org.apache.derby.impl.sql.compile
Class SpecialFunctionNode

java.lang.Object
  extended by org.apache.derby.impl.sql.compile.QueryTreeNode
      extended by org.apache.derby.impl.sql.compile.ValueNode
          extended by org.apache.derby.impl.sql.compile.SpecialFunctionNode
All Implemented Interfaces:
Visitable

public class SpecialFunctionNode
extends ValueNode

SpecialFunctionNode handles system SQL functions. A function value is either obtained by a method call off the LanguageConnectionContext or Activation. LanguageConnectionContext functions are state related to the connection. Activation functions are those related to the statement execution. Each SQL function takes no arguments and returns a SQLvalue.

Functions supported:

This node is used rather than some use of MethodCallNode for runtime performance. MethodCallNode does not provide a fast access to the current language connection or activatation, since it is geared towards user defined routines.


Field Summary
private  java.lang.String methodName
          Java method name
private  java.lang.String methodType
          Return type of Java method.
(package private)  java.lang.String sqlName
          Name of SQL function
 
Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode
transformed
 
Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, isPrivilegeCollectionRequired
 
Constructor Summary
SpecialFunctionNode()
           
 
Method Summary
 ValueNode bindExpression(FromList fromList, SubqueryList subqueryList, java.util.Vector aggregateVector)
          Binding this special function means setting the result DataTypeServices.
 void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)
          Generate an expression that returns a DataValueDescriptor and calls a method off the language connection or the activation.
protected  int getOrderableVariantType()
          Return the variant type for the underlying expression.
protected  boolean isEquivalent(ValueNode o)
          Tests if this node is equivalent to the specified ValueNode.
 java.lang.String toString()
          Convert this object to a String.
 
Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode
bindExpression, categorize, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeType, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, requiresTypeFromContext, selectivity, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop
 
Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
accept, acceptChildren, bindOffsetFetch, bindRowMultiSet, bindUserType, checkReliability, checkReliability, convertDefaultNode, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, foundString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, orReliability, parseStatement, printLabel, printSubNodes, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, stackPrint, treePrint, treePrint, verifyClassExist
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

sqlName

java.lang.String sqlName
Name of SQL function


methodName

private java.lang.String methodName
Java method name


methodType

private java.lang.String methodType
Return type of Java method.

Constructor Detail

SpecialFunctionNode

public SpecialFunctionNode()
Method Detail

bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.Vector aggregateVector)
                         throws StandardException
Binding this special function means setting the result DataTypeServices. In this case, the result type is based on the operation requested.

Overrides:
bindExpression in class ValueNode
Parameters:
fromList - The FROM list for the statement. This parameter is not used in this case.
subqueryList - The subquery list being built as we find SubqueryNodes. Not used in this case.
aggregateVector - The aggregate vector being built as we find AggregateNodes. Not used in this case.
Returns:
The new top of the expression tree.
Throws:
StandardException - Thrown on error

getOrderableVariantType

protected int getOrderableVariantType()
Return the variant type for the underlying expression. All supported special functions are QUERY_INVARIANT

Overrides:
getOrderableVariantType in class ValueNode
Returns:
The variant type for the underlying expression.

generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               MethodBuilder mb)
                        throws StandardException
Generate an expression that returns a DataValueDescriptor and calls a method off the language connection or the activation.

Overrides:
generateExpression in class ValueNode
Parameters:
acb - The ExpressionClassBuilder for the class being built
mb - The method the code to place the code
Throws:
StandardException - Thrown on error

toString

public java.lang.String toString()
Description copied from class: ValueNode
Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

Overrides:
toString in class ValueNode
Returns:
This object as a String

isEquivalent

protected boolean isEquivalent(ValueNode o)
Description copied from class: ValueNode
Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

SELECT c1+c2 FROM t1 GROUP BY c1+c2

In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

Specified by:
isEquivalent in class ValueNode
Parameters:
o - the node to compare this ValueNode against.
Returns:
true if the two nodes are equivalent, false otherwise.

Built on Thu 2012-03-29 21:53:33+0000, from revision ???

Apache Derby V10.6 Internals - Copyright © 2004,2007 The Apache Software Foundation. All Rights Reserved.