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package oracle.toplink.essentials.internal.parsing;

/**
 * INTERNAL
 * <p><b>Purpose</b>: Represent a MOD
 * <p><b>Responsibilities</b>:<ul>
 * <li> Answer the correct expression for a MOD
 * <li> Maintain the parts of a MOD statement
 *
 * e.g.
 * SELECT ... FROM ... WHERE MOD(emp.salary, 2) > 1000
 * </ul>
 *    @author Jon Driscoll and Joel Lucuik
 *    @since TopLink 4.0
 */
import oracle.toplink.essentials.expressions.*;
import oracle.toplink.essentials.exceptions.EJBQLException;

public class ModNode extends ArithmeticFunctionNode {

    private Node denominator = null;

    /** 
     * INTERNAL 
     * Check the child nodes for an unqualified field access and if so,
     * replace it by a qualified field access.
     */
    public Node qualifyAttributeAccess(ParseTreeContext context) {
       if (left != null) {
           left = left.qualifyAttributeAccess(context);
       }
       if (denominator != null) {
           denominator = denominator.qualifyAttributeAccess(context);
       }
       return this;
    }

    /**
     * INTERNAL
     * Validate node and calculate its type.
     */
    public void validate(ParseTreeContext context) {
        TypeHelper typeHelper = context.getTypeHelper();
        if (left != null) {
            left.validate(context);
            left.validateParameter(context, typeHelper.getIntType());

            Object type = left.getType();
            if (!typeHelper.isIntegralType(type))
                throw EJBQLException.invalidFunctionArgument(
                    context.getQueryInfo(), left.getLine(), left.getColumn(), 
                    "MOD", left.getAsString(), "integral type");
        }

        if (denominator != null) {
            denominator.validate(context);
            denominator.validateParameter(context, typeHelper.getIntType());

            Object denominatorType = denominator.getType();
            if (!typeHelper.isIntegralType(denominatorType))
                throw EJBQLException.invalidFunctionArgument(
                    context.getQueryInfo(), denominator.getLine(), denominator.getColumn(), 
                    "MOD", denominator.getAsString(), "integral type");
        }

        setType(typeHelper.getIntType());
    }
    
    /** */
    public Expression generateExpression(GenerationContext context) {
        return ExpressionMath.mod(getLeft().generateExpression(context), 
                                  getDenominator().generateExpression(context));
    }

    // Accessors
    public Node getDenominator() {
        return denominator;
    }

    public void setDenominator(Node denominator) {
        this.denominator = denominator;
    }
}