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

Class BinaryExpression

java.lang.Object

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

All Implemented Interfaces:

GroupingSQLValue<java.lang.Number>, SQLExpression<java.lang.Number>, SQLValue<java.lang.Number>, Targetted<java.lang.Number>

public final class BinaryExpression
extends java.lang.Object
implements SQLExpression<java.lang.Number>

A binary numerical SQLExpression There is a factory method for generating these that can implement simple simplifications. The equals(Object) method is written to reflect commutative Operators.

Field Summary

Fields

Modifier and Type	Field and Description
static Feature	SIMPLIFY_EXPRESSION

Method Summary

Modifier and Type	Method and Description
int	add(java.lang.StringBuilder sb, boolean qualify) Add the expression to a StringBuilder
static SQLExpression<java.lang.Number>	create(AppContext conn, SQLExpression<?> a, Operator op, SQLExpression<?> b) A factory method for binary SQLExpressions.
boolean	equals(java.lang.Object obj)
SQLExpression<?>	getA()
SQLExpression<?>	getB()
Operator	getOp()
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<java.lang.Number>	getTarget() Get the type of the returned object as far as it is known.
int	hashCode()
java.lang.Number	makeObject(java.sql.ResultSet rs, int pos) Extract a result of the expression from a ResultSet into an object of the specified type.
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

addGroup, checkContentsCanGroup, getGroupParameters

Field Detail

SIMPLIFY_EXPRESSION

public static final Feature SIMPLIFY_EXPRESSION

Method Detail

create

public static SQLExpression<java.lang.Number> create(AppContext conn,
                                                     SQLExpression<?> a,
                                                     Operator op,
                                                     SQLExpression<?> b)

A factory method for binary SQLExpressions. Usually this will return a BinaryExpression but may return some other expression as a result of on-the-fly simplification if the AppContext parameter is non-null and the appropriate feature is turned on.

Parameters:

conn - AppContext used to read config, null suppresses simplification

a - SQLExpression first argument

op - Operator to apply

b - SQLExpression second argument.

Returns:

SQLExpression

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<java.lang.Number>

Parameters:

sb - StringBuilder to modify

qualify - boolean should fields be qualified with the table name

Returns:

number of fields added

makeObject

public java.lang.Number 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<java.lang.Number>

Parameters:

rs - ResultSet

Returns:

produced object

Throws:

DataException

java.sql.SQLException

getTarget

public java.lang.Class<java.lang.Number> 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<java.lang.Number>

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<java.lang.Number>

Returns:

null or SQLFilter

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<java.lang.Number>

Parameters:

list - to modify

Returns:

modified list of parameter objects

hashCode

public int hashCode()

Specified by:

hashCode in interface SQLExpression<java.lang.Number>

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface SQLExpression<java.lang.Number>

Overrides:

equals in class java.lang.Object

getA

public SQLExpression<?> getA()

getB

public SQLExpression<?> getB()

getOp

public Operator getOp()