Package com.singularsys.extensions.field.implementations

Class GenericField<E>

java.lang.Object

com.singularsys.extensions.field.AbstractComparativeField

com.singularsys.extensions.field.implementations.GenericField<E>

Type Parameters:

E - Basic type field uses, e.g. Double or Complex.

All Implemented Interfaces:

FieldI, IntegerConvertor, Serializable

Direct Known Subclasses:

BigDecimalField, BigIntegerField, BigModulusField, ExtDocsTest.StringField3, FixedPointField, GenericPowerField, IntegerField, ModulusField

public abstract class GenericField<E>
extends AbstractComparativeField
implements IntegerConvertor

Abstract-generic base class where the type-variable specifies the arguments and return type. Subclasses must implement E cast(Object l) which converts arguments to the type-E, and also methods E addG(E l, E r) etc. The class provides implementations of Object add(Object l,Object r) which calls cast(Object l) on both arguments and then calls addG, if either argument converts to null then null is returned. It has null implementations for the logical operators.

An examples for a Field using Strings:

public class StringField3 extends GenericField<String> {
    private static final long serialVersionUID = 330L;

        @Override
        public String cast(Object l) throws EvaluationException {
                if(l instanceof String) 
                        return ((String) l);
                return null;
        }

        // No need for casting in individual operations
        @Override
        public String addG(String l, String r) throws EvaluationException {
                return l + r;
        }

        // A single method for all comparison operations
        @Override
        public Integer cmpG(String l, String r) throws EvaluationException {
                return l.compareTo(r);
        }

    // other methods just return null
        @Override
        public String subG(String l, String r) { return null; }
        @Override
        public String negG(String l) { return null; }
        @Override
        public String mulG(String l, String r) { return null; }
        @Override
        public String divG(String l, String r) { return null; }
        @Override
        public String modG(String l, String r) { return null; }
        @Override
        public String powG(String l, String r) { return null; }

        // no need to implement comparison operations le(l,r) etc.
        // or logical operations and(l,r), or(l,r), not(l) 
}

Author:

Richard Morris

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
GenericField()

Method Summary

Modifier and Type	Method	Description
Object	add(Object l, Object r)	First calls cast(Object) on both arguments then call the addG(E, E).
abstract E	addG(E l, E r)	Adds two elements of type E.
Boolean	and(Object l, Object r)	Default implementation returns null.
abstract E	cast(Object l)	Convert the input to type E.
Integer	cmp(Object l, Object r)	Compare two elements, return -1,0,1 if the comparison can be carried out, null otherwise.
abstract Integer	cmpG(E l, E r)	Compare two objects of the same type.
abstract E	convertFromInt(Integer l)	Attempt to convert argument from an integer
Integer	convertToInt(Object l)	Attempt to convert argument to an integer
abstract Integer	convertToIntE(E l)	If possible convert the argument to an Integer to enable integral powers.
Object	div(Object l, Object r)	Divides two members of the field.
abstract E	divG(E l, E r)	Divides two elements of type E.
abstract E	getOne()	Get the multiplicative identity for this field.
abstract E	getZero()	Get the additive identity for this field
Object	mod(Object l, Object r)	The modulus of two members of the field.
abstract E	modG(E l, E r)	Modulus of two elements of type E.
Object	mul(Object l, Object r)	Multiplies two members of the field.
abstract E	mulG(E l, E r)	Multiplies two elements of type E.
Object	neg(Object l)	The negation -x of an element.
abstract E	negG(E l)	Negates an elements of type E.
Boolean	not(Object l)	Default implementation returns null.
Boolean	or(Object l, Object r)	Default implementation returns null.
Object	pow(Object l, Object r)	The power operator.
abstract E	powG(E l, E r)	Raises l to the power of r
Object	sub(Object l, Object r)	Subtract two members of the field.
abstract E	subG(E l, E r)	Subtracts two elements of type E.

Methods inherited from class com.singularsys.extensions.field.AbstractComparativeField

eq, ge, gt, le, lt, ne

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

GenericField

public GenericField()

Method Details

getOne

public abstract E getOne()

Description copied from interface: FieldI

Get the multiplicative identity for this field.

Specified by:

getOne in interface FieldI

Returns:

object representing one or null if undefined for this field

getZero

public abstract E getZero()

Description copied from interface: FieldI

Get the additive identity for this field

Specified by:

getZero in interface FieldI

Returns:

object representing zero or null if undefined for this field

cast

public abstract E cast(Object l)
                throws EvaluationException

Convert the input to type E.

Parameters:

l -

Returns:

l cast to type E if possible or null if casting is not possible

Throws:

EvaluationException

addG

public abstract E addG(E l,
 E r)
                throws EvaluationException

Adds two elements of type E.

