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Override Object#equals for Mercury enumerations in the Java grades
and document that this should be used for equality testing in Java
code. The problem with using == is that instances might not have
the same addresses if they are serialized and then deserialized.
MercuryEnum is now a class and not an interface.
compiler/ml_type_gen.m:
Inherit the MercuryEnum class in Mercury enumerations
instead of implementing the MercuryEnum interface.
compiler/mlds_to_java.m:
Don't output the MR_value member in Java classes that correspond to
Mercury enumerations. This member is now inherited from MercuryEnum.
Don't mangle classes in the Mercury runtime.
doc/reference_manual.texi:
Document that the equals method should be used for exported
Mercury enumerations.
java/runtime/MercuryEnum.java:
Make MercuryEnum a class and implement the equals method.
Also implement the hashcode method.
30 lines
750 B
Java
30 lines
750 B
Java
//
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// Copyright (C) 2009 The University of Melbourne.
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// This file may only be copied under the terms of the GNU Library General
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// Public License - see the file COPYING.LIB in the Mercury distribution.
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//
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// This is the superclass of all classes generated by the Java back-end
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// which correspond to Mercury-defined enumeration types.
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//
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package jmercury.runtime;
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public abstract class MercuryEnum {
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public final int MR_value;
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protected MercuryEnum(int val) {
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MR_value = val;
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}
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@Override
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public boolean equals(Object o) {
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return o != null && o instanceof MercuryEnum &&
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((MercuryEnum)o).MR_value == this.MR_value;
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}
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@Override
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public int hashCode() {
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return MR_value;
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}
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}
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