com.akiban.sql.parser
Class ValueNode

java.lang.Object
  com.akiban.sql.parser.QueryTreeNode
      com.akiban.sql.parser.ValueNode

All Implemented Interfaces:

Visitable

Direct Known Subclasses:

BaseColumnNode, BinaryListOperatorNode, BinaryOperatorNode, CastNode, CoalesceFunctionNode, ColumnReference, ConditionalNode, ConstantNode, CurrentDatetimeOperatorNode, CurrentRowLocationNode, CurrentSequenceNode, DefaultNode, ExplicitCollateNode, GenerationClauseNode, InListOperatorNode, JavaToSQLValueNode, NextSequenceNode, ParameterNode, ResultColumn, RowConstructorNode, SimpleCaseNode, SpecialFunctionNode, SubqueryNode, TernaryOperatorNode, UnaryOperatorNode, VirtualColumnNode

public abstract class ValueNode
extends QueryTreeNode

A ValueNode is an abstract class for all nodes that can represent data values, that is, constants, columns, and expressions.

Field Summary

Fields inherited from class com.akiban.sql.parser.QueryTreeNode

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Constructor Summary

ValueNode()

Method Summary

void	copyFrom(QueryTreeNode node) Fill this node with a deep copy of the given node.
String	getColumnName() This is null so that the caller will substitute in the resultset generated name as needed.
String	getSchemaName() This returns the user-supplied schema name of the column.
ResultColumn	getSourceResultColumn() Get the source for this ValueNode.
String	getTableName() This returns the user-supplied table name of the column.
DataTypeDescriptor	getType() Get the DataTypeDescriptor from this ValueNode.
TypeId	getTypeId() Get the TypeId from this ValueNode.
void	init(Object typeId, Object precision, Object scale, Object isNullable, Object maximumWidth) Initializer for numeric types.
boolean	isBinaryEqualsOperatorNode() Returns true if this value node is a equals operator.
boolean	isBooleanFalse() Does this represent a false constant.
boolean	isBooleanTrue() Does this represent a true constant.
boolean	isConstantExpression() Return whether or not this expression tree represents a constant expression.
protected abstract boolean	isEquivalent(ValueNode other) Tests if this node is equivalent to the specified ValueNode.
boolean	isInListProbeNode() Returns true if this value node is an operator created for optimized performance of an IN list.
boolean	isParameterNode() Returns TRUE if this is a parameter node.
boolean	isRelationalOperator() Returns true if this ValueNode is a relational operator.
protected boolean	isSameNodeType(ValueNode other) Tests if this node is of the same type as the specified node as reported by QueryTreeNode.getNodeType().
void	setNullability(boolean nullability) Set the nullability of this value.
void	setType(DataTypeDescriptor type) Set the DataTypeDescriptor for this ValueNode.
String	toString() Convert this object to a String.

Methods inherited from class com.akiban.sql.parser.QueryTreeNode

accept, 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, init, isInstanceOf, makeTableName, makeTableName, nodeHeader, printLabel, printSubNodes, setBeginOffset, setDebugOutput, setEndOffset, setNodeType, setParserContext, setUserData, stackPrint, treePrint, treePrint, treePrint

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ValueNode

public ValueNode()

Method Detail

init

public void init(Object typeId,
                 Object precision,
                 Object scale,
                 Object isNullable,
                 Object maximumWidth)
          throws StandardException

Initializer for numeric types.

Overrides:

init in class QueryTreeNode

Parameters:

typeId - The TypeID of this new node

precision - The precision of this new node

scale - The scale of this new node

isNullable - The nullability of this new node

maximumWidth - The maximum width of this new node

Throws:

StandardException

copyFrom

public void copyFrom(QueryTreeNode node)
              throws StandardException

Fill this node with a deep copy of the given node.

