import syntaxtree.*;
import java.util.*;

class Environment {

    private Stack<MethodEnv> stack;
   
    public Environment() {
	stack = new Stack<MethodEnv>();
    }

    public void pushMethod(MethodEnv m){
	stack.push(m);
    }

    public void popMethod(){
	stack.pop();
    }

    public MethodEnv topMethod(){
	return stack.peek();
    }

    public Object getVarValue(String id){
       MethodEnv m = topMethod();

       if(m.containsVar(id)) 
          return m.getVarValue(id);

       if(m.containsParam(id))
          return m.getParamValue(id);

       ClassEnv c = m.enclosingClass;
       while(c != null) {
          if(c.containsVar(id)) {
              return c.getVarValue(id);
          }
          else {
              if(c.parent() == null) {
                  c = null;
              }
              else {
                  c = c.parent();
              }
          }
       }

       return null;
    }

    public void setVarValue(String id, Object o){
       MethodEnv m = topMethod();

       if(m.containsVar(id)) { 
          m.setVarValue(id, o);
	  return;
       }

       if(m.containsParam(id)) {
          m.setParamValue(id, o);
	  return;
       }

       ClassEnv c = m.enclosingClass;
       while(c != null) {
          if(c.containsVar(id)) {
             c.setVarValue(id, o);
	     return;
          }
          else {
              if(c.parent() == null) {
                  c = null;
              }
              else {
                  c = c.parent();
              }
          }
       }
    }
	
}//Environment

class ClassEnv {

    String id;
    ClassEnv parent;
    Hashtable<String, Object> globals;
    
    public ClassEnv(Class c) {
        id = c.id;
	globals = new Hashtable<String, Object>();
	for (Enumeration e = c.globals.keys(); e.hasMoreElements() ;) 
      	    globals.put((String)(e.nextElement()), new Integer(0));
    }
    
    public ClassEnv() {}
    
    public ClassEnv parent() { return parent; }

    public Object getVarValue(String id) {
	if(containsVar(id)) 
	    return globals.get(id);
        return null;
    }

    public boolean setVarValue(String id, Object o) {
	if(containsVar(id)){ 
	   globals.put(id, o);
	   return true;
	}
	return false;
    }
    
    public boolean containsVar(String id) {
	return globals.containsKey(id);
    }
    
} // ClassEnv

class MethodEnv {

    ClassEnv enclosingClass;	
    Hashtable<String, Object> params;
    Hashtable<String, Object> locals;
    
    public MethodEnv(Method m, ClassEnv ce) {
	enclosingClass = ce;

	params = new Hashtable<String, Object>();
	for (Enumeration e = m.params.elements(); e.hasMoreElements() ;) 
	     params.put(((Variable)(e.nextElement())).id, new Integer(0));

	locals = new Hashtable<String, Object>();
	for (Enumeration e = m.vars.keys(); e.hasMoreElements() ;) 
      	    locals.put((String)(e.nextElement()), new Integer(0));
    }
    
    public boolean setVarValue(String id, Object o) {
	if(locals.containsKey(id)) { 
	    locals.put(id, o);
	    return true;
	}
	return false;
    }
        
    public boolean setParamValue(String id, Object o) {
	if(params.containsKey(id)) { 
	    params.put(id, o);
	    return true;
	}
	return false;
    }

    public Object getVarValue(String id) {
	if(containsVar(id)) 
	   return locals.get(id);
	return null;
    }

    public Object getParamValue(String id) {
	if(containsParam(id)) 
	   return params.get(id);
	return null;
    }
   
    public boolean containsVar(String id) {
	return locals.containsKey(id);
    }
    
    public boolean containsParam(String id) {
	return params.containsKey(id);
    }
 
} // MethodEnv