com.splicemachine.db.impl.ast

Class SpliceASTWalker

java.lang.Object

com.splicemachine.db.impl.ast.SpliceASTWalker

All Implemented Interfaces:

ASTVisitor, Visitor

public class SpliceASTWalker
extends java.lang.Object
implements ASTVisitor

Implementation of Derby's ASTVisitor interface which runs multiple Splice visitors for each of Derby's "ASTWalker" phases:

1 after parsing 2 after binding & 3 after optimization

User: pjt Date: 7/5/13

Field Summary

Fields

Modifier and Type	Field and Description
java.util.Map<CompilationPhase,java.util.List<java.lang.Class<? extends ISpliceVisitor>>>	visitorClasses

Constructor Summary

Constructors

Constructor and Description
SpliceASTWalker(java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterParseClasses, java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterBindClasses, java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterOptimizeClasses)

Method Summary

Modifier and Type	Method and Description
void	begin(java.lang.String statementText, CompilationPhase phase) The compiler calls this method just before walking a query tree.
void	end(CompilationPhase phase) The compiler calls this method when it's done walking a tree.
void	initializeVisitor() Initialize the Visitor before processing any trees.
boolean	skipChildren(Visitable node) Method that is called to indicate whether we should skip all nodes below this node for traversal.
boolean	stopTraversal() Method that is called to see if query tree traversal should be stopped before visiting all nodes.
void	teardownVisitor() Final call to the Visitor.
Visitable	visit(Visitable node, QueryTreeNode parent) This is the default visit operation on a QueryTreeNode.
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

visitorClasses

public final java.util.Map<CompilationPhase,java.util.List<java.lang.Class<? extends ISpliceVisitor>>> visitorClasses

Constructor Detail

SpliceASTWalker

public SpliceASTWalker(java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterParseClasses,
                       java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterBindClasses,
                       java.util.List<java.lang.Class<? extends ISpliceVisitor>> afterOptimizeClasses)

Method Detail

begin

public void begin(java.lang.String statementText,
                  CompilationPhase phase)
           throws StandardException

Description copied from interface: ASTVisitor

The compiler calls this method just before walking a query tree.

Specified by:

begin in interface ASTVisitor

Parameters:

statementText - Text used to create the tree.

phase - of compilation (AFTER_PARSE, AFTER_BIND, or AFTER_OPTIMIZE).

Throws:

StandardException

end

public void end(CompilationPhase phase)
         throws StandardException

Description copied from interface: ASTVisitor

The compiler calls this method when it's done walking a tree.

Specified by:

end in interface ASTVisitor

Parameters:

phase - of compilation (AFTER_PARSE, AFTER_BIND, or AFTER_OPTIMIZE).

Throws:

StandardException

visit

public Visitable visit(Visitable node,
                       QueryTreeNode parent)
                throws StandardException

Description copied from interface: Visitor

This is the default visit operation on a QueryTreeNode. It just returns the node. This will typically suffice as the default visit operation for most visitors unless the visitor needs to count the number of nodes visited or something like that.

Visitors will overload this method by implementing a version with a signature that matches a specific type of node. For example, if I want to do something special with aggregate nodes, then that Visitor will implement a visit(AggregateNode node) method which does the aggregate specific processing.

Specified by:

visit in interface Visitor

Parameters:

node - the node to process

parent - the parent of the node being visited, or, more generally, the node that contains a reference to the node being visited.

Returns:

a query tree node. Often times this is the same node that was passed in, but Visitors that replace nodes with other nodes will use this to return the new replacement node.

Throws:

StandardException - may be throw an error as needed by the visitor (i.e. may be a normal error if a particular node is found, e.g. if checking a group by, we don't expect to find any ColumnReferences that aren't under an AggregateNode -- the easiest thing to do is just throw an error when we find the questionable node).

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()

Description copied from interface: Visitor

Method that is called to see if query tree traversal should be stopped before visiting all nodes. Useful for short circuiting traversal if we already know we are done.

Specified by:

stopTraversal in interface Visitor

Returns:

true/false

skipChildren

public boolean skipChildren(Visitable node)
                     throws StandardException

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

Throws:

StandardException

initializeVisitor

public void initializeVisitor()
                       throws StandardException

Description copied from interface: ASTVisitor

Initialize the Visitor before processing any trees. User-written code calls this method before poking the Visitor into the LanguageConnectionContext. For example, an implementation of this method might open a trace file.

Specified by:

initializeVisitor in interface ASTVisitor

Throws:

StandardException

teardownVisitor

public void teardownVisitor()
                     throws StandardException

Description copied from interface: ASTVisitor

Final call to the Visitor. User-written code calls this method when it is done inspecting query trees. For instance, an implementation of this method might release resources, closing files it has opened.

Specified by:

teardownVisitor in interface ASTVisitor

Throws:

StandardException