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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Microsoft Public License. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Microsoft Public License, please send an email to
* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
* by the terms of the Microsoft Public License.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
namespace Microsoft.Scripting.Utils {
internal static class CollectionExtensions {
/// <summary>
/// Wraps the provided enumerable into a ReadOnlyCollection{T}
///
/// Copies all of the data into a new array, so the data can't be
/// changed after creation. The exception is if the enumerable is
/// already a ReadOnlyCollection{T}, in which case we just return it.
/// </summary>
internal static ReadOnlyCollection<T> ToReadOnly<T>(this IEnumerable<T> enumerable) {
if (enumerable == null) {
return EmptyReadOnlyCollection<T>.Instance;
}
var roCollection = enumerable as ReadOnlyCollection<T>;
if (roCollection != null) {
return roCollection;
}
var collection = enumerable as ICollection<T>;
if (collection != null) {
int count = collection.Count;
if (count == 0) {
return EmptyReadOnlyCollection<T>.Instance;
}
T[] array = new T[count];
collection.CopyTo(array, 0);
return new ReadOnlyCollection<T>(array);
}
// ToArray trims the excess space and speeds up access
return new ReadOnlyCollection<T>(new List<T>(enumerable).ToArray());
}
// We could probably improve the hashing here
internal static int ListHashCode<T>(this IEnumerable<T> list) {
var cmp = EqualityComparer<T>.Default;
int h = 6551;
foreach (T t in list) {
h ^= (h << 5) ^ cmp.GetHashCode(t);
}
return h;
}
internal static bool ListEquals<T>(this ICollection<T> first, ICollection<T> second) {
if (first.Count != second.Count) {
return false;
}
var cmp = EqualityComparer<T>.Default;
var f = first.GetEnumerator();
var s = second.GetEnumerator();
while (f.MoveNext()) {
s.MoveNext();
if (!cmp.Equals(f.Current, s.Current)) {
return false;
}
}
return true;
}
internal static IEnumerable<U> Select<T, U>(this IEnumerable<T> enumerable, Func<T, U> select) {
foreach (T t in enumerable) {
yield return select(t);
}
}
// Name needs to be different so it doesn't conflict with Enumerable.Select
internal static U[] Map<T, U>(this ICollection<T> collection, Func<T, U> select) {
int count = collection.Count;
U[] result = new U[count];
count = 0;
foreach (T t in collection) {
result[count++] = select(t);
}
return result;
}
internal static IEnumerable<T> Where<T>(this IEnumerable<T> enumerable, Func<T, bool> where) {
foreach (T t in enumerable) {
if (where(t)) {
yield return t;
}
}
}
internal static List<T> ToList<T>(this IEnumerable<T> enumerable) {
return new List<T>(enumerable);
}
internal static T[] ToArray<T>(this IEnumerable<T> enumerable) {
var c = enumerable as ICollection<T>;
if (c != null) {
var result = new T[c.Count];
c.CopyTo(result, 0);
return result;
}
return new List<T>(enumerable).ToArray();
}
internal static bool Any<T>(this IEnumerable<T> source) {
using (IEnumerator<T> e = source.GetEnumerator()) {
return e.MoveNext();
}
}
internal static bool Any<T>(this IEnumerable<T> source, Func<T, bool> predicate) {
foreach (T element in source) {
if (predicate(element)) {
return true;
}
}
return false;
}
internal static bool All<T>(this IEnumerable<T> source, Func<T, bool> predicate) {
foreach (T element in source) {
if (!predicate(element)) {
return false;
}
}
return true;
}
internal static TSource Aggregate<TSource>(this IEnumerable<TSource> source, Func<TSource, TSource, TSource> func) {
using (IEnumerator<TSource> e = source.GetEnumerator()) {
if (!e.MoveNext()) throw new ArgumentException("Collection is empty", "source");
TSource result = e.Current;
while (e.MoveNext()) result = func(result, e.Current);
return result;
}
}
internal static TAccumulate Aggregate<TSource, TAccumulate>(this IEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func) {
TAccumulate result = seed;
foreach (TSource element in source) result = func(result, element);
return result;
}
internal static T[] RemoveFirst<T>(this T[] array) {
T[] result = new T[array.Length - 1];
Array.Copy(array, 1, result, 0, result.Length);
return result;
}
internal static T[] RemoveLast<T>(this T[] array) {
T[] result = new T[array.Length - 1];
Array.Copy(array, 0, result, 0, result.Length);
return result;
}
internal static T[] AddFirst<T>(this IList<T> list, T item) {
T[] res = new T[list.Count + 1];
res[0] = item;
list.CopyTo(res, 1);
return res;
}
internal static T[] AddLast<T>(this IList<T> list, T item) {
T[] res = new T[list.Count + 1];
list.CopyTo(res, 0);
res[list.Count] = item;
return res;
}
internal static T[] RemoveAt<T>(this T[] array, int indexToRemove) {
Debug.Assert(array != null);
Debug.Assert(indexToRemove >= 0 && indexToRemove < array.Length);
T[] result = new T[array.Length - 1];
if (indexToRemove > 0) {
Array.Copy(array, 0, result, 0, indexToRemove);
}
int remaining = array.Length - indexToRemove - 1;
if (remaining > 0) {
Array.Copy(array, array.Length - remaining, result, result.Length - remaining, remaining);
}
return result;
}
internal static T[] RotateRight<T>(this T[] array, int count) {
Debug.Assert(count >= 0 && count <= array.Length);
T[] result = new T[array.Length];
// The head of the array is shifted, and the tail will be rotated to the head of the resulting array
int sizeOfShiftedArray = array.Length - count;
Array.Copy(array, 0, result, count, sizeOfShiftedArray);
Array.Copy(array, sizeOfShiftedArray, result, 0, count);
return result;
}
}
internal static class EmptyReadOnlyCollection<T> {
internal static ReadOnlyCollection<T> Instance = new ReadOnlyCollection<T>(new T[0]);
}
// TODO: Should we use this everywhere for empty arrays?
// my thought is, probably more hassle than its worth
internal static class EmptyArray<T> {
internal static T[] Instance = new T[0];
}
}
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