Parameters:

l - lhs argument

r - rhs argument

Returns:

the sum

Throws:

EvaluationException - on error

subG

public abstract E subG(E l,
 E r)
                throws EvaluationException

Subtracts two elements of type E.

Parameters:

l - lhs argument

r - rhs argument

Returns:

the difference

Throws:

EvaluationException - on error

negG

public abstract E negG(E l)
                throws EvaluationException

Negates an elements of type E.

Parameters:

l - the argument

Returns:

the negation

Throws:

EvaluationException - on error

mulG

public abstract E mulG(E l,
 E r)
                throws EvaluationException

Multiplies two elements of type E.

Parameters:

l - lhs argument

r - rhs argument

Returns:

the product

Throws:

EvaluationException - on error

divG

public abstract E divG(E l,
 E r)
                throws EvaluationException

Divides two elements of type E.

Parameters:

l - numerator

r - denominator

Returns:

the division

Throws:

EvaluationException - on error

modG

public abstract E modG(E l,
 E r)
                throws EvaluationException

Modulus of two elements of type E.

Parameters:

l - lhs argument

r - rhs argument

Returns:

the modulus

Throws:

EvaluationException - on error

powG

public abstract E powG(E l,
 E r)
                throws EvaluationException

Raises l to the power of r

Parameters:

l - lhs argument

r - rhs argument

Returns:

the power

Throws:

EvaluationException - on error

cmpG

public abstract Integer cmpG(E l,
 E r)
                      throws EvaluationException

Compare two objects of the same type.

Parameters:

l - left argument

r - right argument

Returns:

-1, 0, 1 or null

Throws:

EvaluationException

add

public Object add(Object l,
 Object r)
           throws EvaluationException

First calls cast(Object) on both arguments then call the addG(E, E). If the result of either cast are null returns null.

Specified by:

add in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

sub

public Object sub(Object l,
 Object r)
           throws EvaluationException

Description copied from interface: FieldI

Subtract two members of the field.

Specified by:

sub in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

neg

public Object neg(Object l)
           throws EvaluationException

Description copied from interface: FieldI

The negation -x of an element.

Specified by:

neg in interface FieldI

Parameters:

l - the argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

mul

public Object mul(Object l,
 Object r)
           throws EvaluationException

Description copied from interface: FieldI

Multiplies two members of the field.

Specified by:

mul in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

div

public Object div(Object l,
 Object r)
           throws EvaluationException

Description copied from interface: FieldI

Divides two members of the field.

Specified by:

div in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

mod

public Object mod(Object l,
 Object r)
           throws EvaluationException

Description copied from interface: FieldI

The modulus of two members of the field.

Specified by:

mod in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

pow

public Object pow(Object l,
 Object r)
           throws EvaluationException

Description copied from interface: FieldI

The power operator.

Specified by:

pow in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

Throws:

EvaluationException - on error

cmp

public Integer cmp(Object l,
 Object r)
            throws EvaluationException

Description copied from class: AbstractComparativeField

Compare two elements, return -1,0,1 if the comparison can be carried out, null otherwise.

Specified by:

cmp in class AbstractComparativeField

Parameters:

l -

r -

Returns:

-1, 0, 1 if l < r, l==r or l > r respectively, or null if comparison cannot be carried out or

Throws:

EvaluationException

and

public Boolean and(Object l,
 Object r)

Default implementation returns null.

Specified by:

and in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

or

public Boolean or(Object l,
 Object r)

Default implementation returns null.

Specified by:

or in interface FieldI

Parameters:

l - left-hand argument

r - right-hand argument

Returns:

an object representing the result or null if it can not be evaluated.

not

public Boolean not(Object l)

Default implementation returns null.

Specified by:

not in interface FieldI

Parameters:

l - argument

Returns:

an object representing the result or null if it can not be evaluated.

convertToIntE

public abstract Integer convertToIntE(E l)
                               throws EvaluationException

If possible convert the argument to an Integer to enable integral powers. If the argument cannot be converted null should be returned and the powG(E,E) method will be called.

Parameters:

l - argument to convert.

Returns:

an integer or null if argument cannot be converted

Throws:

EvaluationException

convertToInt

public Integer convertToInt(Object l)
                     throws EvaluationException

Description copied from interface: IntegerConvertor

Attempt to convert argument to an integer

Specified by:

convertToInt in interface IntegerConvertor

Parameters:

l - value to convert

Returns:

corresponding integer or null if it cannot be converted

Throws:

EvaluationException - on error

convertFromInt

public abstract E convertFromInt(Integer l)
                          throws EvaluationException

Description copied from interface: IntegerConvertor

Attempt to convert argument from an integer

Specified by:

convertFromInt in interface IntegerConvertor

Parameters:

l - value to convert

Returns:

corresponding value in this field or null if it cannot be converted

Throws:

EvaluationException - probably never