File	Doc	Category	Size	Date	Package
SymbolTable.java	API Doc	Glassfish v2 API	6021	Fri May 04 22:35:08 BST 2007	com.sun.jdo.spi.persistence.support.sqlstore.query.util.scope

SymbolTable

• java.lang.Object

Fields Summary
protected int	actualScope The actual scope level.
protected Stack	nestings Stack of old definitions.
protected Hashtable	symbols The table of declared identifier (symbols).

Constructors Summary

Methods Summary
public Definition	declare(java.lang.String ident, Definition def) Add identifier to the actual scope. If the identifier was already declared in the actual scope the symbol table is NOT changed and the old definition is returned. Otherwise a possible definition of a lower level scope is saved in the actual nesting and the new definition is stored in the symbol table. This allows to reinstall the old definition when the sctaul scope is closed. param ident identifier to be declared param definition new definition of identifier return the old definition if the identifier was already declared in the actual scope; null otherwise Definition old = (Definition)symbols.get(ident); def.setScope(actualScope); if ((old == null) || (old.getScope() < actualScope)) { Nesting nest = (Nesting)nestings.peek(); nest.add(ident, old); // save old definition in nesting symbols.put(ident, def); // install new definition as actual definition return null; } else { return old; }
public void	enterScope() Opens a new scope. Prepare everything to handle old definitions when a identifier declaration is hidden. actualScope++; nestings.push(new Nesting());
protected void	forgetNesting(Nesting nesting) Internal method to reinstall the old definitions. The method is called when a scope is closed. For all identifier that were declared in the closed scope their former definition (that was hidden) is reinstalled. param nesting list of hidden definitions String ident = null; Definition hidden = null; Iterator idents = nesting.getIdents(); Iterator hiddenDefs = nesting.getHiddenDefinitions(); while (idents.hasNext()) { ident = (String) idents.next(); hidden = (Definition) hiddenDefs.next(); if (hidden == null) { symbols.remove(ident); } else { symbols.put(ident, hidden); } }
public int	getActualScope() Returns the level of the actual scope. return actual scope level. return actualScope;
public Definition	getDefinition(java.lang.String ident) Checks the symbol table for the actual definition of the specified identifier. If the identifier is declared the definition is returned, otherwise null. param ident the name of identifier return the actual definition of ident is declared; null otherise. return (Definition)symbols.get(ident);
public boolean	isDeclared(java.lang.String ident) Checks whether the specified identifier is declared. param ident the name of identifier to be tested return true if the identifier is declared; false otherwise. return (getDefinition(ident) != null);
public void	leaveScope() Closes the actual scope. Hidden definitions are reinstalled. forgetNesting((Nesting)nestings.pop()); actualScope--;