org.exolab.jms.selector
Interface ExpressionFactory

All Known Implementing Classes:

DefaultExpressionFactory

public interface ExpressionFactory

This interface specifies the methods needed to create all of the expressions supported by the message selector. It exists solely to decouple the expression evaluation classes from the parser.

Version:

$Revision: 1.4 $ $Date: 2003/08/09 15:49:50 $

Author:

Tim Anderson

See Also:

Expression, SelectorTokenTypes, SelectorTreeParser

Method Summary

Expression	between(Expression num1, Expression num2, Expression num3) Create a 'between' expression that returns the result of: num1 >= num2 and num1 <= num3 when evaluated
Expression	binaryOperator(int operator, Expression left, Expression right) Create a binary operator expression
Expression	identifier(java.lang.String name) Create an identifier expression
Expression	in(Expression identifier, java.util.HashSet set) Create an 'in' expression
Expression	isNull(Expression identifier) Create an 'is null' expression
Expression	like(Expression identifier, java.lang.String pattern, java.lang.String escape) Create a 'like' expression
Expression	literal(int type, java.lang.String text) Create a literal expression
Expression	unaryOperator(int operator, Expression operand) Create an unary operator expression

Method Detail

binaryOperator

public Expression binaryOperator(int operator,
                                 Expression left,
                                 Expression right)
                          throws SelectorException

Create a binary operator expression

Parameters:

operator - the operator token type from SelectorTokenTypes

left - the left-hand side of the binary expression

right - the right-hand side of the binary expression

Returns:

a new binary expression

Throws:

SelectorException - if the operator is not a valid binary operator

unaryOperator

public Expression unaryOperator(int operator,
                                Expression operand)
                         throws SelectorException

Create an unary operator expression

Parameters:

operator - the operator token type from SelectorTokenTypes

operand - the expression to apply the operator to

Returns:

a new unary expression

Throws:

SelectorException - if the operator is not a valid unary operator

identifier

public Expression identifier(java.lang.String name)
                      throws SelectorException

Create an identifier expression

Parameters:

name - the name of the identifier

Returns:

a new identifier expression

Throws:

SelectorException - is name is not a valid identifier

isNull

public Expression isNull(Expression identifier)
                  throws SelectorException

Create an 'is null' expression

Parameters:

identifier - the identifer expression to apply the 'is null' test

Returns:

an 'is null' expression

Throws:

SelectorException - for any error

like

public Expression like(Expression identifier,
                       java.lang.String pattern,
                       java.lang.String escape)
                throws SelectorException

Create a 'like' expression

Parameters:

identifier - the identifer to apply the 'like' test to

pattern - the search pattern

escape - the escape character. This may be null

Returns:

a new 'like' expression

Throws:

SelectorException - if the pattern or escape is invalid

between

public Expression between(Expression num1,
                          Expression num2,
                          Expression num3)
                   throws SelectorException

Create a 'between' expression that returns the result of:
num1 >= num2 and num1 <= num3 when evaluated

Parameters:

num1 - an arithmethic expression

num2 - an arithmethic expression

num3 - an arithmethic expression

Returns:

a new 'between' expression

Throws:

SelectorException - for any error

in

public Expression in(Expression identifier,
                     java.util.HashSet set)
              throws SelectorException

Create an 'in' expression

Parameters:

identifier - string identifer to apply the 'in' test to

set - the set of string values to compare against

Returns:

a new 'in' expression

Throws:

SelectorException - for any error

literal

public Expression literal(int type,
                          java.lang.String text)
                   throws SelectorException

Create a literal expression

Parameters:

type - the operator token type from SelectorTokenTypes

text - the literal text

Returns:

a new literal expression

Throws:

SelectorException - if type is not a valid literal type