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using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
namespace Apewer
{
/// <summary>集合的实用工具。</summary>
public static class CollectionUtility
{
#region 判断
/// <summary>判断集合为空。</summary>
public static bool IsEmpty<T>(IEnumerable<T> objects)
{
if (objects == null) return true;
if (objects is T[]) return ((T[])objects).LongLength < 1L;
if (objects is ICollection<T>) return ((ICollection<T>)objects).Count < 1;
foreach (var item in objects) return false;
return true;
}
/// <summary>判断集合存在元素。</summary>
public static bool NotEmpty<T>(IEnumerable<T> objects)
{
if (objects == null) return false;
if (objects is T[]) return ((T[])objects).LongLength > 0L;
if (objects is ICollection<T>) return ((ICollection<T>)objects).Count > 0;
foreach (var item in objects) return true;
return false;
}
/// <summary>获取集合中元素的数量。</summary>
public static int Count<T>(IEnumerable<T> objects)
{
if (objects == null) return 0;
var array = objects as T[];
if (array != null) return array.Length;
var collection = objects as ICollection<T>;
if (collection != null) return collection.Count;
var count = 0;
foreach (var cell in objects) count++;
return count;
}
/// <summary>检查集合是否包含 item。</summary>
public static bool Contains<T>(IEnumerable<T> objects, T cell)
{
if (objects == null) return false;
// objects 实现了含有 Contains 方法的接口。
if (objects is ICollection<T>) return ((ICollection<T>)objects).Contains(cell);
// cell 无效。
if (cell == null)
{
foreach (var i in objects)
{
if (i == null) return true;
}
return false;
}
// cell 有效,进行默认比较。
var comparer = EqualityComparer<T>.Default;
foreach (var i in objects)
{
if (comparer.Equals(i, cell)) return true;
}
return false;
}
/// <summary>获取 item 在集合中的偏移位置,不存在时返回 -1。</summary>
public static int IndexOf<T>(IEnumerable<T> objects, T item)
{
if (objects == null) return -1;
if (objects is IList list) return list.IndexOf(item);
if (item == null)
{
if (objects is T[] array)
{
var length = array.Length;
for (var i = 0; i < length; i++)
{
if (array[i] == null) return i;
}
return -1;
}
var index = 0;
foreach (var obj in objects)
{
if (obj == null) return index;
index++;
}
return -1;
}
else
{
var comparer = EqualityComparer<T>.Default;
if (objects is T[] array)
{
var length = array.Length;
for (var i = 0; i < length; i++)
{
if (comparer.Equals(item, array[i])) return i;
}
return -1;
}
var index = 0;
foreach (var obj in objects)
{
if (comparer.Equals(item, obj)) return index;
index++;
}
return -1;
}
}
#endregion
#region 类型转换
/// <summary>转换模型类型。</summary>
public static TDst[] As<TSrc, TDst>(this TSrc[] array) where TDst : class
{
if (array == null) return null;
var count = array.Length;
var output = new TDst[count];
for (var i = 0; i < count; i++)
{
var item = array[i];
if (item == null) continue;
output[i] = item as TDst;
}
return output;
}
/// <summary>转换模型类型。</summary>
public static TDst[] As<TSrc, TDst>(this TSrc[] array, Func<TSrc, TDst> convert)
{
if (convert == null) throw new ArgumentNullException(nameof(convert));
if (array == null) return null;
var count = array.Length;
var output = new TDst[count];
for (var i = 0; i < count; i++)
{
var item = array[i];
if (item == null) continue;
output[i] = convert(item);
}
return output;
}
/// <summary>安全转换为 List&lt;<typeparamref name="T"/>&gt; 对象。可指定排除 NULL 值元素。</summary>
public static List<T> List<T>(IEnumerable<T> objects, bool excludeNull = false)
{
if (objects == null) return new List<T>();
var list = new List<T>();
var collection = objects as ICollection;
if (collection != null)
{
list.AddRange(objects);
}
else
{
var group = 1024;
var added = 0;
var capacity = 0;
if (objects != null)
{
foreach (var item in objects)
{
if (excludeNull && item == null) continue;
if (added == capacity)
{
capacity += group;
list.Capacity = capacity;
}
list.Add(item);
added += 1;
}
}
list.Capacity = added;
}
return list;
}
/// <summary>安全转换为 &lt;<typeparamref name="T"/>&gt;[] 对象。可指定排除 NULL 值元素。</summary>
public static T[] Array<T>(IEnumerable<T> objects, bool excludeNull = false)
{
if (objects == null) return new T[0];
if (objects is T[]) return (T[])objects;
var collection = objects as ICollection;
if (collection != null)
{
var array = new T[collection.Count];
collection.CopyTo(array, 0);
return array;
}
else
{
var group = 1024;
var array = new T[group];
var added = 0;
var capacity = 0;
foreach (var item in objects)
