Daniel@0: /* Part of DML (Digital Music Laboratory)
Daniel@0: 	Copyright 2014-2015 Samer Abdallah, University of London
Daniel@0: 	 
Daniel@0: 	This program is free software; you can redistribute it and/or
Daniel@0: 	modify it under the terms of the GNU General Public License
Daniel@0: 	as published by the Free Software Foundation; either version 2
Daniel@0: 	of the License, or (at your option) any later version.
Daniel@0: 
Daniel@0: 	This program is distributed in the hope that it will be useful,
Daniel@0: 	but WITHOUT ANY WARRANTY; without even the implied warranty of
Daniel@0: 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Daniel@0: 	GNU General Public License for more details.
Daniel@0: 
Daniel@0: 	You should have received a copy of the GNU General Public
Daniel@0: 	License along with this library; if not, write to the Free Software
Daniel@0: 	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
Daniel@0: */
Daniel@0: 
Daniel@0: :- module(xmltraverse, [traverse/3, op(720,xfx,@), op(750,xfy,~), op(750,xfy,..) ]).
Daniel@0: % for traverse/3 paths
Daniel@0: :- op(720,xfx,@).
Daniel@0: :- op(750,xfy,~).
Daniel@0: :- op(750,xfy,..).
Daniel@0: 
Daniel@0: %% traverse(+Dir:oneof([f,b]), +Doc:xml_element, -P:xml_path) is nondet.
Daniel@0: %
Daniel@0: %  Succeeds once for each path through an XML element starting at the top
Daniel@0: %  and travelling all or part of the way down through the tree structure.
Daniel@0: traverse(f,El,Path) :- traverse_f(El,Path).
Daniel@0: traverse(b,El,Path) :- traverse_b([],El,Path).
Daniel@0: 
Daniel@0: traverse_f(Other,{Other}) :- atomic(Other), !.
Daniel@0: traverse_f(Element,\Element).
Daniel@0: traverse_f(element(Name,_,_), n(Name)).
Daniel@0: traverse_f(element(Name,Attribs,_),Name @ A) :- member(A,Attribs).
Daniel@0: traverse_f(element(Name,_,Content),Name .. Path1) :- 
Daniel@0:    (  Path1 = \Content
Daniel@0:    ;  Path1 = (I~Path2),
Daniel@0:       nth1(I,Content,SubE),
Daniel@0:       traverse_f(SubE,Path2)
Daniel@0:    ).
Daniel@0: 
Daniel@0: 
Daniel@0: traverse_b(L,Other,{Other}..L) :- atomic(Other), !.
Daniel@0: traverse_b(L,element(Name,Attribs,Content),Path) :- !,
Daniel@0:    (  Path = (A @ Name .. L), member(A,Attribs)
Daniel@0:    ;  nth1(N,Content,SubE),
Daniel@0:       traverse_b(N ~ Name..L,SubE,Path)
Daniel@0:    ).
Daniel@0: