T}"/>s of values.
    /// </summary>
    /// <typeparam name="T">The type of values.</typeparam>
#pragma warning disable AZC0012 // Avoid single word type names
    public abstract class Page<T>
#pragma warning restore AZC0012 // Avoid single word type names
    {
        /// <summary>
        /// Gets the values in this <see cref="Page{T}"/>.
        /// </summary>
        public abstract IReadOnlyList<T> Values { get; }

        /// <summary>
        /// Gets the continuation token used to request the next
        /// <see cref="Page{T}"/>.  The continuation token may be null or
        /// empty when there are no more pages.
        /// </summary>
        public abstract string? ContinuationToken { get; }

        /// <summary>
        /// Gets the <see cref="Response"/> that provided this
        /// <see cref="Page{T}"/>.
        /// </summary>
        public abstract Response GetRawResponse();

        /// <summary>
        /// Creates a new <see cref="Page{T}"/>.
        /// </summary>
        /// <param name="values">
        /// The values in this <see cref="Page{T}"/>.
        /// </param>
        /// <param name="continuationToken">
        /// The continuation token used to request the next <see cref="Page{T}"/>.
        /// </param>
        /// <param name="response">
        /// The <see cref="Response"/> that provided this <see cref="Page{T}"/>.
        /// </param>
#pragma warning disable CA1000 // Do not declare static members on generic types
        public static Page<T> FromValues(IReadOnlyList<T> values, string? continuationToken, Response response)
#pragma warning restore CA1000 // Do not declare static members on generic types
        {
            return new PageCore(values, continuationToken, response);
        }

        /// <summary>
        /// Creates a string representation of an <see cref="Page{T}"/>.
        /// </summary>
        /// <returns>
        /// A string representation of an <see cref="Page{T}"/>.
        /// </returns>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public override string? ToString() => base.ToString();

        /// <summary>
        /// Check if two <see cref="Page{T}"/> instances are equal.
        /// </summary>
        /// <param name="obj">The instance to compare to.</param>
        /// <returns>True if they're equal, false otherwise.</returns>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public override bool Equals(object? obj) => base.Equals(obj);

        /// <summary>
        /// Get a hash code for the <see cref="Page{T}"/>.
        /// </summary>
        /// <returns>Hash code for the <see cref="Page{T}"/>.</returns>
        [EditorBrowsable(EditorBrowsableState.Never)]
        public override int GetHashCode() => base.GetHashCode();

        private class PageCore : Page<T>
        {
            private readonly Response _response;

            public PageCore(IReadOnlyList<T> values, string? continuationToken, Response response)
            {
                _response = response;
                Values = values;
                ContinuationToken = continuationToken;
            }

            public override IReadOnlyList<T> Values { get; }
            public override string? ContinuationToken { get; }
            public override Response GetRawResponse() => _response;
        }
    }
}