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 * 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.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashSet;

import java.util.Set;

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.TokenType;

/**

 * BinaryNode nodes represent two operand operations.

 */

@Immutable

public final class BinaryNode extends Expression implements Assignment<Expression>, Optimistic {

    private static final long serialVersionUID = 1L;

    // Placeholder for "undecided optimistic ADD type". Unfortunately, we can't decide the type of ADD during optimistic

    // type calculation as it can have local variables as its operands that will decide its ultimate type.

    private static final Type OPTIMISTIC_UNDECIDED_TYPE = Type.typeFor(new Object(){/*empty*/}.getClass());

    /** Left hand side argument. */

    private final Expression lhs;

    private final Expression rhs;

    private final int programPoint;

    private final Type type;

    private transient Type cachedType;

    @Ignore

    private static final Set<TokenType> CAN_OVERFLOW =

        Collections.unmodifiableSet(new HashSet<>(Arrays.asList(new TokenType[] {

                TokenType.ADD,

                TokenType.DIV,

                TokenType.MOD,

                TokenType.MUL,

                TokenType.SUB,

                TokenType.ASSIGN_ADD,

                TokenType.ASSIGN_DIV,

                TokenType.ASSIGN_MOD,

                TokenType.ASSIGN_MUL,

                TokenType.ASSIGN_SUB

            })));

    /**

     * Constructor

     *

     * @param token  token

     * @param lhs    left hand side

     * @param rhs    right hand side

     */

    public BinaryNode(final long token, final Expression lhs, final Expression rhs) {

        super(token, lhs.getStart(), rhs.getFinish());

        assert !(isTokenType(TokenType.AND) || isTokenType(TokenType.OR)) || lhs instanceof JoinPredecessorExpression;

        this.lhs   = lhs;

        this.rhs   = rhs;

        this.programPoint = INVALID_PROGRAM_POINT;

        this.type = null;

    }

    private BinaryNode(final BinaryNode binaryNode, final Expression lhs, final Expression rhs, final Type type, final int programPoint) {

        super(binaryNode);

        this.lhs = lhs;

        this.rhs = rhs;

        this.programPoint = programPoint;

        this.type = type;

    }

    /**

     * @return true if the node is a comparison operation.

     */

    public boolean isComparison() {

        switch (tokenType()) {

        case EQ:

        case EQ_STRICT:

        case NE:

        case NE_STRICT:

        case LE:

        case LT:

        case GE:

        case GT:

            return true;

        default:

            return false;

        }

    }

    /**

     * Returns true if the node is a logical operation.

     * @return true if the node is a logical operation.

     */

    public boolean isLogical() {

        return isLogical(tokenType());

    }

    /**

     * Returns true if the token type represents a logical operation.

     * @param tokenType the token type

     * @return true if the token type represents a logical operation.

     */

    public static boolean isLogical(final TokenType tokenType) {

        switch (tokenType) {

        case AND:

        case OR:

            return true;

        default:

            return false;

        }

    }

    /**

     * Return the widest possible operand type for this operation.

     *

     * @return Type

     */

    public Type getWidestOperandType() {

        switch (tokenType()) {

        case SHR:

        case ASSIGN_SHR:

            return Type.INT;

        case INSTANCEOF:

            return Type.OBJECT;

        default:

            if (isComparison()) {

                return Type.OBJECT;

            }

            return getWidestOperationType();

        }

    }

    @Override

    public Type getWidestOperationType() {

        switch (tokenType()) {

        case ADD:

        case ASSIGN_ADD: {

            // Compare this logic to decideType(Type, Type); it's similar, but it handles the optimistic type

            // calculation case while this handles the conservative case.

            final Type lhsType = lhs.getType();

            final Type rhsType = rhs.getType();

            if(lhsType == Type.BOOLEAN && rhsType == Type.BOOLEAN) {

                // Will always fit in an int, as the value range is [0, 1, 2]. If we didn't treat them specially here,

                // they'd end up being treated as generic INT operands and their sum would be conservatively considered

                // to be a LONG in the generic case below; we can do better here.

                return Type.INT;

