public abstract class ConstantNode extends ValueNode
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
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX| Constructor and Description |
|---|
ConstantNode() |
| Modifier and Type | Method and Description |
|---|---|
void |
copyFrom(QueryTreeNode node)
Fill this node with a deep copy of the given node.
|
Object |
getValue()
Get the value in this ConstantNode
|
void |
init(Object typeId,
Object nullable,
Object maximumWidth)
Initializer for non-numeric types
|
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.
|
void |
setValue(Object value)
Set the value in this ConstantNode.
|
String |
toString()
Convert this object to a String.
|
getColumnName, getSchemaName, getSourceResultColumn, getTableName, getType, getTypeId, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeType, setNullability, setTypeaccept, convertDefaultNode, debugFlush, debugPrint, formatNodeString, getBeginOffset, getDebugOutput, getEndOffset, getNodeFactory, getNodeType, getNullNode, getParserContext, getStatementType, getUserData, init, init, init, init, init, init, init, init, init, init, init, init, isInstanceOf, makeTableName, makeTableName, nodeHeader, printLabel, printSubNodes, setBeginOffset, setDebugOutput, setEndOffset, setNodeType, setParserContext, setUserData, stackPrint, treePrint, treePrint, treePrintpublic void init(Object typeId, Object nullable, Object maximumWidth) throws StandardException
init in class QueryTreeNodetypeId - The Type ID of the datatypenullable - True means the constant is nullablemaximumWidth - The maximum number of bytes in the data valueStandardExceptionpublic void copyFrom(QueryTreeNode node) throws StandardException
copyFrom in class ValueNodeStandardExceptionpublic Object getValue()
public void setValue(Object value)
public String toString()
public boolean isConstantExpression()
isConstantExpression in class ValueNodeprotected boolean isEquivalent(ValueNode o) throws StandardException
ValueNodeThis 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:
isEquivalent in class ValueNodeo - the node to compare this ValueNode against.true if the two nodes are equivalent,
false otherwise.StandardExceptionCopyright © 2015 FoundationDB, LLC. All rights reserved.