////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.expr;

import net.sf.saxon.expr.parser.Token;
import net.sf.saxon.om.StandardNames;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.AtomicType;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.Converter;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.*;
import net.sf.saxon.z.IntHashMap;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;

/**
 * This class evaluates arithmetic expressions; it acts as a helper class to the ArithmeticExpression
 * class. There are many subclasses for the different kinds of arithmetic expression, and static methods
 * that allow the right subclass to be selected, either at compile time or at run time.
 */

public abstract class Calculator {

    public static final int PLUS = 0;
    public static final int MINUS = 1;
    public static final int TIMES = 2;
    public static final int DIV = 3;
    public static final int MOD = 4;
    public static final int IDIV = 5;

    /**
     * Get the token number corresponding to the operator number
     * @param operator the Calculator operator code
     * @return the corresponding token
     */

    public static int getTokenFromOperator(int operator) {
        return tokens[operator];
    }

    private static final int[] tokens = new int[] {Token.PLUS, Token.MINUS, Token.MULT, Token.DIV, Token.MOD, Token.IDIV};

    /**
     * Get a short code to identify the calculator in expression export files
     * @return a short identifying code that can be used to reconstruct the calculator
     */

    public String code() {
        String name = getClass().getSimpleName();
        return name
            .replaceAll("Any", "a")
            .replaceAll("Double", "d")
            .replaceAll("Float", "f")
            .replaceAll("Decimal", "c")
            .replaceAll("Integer", "i")
            .replaceAll("Numeric", "n")
            .replaceAll("DateTime", "t")
            .replaceAll("Duration", "u")
            .replaceAll("Plus", "+")
            .replaceAll("Minus", "-")
            .replaceAll("Times", "*")
            .replaceAll("Div", "/")
            .replaceAll("Idiv", "~")
            .replaceAll("Mod", "%");
    }

    /**
     * Calculators used for the six operators when the static type information does not allow
     * a more specific calculator to be chosen
     */

    public final static Calculator[] ANY_ANY = {
            new AnyPlusAny(),
            new AnyMinusAny(),
            new AnyTimesAny(),
            new AnyDivAny(),
            new AnyModAny(),
            new AnyIdivAny()
    };

    // NOTE: these fields are public because they are referenced from the Java code generated by the XQuery compiler

    /**
     * Calculators used when the first operand is a double
     */

    public final static Calculator[] DOUBLE_DOUBLE = {
            new DoublePlusDouble(),
            new DoubleMinusDouble(),
            new DoubleTimesDouble(),
            new DoubleDivDouble(),
            new DoubleModDouble(),
            new DoubleIdivDouble()
    };

    public final static Calculator[] DOUBLE_FLOAT = DOUBLE_DOUBLE;
    public final static Calculator[] DOUBLE_DECIMAL = DOUBLE_DOUBLE;
    public final static Calculator[] DOUBLE_INTEGER = DOUBLE_DOUBLE;

    /**
     * Calculators used when the first operand is a float
     */

    public final static Calculator[] FLOAT_DOUBLE = DOUBLE_DOUBLE;
    public final static Calculator[] FLOAT_FLOAT = {
            new FloatPlusFloat(),
            new FloatMinusFloat(),
            new FloatTimesFloat(),
            new FloatDivFloat(),
            new FloatModFloat(),
            new FloatIdivFloat()
    };
    public final static Calculator[] FLOAT_DECIMAL = FLOAT_FLOAT;
    //public final static Calculator[] FLOAT_PDECIMAL = FLOAT_FLOAT;
    public final static Calculator[] FLOAT_INTEGER = FLOAT_FLOAT;

    /**
     * Calculators used when the first operand is a decimal
     */

    public final static Calculator[] DECIMAL_DOUBLE = DOUBLE_DOUBLE;
    public final static Calculator[] DECIMAL_FLOAT = FLOAT_FLOAT;
    public final static Calculator[] DECIMAL_DECIMAL = {
            new DecimalPlusDecimal(),
            new DecimalMinusDecimal(),
            new DecimalTimesDecimal(),
            new DecimalDivDecimal(),
            new DecimalModDecimal(),
            new DecimalIdivDecimal()
    };
    public final static Calculator[] DECIMAL_INTEGER = DECIMAL_DECIMAL;

