using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
namespace Vanara.Collections
{
/// A generic class that creates a read-only dictionary from a list and getter function.
/// The type of keys in the dictionary.
/// The type of values in the dictionary.
public class GenericVirtualReadOnlyDictionary : VirtualReadOnlyDictionary
{
private readonly TryGetValueDelegate getValFunc;
private readonly Func hasKeyFunc;
/// Initializes a new instance of the class.
/// The enumerated list of keys.
/// The function used to get a value given a key. Called directly by TryGetValue.
///
/// An optional function to directly determine if a key exists. If not supplied, the default implementation checks for equality on
/// every value in .
///
public GenericVirtualReadOnlyDictionary(IEnumerable keys, TryGetValueDelegate getValue, Func hasKey = null)
{
Keys = keys ?? throw new ArgumentNullException(nameof(keys));
getValFunc = getValue ?? throw new ArgumentNullException(nameof(getValue));
hasKeyFunc = hasKey ?? DefHasKey;
}
/// Delegate for the implementation of the method.
/// The key whose value to get.
///
/// When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the
/// type of the parameter. This parameter is passed uninitialized.
///
///
/// if the contains an element with the key; otherwise, .
///
public delegate bool TryGetValueDelegate(TKey key, out TValue value);
/// Gets an enumerable collection that contains the keys in the read-only dictionary.
/// An enumerable collection that contains the keys in the read-only dictionary.
public override IEnumerable Keys { get; }
/// Determines whether the contains an element with the specified key.
/// The key to locate in the .
///
/// if the contains an element with the key; otherwise, .
///
public override bool ContainsKey(TKey key) => hasKeyFunc(key);
/// Gets the value associated with the specified key.
/// The key whose value to get.
///
/// When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the
/// type of the parameter. This parameter is passed uninitialized.
///
///
/// if the contains an element with the key; otherwise, .
///
public override bool TryGetValue(TKey key, out TValue value) => getValFunc(key, out value);
private bool DefHasKey(TKey k1) => Keys.Any(k2 => Equals(k1, k2));
}
///
/// A generic base class for providing a dictionary that gets and sets its values using virtual method calls. Useful for exposing lookups
/// into existing list environments like the file system, registry, service controller, etc.
///
/// The type of keys in the dictionary.
/// The type of values in the dictionary.
public abstract class VirtualDictionary : IReadOnlyDictionary, IDictionary
{
/// Initializes a new instance of the class.
/// if set to true makes the collection read-only.
protected VirtualDictionary(bool readOnly) => IsReadOnly = readOnly;
/// Gets a value indicating whether this instance is read only.
/// if this instance is read only; otherwise, .
public bool IsReadOnly { get; internal set; }
/// Gets an containing the keys of the .
/// An containing the keys of the object that implements .
public abstract ICollection Keys { get; }
/// Gets an containing the values in the .
/// An containing the values in the object that implements .
///
/// The order of the keys in the enumerable collection is unspecified, but the implementation must guarantee that the values are in
/// the same order as the corresponding keys in the enumerable collection that is returned by the property.
///
public virtual ICollection Values => Keys.Select(k => this[k]).ToList();
/// Gets the number of elements contained in the .
/// The number of elements contained in the .
public virtual int Count => Keys.Count;
/// Gets an enumerable collection that contains the keys in the read-only dictionary.
/// An enumerable collection that contains the keys in the read-only dictionary.
///
/// The order of the keys in the enumerable collection is unspecified, but the implementation must guarantee that the keys are in the
/// same order as the corresponding values in the enumerable collection that is returned by the property.
///
IEnumerable IReadOnlyDictionary.Keys => Keys;
/// Gets an containing the values in the .
/// An containing the values in the object that implements .
IEnumerable IReadOnlyDictionary.Values => Values;
/// Gets the enumerated list of items.
/// The enumerated list of items.
protected virtual IEnumerable> Items =>
Keys.Select(k => new KeyValuePair(k, this[k]));
/// Gets or sets the with the specified key.
/// The .
/// The key.
/// The with the specified key.
public virtual TValue this[TKey key]
{
get => TryGetValue(key, out var value) ? value : default;
set => SetValue(key, value);
}
/// Removes all items from the .
public virtual void Clear()
{
foreach (var key in Keys.ToList())
Remove(key);
}
/// Determines whether the contains an element with the specified key.
/// The key to locate in the .
///
/// if the contains an element with the key; otherwise, .
