src/jdk/nashorn/internal/ir/UnaryNode.java

/*
 * 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
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package jdk.nashorn.internal.ir;

import static jdk.nashorn.internal.parser.TokenType.BIT_NOT;
import static jdk.nashorn.internal.parser.TokenType.DECPOSTFIX;
import static jdk.nashorn.internal.parser.TokenType.INCPOSTFIX;
import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.annotations.Ignore;
import jdk.nashorn.internal.ir.annotations.Immutable;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;
import jdk.nashorn.internal.parser.Token;
import jdk.nashorn.internal.parser.TokenType;

/**
 * UnaryNode nodes represent single operand operations.
 */
@Immutable
public final class UnaryNode extends Expression implements Assignment<Expression>, Optimistic {
    private static final long serialVersionUID = 1L;

    /** Right hand side argument. */
    private final Expression expression;

    private final int programPoint;

    private final Type type;

    @Ignore
    private static final List<TokenType> CAN_OVERFLOW =
            Collections.unmodifiableList(
                Arrays.asList(new TokenType[] {
                    TokenType.ADD,
                    TokenType.SUB, //negate
                    TokenType.DECPREFIX,
                    TokenType.DECPOSTFIX,
                    TokenType.INCPREFIX,
                    TokenType.INCPOSTFIX,
                }));

    /**
     * Constructor
     *
     * @param token  token
     * @param rhs    expression
     */
    public UnaryNode(final long token, final Expression rhs) {
        this(token, Math.min(rhs.getStart(), Token.descPosition(token)), Math.max(Token.descPosition(token) + Token.descLength(token), rhs.getFinish()), rhs);
    }

    /**
     * Constructor
     *
     * @param token      token
     * @param start      start
     * @param finish     finish
     * @param expression expression
     */
    public UnaryNode(final long token, final int start, final int finish, final Expression expression) {
        super(token, start, finish);
        this.expression   = expression;
        this.programPoint = INVALID_PROGRAM_POINT;
        this.type = null;
    }


    private UnaryNode(final UnaryNode unaryNode, final Expression expression, final Type type, final int programPoint) {
        super(unaryNode);
        this.expression   = expression;
        this.programPoint = programPoint;
        this.type = type;
    }

    /**
     * Is this an assignment - i.e. that mutates something such as a++
     *
     * @return true if assignment
     */
    @Override
    public boolean isAssignment() {
        switch (tokenType()) {
        case DECPOSTFIX:
        case DECPREFIX:
        case INCPOSTFIX:
        case INCPREFIX:
            return true;
        default:
            return false;
        }
    }

    @Override
    public boolean isSelfModifying() {
        return isAssignment();
    }

    @Override
    public Type getWidestOperationType() {
        switch (tokenType()) {
        case ADD:
            final Type operandType = getExpression().getType();
            if(operandType == Type.BOOLEAN) {
                return Type.INT;
            } else if(operandType.isObject()) {
                return Type.NUMBER;
            }
            assert operandType.isNumeric();
            return operandType;
        case SUB:
            // This might seems overly conservative until you consider that -0 can only be represented as a double.
            return Type.NUMBER;
        case NOT:
        case DELETE:
            return Type.BOOLEAN;
        case BIT_NOT:
            return Type.INT;
        case VOID:
            return Type.UNDEFINED;
        default:
            return isAssignment() ? Type.NUMBER : Type.OBJECT;
        }
    }

    @Override
    public Expression getAssignmentDest() {
        return isAssignment() ? getExpression() : null;
    }

    @Override
    public UnaryNode setAssignmentDest(final Expression n) {
        return setExpression(n);
    }

    @Override
    public Expression getAssignmentSource() {
        return getAssignmentDest();
    }

