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%                                                                           %
% File:            qnodexx.dtr                                              %
% Purpose:         Simple test theory for Qnode facility in DATR            %
% Author:          Gerald Gazdar, July 1994                                 %
% Email:           geraldg@cogs.sussex.ac.uk                                %
% Address:         COGS, Sussex University, Brighton BN1 9QH, UK            %
% Version:         1.0                                                      %
%                                                                           %
%      Copyright (c) University of Sussex 1994.  All rights reserved.       %
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%   The Qnode name *always* denotes the query node.  Thus, in simple DATR
%   theories, it duplicates the function of quoted paths, but in DATR
%   theories that change the global context through the use of a quoted
%   node or quoted node-path pair, the Qnode allows you to access the
%   identity of the original query node which would otherwise be lost.
%   Syntactically, once declared, the Qnode behaves exactly like any
%   other node name except, of course, that it cannot appear as the name
%   of a defined node (the compiler needs to flag an error if the user
%   tries to do this).  Semantically, the Qnode can be thought of as a
%   synonym of the query node that is added dynamically (and subsequently
%   retracted) as each query is evaluated (one can implement it this way).

# qnode MyQnodeName.

Top:
    <quoted x> == "<x>"
    <qnoded x> == MyQnodeName:<x>.

Middle:
    <> == Top
    <x> == middle x-value.

Terminal1:
    <> == Middle
    <x> == terminal 1 x-value.

Terminal2:
    <> == "Middle"
    <x> == terminal 2 x-value.

% The relevant theorems:
% 
% Terminal1:
%     <quoted x> = terminal 1 x-value
%     <qnoded x> = terminal 1 x-value.
% 
% Terminal2:
%     <quoted x> = middle x-value
%     <qnoded x> = terminal 2 x-value.

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# hide Top Middle.

# show <quoted x> <qnoded x>.

% The next line is the Revision Control System Id: do not delete it.
% $Id: archive.dtr,v 1.1 1997/04/09 20:40:33 root Exp $