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

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

All Implemented Interfaces:

org.apache.derby.iapi.sql.compile.Visitable

Direct Known Subclasses:

BitConstantNode, BooleanConstantNode, CharConstantNode, LOBConstantNode, NumericConstantNode, SQLBooleanConstantNode, UntypedNullConstantNode, UserTypeConstantNode, XMLConstantNode

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abstract class ConstantNode

extends ValueNode

ConstantNode holds literal constants as well as nulls.

A NULL from the parser may not yet know its type; that must be set during binding, as it is for parameters.

the DataValueDescriptor methods want to throw exceptions when they are of the wrong type, but to do that they must check typeId when the value is null, rather than the instanceof check they do for returning a valid value.

For code generation, we generate a static field. Then we set the field be the proper constant expression (something like getDatavalueFactory().getCharDataValue("hello", ...)) ) in the constructor of the generated method. Ideally we would have just

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Field Summary
protected  org.apache.derby.iapi.types.DataValueDescriptor	value

 

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
(package private)	ConstantNode()           Constructor for untyped nodes, which contain little information

 

Method Summary
ValueNode	bindExpression(FromList fromList, SubqueryList subqueryList, java.util.Vector aggregateVector)           Bind this expression.
boolean	constantExpression(PredicateList whereClause)           Return whether or not this expression tree represents a constant value.
(package private) abstract  void	generateConstant(ExpressionClassBuilder acb, org.apache.derby.iapi.services.compiler.MethodBuilder mb)           This generates the proper constant.
void	generateExpression(ExpressionClassBuilder acb, org.apache.derby.iapi.services.compiler.MethodBuilder mb)           For a ConstantNode, we generate the equivalent literal value.
ValueNode	getClone()           Return a clone of this node.
protected  int	getOrderableVariantType()           Return the variant type for the underlying expression.
org.apache.derby.iapi.types.DataValueDescriptor	getValue()           Get the value in this ConstantNode
void	init(java.lang.Object typeId, java.lang.Object nullable, java.lang.Object maximumWidth)           Initializer for non-numeric types
boolean	isCloneable()           Return whether or not this expression tree is cloneable.
boolean	isConstantExpression()           Return whether or not this expression tree represents a constant expression.
boolean	isNull()           Return whether or not this node represents a typed null constant.
(package private)  void	setValue(org.apache.derby.iapi.types.DataValueDescriptor value)           Set the value in this ConstantNode.
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, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, copyFields, eliminateNots, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getColumnName, getConstantValueAsObject, getDataValueFactory, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, selectivity, setClause, setDescriptor, setTransformed, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

 

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

accept, 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, printSubNodes, referencesSessionSchema, resolveTableToSynonym, 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

value

protected org.apache.derby.iapi.types.DataValueDescriptor value

Constructor Detail

ConstantNode

ConstantNode()

Constructor for untyped nodes, which contain little information

Method Detail

init

public void init(java.lang.Object typeId,
                 java.lang.Object nullable,
                 java.lang.Object maximumWidth)
          throws org.apache.derby.iapi.error.StandardException

Initializer for non-numeric types

Overrides:

init in class QueryTreeNode

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setValue

void setValue(org.apache.derby.iapi.types.DataValueDescriptor value)

Set the value in this ConstantNode.

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getValue

public org.apache.derby.iapi.types.DataValueDescriptor getValue()

Get the value in this ConstantNode

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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

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isCloneable

public boolean isCloneable()

Return whether or not this expression tree is cloneable.

Overrides:

isCloneable in class ValueNode

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getClone

public ValueNode getClone()

Return a clone of this node.

Overrides:

getClone in class ValueNode

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bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.Vector aggregateVector)

Bind this expression. This means binding the sub-expressions, as well as figuring out what the return type is for this expression. In this case, there are no sub-expressions, and the return type is already known, so this is just a stub.

Overrides:

bindExpression in class ValueNode

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isConstantExpression

public boolean isConstantExpression()

Return whether or not this expression tree represents a constant expression.

Overrides:

isConstantExpression in class ValueNode

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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

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generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               org.apache.derby.iapi.services.compiler.MethodBuilder mb)
                        throws org.apache.derby.iapi.error.StandardException

For a ConstantNode, we generate the equivalent literal value. A null is generated as a Null value cast to the type of the constant node. The subtypes of ConstantNode generate literal expressions for non-null values.

Overrides:

generateExpression in class ValueNode

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generateConstant

abstract void generateConstant(ExpressionClassBuilder acb,
                               org.apache.derby.iapi.services.compiler.MethodBuilder mb)
                        throws org.apache.derby.iapi.error.StandardException

This generates the proper constant. It is implemented by every specific constant node (e.g. IntConstantNode).

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isNull

public boolean isNull()

Return whether or not this node represents a typed null constant.

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getOrderableVariantType

protected int getOrderableVariantType()

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 VARIANT - immutable

Overrides:

getOrderableVariantType in class ValueNode

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> apache >> derby >> impl >> sql >> [ compile overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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