ConditionalNode (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.impl.sql.compile.QueryTreeNode
- - org.apache.derby.impl.sql.compile.ValueNode
  - - org.apache.derby.impl.sql.compile.ConditionalNode

All Implemented Interfaces:

Visitable
```
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).

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`private class`	`ConditionalNode.ReplaceCaseOperandVisitor`	A visitor that replaces all occurrences of the `caseOperand` node in a tree with dummy parameter nodes.

Field Summary

Fields
Modifier and Type	Field	Description
`private CachedValueNode`	`caseOperand`	The case operand if this is a simple case expression.
`private ValueNodeList`	`testConditions`	The list of test conditions in the WHEN clauses.
`private ValueNodeList`	`thenElseList`	The list of corresponding THEN expressions to the test conditions in `testConditions`.

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode
transformed

Constructor Summary

Constructors
Constructor	Description
`ConditionalNode(CachedValueNode caseOperand, ValueNodeList testConditions, ValueNodeList thenElseList, ContextManager cm)`	Constructor for a ConditionalNode

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) void`	`acceptChildren(Visitor v)`	Accept the visitor for all visitable children of this node.
`private ValueNodeList`	`bindCaseOperand(CompilerContext cc, FromList fromList, SubqueryList subqueryList, java.util.List<AggregateNode> aggregates)`	Bind the case operand, if there is one, and check that it doesn't contain anything that's illegal in a case operand (such as calls to routines that are non-deterministic or modify SQL).
`(package private) ValueNode`	`bindExpression(FromList fromList, SubqueryList subqueryList, java.util.List<AggregateNode> aggregates)`	Bind this expression.
`(package private) boolean`	`categorize(JBitSet referencedTabs, boolean simplePredsOnly)`	Categorize this predicate.
`(package private) 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.
`(package private) void`	`generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)`	Do code generation for this conditional expression.
`(package private) boolean`	`isConstantExpression()`	Return whether or not this expression tree represents a constant expression.
`(package private) boolean`	`isEquivalent(ValueNode o)`	Tests if this node is equivalent to the specified ValueNode.
`(package private) ValueNode`	`preprocess(int numTables, FromList outerFromList, SubqueryList outerSubqueryList, PredicateList outerPredicateList)`	Preprocess an expression tree.
`(package private) void`	`printSubNodes(int depth)`	Prints the sub-nodes of this object.
`private void`	`recastNullNodes(DataTypeDescriptor castType, FromList fromList, SubqueryList subqueryList, java.util.List<AggregateNode> aggregates)`	This method makes sure any SQL NULLs will be cast to the correct type.
`(package private) ValueNode`	`remapColumnReferencesToExpressions()`	Remap all ColumnReferences in this tree to be clones of the underlying expression.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
accept, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContext, getContextManager, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getLongProperty, getNullNode, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, getUDTDesc, isAtomic, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, optimizerTracingIsOn, orReliability, parseSearchCondition, parseStatement, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist

Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode
bindExpression, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, copyFields, evaluateConstantExpressions, genEqualsFalseTree, generate, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getOrderableVariantType, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeKind, optimizableEqualityNode, putAndsOnTop, requiresTypeFromContext, selectivity, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, toString, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

- Field Detail
  - caseOperand
```
private CachedValueNode caseOperand
```
    The case operand if this is a simple case expression. Otherwise, it is null.
  - testConditions
```
private ValueNodeList testConditions
```
    The list of test conditions in the WHEN clauses.
  - thenElseList
```
private ValueNodeList thenElseList
```
    The list of corresponding THEN expressions to the test conditions in testConditions. The last element represents the ELSE clause.
- Constructor Detail
  - ConditionalNode
```
ConditionalNode(CachedValueNode caseOperand,
                ValueNodeList testConditions,
                ValueNodeList thenElseList,
                ContextManager cm)
```
    Constructor for a ConditionalNode
    
    Parameters:
    
    caseOperand - The case operand if this is a simple case expression, or null otherwise
    
    testConditions - The boolean test conditions
    
    thenElseList - ValueNodeList with then and else expressions
    
    cm - The context manager
- Method Detail
  - printSubNodes
```
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
  - recastNullNodes
```
private void recastNullNodes(DataTypeDescriptor castType,
                             FromList fromList,
                             SubqueryList subqueryList,
                             java.util.List<AggregateNode> aggregates)
                      throws StandardException
```
    This method makes sure any SQL NULLs will be cast to the correct type.
    
    Parameters:
    
    castType - The type to cast SQL parsed NULL's too.
    
    fromList - FromList to pass on to bindExpression if recast is performed
    
    subqueryList - SubqueryList to pass on to bindExpression if recast is performed
    
    aggregates - List of aggregates to pass on to bindExpression if recast is performed
    
    Throws:
    
    StandardException - Thrown on error.
  - bindExpression
```
ValueNode bindExpression(FromList fromList,
                         SubqueryList subqueryList,
                         java.util.List<AggregateNode> aggregates)
                  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
    
    aggregates - The aggregate list being built as we find AggregateNodes
    
    Returns:
    
    The new top of the expression tree.
    
    Throws:
    
    StandardException - Thrown on error
  - bindCaseOperand
```
private ValueNodeList bindCaseOperand(CompilerContext cc,
                                      FromList fromList,
                                      SubqueryList subqueryList,
                                      java.util.List<AggregateNode> aggregates)
                               throws StandardException
```
    Bind the case operand, if there is one, and check that it doesn't contain anything that's illegal in a case operand (such as calls to routines that are non-deterministic or modify SQL).
    
    Also, if the type of the case operand needs to be inferred, insert dummy parameter nodes into testConditions instead of the case operand, so that the type can be inferred individually for each test condition. Later, bindExpression(org.apache.derby.impl.sql.compile.FromList, org.apache.derby.impl.sql.compile.SubqueryList, java.util.List<org.apache.derby.impl.sql.compile.AggregateNode>) will find a common type for all of them, use that type for the case operand, and reinsert the case operand into the test conditions.
    
    Returns:
    
    a list of dummy parameter nodes that have been inserted into the tree instead of the case operand, if such a replacement has happened; otherwise, null is returned
    
    Throws:
    
    StandardException
  - preprocess
```
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
```
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
```
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
```
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
```
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
```
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
    
    Throws:
    
    StandardException - Thrown on error
  - acceptChildren
```
void acceptChildren(Visitor v)
             throws StandardException
```
    Accept the visitor for all visitable children of this node.
    
    Overrides:
    
    acceptChildren in class QueryTreeNode
    
    Parameters:
    
    v - the visitor
    
    Throws:
    
    StandardException - on error
  - isEquivalent
```
boolean isEquivalent(ValueNode o)
              throws StandardException
```
    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:
    - The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
    - If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
    - If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
    - When comparing SQL NULLs in this context, they are considered to be equivalent.
    - If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.
    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.
    
    Throws:
    
    StandardException

Class ConditionalNode

Nested Class Summary

Field Summary

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode

Field Detail

caseOperand

testConditions

thenElseList

Constructor Detail

ConditionalNode

Method Detail

printSubNodes

recastNullNodes

bindExpression

bindCaseOperand

preprocess

categorize

remapColumnReferencesToExpressions

isConstantExpression

constantExpression

eliminateNots

generateExpression

acceptChildren

isEquivalent