Java tutorial
/******************************************************************************* * Copyright (c) 2013, 2014 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; /** * Lambda expression AST node type (added in JLS8 API). * <pre> * LambdaExpression: * Identifier <b>-></b> Body * <b>(</b> [ Identifier { <b>,</b> Identifier } ] <b>)</b> <b>-></b> Body * <b>(</b> [ FormalParameter { <b>,</b> FormalParameter } ] <b>)</b> <b>-></b> Body * </pre> * *<p> * The first two forms use {@link VariableDeclarationFragment} for the parameter or parameters, * while the third form uses {@link SingleVariableDeclaration}.</p> *<p>The Body can be either a {@link Block} or an {@link Expression}.</p> * * @since 3.10 * @noinstantiate This class is not intended to be instantiated by clients */ @SuppressWarnings({ "rawtypes", "unchecked" }) public class LambdaExpression extends Expression { /** * The "parentheses" structural property of this node type (type: {@link Boolean}). * <p> * Note that parentheses are required unless {@link #parameters()} contains * just a single {@link VariableDeclarationFragment}. * ASTRewrite may ignore this property if necessary. * </p> */ public static final SimplePropertyDescriptor PARENTHESES_PROPERTY = new SimplePropertyDescriptor( LambdaExpression.class, "parentheses", boolean.class, MANDATORY); //$NON-NLS-1$ /** * The "parameters" structural property of this node type (element type: {@link VariableDeclaration}). * <p> * Note that all elements must be of the same type, either all {@link SingleVariableDeclaration} or all {@link VariableDeclarationFragment}. * </p> */ public static final ChildListPropertyDescriptor PARAMETERS_PROPERTY = new ChildListPropertyDescriptor( LambdaExpression.class, "parameters", VariableDeclaration.class, CYCLE_RISK); //$NON-NLS-1$ /** * The "body" structural property of this node type (child type: {@link ASTNode}, * must be either a {@link Block} or an {@link Expression}). */ public static final ChildPropertyDescriptor BODY_PROPERTY = new ChildPropertyDescriptor(LambdaExpression.class, "body", ASTNode.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$ /** * A list of property descriptors (element type: * {@link StructuralPropertyDescriptor}), * or null if uninitialized. */ private static final List PROPERTY_DESCRIPTORS_8_0; static { List propertyList = new ArrayList(4); createPropertyList(LambdaExpression.class, propertyList); addProperty(PARENTHESES_PROPERTY, propertyList); addProperty(PARAMETERS_PROPERTY, propertyList); addProperty(BODY_PROPERTY, propertyList); PROPERTY_DESCRIPTORS_8_0 = reapPropertyList(propertyList); } /** * 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 AST.JLS* constants * @return a list of property descriptors (element type: * {@link StructuralPropertyDescriptor}) */ public static List propertyDescriptors(int apiLevel) { return PROPERTY_DESCRIPTORS_8_0; } /** * Indicates whether parentheses are present or not. * Defaults to <code>true</code>. */ private boolean hasParentheses = true; /** * The parameter declarations * (element type: {@link VariableDeclaration}). * Defaults to an empty list. */ private ASTNode.NodeList parameters = new ASTNode.NodeList(PARAMETERS_PROPERTY); /** * The method body. * The method body; lazily initialized, defaults to an empty Block. */ private ASTNode body = null; /** * Creates a new AST node for a LambdaExpression declaration owned * by the given AST. * <p> * N.B. This constructor is package-private; all subclasses must be * declared in the same package; clients are unable to declare * additional subclasses. * </p> * * @param ast the AST that is to own this node */ LambdaExpression(AST ast) { super(ast); unsupportedIn2_3_4(); } @Override final List internalStructuralPropertiesForType(int apiLevel) { return propertyDescriptors(apiLevel); } @Override final boolean internalGetSetBooleanProperty(SimplePropertyDescriptor property, boolean get, boolean value) { if (property == PARENTHESES_PROPERTY) { if (get) { return hasParentheses(); } else { setParentheses(value); return false; } } // allow default implementation to flag the error return