    /**
     * Calculators used when the first operand is an integer
     */

    public final static Calculator[] INTEGER_DOUBLE = DOUBLE_DOUBLE;
    public final static Calculator[] INTEGER_FLOAT = FLOAT_FLOAT;
    public final static Calculator[] INTEGER_DECIMAL = DECIMAL_DECIMAL;
    public final static Calculator[] INTEGER_INTEGER = {
            new IntegerPlusInteger(),
            new IntegerMinusInteger(),
            new IntegerTimesInteger(),
            new IntegerDivInteger(),
            new IntegerModInteger(),
            new IntegerIdivInteger()
    };

    /**
     * Calculators used when both operands are xs:dateTime, xs:date, or xs:time
     */

    /*@Nullable*/ public final static Calculator[] DATETIME_DATETIME = {
            null,
            new DateTimeMinusDateTime(),
            null, null, null, null
    };

    /**
     * Calculators used when the first operand is xs:dateTime, xs:date, or xs:time,
     * and the second is a duration
     */

    public final static Calculator[] DATETIME_DURATION = {
            new DateTimePlusDuration(),
            new DateTimeMinusDuration(),
            null, null, null, null
    };

    /**
     * Calculators used when the second operand is xs:dateTime, xs:date, or xs:time,
     * and the first is a duration
     */

    public final static Calculator[] DURATION_DATETIME = {
            new DurationPlusDateTime(),
            null, null, null, null, null
    };

    /**
     * Calculators used when the both operands are durations
     */

    public final static Calculator[] DURATION_DURATION = {
            new DurationPlusDuration(),
            new DurationMinusDuration(),
            null,
            new DurationDivDuration(),
            null, null
    };

    /**
     * Calculators used when the first operand is a duration and the second is numeric
     */

    public final static Calculator[] DURATION_NUMERIC = {
            null, null,
            new DurationTimesNumeric(),
            new DurationDivNumeric(),
            null, null
    };

    /**
     * Calculators used when the second operand is a duration and the first is numeric
     */

    public final static Calculator[] NUMERIC_DURATION = {
            null, null,
            new NumericTimesDuration(),
            null, null, null
    };

    /**
     * Table mapping argument types to the Calculator class used to implement them
     */

    private static IntHashMap<Calculator[]> table = new IntHashMap<>(100);
    private static IntHashMap<String> nameTable = new IntHashMap<>(100);

    private static void def(int typeA, int typeB, Calculator[] calculatorSet, String setName) {
        int key = (typeA & 0xffff) << 16 | (typeB & 0xffff);
        table.put(key, calculatorSet);
        nameTable.put(key, setName);
        // As well as the entries added directly, we also add derived entries for other types
        // considered primitive
        if (typeA == StandardNames.XS_DURATION) {
            def(StandardNames.XS_DAY_TIME_DURATION, typeB, calculatorSet, setName);
            def(StandardNames.XS_YEAR_MONTH_DURATION, typeB, calculatorSet, setName);
        }
        if (typeB == StandardNames.XS_DURATION) {
            def(typeA, StandardNames.XS_DAY_TIME_DURATION, calculatorSet, setName);
            def(typeA, StandardNames.XS_YEAR_MONTH_DURATION, calculatorSet, setName);
        }
        if (typeA == StandardNames.XS_DATE_TIME) {
            def(StandardNames.XS_DATE, typeB, calculatorSet, setName);
            def(StandardNames.XS_TIME, typeB, calculatorSet, setName);
        }
        if (typeB == StandardNames.XS_DATE_TIME) {
            def(typeA, StandardNames.XS_DATE, calculatorSet, setName);
            def(typeA, StandardNames.XS_TIME, calculatorSet, setName);
        }
        if (typeA == StandardNames.XS_DOUBLE) {
            def(StandardNames.XS_UNTYPED_ATOMIC, typeB, calculatorSet, setName);
        }
        if (typeB == StandardNames.XS_DOUBLE) {
            def(typeA, StandardNames.XS_UNTYPED_ATOMIC, calculatorSet, setName);
        }
    }

