LinkedQL: Fromless Steps

query/linkedql/registry_test.go

@@ -97,7 +97,7 @@ var unmarshalCases = []struct {
 type TestStep struct {
 	Limit int        `json:"limit"`
 	Tags  []string   `json:"tags"`
-	From  PathStep   `json:"from"`
+	From  PathStep   `json:"from" minCardinality:"0"`
 	Sub   []PathStep `json:"sub"`
 }
 

query/linkedql/step_utils.go

@@ -0,0 +1,20 @@
+package linkedql
+
+import (
+	"github.com/cayleygraph/cayley/graph"
+	"github.com/cayleygraph/cayley/query/path"
+	"github.com/cayleygraph/quad/voc"
+)
+
+// BuildFromPath creates a path of a given from
+// In case from is nil defaults to placeholder
+func BuildFromPath(qs graph.QuadStore, ns *voc.Namespaces, from PathStep) (*path.Path, error) {
+	if from == nil {
+		return path.StartMorphism(), nil
+	}
+	fromPath, err := from.BuildPath(qs, ns)
+	if err != nil {
+		return nil, err
+	}
+	return fromPath, nil
+}

query/linkedql/steps/as.go

@@ -26,7 +26,7 @@ func (s *As) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *As) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/back.go

@@ -26,7 +26,7 @@ func (s *Back) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Back) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/both.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*Both)(nil)
 
 // Both corresponds to .both().
 type Both struct {
-	From       linkedql.PathStep      `json:"from"`
+	From       linkedql.PathStep      `json:"from" minCardinality:"0"`
 	Properties *linkedql.PropertyPath `json:"properties"`
 }
 
@@ -26,7 +26,7 @@ func (s *Both) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Both) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/collect.go

@@ -33,7 +33,7 @@ var (
 
 // BuildPath implements linkedql.PathStep.
 func (s *Collect) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/count.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*Count)(nil)
 
 // Count corresponds to .count().
 type Count struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 }
 
 // Description implements Step.
@@ -25,7 +25,7 @@ func (s *Count) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Count) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/difference.go

@@ -26,7 +26,7 @@ func (s *Difference) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Difference) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/greater_than.go

@@ -17,7 +17,7 @@ var _ linkedql.PathStep = (*GreaterThan)(nil)
 
 // GreaterThan corresponds to gt().
 type GreaterThan struct {
-	From  linkedql.PathStep `json:"from"`
+	From  linkedql.PathStep `json:"from" minCardinality:"0"`
 	Value quad.Value        `json:"value"`
 }
 
@@ -28,7 +28,7 @@ func (s *GreaterThan) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *GreaterThan) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/greater_than_equals.go

@@ -17,7 +17,7 @@ var _ linkedql.PathStep = (*GreaterThanEquals)(nil)
 
 // GreaterThanEquals corresponds to gte().
 type GreaterThanEquals struct {
-	From  linkedql.PathStep `json:"from"`
+	From  linkedql.PathStep `json:"from" minCardinality:"0"`
 	Value quad.Value        `json:"value"`
 }
 
@@ -28,7 +28,7 @@ func (s *GreaterThanEquals) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *GreaterThanEquals) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/has.go

@@ -16,7 +16,7 @@ var _ linkedql.PathStep = (*Has)(nil)
 
 // Has corresponds to .has().
 type Has struct {
-	From     linkedql.PathStep      `json:"from"`
+	From     linkedql.PathStep      `json:"from" minCardinality:"0"`
 	Property *linkedql.PropertyPath `json:"property"`
 	Values   []quad.Value           `json:"values"`
 }
@@ -28,7 +28,7 @@ func (s *Has) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Has) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/has_reverse.go

@@ -16,7 +16,7 @@ var _ linkedql.PathStep = (*HasReverse)(nil)
 
 // HasReverse corresponds to .hasR().
 type HasReverse struct {
-	From     linkedql.PathStep      `json:"from"`
+	From     linkedql.PathStep      `json:"from" minCardinality:"0"`
 	Property *linkedql.PropertyPath `json:"property"`
 	Values   []quad.Value           `json:"values"`
 }
@@ -28,7 +28,7 @@ func (s *HasReverse) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *HasReverse) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/intersect.go

@@ -26,7 +26,7 @@ func (s *Intersect) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Intersect) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/labels.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*Labels)(nil)
 
 // Labels corresponds to .labels().
 type Labels struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 }
 
 // Description implements Step.
@@ -25,7 +25,7 @@ func (s *Labels) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Labels) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/less_than.go

@@ -17,7 +17,7 @@ var _ linkedql.PathStep = (*LessThan)(nil)
 
