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

java.lang.Object
  extended byorg.apache.derby.impl.sql.compile.QueryTreeNode
      extended byorg.apache.derby.impl.sql.compile.ValueNode
          extended byorg.apache.derby.impl.sql.compile.ConditionalNode
All Implemented Interfaces:
Visitable

public class ConditionalNode
extends ValueNode

A ConditionalNode represents an if/then/else operator with a single boolean expression on the "left" of the operator and a list of expressions on the "right". This is used to represent the java conditional (aka immediate if).

Author:
Jerry Brenner

Field Summary
(package private)  ValueNode testCondition
           
(package private)  ValueNodeList thenElseList
           
 
Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode
clause, dataTypeServices, IN_HAVING_CLAUSE, IN_SELECT_LIST, IN_UNKNOWN_CLAUSE, IN_WHERE_CLAUSE, transformed
 
Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, beginOffset, endOffset
 
Constructor Summary
ConditionalNode()
           
 
Method Summary
 Visitable accept(Visitor v)
          Accept a visitor, and call v.visit() on child nodes as necessary.
 ValueNode bindExpression(FromList fromList, SubqueryList subqueryList, java.util.Vector aggregateVector)
          Bind this expression.
 boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly)
          Categorize this predicate.
 boolean constantExpression(PredicateList whereClause)
          Return whether or not this expression tree represents a constant value.
(package private)  ValueNode eliminateNots(boolean underNotNode)
          Eliminate NotNodes in the current query block.
 void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)
          Do code generation for this conditional expression.
 void init(java.lang.Object testCondition, java.lang.Object thenElseList)
          Initializer for a ConditionalNode
 boolean isConstantExpression()
          Return whether or not this expression tree represents a constant expression.
 ValueNode preprocess(int numTables, FromList outerFromList, SubqueryList outerSubqueryList, PredicateList outerPredicateList)
          Preprocess an expression tree.
 void printSubNodes(int depth)
          Prints the sub-nodes of this object.
 ValueNode remapColumnReferencesToExpressions()
          Remap all ColumnReferences in this tree to be clones of the underlying expression.
 void setClause(int clause)
          Set the clause that this node appears in.
 
Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode
bindExpression, changeToCNF, checkIsBoolean, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, copyFields, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getOrderableVariantType, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isParameterNode, isRelationalOperator, optimizableEqualityNode, putAndsOnTop, selectivity, setDescriptor, setTransformed, setType, toString, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop
 
Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getSPSName, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeResultDescription, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, referencesSessionSchema, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, treePrint, treePrint, verifyClassExist
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

testCondition

ValueNode testCondition

thenElseList

ValueNodeList thenElseList
Constructor Detail

ConditionalNode

public ConditionalNode()
Method Detail

init

public void init(java.lang.Object testCondition,
                 java.lang.Object thenElseList)
Initializer for a ConditionalNode

Overrides:
init in class QueryTreeNode
Parameters:
testCondition - The boolean test condition
thenElseList - ValueNodeList with then and else expressions

printSubNodes

public void printSubNodes(int depth)
Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.

Overrides:
printSubNodes in class QueryTreeNode
Parameters:
depth - The depth of this node in the tree
Returns:
Nothing

setClause

public void setClause(int clause)
Set the clause that this node appears in.

Overrides:
setClause in class ValueNode
Parameters:
clause - The clause that this node appears in.
Returns:
Nothing.

bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.Vector aggregateVector)
                         throws StandardException
Bind this expression. This means binding the sub-expressions, as well as figuring out what the return type is for this expression.

Overrides:
bindExpression in class ValueNode
Parameters:
fromList - The FROM list for the query this expression is in, for binding columns.
subqueryList - The subquery list being built as we find SubqueryNodes
aggregateVector - The aggregate vector being built as we find AggregateNodes
Returns:
The new top of the expression tree.
Throws:
StandardException - Thrown on error

preprocess

public ValueNode preprocess(int numTables,
                            FromList outerFromList,
                            SubqueryList outerSubqueryList,
                            PredicateList outerPredicateList)
                     throws StandardException
Preprocess an expression tree. We do a number of transformations here (including subqueries, IN lists, LIKE and BETWEEN) plus subquery flattening. NOTE: This is done before the outer ResultSetNode is preprocessed.