    /**
     * Factory method to get a calculator for a given combination of types
     *
     * @param typeA       fingerprint of the primitive type of the first operand
     * @param typeB       fingerprint of the primitive type of the second operand
     * @param operator    the arithmetic operator in use
     * @param mustResolve indicates that a concrete Calculator is required (rather than
     *                    an ANY_ANY calculator which needs to be further resolved at run-time)
     * @return null if no suitable Calculator can be found.
     */

    public static Calculator getCalculator(int typeA, int typeB, int operator, boolean mustResolve) {
        int key = (typeA & 0xffff) << 16 | (typeB & 0xffff);
        Calculator[] set = table.get(key);
        if (set == null) {
            if (mustResolve) {
                return null;
            } else {
                return ANY_ANY[operator];
            }
        } else {
            return set[operator];
        }
    }

    /**
     * Get a calculator given the short code used in the exported expression tree
     * @param code the short code, e.g. i+i for IntegerPlusInteger
     * @return the appropriate Calculator
     */

    public static Calculator reconstructCalculator(String code) {
        int typeA = typeFromCode(code.charAt(0));
        int typeB = typeFromCode(code.charAt(2));
        int operator = operatorFromCode(code.charAt(1));
        return getCalculator(typeA, typeB, operator, false);
    }

    private static int typeFromCode(char code) {
        switch (code) {
            case 'a':
                return StandardNames.XS_ANY_ATOMIC_TYPE;
            case 'd':
                return StandardNames.XS_DOUBLE;
            case 'i':
                return StandardNames.XS_INTEGER;
            case 'f':
                return StandardNames.XS_FLOAT;
            case 'c':
                return StandardNames.XS_DECIMAL;
            case 'n':
                return StandardNames.XS_NUMERIC;
            case 't':
                return StandardNames.XS_DATE_TIME;
            case 'u':
                return StandardNames.XS_DURATION;
            default:
                throw new AssertionError();
        }
    }

    public static int operatorFromCode(char code) {
        switch (code) {
            case '+':
                return PLUS;
            case '-':
                return MINUS;
            case '*':
                return TIMES;
            case '/':
                return DIV;
            case '~':
                return IDIV;
            case '%':
                return MOD;
            default:
                throw new AssertionError();
        }
    }

    /**
     * Get the name of the calculator set for a given combination of types
     *
     * @param typeA the fingerprint of the primitive type of the first operand
     * @param typeB the fingerprint of the primitive type of the second operand
     * @return null if no suitable Calculator can be found.
     */

    public static String getCalculatorSetName(int typeA, int typeB) {
        int key = (typeA & 0xffff) << 16 | (typeB & 0xffff);
        return nameTable.get(key);
    }

