ScopedSymbol.java

package test.antlr.pie;
/***
 * Excerpted from "Language Implementation Patterns",
 * published by The Pragmatic Bookshelf.
 * Copyrights apply to this code. It may not be used to create training material, 
 * courses, books, articles, and the like. Contact us if you are in doubt.
 * We make no guarantees that this code is fit for any purpose. 
 * Visit http://www.pragmaticprogrammer.com/titles/tpdsl for more book information.
***/
import java.util.Map;

public abstract class ScopedSymbol extends Symbol implements Scope {
    Scope enclosingScope;

    public ScopedSymbol(String name, Scope enclosingScope) {
        super(name);
        this.enclosingScope = enclosingScope;
    }

    public Symbol resolve(String name) {
        Symbol s = getMembers().get(name);
        if ( s!=null ) return s;
        // if not here, check any parent scope
        if ( getParentScope() != null ) {
            return getParentScope().resolve(name);
        }
        return null; // not found
    }

    public void define(Symbol sym) {
        getMembers().put(sym.name, sym);
        sym.scope = this; // track the scope in each symbol
    }

    public Scope getParentScope() { return getEnclosingScope(); }
    public Scope getEnclosingScope() { return enclosingScope; }    

    public String getScopeName() { return name; }

    /** Indicate how subclasses store scope members. Allows us to
     *  factor out common code in this class.
     */
    public abstract Map<String, Symbol> getMembers();
}