super.internalGetSetBooleanProperty(property, get, value); } @Override final List internalGetChildListProperty(ChildListPropertyDescriptor property) { if (property == PARAMETERS_PROPERTY) { return parameters(); } // allow default implementation to flag the error return super.internalGetChildListProperty(property); } @Override final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) { if (property == BODY_PROPERTY) { if (get) { return getBody(); } else { setBody(child); return null; } } // allow default implementation to flag the error return super.internalGetSetChildProperty(property, get, child); } @Override final int getNodeType0() { return LAMBDA_EXPRESSION; } @Override ASTNode clone0(AST target) { LambdaExpression result = new LambdaExpression(target); result.setSourceRange(getStartPosition(), getLength()); result.setParentheses(hasParentheses()); result.parameters().addAll(ASTNode.copySubtrees(target, parameters())); result.setBody(ASTNode.copySubtree(target, getBody())); 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 acceptChildren(visitor, this.parameters); acceptChild(visitor, getBody()); } visitor.endVisit(this); } /** * Returns whether parentheses around the parameters are present or not. * <p> * Note that parentheses are required unless {@link #parameters()} contains * just a single {@link VariableDeclarationFragment}. * ASTRewrite may ignore this property if necessary. * </p> * * @return <code>true</code> if this lambda expression has parentheses around * its parameters and <code>false</code> otherwise */ public boolean hasParentheses() { return this.hasParentheses; } /** * Sets whether this lambda expression has parentheses around its parameters or not. * <p> * Note that parentheses are required unless {@link #parameters()} contains * just a single {@link VariableDeclarationFragment}. * ASTRewrite may ignore this property if necessary. * </p> * * @param hasParentheses <code>true</code> if this lambda expression has parentheses around its parameters * and <code>false</code> otherwise */ public void setParentheses(boolean hasParentheses) { preValueChange(PARENTHESES_PROPERTY); this.hasParentheses = hasParentheses; postValueChange(PARENTHESES_PROPERTY); } /** * Returns the live ordered list of formal parameters of this lambda expression. * Note that all elements must be of the same type, either * <ul> * <li>all {@link SingleVariableDeclaration} (explicit type), or</li> * <li>all {@link VariableDeclarationFragment} (inferred type).</li> * </ul> * * @return the live list of formal parameters of this lambda expression * (element type: {@link VariableDeclaration}) */ public List parameters() { return this.parameters; } /** * Returns the body of this lambda expression. * * @return the lambda expression body, which can be either a {@link Block} or an {@link Expression} */ public ASTNode getBody() { if (this.body == null) { // lazy init must be thread-safe for readers synchronized (this) { if (this.body == null) { preLazyInit(); this.body = new Block(this.ast); postLazyInit(this.body, BODY_PROPERTY); } } } return this.body; } /** * Sets the body of this lambda expression. * * @param body a block node or an expression node * @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> * <li>body is neither a {@link Block} nor an {@link Expression}</li> * </ul> */ public void setBody(ASTNode body) { if (!(body instanceof Expression || body instanceof Block)) { throw new IllegalArgumentException(); } ASTNode oldChild = this.body; preReplaceChild(oldChild, body, BODY_PROPERTY); this.body = body; postReplaceChild(oldChild, body, BODY_PROPERTY); } /** * Resolves and returns the binding for the lambda expression * <p> * Note that bindings are generally unavailable unless requested when the * AST is being built. * </p> * * @return the binding, or <code>null</code> if the binding cannot be * resolved */ public IMethodBinding resolveMethodBinding() { return this.ast.getBindingResolver().resolveMethod(this); } @Override int memSize() { return BASE_NODE_SIZE + 3 * 4; } @Override int treeSize() { return memSize() + this.parameters.listSize() + (this.body == null ? 0 : getBody().treeSize()); } }