33 lines
1.5 KiB
C#
33 lines
1.5 KiB
C#
using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Collections.Immutable;
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public class ImmutableDefaultDictionary<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>> {
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public readonly TValue defaultValue;
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public readonly ImmutableDictionary<TKey, TValue> dictionary;
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public ImmutableDefaultDictionary(TValue defaultValue, ImmutableDictionary<TKey, TValue> dictionary) {
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this.defaultValue = defaultValue;
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this.dictionary = dictionary;
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}
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public TValue this[TKey key] {
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get => dictionary.GetOrDefault(key, defaultValue);
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}
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public ImmutableDefaultDictionary<TKey, TValue> With(TKey key, TValue value)
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=> new ImmutableDefaultDictionary<TKey, TValue>(defaultValue, dictionary.Add(key, value));
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public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() => dictionary.GetEnumerator();
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IEnumerator IEnumerable.GetEnumerator() => dictionary.GetEnumerator();
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}
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public static class ImmutableDefaultDictionaryExtensionMethods {
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public static ImmutableDefaultDictionary<UKey, UValue> ToImmutableDefaultDictionary<T, UKey, UValue>(this IEnumerable<T> e, UValue defaultValue, Func<T, UKey> key, Func<T, UValue> value)
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=> new ImmutableDefaultDictionary<UKey, UValue>(defaultValue, e.ToImmutableDictionary(key, value));
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public static ImmutableDefaultDictionary<TKey, TValue> ToImmutableDefaultDictionary<TKey, TValue>(this ImmutableDictionary<TKey, TValue> d, TValue defaultValue)
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=> new ImmutableDefaultDictionary<TKey, TValue>(defaultValue, d);
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} |