    /**
     * Assist in IR navigation.
     * @param visitor IR navigating visitor.
     */
    @Override
    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
        if (visitor.enterUnaryNode(this)) {
            return visitor.leaveUnaryNode(setExpression((Expression)expression.accept(visitor)));
        }

        return this;
    }

    @Override
    public boolean isLocal() {
        switch (tokenType()) {
        case NEW:
            return false;
        case ADD:
        case SUB:
        case NOT:
        case BIT_NOT:
            return expression.isLocal() && expression.getType().isJSPrimitive();
        case DECPOSTFIX:
        case DECPREFIX:
        case INCPOSTFIX:
        case INCPREFIX:
            return expression instanceof IdentNode && expression.isLocal() && expression.getType().isJSPrimitive();
        default:
            return expression.isLocal();
        }
    }

    @Override
    public void toString(final StringBuilder sb, final boolean printType) {
        toString(sb,
                new Runnable() {
                    @Override
                    public void run() {
                        getExpression().toString(sb, printType);
                    }
                },
                printType);
    }

    /**
     * Creates the string representation of this unary node, delegating the creation of the string representation of its
     * operand to a specified runnable.
     * @param sb the string builder to use
     * @param rhsStringBuilder the runnable that appends the string representation of the operand to the string builder
     * @param printType should we print type
     * when invoked.
     */
    public void toString(final StringBuilder sb, final Runnable rhsStringBuilder, final boolean printType) {
        final TokenType tokenType = tokenType();
        final String    name      = tokenType.getName();
        final boolean   isPostfix = tokenType == DECPOSTFIX || tokenType == INCPOSTFIX;

        if (isOptimistic()) {
            sb.append(Expression.OPT_IDENTIFIER);
        }
        boolean rhsParen = tokenType.needsParens(getExpression().tokenType(), false);

        if (!isPostfix) {
            if (name == null) {
                sb.append(tokenType.name());
                rhsParen = true;
            } else {
                sb.append(name);

                if (tokenType.ordinal() > BIT_NOT.ordinal()) {
                    sb.append(' ');
                }
            }
        }

        if (rhsParen) {
            sb.append('(');
        }
        rhsStringBuilder.run();
        if (rhsParen) {
            sb.append(')');
        }

        if (isPostfix) {
            sb.append(tokenType == DECPOSTFIX ? "--" : "++");
        }
    }

    /**
     * Get the right hand side of this if it is inherited by a binary expression,
     * or just the expression itself if still Unary
     *
     * @see BinaryNode
     *
     * @return right hand side or expression node
     */
    public Expression getExpression() {
        return expression;
    }

    /**
     * Reset the right hand side of this if it is inherited by a binary expression,
     * or just the expression itself if still Unary
     *
     * @see BinaryNode
     *
     * @param expression right hand side or expression node
     * @return a node equivalent to this one except for the requested change.
     */
    public UnaryNode setExpression(final Expression expression) {
        if (this.expression == expression) {
            return this;
        }
        return new UnaryNode(this, expression, type, programPoint);
    }

    @Override
    public int getProgramPoint() {
        return programPoint;
    }

    @Override
    public UnaryNode setProgramPoint(final int programPoint) {
        if (this.programPoint == programPoint) {
            return this;
        }
        return new UnaryNode(this, expression, type, programPoint);
    }

    @Override
    public boolean canBeOptimistic() {
        return getMostOptimisticType() != getMostPessimisticType();
    }

    @Override
    public Type getMostOptimisticType() {
        if (CAN_OVERFLOW.contains(tokenType())) {
            return Type.INT;
        }
        return getMostPessimisticType();
    }

    @Override
    public Type getMostPessimisticType() {
        return getWidestOperationType();
    }

    @Override
    public Type getType() {
        final Type widest = getWidestOperationType();
        if(type == null) {
            return widest;
        }
        return Type.narrowest(widest, Type.widest(type, expression.getType()));
    }

    @Override
    public UnaryNode setType(final Type type) {
        if (this.type == type) {
            return this;
        }
        return new UnaryNode(this, expression, type, programPoint);
    }

}