            } else if(isString(lhsType) || isString(rhsType)) {

                // We can statically figure out that this is a string if either operand is a string. In this case, use

                // CHARSEQUENCE to prevent it from being proactively flattened.

                return Type.CHARSEQUENCE;

            }

            final Type widestOperandType = Type.widest(undefinedToNumber(booleanToInt(lhsType)), undefinedToNumber(booleanToInt(rhsType)));

            if(widestOperandType == Type.INT) {

                return Type.LONG;

            } else if (widestOperandType.isNumeric()) {

                return Type.NUMBER;

            }

            // We pretty much can't know what it will be statically. Must presume OBJECT conservatively, as we can end

            // up getting either a string or an object when adding something + object, e.g.:

            // 1 + {} == "1[object Object]", but

            // 1 + {valueOf: function() { return 2 }} == 3. Also:

            // 1 + {valueOf: function() { return "2" }} == "12".

            return Type.OBJECT;

        }

        case SHR:

        case ASSIGN_SHR:

            return Type.LONG;

        case ASSIGN_SAR:

        case ASSIGN_SHL:

        case BIT_AND:

        case BIT_OR:

        case BIT_XOR:

        case ASSIGN_BIT_AND:

        case ASSIGN_BIT_OR:

        case ASSIGN_BIT_XOR:

        case SAR:

        case SHL:

            return Type.INT;

        case DIV:

        case MOD:

        case ASSIGN_DIV:

        case ASSIGN_MOD: {

            // Naively, one might think MOD has the same type as the widest of its operands, this is unfortunately not

            // true when denominator is zero, so even type(int % int) == double.

            return Type.NUMBER;

        }

        case MUL:

        case SUB:

        case ASSIGN_MUL:

        case ASSIGN_SUB: {

            final Type lhsType = lhs.getType();

            final Type rhsType = rhs.getType();

            if(lhsType == Type.BOOLEAN && rhsType == Type.BOOLEAN) {

                return Type.INT;

            }

            final Type widestOperandType = Type.widest(booleanToInt(lhsType), booleanToInt(rhsType));

            if(widestOperandType == Type.INT) {

                return Type.LONG;

            }

            return Type.NUMBER;

        }

        case VOID: {

            return Type.UNDEFINED;

        }

        case ASSIGN: {

            return rhs.getType();

        }

        case INSTANCEOF: {

            return Type.BOOLEAN;

        }

        case COMMALEFT: {

            return lhs.getType();

        }

        case COMMARIGHT: {

            return rhs.getType();

        }

        case AND:

        case OR:{

            return Type.widestReturnType(lhs.getType(), rhs.getType());

        }

        default:

            if (isComparison()) {

                return Type.BOOLEAN;

            }

            return Type.OBJECT;

        }

    }

    private static boolean isString(final Type type) {

        return type == Type.STRING || type == Type.CHARSEQUENCE;

    }

    private static Type booleanToInt(final Type type) {

        return type == Type.BOOLEAN ? Type.INT : type;

    }

    private static Type undefinedToNumber(final Type type) {

        return type == Type.UNDEFINED ? Type.NUMBER : type;

    }

    /**

     * Check if this node is an assignment

     *

     * @return true if this node assigns a value

     */

    @Override

    public boolean isAssignment() {

        switch (tokenType()) {

        case ASSIGN:

        case ASSIGN_ADD:

        case ASSIGN_BIT_AND:

        case ASSIGN_BIT_OR:

        case ASSIGN_BIT_XOR:

        case ASSIGN_DIV:

        case ASSIGN_MOD:

        case ASSIGN_MUL:

        case ASSIGN_SAR:

        case ASSIGN_SHL:

        case ASSIGN_SHR:

        case ASSIGN_SUB:

           return true;

        default:

           return false;

        }

    }

    @Override

    public boolean isSelfModifying() {

        return isAssignment() && tokenType() != TokenType.ASSIGN;

    }

    @Override

    public Expression getAssignmentDest() {

        return isAssignment() ? lhs() : null;

    }

    @Override

    public BinaryNode setAssignmentDest(final Expression n) {

        return setLHS(n);

    }

    @Override

    public Expression getAssignmentSource() {

        return rhs();

    }

    /**

     * Assist in IR navigation.

