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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections;
using System.Diagnostics;
using Microsoft.AspNetCore.Shared;
using Microsoft.Extensions.Primitives;
namespace Microsoft.AspNetCore.Http;
/// <summary>
/// The HttpRequest query string collection
/// </summary>
[DebuggerDisplay("Count = {Count}")]
[DebuggerTypeProxy(typeof(StringValuesDictionaryDebugView))]
public class QueryCollection : IQueryCollection
{
/// <summary>
/// Gets an empty <see cref="QueryCollection"/>.
/// </summary>
public static readonly QueryCollection Empty = new QueryCollection();
private static readonly string[] EmptyKeys = Array.Empty<string>();
// Pre-box
private static readonly IEnumerator<KeyValuePair<string, StringValues>> EmptyIEnumeratorType = default(Enumerator);
private static readonly IEnumerator EmptyIEnumerator = default(Enumerator);
private Dictionary<string, StringValues>? Store { get; }
/// <summary>
/// Initializes a new instance of <see cref="QueryCollection"/>.
/// </summary>
public QueryCollection()
{
}
/// <summary>
/// Initializes a new instance of <see cref="QueryCollection"/>.
/// </summary>
/// <param name="store">The backing store.</param>
public QueryCollection(Dictionary<string, StringValues> store)
{
Store = store;
}
/// <summary>
/// Creates a shallow copy of the specified <paramref name="store"/>.
/// </summary>
/// <param name="store">The <see cref="QueryCollection"/> to clone.</param>
public QueryCollection(QueryCollection store)
{
Store = store.Store;
}
/// <summary>
/// Initializes a new instance of <see cref="QueryCollection"/>.
/// </summary>
/// <param name="capacity">The initial number of query items that this instance can contain.</param>
public QueryCollection(int capacity)
{
Store = new Dictionary<string, StringValues>(capacity, StringComparer.OrdinalIgnoreCase);
}
/// <summary>
/// Gets the associated set of values from the collection.
/// </summary>
/// <param name="key">The key name.</param>
/// <returns>the associated value from the collection as a StringValues or StringValues.Empty if the key is not present.</returns>
public StringValues this[string key]
{
get
{
if (Store == null)
{
return StringValues.Empty;
}
if (TryGetValue(key, out var value))
{
return value;
}
return StringValues.Empty;
}
}
/// <summary>
/// Gets the number of elements contained in the <see cref="QueryCollection" />;.
/// </summary>
/// <returns>The number of elements contained in the <see cref="QueryCollection" />.</returns>
public int Count
{
get
{
if (Store == null)
{
return 0;
}
return Store.Count;
}
}
/// <summary>
/// Gets the collection of query names in this instance.
/// </summary>
public ICollection<string> Keys
{
get
{
if (Store == null)
{
return EmptyKeys;
}
return Store.Keys;
}
}
/// <summary>
/// Determines whether the <see cref="QueryCollection" /> contains a specific key.
/// </summary>
/// <param name="key">The key.</param>
/// <returns>true if the <see cref="QueryCollection" /> contains a specific key; otherwise, false.</returns>
public bool ContainsKey(string key)
{
if (Store == null)
{
return false;
}
return Store.ContainsKey(key);
}
/// <summary>
/// Retrieves a value from the collection.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="value">The value.</param>
/// <returns>true if the <see cref="QueryCollection" /> contains the key; otherwise, false.</returns>
public bool TryGetValue(string key, out StringValues value)
{
if (Store == null)
{
value = default(StringValues);
return false;
}
return Store.TryGetValue(key, out value);
}
/// <summary>
/// Returns an enumerator that iterates through a collection.
/// </summary>
/// <returns>An <see cref="Enumerator" /> object that can be used to iterate through the collection.</returns>
public Enumerator GetEnumerator()
{
if (Store == null || Store.Count == 0)
{
// Non-boxed Enumerator
return default;
}
return new Enumerator(Store.GetEnumerator());
}
/// <summary>
/// Returns an enumerator that iterates through a collection.
/// </summary>
/// <returns>An <see cref="IEnumerator{T}" /> object that can be used to iterate through the collection.</returns>
IEnumerator<KeyValuePair<string, StringValues>> IEnumerable<KeyValuePair<string, StringValues>>.GetEnumerator()
{
if (Store == null || Store.Count == 0)
{
// Non-boxed Enumerator
return EmptyIEnumeratorType;
}
return Store.GetEnumerator();
}
/// <summary>
/// Returns an enumerator that iterates through a collection.
/// </summary>
/// <returns>An <see cref="IEnumerator" /> object that can be used to iterate through the collection.</returns>
IEnumerator IEnumerable.GetEnumerator()
{
if (Store == null || Store.Count == 0)
{
// Non-boxed Enumerator
return EmptyIEnumerator;
}
return Store.GetEnumerator();
}
/// <summary>
/// Enumerates a <see cref="QueryCollection"/>.
/// </summary>
public struct Enumerator : IEnumerator<KeyValuePair<string, StringValues>>
{
// Do NOT make this readonly, or MoveNext will not work
private Dictionary<string, StringValues>.Enumerator _dictionaryEnumerator;
private readonly bool _notEmpty;
internal Enumerator(Dictionary<string, StringValues>.Enumerator dictionaryEnumerator)
{
_dictionaryEnumerator = dictionaryEnumerator;
_notEmpty = true;
}
/// <summary>
/// Advances the enumerator to the next element of the <see cref="HeaderDictionary"/>.
/// </summary>
/// <returns><see langword="true"/> if the enumerator was successfully advanced to the next element;
/// <see langword="false"/> if the enumerator has passed the end of the collection.</returns>
public bool MoveNext()
{
if (_notEmpty)
{
return _dictionaryEnumerator.MoveNext();
}
return false;
}
/// <summary>
/// Gets the element at the current position of the enumerator.
/// </summary>
public KeyValuePair<string, StringValues> Current
{
get
{
if (_notEmpty)
{
return _dictionaryEnumerator.Current;
}
return default(KeyValuePair<string, StringValues>);
}
}
/// <inheritdoc />
public void Dispose()
{
}
object IEnumerator.Current
{
get
{
return Current;
}
}
void IEnumerator.Reset()
{
if (_notEmpty)
{
((IEnumerator)_dictionaryEnumerator).Reset();
}
}
}
}
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