tests/org.eclipse.qvtd.atl.tests/models/tree2list/Tree2List.atl

-- @name Tree structure to List structure
-- @version 1.0
-- @domains 
-- @authors Cyril Faure
-- @date 01/06/2007
-- @description "toy example" of model transformation usually made with a DFS (Depth First Search) imperative algorithms
-- @see http://en.wikipedia.org/wiki/Depth-first_search
-- @path MMTree=/org.eclipse.qvtd.atl.tests/models/tree2list/MMTree.ecore
-- @path MMElementList=/org.eclipse.qvtd.atl.tests/models/tree2list/MMElementList.ecore

module Tree2List;
create elmList : MMElementList from aTree : MMTree;

uses Lib4MMTree;

-- we want to process the tree via DFS and create an ordered list containing :
-- all big leafs, then all medium leafs, then all small leafs. We add the
-- constraint we want all three "sublists" to be ordered on the DFS traversal order
-- Note : the nodes (other than the tree root) are not kept in the destination model

-- The transformation is done with only one matched rule. For each element of its elements reference, we create a MMElementList!CommonElement. 
-- Each element of this list is computed via a distinct keyword which creates a CommonElement for each Leaf of a list we compute via an helper.
rule TreeNodeRoot2RootElement { 
	from 	-- should be unique
		rt : MMTree!Node (rt.isTreeNodeRoot()) 
	to
		lstRt : MMElementList!RootElement (
			name <- rt.name,
			elements <- elmLst
		),
		elmLst : distinct MMElementList!CommonElement foreach(leaf in rt.getLeavesInOrder())(
			name <- leaf.name
		)
}