add View->AutoLayout->Implementation to mdl (#545)

* add View->AutoLayout->Implementation to mdl

* add View->AutoLayout->Implementation to everything else 😅🤞

* replace Implementation as dedicated function parameter with an own function

* fixed whitespaces and unnecessary test

* fixed missed reverts and formatting

dsl/views.go

@@ -16,6 +16,9 @@ type (
 	// RoutingKind is the enum for possible routing algorithms.
 	RoutingKind int
 
+	// ImplementationKind is the enum for possible automatic layout implementations
+	ImplementationKind int
+
 	// RankDirectionKind is the enum for possible automatic layout rank
 	// directions.
 	RankDirectionKind int
@@ -25,6 +28,13 @@ type (
 // DynamicView.
 const Global = 0
 
+const (
+	// ImplementationGraphviz indicates the automatic layout will be using Graphviz
+	ImplementationGraphviz ImplementationKind = iota + 1
+	// ImplementationDagre indicates the automatic layout will be using Dagre
+	ImplementationDagre
+)
+
 const (
 	// RankTopBottom indicates a layout that uses top to bottom rank.
 	RankTopBottom RankDirectionKind = iota + 1
@@ -1442,6 +1452,9 @@ func RemoveUnrelated() {
 	eval.IncompatibleDSL()
 }
 
+// DefaultImplementation sets tje default implementation for the auto layout.
+var DefaultImplementation = ImplementationDagre
+
 // DefaultRankSeparation sets the default rank separation for auto layout.
 var DefaultRankSeparation = 300
 
@@ -1451,8 +1464,9 @@ var DefaultNodeSeparation = 600
 // DefaultEdgeSeparation sets the default edge separation for auto layout.
 var DefaultEdgeSeparation = 200
 
-// AutoLayout enables automatic layout mode for the diagram. The
-// first argument indicates the rank direction, it must be one of
+// AutoLayout enables automatic layout mode for the diagram.
+//
+// The First argument indicates the rank direction, it must be one of
 // RankTopBottom, RankBottomTop, RankLeftRight or RankRightLeft
 //
 // AutoLayout must appear in SystemLandscapeView, SystemContextView,
@@ -1474,6 +1488,7 @@ var DefaultEdgeSeparation = 200
 //	        SystemContextView(SoftwareSystem, "context", "An overview diagram.", func() {
 //	            AddDefault()
 //	            AutoLayout(RankTopBottom, func() {
+//	                Implementation(ImplementationGraphviz)
 //	                RankSeparation(200)
 //	                NodeSeparation(100)
 //	                EdgeSeparation(10)
@@ -1496,10 +1511,11 @@ func AutoLayout(rank RankDirectionKind, args ...func()) {
 		}
 	}
 	layout := &expr.AutoLayout{
-		RankDirection: expr.RankDirectionKind(rank),
-		RankSep:       &DefaultRankSeparation,
-		NodeSep:       &DefaultNodeSeparation,
-		EdgeSep:       &DefaultEdgeSeparation,
+		RankDirection:  expr.RankDirectionKind(rank),
+		Implementation: expr.ImplementationKind(DefaultImplementation),
+		RankSep:        &DefaultRankSeparation,
+		NodeSep:        &DefaultNodeSeparation,
+		EdgeSep:        &DefaultEdgeSeparation,
 	}
 	if dsl != nil {
 		eval.Execute(dsl, layout)
@@ -1823,6 +1839,32 @@ func Position(pos int) {
 	}
 }
 
+// Implementation sets the implementation of the automatic layout, defaults to ImplementationDagre.
+//
+// Implementation must appear in AutoLayout.
+//
+// Implementation takes one argument: the ImplementationKind.
+//
+// Example:
+//
+//	var _ = Design(func() {
+//	    var System = SoftwareSystem("Software System", "My software system.")
+//	    Views(func() {
+//	        SystemContextView(SoftwareSystem, "context", "An overview diagram.", func() {
+//	            AutoLayout(func() {
+//	                Implementation(ImplementationGraphviz)
+//	            })
+//	        })
+//	    })
+//	})
+func Implementation(impl ImplementationKind) {
+	if a, ok := eval.Current().(*expr.AutoLayout); ok {
+		a.Implementation = expr.ImplementationKind(impl)
+		return
+	}
+	eval.IncompatibleDSL()
+}
+
 // RankSeparation sets the separation between ranks in pixels, defaults to 300.
 //
 // RankSeparation must appear in AutoLayout.

expr/view_props.go

@@ -57,11 +57,12 @@ type (
 
 	// AutoLayout describes an automatic layout.
 	AutoLayout struct {
-		RankDirection RankDirectionKind
-		RankSep       *int
-		NodeSep       *int
-		EdgeSep       *int
-		Vertices      *bool
+		Implementation ImplementationKind
+		RankDirection  RankDirectionKind
+		RankSep        *int
+		NodeSep        *int
+		EdgeSep        *int
+		Vertices       *bool
 	}
 
 	// Vertex describes the x and y coordinate of a bend in a line.
@@ -83,6 +84,9 @@ type (
 	// RoutingKind is the enum for possible routing algorithms.
 	RoutingKind int
 
+	// ImplementationKind is the enum for possible automatic layout implementations
+	ImplementationKind int
+
 	// RankDirectionKind is the enum for possible automatic layout rank
 	// directions.
 	RankDirectionKind int
@@ -120,6 +124,12 @@ const (
 	RoutingCurved
 )
 
+const (
+	ImplementationUndefined ImplementationKind = iota
+	ImplementationGraphviz
+	ImplementationDagre
+)
+
 const (
 	RankUndefined RankDirectionKind = iota
 	RankTopBottom

mdl/eval.go

@@ -274,11 +274,12 @@ func modelizeProps(prop *expr.ViewProps) *ViewProps {
 	}
 	if layout := prop.AutoLayout; layout != nil {
 		props.AutoLayout = &AutoLayout{
-			RankDirection: RankDirectionKind(layout.RankDirection),
-			RankSep:       layout.RankSep,
-			NodeSep:       layout.NodeSep,
-			EdgeSep:       layout.EdgeSep,
-			Vertices:      layout.Vertices,
+			Implementation: ImplementationKind(layout.Implementation),
+			RankDirection:  RankDirectionKind(layout.RankDirection),
+			RankSep:        layout.RankSep,
+			NodeSep:        layout.NodeSep,
+			EdgeSep:        layout.EdgeSep,
+			Vertices:       layout.Vertices,
 		}
 	}
 	return props

mdl/views.go

@@ -175,6 +175,8 @@ type (
 
 	// AutoLayout describes an automatic layout.
 	AutoLayout struct {
+		// Implementation used for automatic layouting of the view
+		Implementation ImplementationKind `json:"implementation,omitempty"`
 		// Algorithm rank direction.
 		RankDirection RankDirectionKind `json:"rankDirection,omitempty"`
 		// RankSep defines the separation between ranks in pixels.
@@ -253,6 +255,9 @@ type (
 	// RoutingKind is the enum for possible routing algorithms.
 	RoutingKind int
 
+	// ImplementationKind is the enum for possible automatic layout implementations
+	ImplementationKind int
+
 	// RankDirectionKind is the enum for possible automatic layout rank
 	// directions.
 	RankDirectionKind int
@@ -307,6 +312,12 @@ const (
 	RoutingCurved
 )
 
+const (
+	ImplementationUndefined ImplementationKind = iota
+	ImplementationGraphviz
+	ImplementationDagre
+)
+
 const (
 	RankUndefined RankDirectionKind = iota
 	RankTopBottom
@@ -575,6 +586,18 @@ func (p *PaperSizeKind) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// Name returns the name of the implementation used in the automatic layout of the view.
+func (i ImplementationKind) Name() string {
+	switch i {
+	case ImplementationGraphviz:
+		return "Graphviz"
+	case ImplementationDagre:
+		return "Dagre"
+	default:
+		return "ImplementationUndefined"
+	}
+}
+
 // Name returns the name of the rank direction is specified in the DSL.
 func (r RankDirectionKind) Name() string {
 	switch r {
@@ -623,6 +646,34 @@ func (r *RoutingKind) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// MarshalJSON replaces the constant value with the proper string value.
+func (i ImplementationKind) MarshalJSON() ([]byte, error) {
+	buf := bytes.NewBufferString(`"`)
+	switch i {
+	case ImplementationGraphviz:
+		buf.WriteString("Graphviz")
+	case ImplementationDagre:
+		buf.WriteString("Dagre")
+	}
+	buf.WriteString(`"`)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalJSON sets the constant from its JSON representation.
+func (i *ImplementationKind) UnmarshalJSON(data []byte) error {
+	var val string
+	if err := json.Unmarshal(data, &val); err != nil {
+		return err
+	}
+	switch val {
+	case "Graphviz":
+		*i = ImplementationGraphviz
+	case "Dagre":
+		*i = ImplementationDagre
+	}
+	return nil
+}
+
 // MarshalJSON replaces the constant value with the proper string value.
 func (r RankDirectionKind) MarshalJSON() ([]byte, error) {
 	buf := bytes.NewBufferString(`"`)