Overrides:

copyFrom in class QueryTreeNode

Throws:

StandardException

toString

public 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 QueryTreeNode

Returns:

This object as a String

getType

public DataTypeDescriptor getType()

Get the DataTypeDescriptor from this ValueNode.

Returns:

The DataTypeDescriptor from this ValueNode. This may be null if the node isn't bound yet.

setNullability

public void setNullability(boolean nullability)
                    throws StandardException

Set the nullability of this value.

Throws:

StandardException

getTypeId

public TypeId getTypeId()
                 throws StandardException

Get the TypeId from this ValueNode.

Returns:

The TypeId from this ValueNode. This may be null if the node isn't bound yet.

Throws:

StandardException

setType

public void setType(DataTypeDescriptor type)
             throws StandardException

Set the DataTypeDescriptor for this ValueNode. This method is overridden in ParameterNode.

Parameters:

type - The DataTypeDescriptor to set in this ValueNode

Throws:

StandardException

getSourceResultColumn

public ResultColumn getSourceResultColumn()

Get the source for this ValueNode.

Returns:

The source of this ValueNode, null if this node is not sourced by a column.

getSchemaName

public String getSchemaName()
                     throws StandardException

This returns the user-supplied schema name of the column. At this class level, it simply returns null. But, the subclasses of ValueNode will overwrite this method to return the user-supplied schema name. When the value node is in a result column of a select list, the user can request metadata information. The result column won't have a column descriptor, so we return some default information through the expression. This lets expressions that are simply columns return all of the info, and others use this supertype's default values.

Returns:

the default schema name for an expression -- null

Throws:

StandardException

getTableName

public String getTableName()

This returns the user-supplied table name of the column. At this class level, it simply returns null. But, the subclasses of ValueNode will overwrite this method to return the user-supplied table name. When the value node is in a result column of a select list, the user can request metadata information. The result column won't have a column descriptor, so we return some default information through the expression. This lets expressions that are simply columns return all of the info, and others use this supertype's default values.

Returns:

the default table name for an expression -- null

getColumnName

public String getColumnName()

This is null so that the caller will substitute in the resultset generated name as needed.

Returns:

the default column name for an expression -- null.

isConstantExpression

public boolean isConstantExpression()

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

Returns:

Whether or not this expression tree represents a constant expression.

isBooleanTrue

public boolean isBooleanTrue()

Does this represent a true constant.

Returns:

Whether or not this node represents a true constant.

isBooleanFalse

public boolean isBooleanFalse()

Does this represent a false constant.

Returns:

Whether or not this node represents a false constant.

isRelationalOperator

public boolean isRelationalOperator()

Returns true if this ValueNode is a relational operator. Relational Operators are <, <=, =, >, >=, <> as well as IS NULL and IS NOT NULL. This is the preferred way of figuring out if a ValueNode is relational or not.

See Also:

RelationalOperator, BinaryRelationalOperatorNode, IsNullNode

isBinaryEqualsOperatorNode

public boolean isBinaryEqualsOperatorNode()

Returns true if this value node is a equals operator.

See Also:

isRelationalOperator()

isInListProbeNode

public boolean isInListProbeNode()

Returns true if this value node is an operator created for optimized performance of an IN list. Or more specifically, returns true if this value node is an equals operator of the form "col = ?" that we generated during preprocessing to allow index multi-probing.

isParameterNode

public boolean isParameterNode()

Returns TRUE if this is a parameter node. We do lots of special things with Parameter Nodes.

isEquivalent

protected abstract boolean isEquivalent(ValueNode other)
                                 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.

Parameters:

other - the node to compare this ValueNode against.

Returns:

true if the two nodes are equivalent, false otherwise.

Throws:

StandardException

isSameNodeType

protected final boolean isSameNodeType(ValueNode other)

Tests if this node is of the same type as the specified node as reported by QueryTreeNode.getNodeType().

Parameters:

other - the node to compare this value node against.

Returns:

true if the two nodes are of the same type.