Overrides:
preprocess in class ValueNode
Parameters:
numTables - Number of tables in the DML Statement
outerFromList - FromList from outer query block
outerSubqueryList - SubqueryList from outer query block
outerPredicateList - PredicateList from outer query block
Returns:
The modified expression
Throws:
StandardException - Thrown on error

categorize

public boolean categorize(JBitSet referencedTabs,
                          boolean simplePredsOnly)
                   throws StandardException
Categorize this predicate. Initially, this means building a bit map of the referenced tables for each predicate. If the source of this ColumnReference (at the next underlying level) is not a ColumnReference or a VirtualColumnNode then this predicate will not be pushed down. For example, in: select * from (select 1 from s) a (x) where x = 1 we will not push down x = 1. NOTE: It would be easy to handle the case of a constant, but if the inner SELECT returns an arbitrary expression, then we would have to copy that tree into the pushed predicate, and that tree could contain subqueries and method calls. RESOLVE - revisit this issue once we have views.

Overrides:
categorize in class ValueNode
Parameters:
referencedTabs - JBitSet with bit map of referenced FromTables
simplePredsOnly - Whether or not to consider method calls, field references and conditional nodes when building bit map
Returns:
boolean Whether or not source.expression is a ColumnReference or a VirtualColumnNode.
Throws:
StandardException - Thrown on error

remapColumnReferencesToExpressions

public ValueNode remapColumnReferencesToExpressions()
                                             throws StandardException
Remap all ColumnReferences in this tree to be clones of the underlying expression.

Overrides:
remapColumnReferencesToExpressions in class ValueNode
Returns:
ValueNode The remapped expression tree.
Throws:
StandardException - Thrown on error

isConstantExpression

public boolean isConstantExpression()
Return whether or not this expression tree represents a constant expression.

Overrides:
isConstantExpression in class ValueNode
Returns:
Whether or not this expression tree represents a constant expression.

constantExpression

public boolean constantExpression(PredicateList whereClause)
Description copied from class: ValueNode
Return whether or not this expression tree represents a constant value. In this case, "constant" means that it will always evaluate to the same thing, even if it includes columns. A column is constant if it is compared to a constant expression.

Overrides:
constantExpression in class ValueNode
Returns:
True means this expression tree represents a constant value.
See Also:
ValueNode.constantExpression(org.apache.derby.impl.sql.compile.PredicateList)

eliminateNots

ValueNode eliminateNots(boolean underNotNode)
                  throws StandardException
Eliminate NotNodes in the current query block. We traverse the tree, inverting ANDs and ORs and eliminating NOTs as we go. We stop at ComparisonOperators and boolean expressions. We invert ComparisonOperators and replace boolean expressions with boolean expression = false. NOTE: Since we do not recurse under ComparisonOperators, there still could be NotNodes left in the tree.

Overrides:
eliminateNots in class ValueNode
Parameters:
underNotNode - Whether or not we are under a NotNode.
Returns:
The modified expression
Throws:
StandardException - Thrown on error

generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               MethodBuilder mb)
                        throws StandardException
Do code generation for this conditional expression.

Overrides:
generateExpression in class ValueNode
Parameters:
acb - The ExpressionClassBuilder for the class we're generating
mb - The method the expression will go into
Returns:
An expression to evaluate this operator
Throws:
StandardException - Thrown on error

accept

public Visitable accept(Visitor v)
                 throws StandardException
Accept a visitor, and call v.visit() on child nodes as necessary.

Specified by:
accept in interface Visitable
Overrides:
accept in class QueryTreeNode
Parameters:
v - the visitor
Throws:
StandardException - on error


Apache Derby V10.0 Engine Documentation - Copyright © 1997,2004 The Apache Software Foundation or its licensors, as applicable.