graph/formats: add packages for serialising graphs to js rendering engines

graph/formats/sigmajs/sigmajs.go

@@ -0,0 +1,128 @@
+// Copyright ©2018 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package sigmajs implements marshaling and unmarshaling of Sigma.js JSON documents.
+//
+// See http://sigmajs.org/ for Sigma.js documentation.
+package sigmajs // import "gonum.org/v1/gonum/graph/formats/sigmajs"
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+)
+
+// Graph is a Sigma.js graph.
+type Graph struct {
+	Nodes []Node `json:"nodes"`
+	Edges []Edge `json:"edges"`
+}
+
+// Node is a Sigma.js node.
+type Node struct {
+	ID         string
+	Attributes map[string]interface{}
+}
+
+var (
+	_ json.Marshaler   = (*Node)(nil)
+	_ json.Unmarshaler = (*Node)(nil)
+)
+
+// MarshalJSON implements the json.Marshaler interface.
+func (n *Node) MarshalJSON() ([]byte, error) {
+	if n.Attributes == nil {
+		type node struct {
+			ID string `json:"id"`
+		}
+		return json.Marshal(node{ID: n.ID})
+	}
+	n.Attributes["id"] = n.ID
+	b, err := json.Marshal(n.Attributes)
+	delete(n.Attributes, "id")
+	return b, err
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+func (n *Node) UnmarshalJSON(data []byte) error {
+	var attrs map[string]interface{}
+	err := json.Unmarshal(data, &attrs)
+	if err != nil {
+		return err
+	}
+	id, ok := attrs["id"]
+	if !ok {
+		return errors.New("sigmajs: no ID")
+	}
+	n.ID = fmt.Sprint(id)
+	delete(attrs, "id")
+	if len(attrs) != 0 {
+		n.Attributes = attrs
+	}
+	return nil
+}
+
+// Edge is a Sigma.js edge.
+type Edge struct {
+	ID         string
+	Source     string
+	Target     string
+	Attributes map[string]interface{}
+}
+
+var (
+	_ json.Marshaler   = (*Edge)(nil)
+	_ json.Unmarshaler = (*Edge)(nil)
+)
+
+// MarshalJSON implements the json.Marshaler interface.
+func (e *Edge) MarshalJSON() ([]byte, error) {
+	if e.Attributes == nil {
+		type edge struct {
+			ID     string `json:"id"`
+			Source string `json:"source"`
+			Target string `json:"target"`
+		}
+		return json.Marshal(edge{ID: e.ID, Source: e.Source, Target: e.Target})
+	}
+	e.Attributes["id"] = e.ID
+	e.Attributes["source"] = e.Source
+	e.Attributes["target"] = e.Target
+	b, err := json.Marshal(e.Attributes)
+	delete(e.Attributes, "id")
+	delete(e.Attributes, "source")
+	delete(e.Attributes, "target")
+	return b, err
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface.
+func (e *Edge) UnmarshalJSON(data []byte) error {
+	var attrs map[string]interface{}
+	err := json.Unmarshal(data, &attrs)
+	if err != nil {
+		return err
+	}
+	id, ok := attrs["id"]
+	if !ok {
+		return errors.New("sigmajs: no ID")
+	}
+	source, ok := attrs["source"]
+	if !ok {
+		return errors.New("sigmajs: no source")
+	}
+	target, ok := attrs["target"]
+	if !ok {
+		return errors.New("sigmajs: no target")
+	}
+	e.ID = fmt.Sprint(id)
+	e.Source = fmt.Sprint(source)
+	e.Target = fmt.Sprint(target)
+	delete(attrs, "id")
+	delete(attrs, "source")
+	delete(attrs, "target")
+	if len(attrs) != 0 {
+		e.Attributes = attrs
+	}
+	return nil
+}