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 * 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
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 *
 * 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.
/**
 * 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. /** 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,
                TokenType.SHR,
                TokenType.ASSIGN_SHR
            })));

    
Constructor
Params:
token –  token
lhs –    left hand side
rhs –    right hand side/**
     * 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;
    }

    
Returns true if the node is a comparison operation (either equality, inequality, or relational).
Returns:
true if the node is a comparison operation./**
     * Returns true if the node is a comparison operation (either equality, inequality, or relational).
     * @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 relational operation (less than (or equals), greater than (or equals)).
Returns:
true if the node is a relational operation./**
     * Returns true if the node is a relational operation (less than (or equals), greater than (or equals)).
     * @return true if the node is a relational operation.
     */
    public boolean isRelational() {
        switch (tokenType()) {
        case LT:
        case GT:
        case LE:
        case GE:
            return true;
        default:
            return false;
        }
    }

    
Returns true if the node is a logical operation.
Returns:
true if the node is a logical operation./**
     * 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.
Params:
tokenType – the token type
Returns:
true if the token type represents a logical operation./**
     * 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.
Returns:
Type/**
     * 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.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.NUMBER;
        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;
            }
            return Type.NUMBER;
        }
        case VOID: {
            return Type.UNDEFINED;
        }
        case ASSIGN: {
            return rhs.getType();
        }
        case INSTANCEOF: {
            return Type.BOOLEAN;
        }
        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
Returns:
true if this node assigns a value/**
     * 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() && !isTokenType(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.
Params:
visitor – IR navigating visitor./**
     * 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 COMMARIGHT:
            return rhs.isAlwaysFalse();
        default:
            return false;
        }
    }

    @Override
    public boolean isAlwaysTrue() {
        switch (tokenType()) {
        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 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
Returns:
the left hand side expression/**
     * 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
Returns:
the left hand side expression/**
     * 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
Params:
lhs – new left hand side expression
Returns:
a node equivalent to this one except for the requested change./**
     * 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
Params:
rhs – new right hand side expression
Returns:
a node equivalent to this one except for the requested change./**
     * 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
Params:
lhs – new left hand side expression
rhs – new left hand side expression
Returns:
a node equivalent to this one except for the requested change./**
     * Set both the left and the right hand side expression for this node
     * @param lhs new left hand side expression
     * @param rhs new left hand side expression
     * @return a node equivalent to this one except for the requested change.
     */
    public BinaryNode setOperands(final Expression lhs, final Expression rhs) {
        if (this.lhs == lhs && this.rhs == rhs) {
            return this;
        }
        return new BinaryNode(this, lhs, rhs, type, programPoint);
    }

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

    @Override
    public boolean canBeOptimistic() {
        return isTokenType(TokenType.ADD) || (getMostOptimisticType() != getMostPessimisticType());
    }

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

    @Override
    public Type getMostOptimisticType() {
        final TokenType tokenType = tokenType();
        if(tokenType == TokenType.ADD || tokenType == TokenType.ASSIGN_ADD) {
            return OPTIMISTIC_UNDECIDED_TYPE;
        } else if (CAN_OVERFLOW.contains(tokenType)) {
            return Type.INT;
        }
        return getMostPessimisticType();
    }

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

    
Returns true if the node has the optimistic type of the node is not yet decided. Optimistic ADD nodes start out
as undecided until we can figure out if they're numeric or not.
Returns:
true if the node has the optimistic type of the node is not yet decided./**
     * Returns true if the node has the optimistic type of the node is not yet decided. Optimistic ADD nodes start out
     * as undecided until we can figure out if they're numeric or not.
     * @return true if the node has the optimistic type of the node is not yet decided.
     */
    public boolean isOptimisticUndecidedType() {
        return type == OPTIMISTIC_UNDECIDED_TYPE;
    }

    @Override
    public Type getType() {
        if (cachedType == null) {
            cachedType = getTypeUncached();
        }
        return cachedType;
    }

    private Type getTypeUncached() {
        if(type == OPTIMISTIC_UNDECIDED_TYPE) {
            return decideType(lhs.getType(), rhs.getType());
        }
        final Type widest = getWidestOperationType();
        if(type == null) {
            return widest;
        }
        if (tokenType() == TokenType.ASSIGN_SHR || tokenType() == TokenType.SHR) {
            return type;
        }
        return Type.narrowest(widest, Type.widest(type, Type.widest(lhs.getType(), rhs.getType())));
    }

    private static Type decideType(final Type lhsType, final Type rhsType) {
        // Compare this to getWidestOperationType() for ADD and ASSIGN_ADD cases. There's some similar logic, but these
        // are optimistic decisions, meaning that we don't have to treat boolean addition separately (as it'll become
        // int addition in the general case anyway), and that we also don't conservatively widen sums of ints to
        // longs, or sums of longs to doubles.
        if(isString(lhsType) || isString(rhsType)) {
            return Type.CHARSEQUENCE;
        }
        // NOTE: We don't have optimistic object-to-(int, long) conversions. Therefore, if any operand is an Object, we
        // bail out of optimism here and presume a conservative Object return value, as the object's ToPrimitive() can
        // end up returning either a number or a string, and their common supertype is Object, for better or worse.
        final Type widest = Type.widest(undefinedToNumber(booleanToInt(lhsType)), undefinedToNumber(booleanToInt(rhsType)));
        return widest.isObject() ? Type.OBJECT : widest;
    }

    
If the node is a node representing an add operation and has optimistic
undecided type, decides its type. Should be invoked after its operands types have been finalized. 
Returns:
returns a new node similar to this node, but with its type set to the type decided from the type of its
operands./**
     * If the node is a node representing an add operation and has {@link #isOptimisticUndecidedType() optimistic
     * undecided type}, decides its type. Should be invoked after its operands types have been finalized.
     * @return returns a new node similar to this node, but with its type set to the type decided from the type of its
     * operands.
     */
    public BinaryNode decideType() {
        assert type == OPTIMISTIC_UNDECIDED_TYPE;
        return setType(decideType(lhs.getType(), rhs.getType()));
    }

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