59 lines
1.9 KiB
C#
59 lines
1.9 KiB
C#
using System;
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using System.Linq;
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public static class Equality {
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// TODO: values returned by fieldAccessors should implement IEquatable.
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// T can be any supertype of the instances passed to the == operator.
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public static bool Operator(Object a, Object b) {
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if (Object.ReferenceEquals(a, null)) {
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return Object.ReferenceEquals(b, null);
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} else if (Object.ReferenceEquals(b, null)) {
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return false;
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} else {
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return ((Object)a).Equals(b);
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}
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}
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// T must be the exact type of the receiver object whose
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// Object.Equals(Object other) method is invoking
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// Untyped(this, other).
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public static bool Untyped<T>(T a, Object b, Func<Object, T> cast, params Func<T, Object>[] fieldAccessors) {
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if (Object.ReferenceEquals(a, null)) {
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return Object.ReferenceEquals(b, null);
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} else if (Object.ReferenceEquals(b, null)) {
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return false;
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} else {
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var castB = cast(b);
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if (Object.ReferenceEquals(castB, null)) {
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return false;
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} else {
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foreach (var accessor in fieldAccessors) {
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var aFieldValue = accessor(a);
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var bFieldValue = accessor(castB);
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if (Object.ReferenceEquals(aFieldValue, null)) {
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return Object.ReferenceEquals(bFieldValue, null);
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} else if (Object.ReferenceEquals(bFieldValue, null)) {
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return false;
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} else {
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return aFieldValue.Equals(bFieldValue);
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}
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}
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return true;
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}
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}
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}
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// T must be the exact type of the receiver object whose
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// IEquatable<U>.Equals(U other) method is invoking
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// Equatable(this, other).
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public static bool Equatable<T>(T a, Object b) where T : IEquatable<T> {
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if (Object.ReferenceEquals(a, null)) {
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return Object.ReferenceEquals(b, null);
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} else if (Object.ReferenceEquals(b, null)) {
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return false;
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} else {
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return ((Object)a).Equals(b);
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}
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}
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} |