8308753: Class-File API transition to Preview

Reviewed-by: ihse, mchung, vromero

src/java.base/share/classes/java/lang/classfile/instruction/LocalVariable.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2022, 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.classfile.instruction;
+
+import java.lang.constant.ClassDesc;
+
+import java.lang.classfile.BufWriter;
+import java.lang.classfile.ClassFile;
+import java.lang.classfile.CodeElement;
+import java.lang.classfile.CodeModel;
+import java.lang.classfile.Label;
+import java.lang.classfile.PseudoInstruction;
+import java.lang.classfile.attribute.LocalVariableTableAttribute;
+import java.lang.classfile.constantpool.Utf8Entry;
+import jdk.internal.classfile.impl.AbstractPseudoInstruction;
+import jdk.internal.classfile.impl.BoundLocalVariable;
+import jdk.internal.classfile.impl.TemporaryConstantPool;
+import jdk.internal.javac.PreviewFeature;
+
+/**
+ * A pseudo-instruction which models a single entry in the
+ * {@link LocalVariableTableAttribute}.  Delivered as a {@link CodeElement}
+ * during traversal of the elements of a {@link CodeModel}, according to
+ * the setting of the {@link ClassFile.DebugElementsOption} option.
+ *
+ * @see PseudoInstruction
+ *
+ * @since 22
+ */
+@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
+public sealed interface LocalVariable extends PseudoInstruction
+        permits AbstractPseudoInstruction.UnboundLocalVariable, BoundLocalVariable {
+    /**
+     * {@return the local variable slot}
+     */
+    int slot();
+
+    /**
+     * {@return the local variable name}
+     */
+    Utf8Entry name();
+
+    /**
+     * {@return the local variable field descriptor}
+     */
+    Utf8Entry type();
+
+    /**
+     * {@return the local variable type, as a symbolic descriptor}
+     */
+    default ClassDesc typeSymbol() {
+        return ClassDesc.ofDescriptor(type().stringValue());
+    }
+
+    /**
+     * {@return the start range of the local variable scope}
+     */
+    Label startScope();
+
+    /**
+     * {@return the end range of the local variable scope}
+     */
+    Label endScope();
+
+    /**
+     * Writes the local variable to the specified writer
+     *
+     * @param buf the writer
+     * @return true if the variable has been written
+     */
+    boolean writeTo(BufWriter buf);
+
+    /**
+     * {@return a local variable pseudo-instruction}
+     *
+     * @param slot the local variable slot
+     * @param nameEntry the local variable name
+     * @param descriptorEntry the local variable descriptor
+     * @param startScope the start range of the local variable scope
+     * @param endScope the end range of the local variable scope
+     */
+    static LocalVariable of(int slot, Utf8Entry nameEntry, Utf8Entry descriptorEntry, Label startScope, Label endScope) {
+        return new AbstractPseudoInstruction.UnboundLocalVariable(slot, nameEntry, descriptorEntry,
+                                                                  startScope, endScope);
+    }
+
+    /**
+     * {@return a local variable pseudo-instruction}
+     *
+     * @param slot the local variable slot
+     * @param name the local variable name
+     * @param descriptor the local variable descriptor
+     * @param startScope the start range of the local variable scope
+     * @param endScope the end range of the local variable scope
+     */
+    static LocalVariable of(int slot, String name, ClassDesc descriptor, Label startScope, Label endScope) {
+        return of(slot,
+                  TemporaryConstantPool.INSTANCE.utf8Entry(name),
+                  TemporaryConstantPool.INSTANCE.utf8Entry(descriptor.descriptorString()),
+                  startScope, endScope);
+    }
+}