fix bug with unsorted model

+bids/Model.m

@@ -69,6 +69,8 @@
 
     verbose = true % hides warning if ``false``
 
+    dag_built = false % if the directed acyclic graph has been built
+
   end
 
   methods
@@ -187,6 +189,7 @@
 
         end
 
+        obj = obj.build_dag;
         obj.validate();
 
       end
@@ -367,61 +370,68 @@
 
     end
 
+    function source_nodes = get_parent(obj, node_name)
+      source_nodes = obj.get_source_node(node_name);
+    end
+
     function source_nodes = get_source_node(obj, node_name)
 
-      source_nodes = {};
+      obj = obj.build_dag;
 
-      if isempty(obj.Edges)
-        obj = obj.get_edges_from_nodes;
-      end
+      source_nodes = {};
 
-      if strcmp(node_name, obj.Edges{1}.Source)
-        % The root node cannot have a source
+      % The root node cannot have a source
+      [~, root_node_name] = obj.get_root_node();
+      if strcmp(node_name, root_node_name)
         return
       end
 
-      % we should only get 1 value
-      for i = 1:numel(obj.Edges)
-        if strcmp(obj.Edges{i}.Destination, node_name)
-          source = obj.Edges{i}.Source;
-          source_nodes{end + 1} = obj.get_nodes('Name', source);
-        end
-      end
-
-      assert(numel(source_nodes) == 1);
-
-      if numel(source_nodes) == 1
-        source_nodes = source_nodes{1};
-      end
+      node = obj.get_nodes('Name', node_name);
+      source_nodes = obj.get_nodes('Name', node.parent);
 
     end
 
     function [root_node, root_node_name] = get_root_node(obj)
 
+      obj = obj.build_dag;
       edges = obj.Edges;
 
       if isempty(edges)
+        % assume a serial model
         root_node = obj.Nodes(1);
+        if iscell(root_node)
+          root_node = root_node{1};
+        end
+        root_node_name = root_node.Name;
+        return
+      end
 
-      elseif iscell(edges)
-        root_node_name = edges{1}.Source;
-        root_node = obj.get_nodes('Name', root_node_name);
-
+      % start from the first edge and go up the DAG
+      if iscell(edges)
+        current_node_name = edges{1}.Source;
       elseif isstruct(edges(1))
-        root_node_name = edges(1).Source;
-        root_node = obj.get_nodes('Name', root_node_name);
+        current_node_name = edges(1).Source;
+      end
 
-      else
-        root_node = obj.Nodes(1);
+      while true
 
+        current_node = obj.get_nodes('Name', current_node_name);
+        has_parent = isfield(current_node, 'parent');
+
+        if ~has_parent
+          root_node_name = current_node.Name;
+          break
+        end
+
+        current_node_name = current_node.parent;
       end
 
+      root_node = current_node;
+
       if iscell(root_node)
         root_node = root_node{1};
       end
 
-      root_node_name = root_node.Name;
-
     end
 
     function edge = get_edge(obj, field, value)
@@ -497,6 +507,24 @@
       value = cellfun(@(x) x.Name, obj.Nodes, 'UniformOutput', false);
     end
 
+    function obj = build_dag(obj)
+      if  obj.dag_built
+        return
+      end
+      if isempty(obj.Edges)
+        obj = obj.get_edges_from_nodes;
+      end
+      for iEdge = 1:numel(obj.Edges)
+        source = obj.Edges{iEdge}.Source;
+        destination = obj.Edges{iEdge}.Destination;
+        [~, idx] = obj.get_nodes('Name', destination);
+        % assume can only have a single parent
+        % so we use a char and note cellstr
+        obj.Nodes{idx}.parent = source;
+      end
+      obj.dag_built = true;
+    end
+
     function validate(obj)
       %
       % Very light validation of fields that were not checked on loading.
@@ -873,6 +901,10 @@ function validate_edges(obj)
           end
         end
 
+        if isfield(this_node, 'parent')
+          this_node = rmfield(this_node, 'parent');
+        end
+
         obj.content.Nodes{i} = this_node;
 
       end

tests/test_bids_model.m

@@ -6,6 +6,36 @@
   initTestSuite;
 end
 
+function test_build_dag()
+  %
+  % model is run --> subject --> dataset
+  %             \
+  %              --> session
+  %
+  % but nodes and edges and not ordered properly
+  %
+
+  bm = bids.Model('init', true);
+
+  bm.Nodes{1} = bm.empty_node('dataset');
+  bm.Nodes{4} = bm.empty_node('session');
+  bm.Nodes{2} = bm.empty_node('run');
+  bm.Nodes{3} = bm.empty_node('subject');
+
+  bm.Edges{1} = struct('Source', 'subject', 'Destination', 'dataset');
+  bm.Edges{3} = struct('Source', 'run', 'Destination', 'session');
+  bm.Edges{2} = struct('Source', 'run', 'Destination', 'subject');
+
+  bm = bm.build_dag();
+
+  assertEqual(bm.dag_built, true);
+  assertEqual(bm.Nodes{1}.parent, 'subject');
+  assert(~isfield(bm.Nodes{2}, 'parent'));
+  assertEqual(bm.Nodes{3}.parent, 'run');
+  assertEqual(bm.Nodes{4}.parent, 'run');
+
+end
+
 function test_model_node_not_in_edges()
 
   bm = bids.Model('file', model_file('narps'), 'verbose', false);
@@ -35,6 +65,33 @@ function test_model_load_edges()
 
 end
 
+function test_model_with_edges_and_node_not_in_order()
+  %
+  % model is run --> subject --> dataset
+  %             \
+  %              --> session
+  %
+  % but nodes and edges and not ordered properly
+  %
+
+  bm = bids.Model('init', true);
+
+  bm.Nodes{1} = bm.empty_node('dataset');
+  bm.Nodes{4} = bm.empty_node('session');
+  bm.Nodes{2} = bm.empty_node('run');
+  bm.Nodes{3} = bm.empty_node('subject');
+
+  bm.Edges{1} = struct('Source', 'subject', 'Destination', 'dataset');
+  bm.Edges{3} = struct('Source', 'run', 'Destination', 'session');
+  bm.Edges{2} = struct('Source', 'run', 'Destination', 'subject');
+
+  assertEqual(bm.get_source_node('session'), bm.get_nodes('Name', 'run'));
+
+  [root_node, root_node_name] = bm.get_root_node();
+  assertEqual(root_node_name, 'run');
+
+end
+
 function test_model_get_root_node()
 
   bm = bids.Model('file', model_file('narps'), 'verbose', false);