org.h2.expression
Class JavaFunction

java.lang.Object
  extended by org.h2.expression.Expression
      extended by org.h2.expression.JavaFunction
All Implemented Interfaces:
FunctionCall

public class JavaFunction
extends Expression
implements FunctionCall

This class wraps a user-defined function.


Constructor Summary
JavaFunction(FunctionAlias functionAlias, Expression[] args)
           
 
Method Summary
 Expression[] getArgs()
          Get the function arguments.
 int getCost()
          Estimate the cost to process the expression.
 int getDisplaySize()
          Get the display size of this expression.
 java.lang.String getName()
          Get the name of the function.
 int getParameterCount()
          Get the number of parameters.
 long getPrecision()
          Get the precision of this expression.
 int getScale()
          Get the scale of this expression.
 java.lang.String getSQL()
          Get the SQL statement of this expression.
 int getType()
          Return the data type.
 Value getValue(Session session)
          Return the resulting value for the current row.
 ValueResultSet getValueForColumnList(Session session, Expression[] args)
          Get an empty result set with the column names set.
 boolean isDeterministic()
          Whether the function always returns the same result for the same parameters.
 boolean isEverything(ExpressionVisitor visitor)
          Check if this expression and all sub-expressions can fulfill a criteria.
 void mapColumns(ColumnResolver resolver, int level)
          Map the columns of the resolver to expression columns.
 Expression optimize(Session session)
          Try to optimize the expression.
 void setEvaluatable(TableFilter tableFilter, boolean b)
          Tell the expression columns whether the table filter can return values now.
 void updateAggregate(Session session)
          Update an aggregate value.
 
Methods inherited from class org.h2.expression.Expression
addFilterConditions, createIndexConditions, getAlias, getBooleanValue, getColumnName, getNonAliasExpression, getNotIfPossible, getNullable, getSchemaName, getTableAlias, getTableName, isAutoIncrement, isConstant, isEverything, isValueSet, isWildcard, optimizeInJoin, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

JavaFunction

public JavaFunction(FunctionAlias functionAlias,
                    Expression[] args)
             throws java.sql.SQLException
Throws:
java.sql.SQLException
Method Detail

getValue

public Value getValue(Session session)
               throws java.sql.SQLException
Description copied from class: Expression
Return the resulting value for the current row.

Specified by:
getValue in interface FunctionCall
Specified by:
getValue in class Expression
Parameters:
session - the session
Returns:
the result
Throws:
java.sql.SQLException

getType

public int getType()
Description copied from class: Expression
Return the data type. The data type may not be known before the optimization phase.

Specified by:
getType in interface FunctionCall
Specified by:
getType in class Expression
Returns:
the type

mapColumns

public void mapColumns(ColumnResolver resolver,
                       int level)
                throws java.sql.SQLException
Description copied from class: Expression
Map the columns of the resolver to expression columns.

Specified by:
mapColumns in class Expression
Parameters:
resolver - the column resolver
level - the subquery nesting level
Throws:
java.sql.SQLException

optimize

public Expression optimize(Session session)
                    throws java.sql.SQLException
Description copied from class: Expression
Try to optimize the expression.

Specified by:
optimize in interface FunctionCall
Specified by:
optimize in class Expression
Parameters:
session - the session
Returns:
the optimized expression
Throws:
java.sql.SQLException

setEvaluatable

public void setEvaluatable(TableFilter tableFilter,
                           boolean b)
Description copied from class: Expression
Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.

Specified by:
setEvaluatable in class Expression
Parameters:
tableFilter - the table filter
b - true if the table filter can return value

getScale

public int getScale()
Description copied from class: Expression
Get the scale of this expression.

Specified by:
getScale in class Expression
Returns:
the scale

getPrecision

public long getPrecision()
Description copied from class: Expression
Get the precision of this expression.

Specified by:
getPrecision in class Expression
Returns:
the precision

getDisplaySize

public int getDisplaySize()
Description copied from class: Expression
Get the display size of this expression.

Specified by:
getDisplaySize in class Expression
Returns:
the display size

getSQL

public java.lang.String getSQL()
Description copied from class: Expression
Get the SQL statement of this expression. This may not always be the original SQL statement, specially after optimization.

Specified by:
getSQL in interface FunctionCall
Specified by:
getSQL in class Expression
Returns:
the SQL statement

updateAggregate

public void updateAggregate(Session session)
                     throws java.sql.SQLException
Description copied from class: Expression
Update an aggregate value. This method is called at statement execution time. It is usually called once for each row, but if the expression is used multiple times (for example in the column list, and as part of the HAVING expression) it is called multiple times - the row counter needs to be used to make sure the internal state is only updated once.

Specified by:
updateAggregate in class Expression
Parameters:
session - the session
Throws:
java.sql.SQLException

getName

public java.lang.String getName()
Description copied from interface: FunctionCall
Get the name of the function.

Specified by:
getName in interface FunctionCall
Returns:
the name

getParameterCount

public int getParameterCount()
Description copied from interface: FunctionCall
Get the number of parameters.

Specified by:
getParameterCount in interface FunctionCall
Returns:
the number of parameters

getValueForColumnList

public ValueResultSet getValueForColumnList(Session session,
                                            Expression[] args)
                                     throws java.sql.SQLException
Description copied from interface: FunctionCall
Get an empty result set with the column names set.

Specified by:
getValueForColumnList in interface FunctionCall
Parameters:
session - the session
args - the argument list (some arguments may be null)
Returns:
the empty result set
Throws:
java.sql.SQLException

getArgs

public Expression[] getArgs()
Description copied from interface: FunctionCall
Get the function arguments.

Specified by:
getArgs in interface FunctionCall
Returns:
argument list

isEverything

public boolean isEverything(ExpressionVisitor visitor)
Description copied from class: Expression
Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.

Specified by:
isEverything in class Expression
Parameters:
visitor - the visitor
Returns:
if the criteria can be fulfilled

getCost

public int getCost()
Description copied from class: Expression
Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.

Specified by:
getCost in class Expression
Returns:
the estimated cost

isDeterministic

public boolean isDeterministic()
Description copied from interface: FunctionCall
Whether the function always returns the same result for the same parameters.

Specified by:
isDeterministic in interface FunctionCall
Returns:
true if it does