    static {
        def(StandardNames.XS_DOUBLE, StandardNames.XS_DOUBLE, DOUBLE_DOUBLE, "DOUBLE_DOUBLE");
        def(StandardNames.XS_DOUBLE, StandardNames.XS_FLOAT, DOUBLE_FLOAT, "DOUBLE_FLOAT");
        def(StandardNames.XS_DOUBLE, StandardNames.XS_DECIMAL, DOUBLE_DECIMAL, "DOUBLE_DECIMAL");
        def(StandardNames.XS_DOUBLE, StandardNames.XS_INTEGER, DOUBLE_INTEGER, "DOUBLE_INTEGER");
        def(StandardNames.XS_FLOAT, StandardNames.XS_DOUBLE, FLOAT_DOUBLE, "FLOAT_DOUBLE");
        def(StandardNames.XS_FLOAT, StandardNames.XS_FLOAT, FLOAT_FLOAT, "FLOAT_FLOAT");
        def(StandardNames.XS_FLOAT, StandardNames.XS_DECIMAL, FLOAT_DECIMAL, "FLOAT_DECIMAL");
        def(StandardNames.XS_FLOAT, StandardNames.XS_INTEGER, FLOAT_INTEGER, "FLOAT_INTEGER");
        def(StandardNames.XS_DECIMAL, StandardNames.XS_DOUBLE, DECIMAL_DOUBLE, "DECIMAL_DOUBLE");
        def(StandardNames.XS_DECIMAL, StandardNames.XS_FLOAT, DECIMAL_FLOAT, "DECIMAL_FLOAT");
        def(StandardNames.XS_DECIMAL, StandardNames.XS_DECIMAL, DECIMAL_DECIMAL, "DECIMAL_DECIMAL");
        def(StandardNames.XS_DECIMAL, StandardNames.XS_INTEGER, DECIMAL_INTEGER, "DECIMAL_INTEGER");
        def(StandardNames.XS_INTEGER, StandardNames.XS_DOUBLE, INTEGER_DOUBLE, "INTEGER_DOUBLE");
        def(StandardNames.XS_INTEGER, StandardNames.XS_FLOAT, INTEGER_FLOAT, "INTEGER_FLOAT");
        def(StandardNames.XS_INTEGER, StandardNames.XS_DECIMAL, INTEGER_DECIMAL, "INTEGER_DECIMAL");
        def(StandardNames.XS_INTEGER, StandardNames.XS_INTEGER, INTEGER_INTEGER, "INTEGER_INTEGER");
        def(StandardNames.XS_DATE_TIME, StandardNames.XS_DATE_TIME, DATETIME_DATETIME, "DATETIME_DATETIME");
        def(StandardNames.XS_DATE_TIME, StandardNames.XS_DURATION, DATETIME_DURATION, "DATETIME_DURATION");
        def(StandardNames.XS_DURATION, StandardNames.XS_DATE_TIME, DURATION_DATETIME, "DURATION_DATETIME");
        def(StandardNames.XS_DURATION, StandardNames.XS_DURATION, DURATION_DURATION, "DURATION_DURATION");
        def(StandardNames.XS_DURATION, StandardNames.XS_DOUBLE, DURATION_NUMERIC, "DURATION_NUMERIC");
        def(StandardNames.XS_DURATION, StandardNames.XS_FLOAT, DURATION_NUMERIC, "DURATION_NUMERIC");
        def(StandardNames.XS_DURATION, StandardNames.XS_DECIMAL, DURATION_NUMERIC, "DURATION_NUMERIC");
        def(StandardNames.XS_DURATION, StandardNames.XS_INTEGER, DURATION_NUMERIC, "DURATION_NUMERIC");
        def(StandardNames.XS_DOUBLE, StandardNames.XS_DURATION, NUMERIC_DURATION, "NUMERIC_DURATION");
        def(StandardNames.XS_FLOAT, StandardNames.XS_DURATION, NUMERIC_DURATION, "NUMERIC_DURATION");
        def(StandardNames.XS_DECIMAL, StandardNames.XS_DURATION, NUMERIC_DURATION, "NUMERIC_DURATION");
        def(StandardNames.XS_INTEGER, StandardNames.XS_DURATION, NUMERIC_DURATION, "NUMERIC_DURATION");
    }

    /**
     * Perform an arithmetic operation
     *
     * @param a the first operand. Must not be null, and must be an instance of the type implied by the
     *          class name.
     * @param b the second operand. Must not be null, and must be an instance of the type implied by the
     *          class name.
     * @param c the XPath dynamic evaluation context
     * @return the result of the computation, as a value of the correct primitive type
     * @throws XPathException in the event of an arithmetic error
     */

    public abstract AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException;

    /**
     * Get the type of the result of the calculator, given arguments types typeA and typeB
     *
     * @param typeA the type of the first operand
     * @param typeB the type of the second operand
     * @return the type of the result
     */

    public abstract AtomicType getResultType(AtomicType typeA, AtomicType typeB);

