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

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

All Implemented Interfaces:

Node, Visitable

public class CastNode
extends ValueNode

An CastNode represents a cast expressionr.

Field Summary

private boolean	assignmentSemantics Method calls: Argument type has the same semantics as assignment: Section 9.2 (Store assignment).
(package private) ValueNode	castOperand
private boolean	externallyGeneratedCastNode This variable gets set by the parser to indiciate that this CAST node has been generated by the parser.
private boolean	forDataTypeFunction
(package private) TypeId	sourceCTI
private int	targetCharType

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

CastNode()

Method Summary

(package private) void	acceptChildren(Visitor v) Accept the visitor for all visitable children of this node.
void	bindCastNodeOnly() Bind this node but not its child.
ValueNode	bindExpression(FromList fromList, SubqueryList subqueryList, java.util.List 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.
private void	genDataValueConversion(ExpressionClassBuilder acb, MethodBuilder mb)
void	generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) Do code generation for this unary operator.
private ValueNode	getCastFromCharConstant(int destJDBCTypeId) Get a constant representing the cast from a CHAR to another type.
private ValueNode	getCastFromIntegralType(long longValue, int destJDBCTypeId) Get a constant representing the cast from an integral type to another type.
private ValueNode	getCastFromNumericType(DataValueDescriptor constantValue, int destJDBCTypeId) Get a constant representing the cast from a non-integral type to another type.
(package private) java.lang.Object	getConstantValueAsObject() Return an Object representing the bind time value of this expression tree.
protected int	getOrderableVariantType() Return the variant type for the underlying expression.
void	init(java.lang.Object castOperand, java.lang.Object castTarget) Initializer for a CastNode
void	init(java.lang.Object castOperand, java.lang.Object charType, java.lang.Object charLength) Initializer for a CastNode
boolean	isConstantExpression() Return whether or not this expression tree represents a constant expression.
protected boolean	isEquivalent(ValueNode o) Tests if this node is equivalent to the specified ValueNode.
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.
(package private) void	setAssignmentSemantics() Set assignmentSemantics to true.
(package private) void	setForDataTypeFunction(boolean b) set this to be a dataTypeScalarFunction
(package private) void	setForExternallyGeneratedCASTnode() This method gets called by the parser to indiciate that this CAST node has been generated by the parser.
java.lang.String	toString() Convert this object to a String.

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

bindExpression, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClone, getColumnName, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeType, optimizableEqualityNode, putAndsOnTop, 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, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, 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, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, orReliability, parseStatement, printLabel, 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

castOperand

ValueNode castOperand

targetCharType

private int targetCharType

sourceCTI

TypeId sourceCTI

forDataTypeFunction

private boolean forDataTypeFunction

externallyGeneratedCastNode

private boolean externallyGeneratedCastNode

This variable gets set by the parser to indiciate that this CAST node has been generated by the parser. This means that we should use the collation info of the current compilation schmea for this node's collation setting. If this variable does not get set to true, then it means that this CAST node has been an internally generated node and we should not touch the collation info set for this CAST node because it has been already set correctly by the class that generated this CAST node. Collation info is part of the DataTypeDescriptor that's defined on the ValueNode (the super class of this CastNode class)

assignmentSemantics

private boolean assignmentSemantics

Method calls: Argument type has the same semantics as assignment: Section 9.2 (Store assignment). There, General Rule 2.b.v.2 says that the database should raise an exception if truncation occurs when stuffing a string value into a VARCHAR, so make sure CAST doesn't issue warning only.

