added yesternight's changes

Documentation/Books/Users/Aql/GraphFunctions.mdpp

@@ -165,14 +165,15 @@ instead.
     *false*, any return value of the visitor function will be ignored. Instead, the visitor 
     function can modify its *result* parameter value in-place. At the end of the traversal,
     *result* is expected to be an array.
-
-  - *data*: only useful in combination with a custom AQL visitor function. This attribute can
+  
+  - *data*: only useful in combination with custom AQL visitor or filter functions. This attribute can
     be used to pass arbitrary data into the custom visitor function. The value contained in the
-    *data* attribute will be made available to the *visitor* function in the *config.data*
+    *data* attribute will be made available to the *visitor* and *filterVertices* functions in the *config.data*
     attribute.
 
   By default, the result of the TRAVERSAL function is an array of traversed points. Each point 
   is an object consisting of the following attributes:
+
   - *vertex*: The vertex at the traversal point
   - *path*: The path history for the traversal point. The path is a document with the
     attributes *vertices* and *edges*, which are both arrays. Note that *path* is only present
@@ -239,7 +240,10 @@ instead.
         order: "preorder-expander"
       })
 
-      // registering the custom leaf node visitor function
+      // to register the custom AQL function visitor that only returns leaf nodes, run
+      // the following commands in arangosh once:
+      var aqlfunctions = require("org/arangodb/aql/functions");
+
       aqlfunctions.register("myfunctions::leafnodevisitor", function (config, vertex, edge, path, connections) { 
         if (connected && connected.length === 0) {
           // will put the vertex into the result if it does not have any further connections
@@ -269,6 +273,19 @@ instead.
       }, false);
 
 
+      // using one of the predefined visitor functions
+      TRAVERSAL(friends, friendrelations, "friends/john", "outbound", {
+        visitor: "_AQL::COUNTINGVISITOR"
+      })
+
+
+      // passing data into a visitor
+      TRAVERSAL(friends, friendrelations, "friends/john", "outbound", {
+        visitor: "_AQL::PROJECTINGVISITOR",
+        data: { attributes: [ "_id", "_key", "name" ] }
+      })
+
+
 - *TRAVERSAL_TREE(vertexcollection, edgecollection, startVertex, direction, connectName, options)*: 
   Traverses the graph described by *vertexcollection* and *edgecollection*, 
   starting at the vertex identified by id *startVertex* and creates a hierarchical result.
@@ -343,6 +360,7 @@ instead.
         function (config, vertex, path)
 
     If a custom AQL function is used, it is expected to return one of the following values:
+
     - *[ ]*: Include the vertex in the result and descend into its connected edges
     - *[ "prune" ]*: Will include the vertex in the result but not descend into its connected edges
     - *[ "exclude" ]*: Will not include the vertex in the result but descend into its connected edges
@@ -372,6 +390,10 @@ instead.
     function can modify its *result* parameter value in-place. At the end of the traversal,
     *result* is expected to be an array.
 
+  - *data*: only useful in combination with custom AQL visitor or filter functions. This attribute can
+    be used to pass arbitrary data into the custom visitor function. The value contained in the
+    *data* attribute will be made available to the *visitor* and *filterVertices* functions in the *config.data*
+    attribute.
 
   By default, the result of the SHORTEST_PATH function is an array with the components of the 
   shortest path. Each component is a document consisting of the following attributes:

js/server/modules/org/arangodb/aql.js

@@ -313,6 +313,24 @@ function GET_FILTER (name, config) {
   };
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief create a user-defined expand filter from a function name
+////////////////////////////////////////////////////////////////////////////////
+
+function GET_EXPANDFILTER (name, config) {
+  var func = GET_USERFUNCTION(name, config);
+
+  return function (config, vertex, edge, path) {
+    try {
+      var filterResult = func.apply(null, arguments);
+      return FIX_VALUE(filterResult);
+    }
+    catch (err) {
+      WARN(name, INTERNAL.errors.ERROR_QUERY_FUNCTION_RUNTIME_ERROR, AQL_TO_STRING(err));
+    }
+  };
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief normalise a function name
 ////////////////////////////////////////////////////////////////////////////////
@@ -5118,10 +5136,7 @@ function TRAVERSAL_FUNC (func,
 
   if (params.followEdges) {
     if (typeof params.followEdges === 'string') {
-      var f1 = params.followEdges.toUpperCase();
-      config.expandFilter = function (config, vertex, edge, path) {
-        return FCALL_USER(f1, [ config, vertex, edge, path ]);
-      };
+      config.expandFilter = GET_EXPANDFILTER(params.followEdges, params);
     }
     else {
       config.expandFilter = TRAVERSAL_EDGE_EXAMPLE_FILTER;
@@ -5135,10 +5150,7 @@ function TRAVERSAL_FUNC (func,
 
   if (params.filterVertices) {
     if (typeof params.filterVertices === 'string') {
-      var f2 = params.filterVertices.toUpperCase();
-      config.filter = function (config, vertex, edge, path) {
-        return FCALL_USER(f2, [ config, vertex, path ]);
-      };
+      config.filter = GET_FILTER(params.filterVertices, params);
     }
     else {
       config.filter = TRAVERSAL_VERTEX_FILTER;
@@ -5512,11 +5524,6 @@ function SHORTEST_PATH_PARAMS (params) {
     params.visitor = TRAVERSAL_VISITOR;
   }
 
-  // add user-defined filter, if specified
-  if (typeof params.filter === "string") {
-    params.filter = GET_FILTER(params.filter, params);
-  }
-
   if (typeof params.distance === "string") {
     var name = params.distance.toUpperCase();
 
@@ -5742,11 +5749,6 @@ function TRAVERSAL_PARAMS (params) {
     params.visitor = TRAVERSAL_VISITOR;
   }
 
-  // add user-defined filter, if specified
-  if (typeof params.filter === "string") {
-    params.filter = GET_FILTER(params.filter, params);
-  }
-
   return params;
 }
 
@@ -6101,11 +6103,6 @@ function TRAVERSAL_TREE_PARAMS (params, connectName, func) {
     params.visitor = TRAVERSAL_TREE_VISITOR;
   }
   
-  // add user-defined filter, if specified
-  if (typeof params.filter === "string") {
-    params.filter = GET_FILTER(params.filter, params);
-  }
-
   params.connect  = AQL_TO_STRING(connectName);
 
   if (params.connect === "") {