    /**
     * Arithmetic: anyAtomicType + AnyAtomicType
     */

    public static class AnyPlusAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), PLUS, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for + operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: anyAtomicType - AnyAtomicType
     */

    public static class AnyMinusAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), MINUS, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for - operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: anyAtomicType * AnyAtomicType
     */

    public static class AnyTimesAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), TIMES, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for * operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: anyAtomicType div AnyAtomicType
     */

    public static class AnyDivAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), DIV, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for div operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: anyAtomicType mod AnyAtomicType
     */

    public static class AnyModAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), MOD, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for mod operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: anyAtomicType idiv AnyAtomicType
     */

    public static class AnyIdivAny extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            Calculator calc = getCalculator(
                    a.getItemType().getPrimitiveType(), b.getItemType().getPrimitiveType(), IDIV, true);
            if (calc == null) {
                throw new XPathException("Unsuitable types for idiv operation (" +
                        Type.displayTypeName(a) + ", " + Type.displayTypeName(b) + ")", "XPTY0004", c);
            } else {
                return calc.compute(a, b, c);
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.ANY_ATOMIC;
        }
    }

    /**
     * Arithmetic: double + double (including types that promote to double)
     */

    public static class DoublePlusDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new DoubleValue(((NumericValue) a).getDoubleValue() + ((NumericValue) b).getDoubleValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DOUBLE;
        }
    }

    /**
     * Arithmetic: double - double (including types that promote to double)
     */

    public static class DoubleMinusDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new DoubleValue(((NumericValue) a).getDoubleValue() - ((NumericValue) b).getDoubleValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DOUBLE;
        }
    }

    /**
     * Arithmetic: double * double (including types that promote to double)
     */

    public static class DoubleTimesDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new DoubleValue(((NumericValue) a).getDoubleValue() * ((NumericValue) b).getDoubleValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DOUBLE;
        }
    }

    /**
     * Arithmetic: double div double (including types that promote to double)
     */

    public static class DoubleDivDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new DoubleValue(((NumericValue) a).getDoubleValue() / ((NumericValue) b).getDoubleValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DOUBLE;
        }
    }

    /**
     * Arithmetic: double mod double (including types that promote to double)
     */

    public static class DoubleModDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new DoubleValue(((NumericValue) a).getDoubleValue() % ((NumericValue) b).getDoubleValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DOUBLE;
        }
    }

    /**
     * Arithmetic: double idiv double (including types that promote to double)
     */

    private static class DoubleIdivDouble extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            double A = ((NumericValue) a).getDoubleValue();
            double B = ((NumericValue) b).getDoubleValue();
            if (B == 0.0) {
                throw new XPathException("Integer division by zero", "FOAR0001", c);
            }
            if (Double.isNaN(A) || Double.isInfinite(A)) {
                throw new XPathException("First operand of idiv is NaN or infinity", "FOAR0002", c);
            }
            if (Double.isNaN(B)) {
                throw new XPathException("Second operand of idiv is NaN", "FOAR0002", c);
            }
            return IntegerValue.makeIntegerValue(new DoubleValue(A / B)).asAtomic();
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: float + float (including types that promote to float)
     */

    public static class FloatPlusFloat extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new FloatValue(((NumericValue) a).getFloatValue() + ((NumericValue) b).getFloatValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.FLOAT;
        }
    }

    /**
     * Arithmetic: float - float (including types that promote to float)
     */

    public static class FloatMinusFloat extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new FloatValue(((NumericValue) a).getFloatValue() - ((NumericValue) b).getFloatValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.FLOAT;
        }
    }

    /**
     * Arithmetic: float * float (including types that promote to float)
     */

    public static class FloatTimesFloat extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new FloatValue(((NumericValue) a).getFloatValue() * ((NumericValue) b).getFloatValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.FLOAT;
        }
    }

