| /* |
| * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.ir; |
| |
| import jdk.nashorn.internal.codegen.types.Type; |
| import jdk.nashorn.internal.runtime.UnwarrantedOptimismException; |
| |
| /** |
| * Common superclass for all expression nodes. Expression nodes can have |
| * an associated symbol as well as a type. |
| * |
| */ |
| public abstract class Expression extends Node { |
| private static final long serialVersionUID = 1L; |
| |
| static final String OPT_IDENTIFIER = "%"; |
| |
| protected Expression(final long token, final int start, final int finish) { |
| super(token, start, finish); |
| } |
| |
| Expression(final long token, final int finish) { |
| super(token, finish); |
| } |
| |
| Expression(final Expression expr) { |
| super(expr); |
| } |
| |
| /** |
| * Returns the type of the expression. |
| * |
| * @return the type of the expression. |
| */ |
| public abstract Type getType(); |
| |
| /** |
| * Returns {@code true} if this expression depends exclusively on state that is constant |
| * or local to the currently running function and thus inaccessible to other functions. |
| * This implies that a local expression must not call any other functions (neither directly |
| * nor implicitly through a getter, setter, or object-to-primitive type conversion). |
| * |
| * @return true if this expression does not depend on state shared with other functions. |
| */ |
| public boolean isLocal() { |
| return false; |
| } |
| |
| /** |
| * Is this a self modifying assignment? |
| * @return true if self modifying, e.g. a++, or a*= 17 |
| */ |
| public boolean isSelfModifying() { |
| return false; |
| } |
| |
| /** |
| * Returns widest operation type of this operation. |
| * |
| * @return the widest type for this operation |
| */ |
| public Type getWidestOperationType() { |
| return Type.OBJECT; |
| } |
| |
| /** |
| * Returns true if the type of this expression is narrower than its widest operation type (thus, it is |
| * optimistically typed). |
| * @return true if this expression is optimistically typed. |
| */ |
| public final boolean isOptimistic() { |
| return getType().narrowerThan(getWidestOperationType()); |
| } |
| |
| void optimisticTypeToString(final StringBuilder sb) { |
| optimisticTypeToString(sb, isOptimistic()); |
| } |
| |
| void optimisticTypeToString(final StringBuilder sb, final boolean optimistic) { |
| sb.append('{'); |
| final Type type = getType(); |
| final String desc = type == Type.UNDEFINED ? "U" : type.getDescriptor(); |
| |
| sb.append(desc.charAt(desc.length() - 1) == ';' ? "O" : desc); |
| if (isOptimistic() && optimistic) { |
| sb.append(OPT_IDENTIFIER); |
| final int pp = ((Optimistic)this).getProgramPoint(); |
| if (UnwarrantedOptimismException.isValid(pp)) { |
| sb.append('_').append(pp); |
| } |
| } |
| sb.append('}'); |
| } |
| |
| /** |
| * Returns true if the runtime value of this expression is always false when converted to boolean as per ECMAScript |
| * ToBoolean conversion. Used in control flow calculations. |
| * @return true if this expression's runtime value converted to boolean is always false. |
| */ |
| public boolean isAlwaysFalse() { |
| return false; |
| } |
| |
| /** |
| * Returns true if the runtime value of this expression is always true when converted to boolean as per ECMAScript |
| * ToBoolean conversion. Used in control flow calculations. |
| * @return true if this expression's runtime value converted to boolean is always true. |
| */ |
| public boolean isAlwaysTrue() { |
| return false; |
| } |
| |
| /** |
| * Returns true if the expression is not null and {@link #isAlwaysFalse()}. |
| * @param test a test expression used as a predicate of a branch or a loop. |
| * @return true if the expression is not null and {@link #isAlwaysFalse()}. |
| */ |
| public static boolean isAlwaysFalse(final Expression test) { |
| return test != null && test.isAlwaysFalse(); |
| } |
| |
| |
| /** |
| * Returns true if the expression is null or {@link #isAlwaysTrue()}. Null is considered to be always true as a |
| * for loop with no test is equivalent to a for loop with always-true test. |
| * @param test a test expression used as a predicate of a branch or a loop. |
| * @return true if the expression is null or {@link #isAlwaysFalse()}. |
| */ |
| public static boolean isAlwaysTrue(final Expression test) { |
| return test == null || test.isAlwaysTrue(); |
| } |
| } |