gecko-dev/js/js2/JSScope.h
2000-04-08 02:29:07 +00:00

80 lines
2.8 KiB
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Executable File

// -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
//
// The contents of this file are subject to the Netscape Public
// License Version 1.1 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of
// the License at http://www.mozilla.org/NPL/
//
// Software distributed under the License is distributed on an "AS
// IS" basis, WITHOUT WARRANTY OF ANY KIND, either express oqr
// implied. See the License for the specific language governing
// rights and limitations under the License.
//
// The Original Code is the JavaScript 2 Prototype.
//
// The Initial Developer of the Original Code is Netscape
// Communications Corporation. Portions created by Netscape are
// Copyright (C) 1998 Netscape Communications Corporation. All
// Rights Reserved.
/**
* Opaque reference to a JavaScript object.
*/
class JSObject;
/**
* Opaque reference to a general JavaScript identifier key.
* This can represent both UNICODE strings, and other more
* efficient representations, such as hashcodes, etc.
*/
class JSIdentifier;
/**
* Some fundamental constants.
*/
#define JSNULL (0)
#define JSUNDEFINED = ((JSObject*)(-1))
/**
* Basic abstraction to associate names with values in a chain of scopes.
* Can represent any kind of scope, including lexical scopes (closures),
* namespaces, and classes. Access control can be implemented
*/
class JSScope {
public:
/**
* Gets the enclosing scope of this scope (if any).
* @return enclosing scope or JSNULL if none.
*/
virtual JSScope* getParent() = 0;
/**
* Defines a new identifier in the current scope. In a completely static
* model, this may not be possible, and so this operation will be ignored.
* @param start the evaluation scope
* @param id identifier to define
* @param value optional value to associate with id
*/
virtual void defineValue(JSScope* start, JSIndentifier* id, JSObject* value = JSUNDEFINED) = 0;
/**
* Looks up a value corresponding to the given identifier starting
* with the current scope, and proceeding up the scope chain. If
* the identifier's is not defined in any of the scopes, the value
* JSUNDEFINED is returned.
* @param start the evaluation scope
* @parm id the identifer to lookup
* @return result of lookup or JSUNDEFINED
*/
virtual JSObject* getValue(JSScope* start, JSIdentifier* id) = 0;
/**
* Associates a value with an identifier in a given scope.
* @param start the evaluation scope
* @param id identifier to assign to
* @param value new value to give to id
* @return old value associated with identifier
*/
virtual JSObject* setValue(JSScope* start, JSIdentifier* id, JSObject* value) = 0;
};