    /**
     * Arithmetic: float div float (including types that promote to float)
     */

    public static class FloatDivFloat extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new FloatValue(((NumericValue) a).getFloatValue() / ((NumericValue) b).getFloatValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.FLOAT;
        }
    }

    /**
     * Arithmetic: float mod float (including types that promote to float)
     */

    public static class FloatModFloat extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return new FloatValue(((NumericValue) a).getFloatValue() % ((NumericValue) b).getFloatValue());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.FLOAT;
        }
    }

    /**
     * Arithmetic: float idiv float (including types that promote to float)
     */

    public static class FloatIdivFloat extends Calculator {
        public IntegerValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            float A = ((NumericValue) a).getFloatValue();
            float B = ((NumericValue) b).getFloatValue();
            if (B == 0.0) {
                throw new XPathException("Integer division by zero", "FOAR0001", c);
            }
            if (Float.isNaN(A) || Float.isInfinite(A)) {
                throw new XPathException("First operand of idiv is NaN or infinity", "FOAR0002", c);
            }
            if (Float.isNaN(B)) {
                throw new XPathException("Second operand of idiv is NaN", "FOAR0002", c);
            }
            float quotient = A / B;
            if (Float.isInfinite(quotient)) {
                // bug 29171, test cbcl-numeric-idivide-008
                return new DecimalIdivDecimal().compute(
                    new BigDecimalValue(((NumericValue) a).getDecimalValue()),
                    new BigDecimalValue(((NumericValue) b).getDecimalValue()),
                    c);
            } else {
                return (IntegerValue)Converter.FloatToInteger.INSTANCE.convert(new FloatValue(quotient)).asAtomic();
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: decimal + decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalPlusDecimal extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof IntegerValue && b instanceof IntegerValue) {
                return ((IntegerValue) a).plus((IntegerValue) b);
            } else {
                return new BigDecimalValue(
                        ((NumericValue) a).getDecimalValue().add(((NumericValue) b).getDecimalValue()));
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: decimal - decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalMinusDecimal extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof IntegerValue && b instanceof IntegerValue) {
                return ((IntegerValue) a).minus((IntegerValue) b);
            } else {
                return new BigDecimalValue(
                        ((NumericValue) a).getDecimalValue().subtract(((NumericValue) b).getDecimalValue()));
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: decimal * decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalTimesDecimal extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof IntegerValue && b instanceof IntegerValue) {
                return ((IntegerValue) a).times((IntegerValue) b);
            } else {
                return new BigDecimalValue(
                        ((NumericValue) a).getDecimalValue().multiply(((NumericValue) b).getDecimalValue()));
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: decimal div decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalDivDecimal extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return decimalDivide((NumericValue) a, (NumericValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    public static BigDecimalValue decimalDivide(NumericValue a, NumericValue b) throws XPathException {
        final BigDecimal A = a.getDecimalValue();
        final BigDecimal B = b.getDecimalValue();
//        int scale = Math.max(DecimalValue.DIVIDE_PRECISION,
//                Math.max(A.scale(), B.scale()));
        int scale = Math.max(BigDecimalValue.DIVIDE_PRECISION, A.scale() - B.scale() + BigDecimalValue.DIVIDE_PRECISION);

        try {
            BigDecimal result = A.divide(B, scale, RoundingMode.HALF_DOWN);
            return new BigDecimalValue(result);
        } catch (ArithmeticException err) {
            if (b.compareTo(0) == 0) {
                throw new XPathException("Decimal divide by zero", "FOAR0001");
            } else {
                throw err;
            }
        }
    }