{
if (excludeNull && item == null) continue;
if (added == capacity)
{
capacity += group;
var temp = new T[capacity];
System.Array.Copy(array, 0, temp, 0, added);
array = temp;
}
array[added] = item;
added += 1;
}
if (added < 1 || added == capacity) return array;
var collapsed = new T[added];
System.Array.Copy(array, 0, collapsed, 0, added);
return collapsed;
}
}
/// <summary>生成 StringPairs 对象实例为副本。</summary>
public static StringPairs StringPairs(NameValueCollection @this) => Apewer.StringPairs.From(@this);
/// <summary>转换集合为数组。</summary>
/// <param name="collection"></param>
/// <returns></returns>
public static Dictionary<string, string[]> Dictionary(NameValueCollection collection)
{
if (collection == null) return null;
var count = collection.Count;
var dict = new Dictionary<string, string[]>();
for (var i = 0; i < count; i++)
{
var key = collection.GetKey(i);
var values = collection.GetValues(i);
dict.Add(key, values);
}
return dict;
}
/// <summary>转换集合为字典。</summary>
/// <typeparam name="TKey">字典 Key 的类型。</typeparam>
/// <typeparam name="TValue">字典 Value 的类型。</typeparam>
/// <param name="items">要转换的集合。</param>
/// <param name="key">根据元素获取 Key 的函数。</param>
/// <exception cref="ArgumentNullException"></exception>
public static Dictionary<TKey, TValue> Dictionary<TKey, TValue>(IEnumerable<TValue> items, Func<TValue, TKey> key)
{
if (items == null) throw new ArgumentNullException(nameof(items));
if (key == null) throw new ArgumentNullException(nameof(key));
var dict = new Dictionary<TKey, TValue>();
foreach (var i in items)
{
if (i == null) continue;
var k = key(i);
if (k.IsNull()) continue;
if (dict.ContainsKey(k)) continue;
dict.Add(k, i);
}
return dict;
}
#endregion
#region 修改集合
/// <summary>添加多个元素。</summary>
public static void Add<T>(List<T> list, params T[] items)
{
if (list != null && items != null) list.AddRange(items);
}
/// <summary>添加多个元素。</summary>
public static IList<T> Add<T>(IList<T> list, IEnumerable<T> items)
{
if (list != null && items != null)
{
foreach (var item in items) list.Add(item);
}
return list;
}
/// <summary>添加元素。</summary>
public static bool Add<TKey, TValue>(IList<KeyValuePair<TKey, TValue>> list, TKey key, TValue value)
{
if (list == null) return false;
list.Add(new KeyValuePair<TKey, TValue>(key, value));
return true;
}
/// <summary>对元素去重,且去除 NULL 值。</summary>
public static T[] Distinct<T>(IEnumerable<T> items)
{
if (items == null) throw new ArgumentNullException(nameof(items));
var count = Count(items);
var added = 0;
var array = new T[count];
var comparer = EqualityComparer<T>.Default;
foreach (var item in items)
{
if (item == null) continue;
var contains = false;
foreach (var i in array)
{
if (comparer.Equals(i, item))
{
contains = true;
break;
}
}
if (contains) continue;
array[added] = item;
added++;
}
if (added < count)
{
var temp = new T[added];
System.Array.Copy(array, 0, temp, 0, added);
array = temp;
}
return array;
}
/// <summary>获取可枚举集合的部分元素。</summary>
/// <typeparam name="T">集合元素的类型。</typeparam>
/// <param name="objects">原集合。</param>
/// <param name="skip">在集合前段要跳过的元素数量。</param>
/// <param name="count">要获取的元素数量,指定为负数时不限元素数量。</param>
/// <param name="stuffer">填充器,获取范围超出原集合的部分,使用此方法填充元素;此函数默认返回 <typeparamref name="T"/> 的默认值。</param>
/// <returns>数量符合 count 的数组。</returns>
public static T[] Slice<T>(IEnumerable<T> objects, int skip = 0, int count = -1, Func<T> stuffer = null)
{
if (count == 0) return new T[0];
var ab = new ArrayBuilder<T>();
var added = 0;
if (skip < 0)
{
var end = 0 - skip;
for (var i = 0; i < end; i++)
{
ab.Add(stuffer == null ? default : stuffer());
added++;
if (count > 0 && added == count) return ab.Export();
}
}
if (objects != null)
{
var offset = 0;
foreach (var item in objects)
{
if (offset < skip)
{
offset++;
continue;
}
ab.Add(item);
added++;
offset++;
if (count > 0 && added == count) return ab.Export();
}
}
while (added < count)
{
ab.Add(stuffer == null ? default : stuffer());
added++;
}
return ab.Export();
}
#endregion
#region 排序
/// <summary>对列表中的元素排序。</summary>
public static List<T> Sort<T>(List<T> list, Func<T, T, int> comparison)
{
if (list == null) return null;
if (comparison == null) return list;
list.Sort(new Comparison<T>(comparison));
return list;
}
/// <summary>对数组排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static T[] Sort<T>(T[] array, Func<T, T, int> comparison)
{
if (array == null) return array;