Constructor Detail

CastNode

public CastNode()

Method Detail

init

public void init(java.lang.Object castOperand,
                 java.lang.Object castTarget)
          throws StandardException

Initializer for a CastNode

Specified by:

init in interface Node

Overrides:

init in class QueryTreeNode

Parameters:

castOperand - The operand of the node

castTarget - DataTypeServices (target type of cast)

Throws:

StandardException - Thrown on error

init

public void init(java.lang.Object castOperand,
                 java.lang.Object charType,
                 java.lang.Object charLength)
          throws StandardException

Initializer for a CastNode

Specified by:

init in interface Node

Overrides:

init in class QueryTreeNode

Parameters:

castOperand - The operand of the node

charType - CHAR or VARCHAR JDBC type as target

charLength - target type length

Throws:

StandardException - Thrown on error

toString

public java.lang.String toString()

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

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

getOrderableVariantType

protected int getOrderableVariantType()
                               throws StandardException

Description copied from class: ValueNode

Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)

Overrides:

getOrderableVariantType in class ValueNode

Returns:

The variant type for the underlying expression.

Throws:

StandardException - Thrown on error

bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.List 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

bindCastNodeOnly

public void bindCastNodeOnly()
                      throws StandardException

Bind this node but not its child. Caller has already bound the child. This is useful for when we generate a CastNode during binding after having already bound the child.

Throws:

StandardException - Thrown on error

getCastFromCharConstant

private ValueNode getCastFromCharConstant(int destJDBCTypeId)
                                   throws StandardException

Get a constant representing the cast from a CHAR to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- char boolean char date/time/ts char non-decimal numeric

Parameters:

destJDBCTypeId - The destination JDBC TypeId

Returns:

The new top of the tree (this CastNode or a new Constant)

Throws:

StandardException - Thrown on error

getCastFromIntegralType

private ValueNode getCastFromIntegralType(long longValue,
                                          int destJDBCTypeId)
                                   throws StandardException

Get a constant representing the cast from an integral type to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- integral type non-decimal numeric integral type char

Parameters:

longValue - integral type as a long to cast from

destJDBCTypeId - The destination JDBC TypeId

Returns:

The new top of the tree (this CastNode or a new Constant)

Throws:

StandardException - Thrown on error

getCastFromNumericType

private ValueNode getCastFromNumericType(DataValueDescriptor constantValue,
                                         int destJDBCTypeId)
                                  throws StandardException

Get a constant representing the cast from a non-integral type to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- non-integral type non-decimal numeric non-integral type char

Parameters:

constantValue - non-integral type a a double to cast from

destJDBCTypeId - The destination JDBC TypeId

Returns:

The new top of the tree (this CastNode or a new Constant)

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)

getConstantValueAsObject

java.lang.Object getConstantValueAsObject()
                                    throws StandardException

Return an Object representing the bind time value of this expression tree. If the expression tree does not evaluate to a constant at bind time then we return null. This is useful for bind time resolution of VTIs. RESOLVE: What do we do for primitives?

Overrides:

getConstantValueAsObject in class ValueNode

Returns:

An Object representing the bind time value of this expression tree. (null if not a bind time constant.)

Throws:

StandardException - Thrown on error

generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               MethodBuilder mb)
                        throws StandardException

Do code generation for this unary operator.

Overrides:

generateExpression in class ValueNode

Parameters:

acb - The ExpressionClassBuilder for the class we're generating

mb - The method the code to place the code

Throws:

StandardException - Thrown on error

genDataValueConversion

private void genDataValueConversion(ExpressionClassBuilder acb,
                                    MethodBuilder mb)
                             throws StandardException

Throws:

StandardException

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

setForExternallyGeneratedCASTnode

void setForExternallyGeneratedCASTnode()

This method gets called by the parser to indiciate that this CAST node has been generated by the parser. This means that we should use the collation info of the current compilation schmea for this node's collation setting. If this method does not get called, then it means that this CAST node has been an internally generated node and we should not touch the collation of this CAST node because it has been already set correctly by the class that generated this CAST node.

setForDataTypeFunction

void setForDataTypeFunction(boolean b)

set this to be a dataTypeScalarFunction

Parameters:

b - true to use function conversion rules

setAssignmentSemantics

void setAssignmentSemantics()

Set assignmentSemantics to true. Used by method calls for casting actual arguments

isEquivalent

protected 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