     * @param visitor IR navigating visitor.

     */

    @Override

    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {

        if (visitor.enterBinaryNode(this)) {

            return visitor.leaveBinaryNode(setLHS((Expression)lhs.accept(visitor)).setRHS((Expression)rhs.accept(visitor)));

        }

        return this;

    }

    @Override

    public boolean isLocal() {

        switch (tokenType()) {

        case SAR:

        case SHL:

        case SHR:

        case BIT_AND:

        case BIT_OR:

        case BIT_XOR:

        case ADD:

        case DIV:

        case MOD:

        case MUL:

        case SUB:

            return lhs.isLocal() && lhs.getType().isJSPrimitive()

                && rhs.isLocal() && rhs.getType().isJSPrimitive();

        case ASSIGN_ADD:

        case ASSIGN_BIT_AND:

        case ASSIGN_BIT_OR:

        case ASSIGN_BIT_XOR:

        case ASSIGN_DIV:

        case ASSIGN_MOD:

        case ASSIGN_MUL:

        case ASSIGN_SAR:

        case ASSIGN_SHL:

        case ASSIGN_SHR:

        case ASSIGN_SUB:

            return lhs instanceof IdentNode && lhs.isLocal() && lhs.getType().isJSPrimitive()

                    && rhs.isLocal() && rhs.getType().isJSPrimitive();

        case ASSIGN:

            return lhs instanceof IdentNode && lhs.isLocal() && rhs.isLocal();

        default:

            return false;

        }

    }

    @Override

    public boolean isAlwaysFalse() {

        switch (tokenType()) {

        case COMMALEFT:

            return lhs.isAlwaysFalse();

        case COMMARIGHT:

            return rhs.isAlwaysFalse();

        default:

            return false;

        }

    }

    @Override

    public boolean isAlwaysTrue() {

        switch (tokenType()) {

        case COMMALEFT:

            return lhs.isAlwaysTrue();

        case COMMARIGHT:

            return rhs.isAlwaysTrue();

        default:

            return false;

        }

    }

    @Override

    public void toString(final StringBuilder sb, final boolean printType) {

        final TokenType tokenType = tokenType();

        final boolean lhsParen = tokenType.needsParens(lhs().tokenType(), true);

        final boolean rhsParen = tokenType.needsParens(rhs().tokenType(), false);

        if (lhsParen) {

            sb.append('(');

        }

        lhs().toString(sb, printType);

        if (lhsParen) {

            sb.append(')');

        }

        sb.append(' ');

        switch (tokenType) {

        case COMMALEFT:

            sb.append(",<");

            break;

        case COMMARIGHT:

            sb.append(",>");

            break;

        case INCPREFIX:

        case DECPREFIX:

            sb.append("++");

            break;

        default:

            sb.append(tokenType.getName());

            break;

        }

        if (isOptimistic()) {

            sb.append(Expression.OPT_IDENTIFIER);

        }

        sb.append(' ');

        if (rhsParen) {

            sb.append('(');

        }

        rhs().toString(sb, printType);

        if (rhsParen) {

            sb.append(')');

        }

    }

    /**

     * Get the left hand side expression for this node

     * @return the left hand side expression

     */

    public Expression lhs() {

        return lhs;

    }

    /**

     * Get the right hand side expression for this node

     * @return the left hand side expression

     */

    public Expression rhs() {

        return rhs;

    }

    /**

     * Set the left hand side expression for this node

     * @param lhs new left hand side expression

     * @return a node equivalent to this one except for the requested change.

     */

    public BinaryNode setLHS(final Expression lhs) {

        if (this.lhs == lhs) {

            return this;

        }

        return new BinaryNode(this, lhs, rhs, type, programPoint);

    }

    /**

     * Set the right hand side expression for this node

     * @param rhs new right hand side expression

     * @return a node equivalent to this one except for the requested change.

     */

    public BinaryNode setRHS(final Expression rhs) {

        if (this.rhs == rhs) {

            return this;

        }

        return new BinaryNode(this, lhs, rhs, type, programPoint);

    }

    /**

     * Set both the left and the right hand side expression for this node