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eaa80ad08c
8300545: Compiler Implementation for Record Patterns Co-authored-by: Aggelos Biboudis <abimpoudis@openjdk.org> Reviewed-by: vromero, mcimadamore
97 lines
4.7 KiB
Java
97 lines
4.7 KiB
Java
/*
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* Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang;
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/**
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* Thrown to indicate an unexpected failure in pattern matching.
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*
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* <p>{@code MatchException} may be thrown when an exhaustive pattern matching
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* language construct (such as a {@code switch} expression) encounters a value
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* that does not match any of the specified patterns at run time, even though
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* the construct has been deemed exhaustive. This is intentional and can arise
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* from a number of cases:
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*
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* <ul>
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* <li>Separate compilation anomalies, where parts of the type hierarchy that
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* the patterns reference have been changed, but the pattern matching
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* construct has not been recompiled. For example, if a sealed interface
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* has a different set of permitted subtypes at run time than it had at
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* compile time, or if an enum class has a different set of enum constants
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* at runtime than it had at compile time, or if the type hierarchy has
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* been changed in some incompatible way between compile time and run time.</li>
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*
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* <li>{@code null} values and nested patterns involving sealed classes. If,
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* for example, an interface {@code I} is {@code sealed} with two permitted
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* subclasses {@code A} and {@code B}, and a record class {@code R} has a
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* single component of type {@code I}, then the two record patterns {@code
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* R(A a)} and {@code R(B b)} together are considered to be exhaustive for
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* the type {@code R}, but neither of these patterns will match against the
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* result of {@code new R(null)}.</li>
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*
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* <li>{@code null} values and nested record patterns. Given a record class
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* {@code S} with a single component of type {@code T}, where {@code T} is
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* another record class with a single component of type {@code String},
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* then the nested record pattern {@code R(S(var s))} is considered
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* exhaustive for the type {@code R} but it does not match against the
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* result of {@code new R(null)} (whereas it does match against the result
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* of {@code new R(new S(null))} does).</li>
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* </ul>
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*
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* <p>{@code MatchException} may also be thrown by the process of pattern matching
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* a value against a pattern. For example, pattern matching involving a record
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* pattern may require accessor methods to be implicitly invoked in order to
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* extract the component values. If any of these accessor methods throws an
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* exception, pattern matching completes abruptly and throws {@code
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* MatchException}. The original exception will be set as a {@link
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* Throwable#getCause() cause} of the {@code MatchException}. No {@link
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* Throwable#addSuppressed(java.lang.Throwable) suppressed} exceptions will be
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* recorded.
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*
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* @jls 14.11.3 Execution of a {@code switch} Statement
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* @jls 14.30.2 Pattern Matching
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* @jls 15.28.2 Run-Time Evaluation of {@code switch} Expressions
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*
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* @since 21
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*/
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public final class MatchException extends RuntimeException {
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@java.io.Serial
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private static final long serialVersionUID = 0L;
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/**
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* Constructs an {@code MatchException} with the specified detail message and
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* cause.
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*
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* @param message the detail message (which is saved for later retrieval
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* by the {@link #getMessage()} method).
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* @param cause the cause (which is saved for later retrieval by the
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* {@link #getCause()} method). (A {@code null} value is
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* permitted, and indicates that the cause is nonexistent or
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* unknown.)
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*/
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public MatchException(String message, Throwable cause) {
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super(message, cause);
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}
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}
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