| /******************************************************************************* |
| * Copyright (c) 2015, 2016 Google, Inc and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * Stefan Xenos (Google) - Initial implementation |
| *******************************************************************************/ |
| package org.eclipse.jdt.internal.core.nd.field; |
| |
| import org.eclipse.jdt.internal.core.nd.ITypeFactory; |
| import org.eclipse.jdt.internal.core.nd.Nd; |
| import org.eclipse.jdt.internal.core.nd.db.Database; |
| |
| /** |
| * Used to represent a single field of an object stored in the database. Objects |
| * which store themselves in the database should store a set of static final |
| * FieldDefinitions at the top of their class definition to indicate their memory map. |
| * This serves as a standard way to document the memory map for such structs, provides |
| * access to the field offsets, and provides a convenience getter. |
| * <p> |
| * There are two ways to use this. Callers can either use the "get" method to access |
| * the value of the field, or can use the public "offset" attribute to perform the reads |
| * manually. The get function is more convenient but allocates objects and so should |
| * probably not be used for frequently-accessed fields or primitive types that would |
| * end up being autoboxed unnecessarily. |
| * |
| * @param <T> |
| */ |
| public final class Field<T> extends BaseField implements IDestructableField { |
| public final ITypeFactory<T> factory; |
| |
| public Field(ITypeFactory<T> objectFactory, String structName, int fieldNumber) { |
| setFieldName("field " + fieldNumber + ", a " + getClass().getSimpleName() //$NON-NLS-1$//$NON-NLS-2$ |
| + " in struct " + structName); //$NON-NLS-1$ |
| this.factory = objectFactory; |
| } |
| |
| public T get(Nd nd, long address) { |
| return this.factory.create(nd, address + this.offset); |
| } |
| |
| public boolean hasDestructor() { |
| return this.factory.hasDestructor(); |
| } |
| |
| @Override |
| public void destruct(Nd nd, long address) { |
| this.factory.destruct(nd, address + this.offset); |
| } |
| |
| @Override |
| public int getRecordSize() { |
| return this.factory.getRecordSize(); |
| } |
| |
| @Override |
| public int getAlignment() { |
| // This sort of field is almost always used for embedding NdStructs within |
| // other data types. Since most NdStructs allow incoming record pointers, they need to |
| // be properly aligned. If we ever want to use this sort of field for other data types |
| // that don't require alignment, we may want to replace this with something smarter |
| // that can figure out the correct alignment based on the requirements of the actual |
| // data type. |
| return Database.BLOCK_SIZE_DELTA; |
| } |
| |
| /** |
| * Creates a new {@link Field} in the given struct with the given type. |
| * |
| * @param struct the struct that will contain the newly-created field (must not have had |
| * {@link StructDef#done()} called on it yet). |
| * @param fieldType the data type for the contents of the newly created field |
| * @return the newly-constructed field |
| */ |
| public static <T> Field<T> create(StructDef<?> struct, StructDef<T> fieldType) { |
| Field<T> result = new Field<>(fieldType.getFactory(), struct.getStructName(), struct.getNumFields()); |
| struct.add(result); |
| struct.addDestructableField(result); |
| fieldType.addDependency(struct); |
| return result; |
| } |
| } |