org.josef.jpa

Class WhereClauseRpn

java.lang.Object

org.josef.jpa.WhereClauseRpn

@Status(stage=TEST,
        unitTests=COMPLETE)
 @Review(by="Kees Schotanus",
        at="2009-10-08",
        reason="After creation of unit tests")
public class WhereClauseRpn
extends Object

Abstraction of a JP/QL where clause builder using Reverse Polish Notation.
For example: Assume you have to create the following where clause from its individual parts: a = 3 and (b = 7 or (c=8 and d=9))
Using this where clause builder the code you need looks like this:

     final WhereClauseRpn whereClause = new WhereClauseRpn();
     whereClause.push("a=3").push("b=7").push("c=8").push("d=9");
     whereClause.and();
     whereClause.or();
     whereClause.and();
 

Version:

1.0 $Revision: 6488 $

Author:

Kees Schotanus

Constructor Summary

Constructors

Constructor and Description
WhereClauseRpn()

Method Summary

Modifier and Type	Method and Description
WhereClauseRpn	and() Performs an AND operation.
List<Object>	getParameters() Gets all the JP/QL parameters.
WhereClauseRpn	or() Performs an OR operation.
WhereClauseRpn	push(String expression) Pushes the supplied expression on the stack.
void	pushBetween(String column, Object minimum, Object maximum) Pushes a BETWEEN expression, created from the supplied column and minimum and maximum values, on the stack.
void	pushEndsWith(String column, String value) Pushes a LIKE expression (where the percent sign is at the beginning of the expression), created from the supplied column and value on the stack.
void	pushIsNotNull(String column) Pushes an IS NOT NULL expression, created from the supplied column, on the stack.
void	pushIsNull(String column) Pushes an IS NULL expression, created from the supplied column, on the stack.
void	pushRelationalExpression(String column, RelationalOperator operator, Object value) Pushes a relational expression, constructed from the supplied column, operator and value on the stack.
void	pushStartsWith(String column, String value) Pushes a LIKE expression (where the percent sign is at the end of the expression), created from the supplied column and value on the stack.
String	toString() Creates a String representation of this WhereClauseRpn consisting of the where clause (provided the where clause has been build).

Methods inherited from class java.lang.Object

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

Constructor Detail

WhereClauseRpn

public WhereClauseRpn()

Method Detail

push

public WhereClauseRpn push(String expression)

Pushes the supplied expression on the stack.

Parameters:

expression - The expression to push on the stack.

Returns:

This WherelauseRpn.

Throws:

IllegalArgumentException - When the supplied expression is empty.

NullPointerException - When the supplied expression is null.

pushRelationalExpression

public void pushRelationalExpression(String column,
                                     RelationalOperator operator,
                                     Object value)

Pushes a relational expression, constructed from the supplied column, operator and value on the stack.
Note: No expression is pushed when the supplied value is null, or is of type String and is empty.

Parameters:

column - The column.

operator - The relational operator to apply.

value - The value.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When either the supplied column or operator is null.

pushStartsWith

public void pushStartsWith(String column,
                           String value)

Pushes a LIKE expression (where the percent sign is at the end of the expression), created from the supplied column and value on the stack.
Note: No expression is added when the supplied value is null or empty.
Note: This method has build in protection against the supplied value already containing a wild-card character. In such cases the '%' wild-card character is not added.

Parameters:

column - The column.

value - The value.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When the supplied column is null.

pushEndsWith

public void pushEndsWith(String column,
                         String value)

Pushes a LIKE expression (where the percent sign is at the beginning of the expression), created from the supplied column and value on the stack.
Note: No expression is added when the supplied value is null or empty.
Note: This method has build in protection against the supplied value already containing a wild-card character. In such cases the '%' wild-card character is not added.

Parameters:

column - The column.

value - The value.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When the supplied column is null.

pushBetween

public void pushBetween(String column,
                        Object minimum,
                        Object maximum)

Pushes a BETWEEN expression, created from the supplied column and minimum and maximum values, on the stack.
Note: No expression is added when both minimum and maximum are null.

Parameters:

column - The column.

minimum - The minimum value.

maximum - The maximum value.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When the supplied column is null.

pushIsNull

public void pushIsNull(String column)

Pushes an IS NULL expression, created from the supplied column, on the stack.

Parameters:

column - The column.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When the supplied column is null.

pushIsNotNull

public void pushIsNotNull(String column)

Pushes an IS NOT NULL expression, created from the supplied column, on the stack.

Parameters:

column - The column.

Throws:

IllegalArgumentException - When the supplied column is empty.

NullPointerException - When the supplied column is null.

and

public WhereClauseRpn and()

Performs an AND operation.

Returns:

This WherelauseRpn.

Throws:

NoSuchElementException - When the stack contains less than two expressions.

or

public WhereClauseRpn or()

Performs an OR operation.

Returns:

This WherelauseRpn.

Throws:

NoSuchElementException - When the stack contains less than two expressions.

toString

public String toString()

Creates a String representation of this WhereClauseRpn consisting of the where clause (provided the where clause has been build).
Note: As long as the where clause has not been build, this method returns the expression at the top of the stack.

Overrides:

toString in class Object

Returns:

The where clause.

getParameters

public List<Object> getParameters()

Gets all the JP/QL parameters.

Returns:

The JP/QL parameters.
The returned List may be empty but will never be null!