Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2019 IBM Corporation 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: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.jdt.core.dom; import java.util.ArrayList; import java.util.List; /** * Field access expression AST node type. * * <pre> * FieldAccess: * Expression <b>.</b> Identifier * </pre> * * <p> * Note that there are several kinds of expressions that resemble field access * expressions: qualified names, this expressions, and super field access * expressions. The following guidelines help with correct usage: * </p> * <ul> * <li>An expression like "foo.this" can only be represented as a this * expression (<code>ThisExpression</code>) containing a simple name. * "this" is a keyword, and therefore invalid as an identifier.</li> * <li>An expression like "this.foo" can only be represented as a field * access expression (<code>FieldAccess</code>) containing a this expression * and a simple name. Again, this is because "this" is a keyword, and * therefore invalid as an identifier.</li> * <li>An expression with "super" can only be represented as a super field * access expression (<code>SuperFieldAccess</code>). "super" is a also * keyword, and therefore invalid as an identifier.</li> * <li>An expression like "foo.bar" can be represented either as a * qualified name (<code>QualifiedName</code>) or as a field access * expression (<code>FieldAccess</code>) containing simple names. Either * is acceptable, and there is no way to choose between them without * information about what the names resolve to * (<code>ASTParser</code> may return either).</li> * <li>Other expressions ending in an identifier, such as "foo().bar" can * only be represented as field access expressions * (<code>FieldAccess</code>).</li> * </ul> * * @see QualifiedName * @see ThisExpression * @see SuperFieldAccess * @since 2.0 * @noinstantiate This class is not intended to be instantiated by clients. */ @SuppressWarnings("rawtypes") public class FieldAccess extends Expression { /** * The "expression" structural property of this node type (child type: {@link Expression}). * @since 3.0 */ public static final ChildPropertyDescriptor EXPRESSION_PROPERTY = new ChildPropertyDescriptor(FieldAccess.class, "expression", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$ /** * The "name" structural property of this node type (child type: {@link SimpleName}). * @since 3.0 */ public static final ChildPropertyDescriptor NAME_PROPERTY = new ChildPropertyDescriptor(FieldAccess.class, "name", SimpleName.class, MANDATORY, NO_CYCLE_RISK); //$NON-NLS-1$ /** * A list of property descriptors (element type: * {@link StructuralPropertyDescriptor}), * or null if uninitialized. */ private static final List PROPERTY_DESCRIPTORS; static { List properyList = new ArrayList(3); createPropertyList(FieldAccess.class, properyList); addProperty(EXPRESSION_PROPERTY, properyList); addProperty(NAME_PROPERTY, properyList); PROPERTY_DESCRIPTORS = reapPropertyList(properyList); } /** * Returns a list of structural property descriptors for this node type. * Clients must not modify the result. * * @param apiLevel the API level; one of the * <code>AST.JLS*</code> constants * @return a list of property descriptors (element type: * {@link StructuralPropertyDescriptor}) * @since 3.0 */ public static List propertyDescriptors(int apiLevel) { return PROPERTY_DESCRIPTORS; } /** * The expression; lazily initialized; defaults to an unspecified, * but legal, simple name. */ private Expression expression = null; /** * The field; lazily initialized; defaults to an unspecified, * but legal, simple field name. */ private SimpleName fieldName = null; /** * Creates a new unparented node for a field access expression owned by the * given AST. By default, the expression and field are both unspecified, * but legal, names. * <p> * N.B. This constructor is package-private. * </p> * * @param ast the AST that is to own this node */ FieldAccess(AST ast) { super(ast); } @Override final List internalStructuralPropertiesForType(int apiLevel) { return propertyDescriptors(apiLevel); } @Override final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) { if (property == EXPRESSION_PROPERTY) { if (get) { return getExpression(); } else { setExpression((Expression) child); return null; } } if (property == NAME_PROPERTY) { if (get) { return getName(); } else { setName((SimpleName) child); return null; } } // allow default implementation to flag the error return super.internalGetSetChildProperty(property, get, child); } @Override final int getNodeType0() { return FIELD_ACCESS; } @Override ASTNode clone0(AST target) { FieldAccess result = new FieldAccess(target); result.setSourceRange(getStartPosition(), getLength()); result.setExpression((Expression) getExpression().clone(target)); result.setName((SimpleName) getName().clone(target)); return result; } @Override final boolean subtreeMatch0(ASTMatcher matcher, Object other) { // dispatch to correct overloaded match method return matcher.match(this, other); } @Override void accept0(ASTVisitor visitor) { boolean visitChildren = visitor.visit(this); if (visitChildren) { // visit children in normal left to right reading order acceptChild(visitor, getExpression()); acceptChild(visitor, getName()); } visitor.endVisit(this); } /** * Returns the expression of this field access expression. * * @return the expression node */ public Expression getExpression() { if (this.expression == null) { // lazy init must be thread-safe for readers synchronized (this) { if (this.expression == null) { preLazyInit(); this.expression = new SimpleName(this.ast); postLazyInit(this.expression, EXPRESSION_PROPERTY); } } } return this.expression; } /** * Sets the expression of this field access expression. * * @param expression the new expression * @exception IllegalArgumentException if: * <ul> * <li>the node belongs to a different AST</li> * <li>the node already has a parent</li> * <li>a cycle in would be created</li> * </ul> */ public void setExpression(Expression expression) { if (expression == null) { throw new IllegalArgumentException(); } ASTNode oldChild = this.expression; preReplaceChild(oldChild, expression, EXPRESSION_PROPERTY); this.expression = expression; postReplaceChild(oldChild, expression, EXPRESSION_PROPERTY); } /** * Returns the name of the field accessed in this field access expression. * * @return the field name */ public SimpleName getName() { if (this.fieldName == null) { // lazy init must be thread-safe for readers synchronized (this) { if (this.fieldName == null) { preLazyInit(); this.fieldName = new SimpleName(this.ast); postLazyInit(this.fieldName, NAME_PROPERTY); } } } return this.fieldName; } /** * Sets the name of the field accessed in this field access expression. * * @param fieldName the field name * @exception IllegalArgumentException if: * <ul> * <li>the node belongs to a different AST</li> * <li>the node already has a parent</li> * </ul> */ public void setName(SimpleName fieldName) { if (fieldName == null) { throw new IllegalArgumentException(); } ASTNode oldChild = this.fieldName; preReplaceChild(oldChild, fieldName, NAME_PROPERTY); this.fieldName = fieldName; postReplaceChild(oldChild, fieldName, NAME_PROPERTY); } @Override int memSize() { // treat Code as free return BASE_NODE_SIZE + 2 * 4; } /** * Resolves and returns the binding for the field accessed by this * expression. * <p> * Note that bindings are generally unavailable unless requested when the * AST is being built. * </p> * * @return the variable binding, or <code>null</code> if the binding cannot * be resolved * @since 3.0 */ public IVariableBinding resolveFieldBinding() { return this.ast.getBindingResolver().resolveField(this); } @Override int treeSize() { return memSize() + (this.expression == null ? 0 : getExpression().treeSize()) + (this.fieldName == null ? 0 : getName().treeSize()); } }