HasVariantValueNodeVisitor (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.impl.sql.compile.HasVariantValueNodeVisitor

All Implemented Interfaces:: Visitor

class HasVariantValueNodeVisitor
extends java.lang.Object
implements Visitor

Find out if we have a value node with variant type less than what the caller desires, anywhere below us. Stop traversal as soon as we find one. This is used in two places: one to check the values clause of an insert statement; i.e

 insert into  values (?, 1, foobar());
 
 If all the expressions in the values clause are QUERY_INVARIANT (and an
 exception is made for parameters) then we can cache the results in the
 RowResultNode. This is useful when we have a prepared insert statement which
 is repeatedly executed.
 
 The second place where this is used is to check if a subquery can be
 materialized or not.

See Also:
Qualifier








Field Summary





Fields 

Modifier and Type
Field
Description


private boolean
hasVariant
 


private boolean
ignoreParameters
 


private int
variantType

Fields
Modifier and Type	Field	Description
`private boolean`	`hasVariant`
`private boolean`	`ignoreParameters`
`private int`	`variantType`

Constructor Summary

Constructors
Constructor	Description
`HasVariantValueNodeVisitor()`	Construct a visitor
`HasVariantValueNodeVisitor(int variantType, boolean ignoreParameters)`	Construct a visitor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) boolean`	`hasVariant()`	Indicate whether we found the node in question
`boolean`	`skipChildren(Visitable node)`	Method that is called to indicate whether we should skip all nodes below this node for traversal.
`boolean`	`stopTraversal()`	Stop traversal if we found the target node
`Visitable`	`visit(Visitable node)`	If we have found the target node, we are done.
`boolean`	`visitChildrenFirst(Visitable node)`	Method that is called to see if `visit()` should be called on the children of `node` before it is called on `node` itself.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - hasVariant
```
private boolean hasVariant
```
  - variantType
```
private int variantType
```
  - ignoreParameters
```
private boolean ignoreParameters
```
- Constructor Detail
  - HasVariantValueNodeVisitor
```
HasVariantValueNodeVisitor()
```
    Construct a visitor
  - HasVariantValueNodeVisitor
```
HasVariantValueNodeVisitor(int variantType,
                           boolean ignoreParameters)
```
    Construct a visitor. Pass in the variant type. We look for nodes that are less than or equal to this variant type. E.g., if the variantType is Qualifier.SCAN_VARIANT, then any node that is either VARIANT or SCAN_VARIANT will cause the visitor to consider it variant.
    
    Parameters:
    
    variantType - the type of variance we consider variant
    
    ignoreParameters - should I ignore parameter nodes?
- Method Detail
  - visit
```
public Visitable visit(Visitable node)
                throws StandardException
```
    If we have found the target node, we are done.
    
    Specified by:
    
    visit in interface Visitor
    
    Parameters:
    
    node - the node to process
    
    Returns:
    
    me
    
    Throws:
    
    StandardException - on error
  - skipChildren
```
public boolean skipChildren(Visitable node)
```
    Description copied from interface: Visitor
    
    Method that is called to indicate whether we should skip all nodes below this node for traversal. Useful if we want to effectively ignore/prune all branches under a particular node.
    Differs from stopTraversal() in that it only affects subtrees, rather than the entire traversal.
    
    Specified by:
    
    skipChildren in interface Visitor
    
    Parameters:
    
    node - the node to process
    
    Returns:
    
    true/false
  - visitChildrenFirst
```
public boolean visitChildrenFirst(Visitable node)
```
    Description copied from interface: Visitor
    
    Method that is called to see if visit() should be called on the children of node before it is called on node itself. If this method always returns true, the visitor will walk the tree bottom-up. If it always returns false, the tree is visited top-down.
    
    Specified by:
    
    visitChildrenFirst in interface Visitor
    
    Parameters:
    
    node - the top node of a sub-tree about to be visited
    
    Returns:
    
    true if node's children should be visited before node, false otherwise
  - stopTraversal
```
public boolean stopTraversal()
```
    Stop traversal if we found the target node
    
    Specified by:
    
    stopTraversal in interface Visitor
    
    Returns:
    
    true/false
  - hasVariant
```
boolean hasVariant()
```
    Indicate whether we found the node in question
    
    Returns:
    
    true/false

Class HasVariantValueNodeVisitor

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

hasVariant

variantType

ignoreParameters

Constructor Detail

HasVariantValueNodeVisitor

HasVariantValueNodeVisitor

Method Detail

visit

skipChildren

visitChildrenFirst

stopTraversal

hasVariant