    /**
     * Arithmetic: decimal mod decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalModDecimal extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof IntegerValue && b instanceof IntegerValue) {
                return ((IntegerValue) a).mod((IntegerValue) b);
            }

            final BigDecimal A = ((NumericValue) a).getDecimalValue();
            final BigDecimal B = ((NumericValue) b).getDecimalValue();
            try {
                //BigDecimal quotient = A.divide(B, 0, BigDecimal.ROUND_DOWN);
                //BigDecimal remainder = A.subtract(quotient.multiply(B));
                return new BigDecimalValue(A.remainder(B));
            } catch (ArithmeticException err) {
                if (((NumericValue) b).compareTo(0) == 0) {
                    throw new XPathException("Decimal modulo zero", "FOAR0001", c);
                } else {
                    throw err;
                }
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: decimal idiv decimal (including types that promote to decimal, that is, integer)
     */

    public static class DecimalIdivDecimal extends Calculator {
        public IntegerValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof IntegerValue && b instanceof IntegerValue) {
                return ((IntegerValue) a).idiv((IntegerValue) b);
            }

            final BigDecimal A = ((NumericValue) a).getDecimalValue();
            final BigDecimal B = ((NumericValue) b).getDecimalValue();
            if (B.signum() == 0) {
                throw new XPathException("Integer division by zero", "FOAR0001", c);
            }
            //BigInteger quot = A.divide(B, 0, BigDecimal.ROUND_DOWN).toBigInteger();
            BigInteger quot = A.divideToIntegralValue(B).toBigInteger();
            return BigIntegerValue.makeIntegerValue(quot);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: integer + integer
     */

    public static class IntegerPlusInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).plus((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: integer - integer
     */

    public static class IntegerMinusInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).minus((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: integer * integer
     */

    public static class IntegerTimesInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).times((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: integer div integer
     */

    public static class IntegerDivInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).div((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: integer mod integer
     */

    public static class IntegerModInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).mod((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: integer idiv integer
     */

    public static class IntegerIdivInteger extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((IntegerValue) a).idiv((IntegerValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.INTEGER;
        }
    }

    /**
     * Arithmetic: date/time/dateTime - date/time/dateTime
     */

    private static class DateTimeMinusDateTime extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((CalendarValue) a).subtract((CalendarValue) b, c);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DAY_TIME_DURATION;
        }
    }

    /**
     * Arithmetic: date/time/dateTime + duration
     */

    private static class DateTimePlusDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((CalendarValue) a).add((DurationValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

    /**
     * Arithmetic: date/time/dateTime - duration
     */

    private static class DateTimeMinusDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((CalendarValue) a).add(((DurationValue) b).negate());
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

    /**
     * Arithmetic: duration + date/time/dateTime
     */

    private static class DurationPlusDateTime extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((CalendarValue) b).add((DurationValue) a);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeB;
        }
    }

    /**
     * Arithmetic: duration + duration
     */

    private static class DurationPlusDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((DurationValue) a).add((DurationValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

    /**
     * Arithmetic: duration - duration
     */

    private static class DurationMinusDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((DurationValue) a).subtract((DurationValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

    /**
     * Arithmetic: duration div duration
     */

    private static class DurationDivDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            return ((DurationValue) a).divide((DurationValue) b);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return BuiltInAtomicType.DECIMAL;
        }
    }

    /**
     * Arithmetic: duration * number
     */

    private static class DurationTimesNumeric extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (b instanceof Int64Value) {
                return ((DurationValue) a).multiply(((Int64Value) b).longValue());
            } else {
                return ((DurationValue) a).multiply(((NumericValue) b).getDoubleValue());
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

    /**
     * Arithmetic: number * duration
     */

    private static class NumericTimesDuration extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            if (a instanceof Int64Value) {
                return ((DurationValue) b).multiply(((Int64Value) a).longValue());
            } else {
                return ((DurationValue) b).multiply(((NumericValue) a).getDoubleValue());
            }
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeB;
        }
    }

    /**
     * Arithmetic: duration div number
     */

    private static class DurationDivNumeric extends Calculator {
        public AtomicValue compute(AtomicValue a, AtomicValue b, XPathContext c) throws XPathException {
            double d = 1.0 / ((NumericValue) b).getDoubleValue();
            return ((DurationValue) a).multiply(d);
        }

        public AtomicType getResultType(AtomicType typeA, AtomicType typeB) {
            return typeA;
        }
    }

}