if (comparison == null) return array;
System.Array.Sort(array, new Comparison<T>(comparison));
return array;
}
/// <summary>获取集合中的第一个元素。可指定失败时的默认返回值。</summary>
public static T First<T>(IEnumerable<T> collection, T failed = default(T))
{
if (collection == null) return failed;
var array = collection as T[];
if (array != null) return array.Length > 0 ? array[0] : failed;
var list = collection as IList<T>;
if (list != null) return list.Count > 0 ? list[0] : failed;
foreach (var item in collection) return item;
return failed;
}
/// <summary>获取集合中的最后一个元素。可指定失败时的默认返回值。</summary>
public static T Last<T>(IEnumerable<T> collection, T failed = default(T))
{
if (collection == null) return failed;
var array = collection as T[];
if (array != null) return array.Length > 0 ? array[array.Length - 1] : failed;
var list = collection as IList<T>;
if (list != null) return list.Count > 0 ? list[list.Count - 1] : failed;
var value = failed;
foreach (var item in collection) value = item;
return value;
}
/// <summary>对数组升序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static T[] Ascend<T>(T[] array) where T : IComparable<T>
{
if (array == null) return null;
array.Sort((a, b) => a.CompareTo(b));
return array;
}
/// <summary>对数组升序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static List<T> Ascend<T>(List<T> list) where T : IComparable<T>
{
if (list == null) return null;
list.Sort((a, b) => a.CompareTo(b));
return list;
}
/// <summary>对数组升序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static void Ascend<T, TProp>(T[] array, Func<T, TProp> func) where TProp : IComparable<TProp>
{
if (array != null && func != null) Sort(array, (a, b) => func(a).CompareTo(func(b)));
}
/// <summary>对数组降序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static T[] Descend<T>(T[] array) where T : IComparable<T>
{
if (array == null) return array;
Sort(array, (a, b) => 0 - a.CompareTo(b));
return array;
}
/// <summary>对数组降序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static List<T> Descend<T>(List<T> list) where T : IComparable<T>
{
if (list == null) return null;
list.Sort((a, b) => -a.CompareTo(b));
return list;
}
/// <summary>对数组降序排序。</summary>
/// <exception cref="NullReferenceException"></exception>
public static void Descend<T, TProp>(T[] array, Func<T, TProp> func) where TProp : IComparable<TProp>
{
if (array != null && func != null) Sort(array, (a, b) => 0 - func(a).CompareTo(func(b)));
}
/// <summary>对字典中的键排序。</summary>
public static Dictionary<TKey, TValue> SortKey<TKey, TValue>(Dictionary<TKey, TValue> dict, Func<TKey, TKey, int> comparison)
{
if (dict == null) return null;
if (comparison == null) return null;
var list = new List<KeyValuePair<TKey, TValue>>(dict);
list.Sort(new Comparison<KeyValuePair<TKey, TValue>>((a, b) => comparison(a.Key, b.Key)));
dict.Clear();
foreach (var item in list) dict.Add(item.Key, item.Value);
return dict;
}
/// <summary>对字典中的键排序。</summary>
public static Dictionary<TKey, TValue> SortKey<TKey, TValue>(Dictionary<TKey, TValue> @this) where TKey : IComparable<TKey>
{
return SortKey(@this, (a, b) => a.CompareTo(b));
}
/// <summary>对字典中的值排序。</summary>
public static Dictionary<TKey, TValue> SortValue<TKey, TValue>(Dictionary<TKey, TValue> dict, Func<TValue, TValue, int> comparison)
{
if (dict == null) return null;
if (comparison == null) return dict;
var list = new List<KeyValuePair<TKey, TValue>>(dict);
list.Sort(new Comparison<KeyValuePair<TKey, TValue>>((a, b) => comparison(a.Value, b.Value)));
dict.Clear();
foreach (var item in list) dict.Add(item.Key, item.Value);
return dict;
}
/// <summary>对字典中的值排序。</summary>
public static Dictionary<TKey, TValue> SortValue<TKey, TValue>(Dictionary<TKey, TValue> @this) where TValue : IComparable<TValue>
{
return SortValue(@this, (a, b) => a.CompareTo(b));
}
#endregion
#region params
internal static object[] ParseParams(object cells)
{
var parsed = new ArrayBuilder<object>();
ParseParams(cells, parsed, 1);
return parsed;
}
static void ParseParams(object cells, ArrayBuilder<object> parsed, int depth)
{
if (cells.IsNull()) return;
if (cells is string str)
{
parsed.Add(cells);
return;
}
if (cells is IList items)
{
if (depth > 64)
{
parsed.Add(nameof(IList));
return;
}
var count = items.Count;
for (var i = 0; i < count; i++)
{
ParseParams(items[i], parsed, depth + 1);
}
return;
}
parsed.Add(cells.ToString());
}
#endregion
}
}