| 1 | /******************************************************************************* |
|---|---|
| 2 | * Copyright (c) 2000, 2019 IBM Corporation and others. |
| 3 | * |
| 4 | * This program and the accompanying materials |
| 5 | * are made available under the terms of the Eclipse Public License 2.0 |
| 6 | * which accompanies this distribution, and is available at |
| 7 | * https://www.eclipse.org/legal/epl-2.0/ |
| 8 | * |
| 9 | * SPDX-License-Identifier: EPL-2.0 |
| 10 | * Contributors: |
| 11 | * IBM Corporation - initial API and implementation |
| 12 | *******************************************************************************/ |
| 13 | |
| 14 | package org.eclipse.jdt.core.dom; |
| 15 | |
| 16 | /** |
| 17 | * Abstract base class of AST nodes that represent expressions. |
| 18 | * There are several kinds of expressions. |
| 19 | * <pre> |
| 20 | * Expression: |
| 21 | * {@link Annotation}, |
| 22 | * {@link ArrayAccess}, |
| 23 | * {@link ArrayCreation}, |
| 24 | * {@link ArrayInitializer}, |
| 25 | * {@link Assignment}, |
| 26 | * {@link BooleanLiteral}, |
| 27 | * {@link CaseDefaultExpression}, |
| 28 | * {@link CastExpression}, |
| 29 | * {@link CharacterLiteral}, |
| 30 | * {@link ClassInstanceCreation}, |
| 31 | * {@link ConditionalExpression}, |
| 32 | * {@link CreationReference}, |
| 33 | * {@link ExpressionMethodReference}, |
| 34 | * {@link FieldAccess}, |
| 35 | * {@link InfixExpression}, |
| 36 | * {@link InstanceofExpression}, |
| 37 | * {@link LambdaExpression}, |
| 38 | * {@link MethodInvocation}, |
| 39 | * {@link MethodReference}, |
| 40 | * {@link Name}, |
| 41 | * {@link NullLiteral}, |
| 42 | * {@link NumberLiteral}, |
| 43 | * {@link Pattern}, |
| 44 | * {@link ParenthesizedExpression}, |
| 45 | * {@link PostfixExpression}, |
| 46 | * {@link PrefixExpression}, |
| 47 | * {@link StringLiteral}, |
| 48 | * {@link SuperFieldAccess}, |
| 49 | * {@link SuperMethodInvocation}, |
| 50 | * {@link SuperMethodReference}, |
| 51 | * {@link SwitchExpression}, |
| 52 | * {@link ThisExpression}, |
| 53 | * {@link TypeLiteral}, |
| 54 | * {@link TypeMethodReference}, |
| 55 | * {@link VariableDeclarationExpression} |
| 56 | * </pre> |
| 57 | * |
| 58 | * @since 2.0 |
| 59 | */ |
| 60 | public abstract class Expression extends ASTNode { |
| 61 | |
| 62 | /** |
| 63 | * Creates a new AST node for an expression owned by the given AST. |
| 64 | * <p> |
| 65 | * N.B. This constructor is package-private. |
| 66 | * </p> |
| 67 | * |
| 68 | * @param ast the AST that is to own this node |
| 69 | */ |
| 70 | Expression(AST ast) { |
| 71 | super(ast); |
| 72 | } |
| 73 | |
| 74 | /** |
| 75 | * Resolves and returns the compile-time constant expression value as |
| 76 | * specified in JLS2 15.28, if this expression has one. Constant expression |
| 77 | * values are unavailable unless bindings are requested when the AST is |
| 78 | * being built. If the type of the value is a primitive type, the result |
| 79 | * is the boxed equivalent (i.e., int returned as an <code>Integer</code>); |
| 80 | * if the type of the value is <code>String</code>, the result is the string |
| 81 | * itself. If the expression does not have a compile-time constant expression |
| 82 | * value, the result is <code>null</code>. |
| 83 | * <p> |
| 84 | * Resolving constant expressions takes into account the value of simple |
| 85 | * and qualified names that refer to constant variables (JLS2 4.12.4). |
| 86 | * </p> |
| 87 | * <p> |
| 88 | * Note 1: enum constants are not considered constant expressions. |
| 89 | * The result is always <code>null</code> for these. |
| 90 | * </p> |
| 91 | * <p> |
| 92 | * Note 2: Compile-time constant expressions cannot denote <code>null</code>. |
| 93 | * So technically {@link NullLiteral} nodes are not constant expressions. |
| 94 | * The result is <code>null</code> for these nonetheless. |
| 95 | * </p> |
| 96 | * |
| 97 | * @return the constant expression value, or <code>null</code> if this |
| 98 | * expression has no constant expression value or if bindings were not |
| 99 | * requested when the AST was created |
| 100 | * @since 3.1 |
| 101 | */ |
| 102 | public final Object resolveConstantExpressionValue() { |
| 103 | return this.ast.getBindingResolver().resolveConstantExpressionValue(this); |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Resolves and returns the binding for the type of this expression. |
| 108 | * <p> |
| 109 | * Note that bindings are generally unavailable unless requested when the |
| 110 | * AST is being built. |
| 111 | * </p> |
| 112 | * |
| 113 | * @return the binding for the type of this expression, or |
| 114 | * <code>null</code> if the type cannot be resolved |
| 115 | */ |
| 116 | public final ITypeBinding resolveTypeBinding() { |
| 117 | return this.ast.getBindingResolver().resolveExpressionType(this); |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Returns whether this expression node is the site of a boxing |
| 122 | * conversion (JLS3 5.1.7). This information is available only |
| 123 | * when bindings are requested when the AST is being built. |
| 124 | * |
| 125 | * @return <code>true</code> if this expression is the site of a |
| 126 | * boxing conversion, or <code>false</code> if either no boxing conversion |
| 127 | * is involved or if bindings were not requested when the AST was created |
| 128 | * @since 3.1 |
| 129 | */ |
| 130 | public final boolean resolveBoxing() { |
| 131 | return this.ast.getBindingResolver().resolveBoxing(this); |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Returns whether this expression node is the site of an unboxing |
| 136 | * conversion (JLS3 5.1.8). This information is available only |
| 137 | * when bindings are requested when the AST is being built. |
| 138 | * |
| 139 | * @return <code>true</code> if this expression is the site of an |
| 140 | * unboxing conversion, or <code>false</code> if either no unboxing |
| 141 | * conversion is involved or if bindings were not requested when the |
| 142 | * AST was created |
| 143 | * @since 3.1 |
| 144 | */ |
| 145 | public final boolean resolveUnboxing() { |
| 146 | return this.ast.getBindingResolver().resolveUnboxing(this); |
| 147 | } |
| 148 | } |
| 149 | |
| 150 |
Members