com.metamatrix.query.sql.visitor
Class ExpressionSymbolCollector

java.lang.Object
  com.metamatrix.query.sql.LanguageVisitor
      com.metamatrix.query.sql.visitor.ExpressionSymbolCollector

public class ExpressionSymbolCollector
extends LanguageVisitor

This visitor class will traverse a language object tree and collect all expression element symbol references it finds. It uses a collection to collect the symbols in so different collections will give you different collection properties - for instance, using a Set will remove duplicates.

The easiest way to use this visitor is to call the static methods which create the visitor (and possibly the collection), run the visitor, and return the collection. The public visit() methods should NOT be called directly.

Constructor Summary

ExpressionSymbolCollector(java.util.Collection elements)
Construct a new visitor with the specified collection, which should be non-null.

Method Summary

java.util.Collection	getSymbols() Get the elements collected by the visitor.
static void	getSymbols(LanguageObject obj, java.util.Collection elements) Helper to quickly get the elements from obj in the elements collection
void	visit(AggregateSymbol obj) Visit a language object and collect symbols.
void	visit(ExpressionSymbol obj) Visit a language object and collect symbols.

Methods inherited from class com.metamatrix.query.sql.LanguageVisitor

setAbort, shouldAbort, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionSymbolCollector

public ExpressionSymbolCollector(java.util.Collection elements)

Construct a new visitor with the specified collection, which should be non-null.

Parameters:

elements - Collection to use for elements

Throws:

java.lang.IllegalArgumentException - If elements is null

Method Detail

getSymbols

public java.util.Collection getSymbols()

Get the elements collected by the visitor. This should best be called after the visitor has been run on the language object tree.

Returns:

Collection of ElementSymbol

visit

public void visit(ExpressionSymbol obj)

Visit a language object and collect symbols. This method should NOT be called directly.

Overrides:

visit in class LanguageVisitor

Parameters:

obj - Language object

visit

public void visit(AggregateSymbol obj)

Visit a language object and collect symbols. This method should NOT be called directly.

Overrides:

visit in class LanguageVisitor

Parameters:

obj - Language object

getSymbols

public static final void getSymbols(LanguageObject obj,
                                    java.util.Collection elements)

Helper to quickly get the elements from obj in the elements collection

Parameters:

obj - Language object

elements - Collection to collect elements in