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graph.go
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graph.go
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// The dot package contains utilities for working with DOT graphs.
package dot
import (
"bytes"
"fmt"
"sort"
"strings"
)
// Graph is a representation of a drawable DOT graph.
type Graph struct {
// Whether this is a "digraph" or just a "graph"
Directed bool
// Used for K/V settings in the DOT
Attrs map[string]string
Nodes []*Node
Edges []*Edge
Subgraphs []*Subgraph
nodesByName map[string]*Node
}
// Subgraph is a Graph that lives inside a Parent graph, and contains some
// additional parameters to control how it is drawn.
type Subgraph struct {
Graph
Name string
Parent *Graph
Cluster bool
}
// An Edge in a DOT graph, as expressed by recording the Name of the Node at
// each end.
type Edge struct {
// Name of source node.
Source string
// Name of dest node.
Dest string
// List of K/V attributes for this edge.
Attrs map[string]string
}
// A Node in a DOT graph.
type Node struct {
Name string
Attrs map[string]string
}
// Creates a properly initialized DOT Graph.
func NewGraph(attrs map[string]string) *Graph {
return &Graph{
Attrs: attrs,
nodesByName: make(map[string]*Node),
}
}
func NewEdge(src, dst string, attrs map[string]string) *Edge {
return &Edge{
Source: src,
Dest: dst,
Attrs: attrs,
}
}
func NewNode(n string, attrs map[string]string) *Node {
return &Node{
Name: n,
Attrs: attrs,
}
}
// Initializes a Subgraph with the provided name, attaches is to this Graph,
// and returns it.
func (g *Graph) AddSubgraph(name string) *Subgraph {
subgraph := &Subgraph{
Graph: *NewGraph(map[string]string{}),
Parent: g,
Name: name,
}
g.Subgraphs = append(g.Subgraphs, subgraph)
return subgraph
}
func (g *Graph) AddAttr(k, v string) {
g.Attrs[k] = v
}
func (g *Graph) AddNode(n *Node) {
g.Nodes = append(g.Nodes, n)
g.nodesByName[n.Name] = n
}
func (g *Graph) AddEdge(e *Edge) {
g.Edges = append(g.Edges, e)
}
// Adds an edge between two Nodes.
//
// Note this does not do any verification of the existence of these nodes,
// which means that any strings you provide that are not existing nodes will
// result in extra auto-defined nodes in your resulting DOT.
func (g *Graph) AddEdgeBetween(src, dst string, attrs map[string]string) error {
g.AddEdge(NewEdge(src, dst, attrs))
return nil
}
// Look up a node by name
func (g *Graph) GetNode(name string) (*Node, error) {
node, ok := g.nodesByName[name]
if !ok {
return nil, fmt.Errorf("Could not find node: %s", name)
}
return node, nil
}
// Returns the DOT representation of this Graph.
func (g *Graph) String() string {
w := newGraphWriter()
g.drawHeader(w)
w.Indent()
g.drawBody(w)
w.Unindent()
g.drawFooter(w)
return w.String()
}
func (g *Graph) drawHeader(w *graphWriter) {
if g.Directed {
w.Printf("digraph {\n")
} else {
w.Printf("graph {\n")
}
}
func (g *Graph) drawBody(w *graphWriter) {
for _, as := range attrStrings(g.Attrs) {
w.Printf("%s\n", as)
}
nodeStrings := make([]string, 0, len(g.Nodes))
for _, n := range g.Nodes {
nodeStrings = append(nodeStrings, n.String())
}
sort.Strings(nodeStrings)
for _, ns := range nodeStrings {
w.Printf(ns)
}
edgeStrings := make([]string, 0, len(g.Edges))
for _, e := range g.Edges {
edgeStrings = append(edgeStrings, e.String())
}
sort.Strings(edgeStrings)
for _, es := range edgeStrings {
w.Printf(es)
}
for _, s := range g.Subgraphs {
s.drawHeader(w)
w.Indent()
s.drawBody(w)
w.Unindent()
s.drawFooter(w)
}
}
func (g *Graph) drawFooter(w *graphWriter) {
w.Printf("}\n")
}
// Returns the DOT representation of this Edge.
func (e *Edge) String() string {
var buf bytes.Buffer
buf.WriteString(
fmt.Sprintf(
"%q -> %q", e.Source, e.Dest))
writeAttrs(&buf, e.Attrs)
buf.WriteString("\n")
return buf.String()
}
func (s *Subgraph) drawHeader(w *graphWriter) {
name := s.Name
if s.Cluster {
name = fmt.Sprintf("cluster_%s", name)
}
w.Printf("subgraph %q {\n", name)
}
// Returns the DOT representation of this Node.
func (n *Node) String() string {
var buf bytes.Buffer
buf.WriteString(fmt.Sprintf("%q", n.Name))
writeAttrs(&buf, n.Attrs)
buf.WriteString("\n")
return buf.String()
}
func writeAttrs(buf *bytes.Buffer, attrs map[string]string) {
if len(attrs) > 0 {
buf.WriteString(" [")
buf.WriteString(strings.Join(attrStrings(attrs), ", "))
buf.WriteString("]")
}
}
func attrStrings(attrs map[string]string) []string {
strings := make([]string, 0, len(attrs))
for k, v := range attrs {
strings = append(strings, fmt.Sprintf("%s = %q", k, v))
}
sort.Strings(strings)
return strings
}