 // LessThan corresponds to lt().
 type LessThan struct {
-	From  linkedql.PathStep `json:"from"`
+	From  linkedql.PathStep `json:"from" minCardinality:"0"`
 	Value quad.Value        `json:"value"`
 }
 
@@ -28,7 +28,7 @@ func (s *LessThan) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *LessThan) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/less_than_equals.go

@@ -17,7 +17,7 @@ var _ linkedql.PathStep = (*LessThanEquals)(nil)
 
 // LessThanEquals corresponds to lte().
 type LessThanEquals struct {
-	From  linkedql.PathStep `json:"from"`
+	From  linkedql.PathStep `json:"from" minCardinality:"0"`
 	Value quad.Value        `json:"value"`
 }
 
@@ -28,7 +28,7 @@ func (s *LessThanEquals) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *LessThanEquals) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/like.go

@@ -16,7 +16,7 @@ var _ linkedql.PathStep = (*Like)(nil)
 
 // Like corresponds to like().
 type Like struct {
-	From    linkedql.PathStep `json:"from"`
+	From    linkedql.PathStep `json:"from" minCardinality:"0"`
 	Pattern string            `json:"likePattern"`
 }
 
@@ -27,7 +27,7 @@ func (s *Like) Description() string {
 
 // BuildPath implements PathStep.
 func (s *Like) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/limit.go

@@ -26,7 +26,7 @@ func (s *Limit) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Limit) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/optional.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*Optional)(nil)
 
 // Optional corresponds to .optional().
 type Optional struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 	Step linkedql.PathStep `json:"step"`
 }
 
@@ -26,7 +26,7 @@ func (s *Optional) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Optional) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/order.go

@@ -25,7 +25,7 @@ func (s *Order) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Order) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/properties.go

@@ -18,7 +18,7 @@ var _ linkedql.PathStep = (*Properties)(nil)
 
 // Properties corresponds to .properties().
 type Properties struct {
-	From  linkedql.PathStep      `json:"from"`
+	From  linkedql.PathStep      `json:"from" minCardinality:"0"`
 	Names *linkedql.PropertyPath `json:"names"`
 }
 
@@ -49,7 +49,7 @@ func resolveNames(names *linkedql.PropertyPath) (linkedql.PropertyIRIs, error) {
 
 // BuildPath implements linkedql.PathStep.
 func (s *Properties) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/property_names.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*PropertyNames)(nil)
 
 // PropertyNames corresponds to .propertyNames().
 type PropertyNames struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 }
 
 // Description implements Step.
@@ -25,7 +25,7 @@ func (s *PropertyNames) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *PropertyNames) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/property_names_as.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*PropertyNamesAs)(nil)
 
 // PropertyNamesAs corresponds to .propertyNamesAs().
 type PropertyNamesAs struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 	Tag  string            `json:"tag"`
 }
 
@@ -26,7 +26,7 @@ func (s *PropertyNamesAs) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *PropertyNamesAs) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/regexp.go

@@ -29,7 +29,7 @@ func (s *RegExp) Description() string {
 
 // BuildPath implements PathStep.
 func (s *RegExp) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/reverse_properties.go

@@ -16,7 +16,7 @@ var _ linkedql.PathStep = (*ReverseProperties)(nil)
 
 // ReverseProperties corresponds to .reverseProperties().
 type ReverseProperties struct {
-	From  linkedql.PathStep      `json:"from"`
+	From  linkedql.PathStep      `json:"from" minCardinality:"0"`
 	Names *linkedql.PropertyPath `json:"names"`
 }
 
@@ -27,7 +27,7 @@ func (s *ReverseProperties) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *ReverseProperties) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}

query/linkedql/steps/reverse_property_names.go

@@ -15,7 +15,7 @@ var _ linkedql.PathStep = (*ReversePropertyNames)(nil)
 
 // ReversePropertyNames corresponds to .reversePropertyNames().
 type ReversePropertyNames struct {
-	From linkedql.PathStep `json:"from"`
+	From linkedql.PathStep `json:"from" minCardinality:"0"`
 }
 
 // Description implements Step.
@@ -25,7 +25,7 @@ func (s *ReversePropertyNames) Description() string {
 
 // BuildPath implements linkedql.PathStep.
 func (s *ReversePropertyNames) BuildPath(qs graph.QuadStore, ns *voc.Namespaces) (*path.Path, error) {
-	fromPath, err := s.From.BuildPath(qs, ns)
+	fromPath, err := linkedql.BuildFromPath(qs, ns, s.From)
 	if err != nil {
 		return nil, err
 	}