2.17.2: 2011-06-17

net.sf.basedb.core.query
Class LogExpression

java.lang.Object
  extended by 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: 2010-04-21 11:48:29 +0200 (Wed, 21 Apr 2010) $

Field Summary
private  double base
           
private  Expression e1
           
 
Constructor Summary
LogExpression(double base, Expression e1)
           
 
Method Summary
 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 Detail

base

private final double base

e1

private final Expression e1
Constructor Detail

LogExpression

LogExpression(double base,
              Expression e1)
Method Detail

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

2.17.2: 2011-06-17