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8303374: Implement JEP 455: Primitive Types in Patterns, instanceof, and switch (Preview)

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Co-authored-by: Jan Lahoda <jlahoda@openjdk.org>
Co-authored-by: Maurizio Cimadamore <mcimadamore@openjdk.org>
Co-authored-by: Gavin Bierman <gbierman@openjdk.org>
Co-authored-by: Brian Goetz <briangoetz@openjdk.org>
Co-authored-by: Raffaello Giulietti <rgiulietti@openjdk.org>
Co-authored-by: Aggelos Biboudis <abimpoudis@openjdk.org>
Reviewed-by: vromero, jlahoda
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Aggelos Biboudis 2024-01-31 14:18:13 +00:00
parent 66971600f7
commit 1733d2ea24
43 changed files with 3564 additions and 391 deletions
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src/java.base/share/classes/java/lang/runtime/ExactConversionsSupport.java Normal file
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/*
* Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.lang.runtime;
/**
* A testing conversion of a value is exact if it yields a result without loss
* of information or throwing an exception. Otherwise, it is inexact. Some
* conversions are always exact regardless of the value. These conversions are
* said to be unconditionally exact.
* <p>
* For example, a conversion from {@code int} to {@code byte} for the value 10
* is exact because the result, 10, is the same as the original value. In
* contrast, if the {@code int} variable {@code i} stores the value 1000 then a
* narrowing primitive conversion to {@code byte} will yield the result -24.
* Loss of information has occurred: both the magnitude and the sign of the
* result are different than those of the original value. As such, a conversion
* from {@code int} to {@code byte} for the value 1000 is inexact. Finally a
* widening primitive conversion from {@code byte} to {@code int} is
* unconditionally exact because it will always succeed with no loss of
* information about the magnitude of the numeric value.
* <p>
* The methods in this class provide the run-time support for the exactness
* checks of testing conversions from a primitive type to primitive type. These
* methods may be used, for example, by Java compiler implementations to
* implement checks for {@code instanceof} and pattern matching runtime
* implementations. Unconditionally exact testing conversions do not require a
* corresponding action at run time and, for this reason, methods corresponding
* to these exactness checks are omitted here.
* <p>
* The run time conversion checks examine whether loss of information would
* occur if a testing conversion would be to be applied. In those cases where a
* floating-point primitive type is involved, and the value of the testing
* conversion is either signed zero, signed infinity or {@code NaN}, these
* methods comply with the following:
*
* <ul>
* <li>Converting a floating-point negative zero to an integer type is considered
* inexact.</li>
* <li>Converting a floating-point {@code NaN} or infinity to an integer type is
* considered inexact.</li>
* <li>Converting a floating-point {@code NaN} or infinity or signed zero to another
* floating-point type is considered exact.</li>
* </ul>
*
* @jls 5.7.1 Exact Testing Conversions
* @jls 5.7.2 Unconditionally Exact Testing Conversions
* @jls 15.20.2 The instanceof Operator
*
* @implNote Some exactness checks describe a test which can be redirected
* safely through one of the existing methods. Those are omitted too (i.e.,
* {@code byte} to {@code char} can be redirected to
* {@link ExactConversionsSupport#isIntToCharExact(int)}, {@code short} to
* {@code byte} can be redirected to
* {@link ExactConversionsSupport#isIntToByteExact(int)} and similarly for
* {@code short} to {@code char}, {@code char} to {@code byte} and {@code char}
* to {@code short} to the corresponding methods that take an {@code int}).
*
* @since 23
*/
public final class ExactConversionsSupport {
private ExactConversionsSupport() { }
/**
* Exactness method from int to byte
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isIntToByteExact(int n) {return n == (int)(byte)n;}
/**
* Exactness method from int to short
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isIntToShortExact(int n) {return n == (int)(short)n;}
/**
* Exactness method from int to char
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isIntToCharExact(int n) {return n == (int)(char)n;}
/**
* Exactness method from int to float
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isIntToFloatExact(int n) {
return n == (int)(float)n && n != Integer.MAX_VALUE;
}
/**
* Exactness method from long to byte
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isLongToByteExact(long n) {return n == (long)(byte)n;}
/**
* Exactness method from long to short
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isLongToShortExact(long n) {return n == (long)(short)n;}
/**
* Exactness method from long to char
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isLongToCharExact(long n) {return n == (long)(char)n;}
/**
* Exactness method from long to int
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
*/
public static boolean isLongToIntExact(long n) {return n == (long)(int)n;}
/**
* Exactness method from long to float
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isLongToFloatExact(long n) {
return n == (long)(float)n && n != Long.MAX_VALUE;
}
/**
* Exactness method from long to double
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isLongToDoubleExact(long n) {
return n == (long)(double)n && n != Long.MAX_VALUE;
}
/**
* Exactness method from float to byte
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isFloatToByteExact(float n) {
return n == (float)(byte)n && !isNegativeZero(n);
}
/**
* Exactness method from float to short
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isFloatToShortExact(float n) {
return n == (float)(short)n && !isNegativeZero(n);
}
/**
* Exactness method from float to char
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isFloatToCharExact(float n) {
return n == (float)(char)n && !isNegativeZero(n);
}
/**
* Exactness method from float to int
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isFloatToIntExact(float n) {
return n == (float)(int)n && n != 0x1p31f && !isNegativeZero(n);
}
/**
* Exactness method from float to long
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isFloatToLongExact(float n) {
return n == (float)(long)n && n != 0x1p63f && !isNegativeZero(n);
}
/**
* Exactness method from double to byte
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToByteExact(double n) {
return n == (double)(byte)n && !isNegativeZero(n);
}
/**
* Exactness method from double to short
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToShortExact(double n){
return n == (double)(short)n && !isNegativeZero(n);
}
/**
* Exactness method from double to char
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToCharExact(double n) {
return n == (double)(char)n && !isNegativeZero(n);
}
/**
* Exactness method from double to int
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToIntExact(double n) {
return n == (double)(int)n && !isNegativeZero(n);
}
/**
* Exactness method from double to long
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToLongExact(double n) {
return n == (double)(long)n && n != 0x1p63 && !isNegativeZero(n);
}
/**
* Exactness method from double to float
* @param n value
* @return true if and only if the passed value can be converted exactly to the target type
* @implSpec relies on the notion of representation equivalence defined in the
* specification of the {@linkplain Double} class.
*/
public static boolean isDoubleToFloatExact(double n) {
return n == (double)(float)n || n != n;
}
private static boolean isNegativeZero(float n) {
return Float.floatToRawIntBits(n) == Integer.MIN_VALUE;
}
private static boolean isNegativeZero(double n) {
return Double.doubleToRawLongBits(n) == Long.MIN_VALUE;
}
}