package runEnv;

import env.*;

public class RunEnv {

/*
Represents the run time environment, composed of 
the globals, current instance, and current invocation.
*/
	private PtrValue globals;
	private PtrValue instance;
	private PtrValue locals;
	
	public PtrValue globals() { return globals; }
	public PtrValue instance() { return instance; }
	public PtrValue locals() { return locals; }
	
	public RunEnv( 
		PtrValue globals,
		PtrValue instance,
		PtrValue locals ) {
		this.globals = globals;
		this.instance = instance;
		this.locals = locals;
		}

	public RunEnv( 
		PtrValue globals ) {
		this.globals = globals;
		this.instance = null;
		this.locals = null;
		}

	public PtrValue elementAt( Decl decl ) {
		switch ( decl.env().envKind() ) {
			case Env.ENV_GLOBAL:
				return globals().elementAt( decl.offset().interp() );
			case Env.ENV_CLASS:
				return instance().elementAt( decl.offset().interp() );
			case Env.ENV_METHOD:
				return locals().elementAt( decl.offset().interp() );
			default:
				throw new Error( 
					"Invalid section of " + Decl.sectionText( decl.section() )
					+ " for identifier " + decl.ident() );
			}
		}

	public RunValue getValue( Decl decl ) {
		return elementAt( decl ).getValue();
		}
		
	}