///
public virtual bool ContainsKey(TKey key) => Keys.Contains(key);
///
/// Copies the elements of the to an , starting
/// at a particular index.
///
///
/// The one-dimensional that is the destination of the elements copied from
/// . The must have zero-based indexing.
///
/// The zero-based index in at which copying begins.
public virtual void CopyTo(KeyValuePair[] array, int arrayIndex)
{
var items = Items.ToArray();
Array.Copy(items, 0, array, arrayIndex, items.Length);
}
/// Returns an enumerator that iterates through the collection.
/// An enumerator that can be used to iterate through the collection.
public IEnumerator> GetEnumerator() => Items.GetEnumerator();
/// Removes the element with the specified key from the .
/// The key of the element to remove.
///
/// if the element is successfully removed; otherwise, . This method also returns false
/// if key was not found in the original .
///
public virtual bool Remove(TKey key) => throw new NotSupportedException();
/// Gets the value associated with the specified key.
/// The key whose value to get.
///
/// When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the
/// type of the parameter. This parameter is passed uninitialized.
///
///
/// if the contains an element with the key; otherwise, .
///
public abstract bool TryGetValue(TKey key, out TValue value);
/// Adds an element with the provided key and value to the .
/// The object to use as the key of the element to add.
/// The object to use as the value of the element to add.
void IDictionary.Add(TKey key, TValue value) => SetValue(key, value);
/// Adds an item to the .
/// The object to add to the .
void ICollection>.Add(KeyValuePair item) => SetValue(item.Key, item.Value);
/// Determines whether this instance contains the object.
/// The object to locate in the .
///
/// true if is found in the ; otherwise, false.
///
bool ICollection>.Contains(KeyValuePair item) =>
ContainsKey(item.Key) && Equals(this[item.Key], item.Value);
/// Returns an enumerator that iterates through a collection.
/// An object that can be used to iterate through the collection.
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
///
/// Removes the first occurrence of a specific object from the .
///
/// The object to remove from the .
///
/// true if was successfully removed from the ; otherwise, false. This method also returns false if is not found in the original .
///
bool ICollection>.Remove(KeyValuePair item) => ((ICollection>)this).Contains(item) && Remove(item.Key);
///
/// Sets the value that is associated with the specified key. If the value for does not exist, this method
/// should create it. If the value does exist, this method should update it to match .
///
/// The key for which to set the data.
/// The value to associate with the key.
protected virtual void SetValue(TKey key, TValue value) => throw new NotSupportedException();
}
///
/// A generic base class for providing a read-only dictionary that gets its values using virtual method calls. Useful for exposing
/// lookups into existing list environments like the file system, registry, service controller, etc.
///
/// The type of keys in the dictionary.
/// The type of values in the dictionary.
public abstract class VirtualReadOnlyDictionary : IReadOnlyDictionary
{
/// Gets an enumerable collection that contains the keys in the read-only dictionary.
/// An enumerable collection that contains the keys in the read-only dictionary.
///
/// The order of the keys in the enumerable collection is unspecified, but the implementation must guarantee that the keys are in the
/// same order as the corresponding values in the enumerable collection that is returned by the property.
///
public abstract IEnumerable Keys { get; }
///
/// Gets an containing the values in the .
/// An containing the values in the object that implements .
public virtual IEnumerable Values => Keys.Select(k => this[k]).ToList();
/// Gets the number of elements contained in the .
/// The number of elements contained in the .
public virtual int Count => Keys.Count();
/// Gets the enumerated list of items.
/// The enumerated list of items.
protected IEnumerable> Items =>
Keys.Select(k => new KeyValuePair(k, this[k]));
/// Gets the with the specified key.
/// The element with the specified key.
/// The key of the element to get.
public virtual TValue this[TKey key] => TryGetValue(key, out var value) ? value : default;
/// Determines whether the contains an element with the specified key.
/// The key to locate in the .
///
/// if the contains an element with the key; otherwise, .
///
public abstract bool ContainsKey(TKey key);
/// Returns an enumerator that iterates through the collection.
/// An enumerator that can be used to iterate through the collection.
public IEnumerator> GetEnumerator() => Items.GetEnumerator();
/// Gets the value associated with the specified key.
/// The key whose value to get.
///
/// When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the
/// type of the parameter. This parameter is passed uninitialized.
///
///
/// if the contains an element with the key; otherwise, .
///
public abstract bool TryGetValue(TKey key, out TValue value);
/// Returns an enumerator that iterates through a collection.
/// An object that can be used to iterate through the collection.
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}
}