Class ConditionalNode
- 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 thecaseOperand
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 intestConditions
.-
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_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX
-
-
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 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
-
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
-
-
-
-
Field Detail
-
caseOperand
private CachedValueNode caseOperand
The case operand if this is a simple case expression. Otherwise, it isnull
.
-
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 intestConditions
. 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, ornull
otherwisetestConditions
- The boolean test conditionsthenElseList
- ValueNodeList with then and else expressionscm
- 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 classQueryTreeNode
- 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 performedsubqueryList
- SubqueryList to pass on to bindExpression if recast is performedaggregates
- 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 classValueNode
- Parameters:
fromList
- The FROM list for the query this expression is in, for binding columns.subqueryList
- The subquery list being built as we find SubqueryNodesaggregates
- 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 classValueNode
- Parameters:
numTables
- Number of tables in the DML StatementouterFromList
- FromList from outer query blockouterSubqueryList
- SubqueryList from outer query blockouterPredicateList
- 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 classValueNode
- Parameters:
referencedTabs
- JBitSet with bit map of referenced FromTablessimplePredsOnly
- 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 classValueNode
- 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 classValueNode
- 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 classValueNode
- 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 classValueNode
- 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 classValueNode
- Parameters:
acb
- The ExpressionClassBuilder for the class we're generatingmb
- 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 classQueryTreeNode
- 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 classValueNode
- Parameters:
o
- the node to compare this ValueNode against.- Returns:
true
if the two nodes are equivalent,false
otherwise.- Throws:
StandardException
-
-