// viewPathToGraphPath translates the path in a view into a "path"
// utilized in graph queries.
func viewPathToGraphPath(v *view.View, key string, graphDB *cayley.Handle) (*path.Path, error) {
// outputPath is the final tranlated graph path.
var outputPath *path.Path
// Loop over the paths in the view translating the metadata.
for idx, pth := range v.Paths {
// We create an alias prefix for tags, so we can track which
// path a tag is in.
alias := strconv.Itoa(idx+1) + "_"
// Sort the view Path value.
sort.Sort(pth.Segments)
// graphPath will contain the entire strict graph path.
var graphPath *path.Path
// subPaths will contain each sub path of the full graph path,
// as a separate graph path.
var subPaths []path.Path
// Loop over the path segments translating the path.
level := 1
for _, segment := range pth.Segments {
// Check that the level is the level we expect (i.e., that the levels
// are in order)
if level != segment.Level {
err := fmt.Errorf("Invalid view path level, expected %d but seeing %d", level, segment.Level)
return graphPath, err
}
// Initialize the path, if we are on level 1.
if level == 1 {
// Add the first level relationship.
switch segment.Direction {
case inString:
graphPath = cayley.StartPath(graphDB, quad.String(key)).In(quad.String(segment.Predicate))
case outString:
graphPath = cayley.StartPath(graphDB, quad.String(key)).Out(quad.String(segment.Predicate))
}
// Add the tag, if present.
if segment.Tag != "" {
graphPath = graphPath.Clone().Tag(alias + segment.Tag)
}
// Track this as a subpath.
subPaths = append(subPaths, *graphPath.Clone())
level++
continue
}
// Add the relationship.
switch segment.Direction {
case inString:
graphPath = graphPath.Clone().In(quad.String(segment.Predicate))
case outString:
graphPath = graphPath.Clone().Out(quad.String(segment.Predicate))
}
// Add the tag, if present.
if segment.Tag != "" {
graphPath = graphPath.Clone().Tag(alias + segment.Tag)
}
// Add this as a subpath.
subPaths = append(subPaths, *graphPath.Clone())
level++
}
// If we are forcing a strict path, return only the resulting or
// tagged items along the full path.
if pth.StrictPath {
if outputPath == nil {
outputPath = graphPath
continue
}
outputPath = outputPath.Clone().Or(graphPath)
continue
}
// Otherwise add all the subpaths to the output path.
for _, subPath := range subPaths {
if outputPath == nil {
addedPath := &subPath
outputPath = addedPath.Clone()
continue
}
outputPath = outputPath.Clone().Or(&subPath)
}
}
return outputPath, nil
}
