edge.go

// Copyright 2021 Cloud Privacy Labs, LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package lpg

import (
	"encoding/json"
	"fmt"
)

// An Edge connects two nodes of a graph
type Edge struct {
	from, to *Node
	label    string
	properties
	id int
	// 0: all edges list
	// 1: outgoing edges list
	// 2: incoming edges list
	listElements [3]edgeElement
}

// EdgeDir is used to show edge direction
type EdgeDir int

// Incoming and outgoing edge direction constants
const (
	IncomingEdge EdgeDir = -1
	AnyEdge      EdgeDir = 0
	OutgoingEdge EdgeDir = 1
)

// GetID returns the unique identifier for the edge. The identifier is
// unique in this graph, and meaningless once the edge is
// disconnected.
func (edge *Edge) GetID() int { return edge.id }

// GetGraph returns the graph of the edge.
func (edge *Edge) GetGraph() *Graph { return edge.from.graph }

// GetLabel returns the edge label
func (edge *Edge) GetLabel() string { return edge.label }

// GetFrom returns the source node
func (edge *Edge) GetFrom() *Node { return edge.from }

// GetTo returns the target node
func (edge *Edge) GetTo() *Node { return edge.to }

// SetLabel sets the edge label
func (edge *Edge) SetLabel(label string) {
	if label != edge.label {
		edge.from.graph.setEdgeLabel(edge, label)
	}
}

// SetProperty sets an edge property
func (edge *Edge) SetProperty(key string, value interface{}) {
	edge.from.graph.setEdgeProperty(edge, key, value)
}

// RemoveProperty removes an edge property
func (edge *Edge) RemoveProperty(key string) {
	edge.from.graph.removeEdgeProperty(edge, key)
}

// write public func for GetProperty, ForEachProperty
func (edge *Edge) GetProperty(key string) (interface{}, bool) {
	return edge.getProperty(key)
}

func (edge *Edge) ForEachProperty(f func(string, interface{}) bool) bool {
	return edge.forEachProperty(f)
}

// Remove an edge
func (edge *Edge) Remove() {
	edge.from.graph.removeEdge(edge)
}

// Returns the string representation of an edge
func (edge *Edge) String() string {
	return fmt.Sprintf("[:%s %s]", edge.label, edge.properties)
}

func (edge *Edge) MarshalJSON() ([]byte, error) {
	return json.Marshal(edge.String())
}