uk.ac.ed.epcc.webapp.jdbc.expr

Class ConstExpression<T,R>

java.lang.Object

uk.ac.ed.epcc.webapp.jdbc.expr.ConstExpression<T,R>

Type Parameters:

T - type of constant

R - type of target object

All Implemented Interfaces:

Accessor<T,R>, FilterProvider<R,T>, GroupingSQLValue<T>, SQLAccessor<T,R>, SQLExpression<T>, SQLValue<T>, Targetted<T>

public final class ConstExpression<T,R>
extends java.lang.Object
implements SQLExpression<T>, SQLAccessor<T,R>, GroupingSQLValue<T>, FilterProvider<R,T>

A constant value SQLAccessor

Constructor Summary

Constructors

Constructor and Description
ConstExpression(java.lang.Class<R> filter_type, java.lang.Class<T> target, T n)
ConstExpression(java.lang.Class<R> filter_type, java.lang.Class<T> target, T n, boolean log)
ConstExpression(java.lang.Class<T> target, T n)

Method Summary

Modifier and Type	Method and Description
int	add(java.lang.StringBuilder sb, boolean qualify) Add the expression to a StringBuilder
int	addGroup(java.lang.StringBuilder sb, boolean qualify) Add the group-by clause to a query.
boolean	canSet() does this Accessor support setting values.
boolean	equals(java.lang.Object obj)
SQLFilter<R>	getFilter(MatchCondition match, T val) Create a SQLFilter comparing against the target value
java.lang.Class<R>	getFilterType() get the type bounds on the produced SQLFilter.
java.util.List<PatternArgument>	getGroupParameters(java.util.List<PatternArgument> list) Get the parameters for a group-by clause.
SQLFilter<R>	getNullFilter(boolean is_null) create a SQLFilter checking if the target value is or is not null.
SQLFilter<R>	getOrderFilter(boolean descending) create a SQLFilter that orders results by the target value.
java.util.List<PatternArgument>	getParameters(java.util.List<PatternArgument> list) Add parameters for this value to a list.
SQLFilter	getRequiredFilter() Get an SQLFilter required to be added to the filter set.
java.lang.Class<T>	getTarget() Get the type of the returned object as far as it is known.
T	getValue()
T	getValue(R r) get the value from the target object
int	hashCode()
T	makeObject(java.sql.ResultSet rs, int pos) Extract a result of the expression from a ResultSet into an object of the specified type.
void	setValue(R r, T value) Set value if supported otherwise throw a UnsupportedOperationException.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface uk.ac.ed.epcc.webapp.jdbc.expr.SQLExpression

groupingIsomorphic

Methods inherited from interface uk.ac.ed.epcc.webapp.jdbc.expr.GroupingSQLValue

checkContentsCanGroup

Constructor Detail

ConstExpression

public ConstExpression(java.lang.Class<T> target,
                       T n)

ConstExpression

public ConstExpression(java.lang.Class<R> filter_type,
                       java.lang.Class<T> target,
                       T n)

ConstExpression

public ConstExpression(java.lang.Class<R> filter_type,
                       java.lang.Class<T> target,
                       T n,
                       boolean log)

Method Detail

add

public int add(java.lang.StringBuilder sb,
               boolean qualify)

Description copied from interface: SQLValue

Add the expression to a StringBuilder

Specified by:

add in interface SQLValue<T>

Parameters:

sb - StringBuilder to modify

qualify - boolean should fields be qualified with the table name

Returns:

number of fields added

getParameters

public java.util.List<PatternArgument> getParameters(java.util.List<PatternArgument> list)

Description copied from interface: SQLValue

Add parameters for this value to a list.

Specified by:

getParameters in interface SQLValue<T>

Parameters:

list - to modify

Returns:

modified list of parameter objects

makeObject

public T makeObject(java.sql.ResultSet rs,
                    int pos)
             throws DataException,
                    java.sql.SQLException

Description copied from interface: SQLValue

Extract a result of the expression from a ResultSet into an object of the specified type. Note that this method is also used to extract the result of functions over the result type.

Specified by:

makeObject in interface SQLValue<T>

Parameters:

rs - ResultSet

Returns:

produced object

Throws:

DataException

java.sql.SQLException

getTarget

public java.lang.Class<T> getTarget()

Description copied from interface: Targetted

Get the type of the returned object as far as it is known. Normally this should be the erasure type corresponding to T.

Specified by:

getTarget in interface Targetted<T>

Returns:

Class object for return type

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getRequiredFilter

public SQLFilter getRequiredFilter()

Description copied from interface: SQLValue

Get an SQLFilter required to be added to the filter set. This is usually to implement a join.

Specified by:

getRequiredFilter in interface SQLValue<T>

Returns:

null or SQLFilter

getValue

public T getValue(R r)

Description copied from interface: Accessor

get the value from the target object

Specified by:

getValue in interface Accessor<T,R>

Parameters:

r - target object

Returns:

value

getValue

public T getValue()

canSet

public boolean canSet()

Description copied from interface: Accessor

does this Accessor support setting values.

Specified by:

canSet in interface Accessor<T,R>

Returns:

setValue

public void setValue(R r,
                     T value)

Description copied from interface: Accessor

Set value if supported otherwise throw a UnsupportedOperationException.

Specified by:

setValue in interface Accessor<T,R>

hashCode

public int hashCode()

Specified by:

hashCode in interface SQLExpression<T>

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface SQLExpression<T>

Overrides:

equals in class java.lang.Object

addGroup

public int addGroup(java.lang.StringBuilder sb,
                    boolean qualify)

Description copied from interface: GroupingSQLValue

Add the group-by clause to a query. Note this can be a null operation in which case it will return zero.

Specified by:

addGroup in interface GroupingSQLValue<T>

Returns:

actual number of fields added

getGroupParameters

public java.util.List<PatternArgument> getGroupParameters(java.util.List<PatternArgument> list)

Description copied from interface: GroupingSQLValue

Get the parameters for a group-by clause.

Specified by:

getGroupParameters in interface GroupingSQLValue<T>

Returns:

modified list

getFilter

public SQLFilter<R> getFilter(MatchCondition match,
                              T val)
                       throws CannotFilterException,
                              NoSQLFilterException

Description copied from interface: FilterProvider

Create a SQLFilter comparing against the target value

Specified by:

getFilter in interface FilterProvider<R,T>

Returns:

SQLFilter

Throws:

CannotFilterException

NoSQLFilterException

getNullFilter

public SQLFilter<R> getNullFilter(boolean is_null)
                           throws CannotFilterException,
                                  NoSQLFilterException

Description copied from interface: FilterProvider

create a SQLFilter checking if the target value is or is not null.

Specified by:

getNullFilter in interface FilterProvider<R,T>

Returns:

SQLFilter

Throws:

CannotFilterException

NoSQLFilterException

getOrderFilter

public SQLFilter<R> getOrderFilter(boolean descending)
                            throws CannotFilterException,
                                   NoSQLFilterException

Description copied from interface: FilterProvider

create a SQLFilter that orders results by the target value. This may involve joins so may not be just an OrderFilter though it will contain one.

Specified by:

getOrderFilter in interface FilterProvider<R,T>

Returns:

SQLFilter

Throws:

CannotFilterException

NoSQLFilterException

getFilterType

public java.lang.Class<R> getFilterType()

Description copied from interface: FilterProvider

get the type bounds on the produced SQLFilter.

Specified by:

getFilterType in interface FilterProvider<R,T>

Returns:

Class