Package net.sf.basedb.core.query

Class LogExpression

java.lang.Object

net.sf.basedb.core.query.LogExpression

All Implemented Interfaces:

Expression, QueryElement

public class LogExpression
extends Object
implements Expression

Take the n-based logarithm of an expression: log(n, e).

The n-based logarithm is easily calculated as the natural logarithm of x divided natural logarithm of the base, ie. log(n, e) = ln(e) / ln(n)

Version:

2.0

Author:

Nicklas

See Also:

• Expressions.log(double, Expression)

Last modified

$Date: 2012-09-14 09:28:35 +0200 (fr, 14 sep 2012) $

Field Summary

Fields

Modifier and Type	Field	Description
private final double	base
private final Expression	e1

Constructor Summary

Constructors

Constructor	Description
LogExpression(double base, Expression e1)

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object other)	This expression is equal to another LogExpression if their child expressions and bases are equal.
Collection<? extends QueryElement>	getChildren()	Get the children of this query element or null if it has no children.
int	hashCode()
String	toQl(Query query, DbControl dc)	Create a query language string of the query element.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

base

private final double base

e1

private final Expression e1

Constructor Details

LogExpression

LogExpression(double base,
 Expression e1)

Method Details

toQl

public String toQl(Query query,
 DbControl dc)
            throws BaseException

Description copied from interface: QueryElement

Create a query language string of the query element. Use the Query.getQueryType() method to find out which query language is wanted in case the element requires different syntax for different languages.

Specified by:

toQl in interface QueryElement

Parameters:

query - The query that is about to be executed

dc - The DbControl object used to execute the query

Throws:

BaseException - If there is any other error

getChildren

public Collection<? extends QueryElement> getChildren()

Description copied from interface: QueryElement

Get the children of this query element or null if it has no children. For example the AddExpression has two children, the expression beeing added.

Specified by:

getChildren in interface QueryElement

Returns:

The expression

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object other)

This expression is equal to another LogExpression if their child expressions and bases are equal.

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object