package dag
import (
"bytes"
"encoding/json"
"fmt"
"io"
"sort"
)
// Graph is used to represent a dependency graph.
type Graph struct {
vertices *Set
edges *Set
downEdges map[interface{}]*Set
upEdges map[interface{}]*Set
// JSON encoder for recording debug information
debug *encoder
}
// Subgrapher allows a Vertex to be a Graph itself, by returning a Grapher.
type Subgrapher interface {
Subgraph() Grapher
}
// A Grapher is any type that returns a Grapher, mainly used to identify
// dag.Graph and dag.AcyclicGraph. In the case of Graph and AcyclicGraph, they
// return themselves.
type Grapher interface {
DirectedGraph() Grapher
}
// Vertex of the graph.
type Vertex interface{}
// NamedVertex is an optional interface that can be implemented by Vertex
// to give it a human-friendly name that is used for outputting the graph.
type NamedVertex interface {
Vertex
Name() string
}
func (g *Graph) DirectedGraph() Grapher {
return g
}
// Vertices returns the list of all the vertices in the graph.
func (g *Graph) Vertices() []Vertex {
list := g.vertices.List()
result := make([]Vertex, len(list))
for i, v := range list {
result[i] = v.(Vertex)
}
return result
}
// Edges returns the list of all the edges in the graph.
func (g *Graph) Edges() []Edge {
list := g.edges.List()
result := make([]Edge, len(list))
for i, v := range list {
result[i] = v.(Edge)
}
return result
}
// EdgesFrom returns the list of edges from the given source.
func (g *Graph) EdgesFrom(v Vertex) []Edge {
var result []Edge
from := hashcode(v)
for _, e := range g.Edges() {
if hashcode(e.Source()) == from {
result = append(result, e)
}
}
return result
}
// EdgesTo returns the list of edges to the given target.
func (g *Graph) EdgesTo(v Vertex) []Edge {
var result []Edge
search := hashcode(v)
for _, e := range g.Edges() {
if hashcode(e.Target()) == search {
result = append(result, e)
}
}
return result
}
// HasVertex checks if the given Vertex is present in the graph.
func (g *Graph) HasVertex(v Vertex) bool {
return g.vertices.Include(v)
}
// HasEdge checks if the given Edge is present in the graph.
func (g *Graph) HasEdge(e Edge) bool {
return g.edges.Include(e)
}
// Add adds a vertex to the graph. This is safe to call multiple time with
// the same Vertex.
func (g *Graph) Add(v Vertex) Vertex {
g.init()
g.vertices.Add(v)
g.debug.Add(v)
return v
}
// Remove removes a vertex from the graph. This will also remove any
// edges with this vertex as a source or target.
func (g *Graph) Remove(v Vertex) Vertex {
// Delete the vertex itself
g.vertices.Delete(v)
g.debug.Remove(v)
// Delete the edges to non-existent things
for _, target := range g.DownEdges(v).List() {
g.RemoveEdge(BasicEdge(v, target))
}
for _, source := range g.UpEdges(v).List() {
g.RemoveEdge(BasicEdge(source, v))
}
return nil
}
// Replace replaces the original Vertex with replacement. If the original
// does not exist within the graph, then false is returned. Otherwise, true
// is returned.
func (g *Graph) Replace(original, replacement Vertex) bool {
// If we don't have the original, we can't do anything
if !g.vertices.Include(original) {
return false
}
defer g.debug.BeginOperation("Replace", "").End("")
// If they're the same, then don't do anything
if original == replacement {
return true
}
// Add our new vertex, then copy all the edges
g.Add(replacement)
for _, target := range g.DownEdges(original).List() {
g.Connect(BasicEdge(replacement, target))
}
for _, source := range g.UpEdges(original).List() {
g.Connect(BasicEdge(source, replacement))
}
// Remove our old vertex, which will also remove all the edges
g.Remove(original)
return true
}
// RemoveEdge removes an edge from the graph.
func (g *Graph) RemoveEdge(edge Edge) {
g.init()
g.debug.RemoveEdge(edge)
// Delete the edge from the set
g.edges.Delete(edge)
// Delete the up/down edges
if s, ok := g.downEdges[hashcode(edge.Source())]; ok {
s.Delete(edge.Target())
}
if s, ok := g.upEdges[hashcode(edge.Target())]; ok {
s.Delete(edge.Source())
}
}
// DownEdges returns the outward edges from the source Vertex v.
func (g *Graph) DownEdges(v Vertex) *Set {
g.init()
return g.downEdges[hashcode(v)]
}
// UpEdges returns the inward edges to the destination Vertex v.
func (g *Graph) UpEdges(v Vertex) *Set {
g.init()
return g.upEdges[hashcode(v)]
}
// Connect adds an edge with the given source and target. This is safe to
// call multiple times with the same value. Note that the same value is
// verified through pointer equality of the vertices, not through the
// value of the edge itself.
func (g *Graph) Connect(edge Edge) {
g.init()
g.debug.Connect(edge)
source := edge.Source()
target := edge.Target()
sourceCode := hashcode(source)
targetCode := hashcode(target)
// Do we have this already? If so, don't add it again.
if s, ok := g.downEdges[sourceCode]; ok && s.Include(target) {
return
}
// Add the edge to the set
g.edges.Add(edge)
// Add the down edge
s, ok := g.downEdges[sourceCode]
if !ok {
s = new(Set)
g.downEdges[sourceCode] = s
}
s.Add(target)
// Add the up edge
s, ok = g.upEdges[targetCode]
if !ok {
s = new(Set)
g.upEdges[targetCode] = s
}
s.Add(source)
}
// String outputs some human-friendly output for the graph structure.
func (g *Graph) StringWithNodeTypes() string {
var buf bytes.Buffer
// Build the list of node names and a mapping so that we can more
// easily alphabetize the output to remain deterministic.
vertices := g.Vertices()
names := make([]string, 0, len(vertices))
mapping := make(map[string]Vertex, len(vertices))
for _, v := range vertices {
name := VertexName(v)
names = append(names, name)
mapping[name] = v
}
sort.Strings(names)
// Write each node in order...
for _, name := range names {
v := mapping[name]
targets := g.downEdges[hashcode(v)]
buf.WriteString(fmt.Sprintf("%s - %T\n", name, v))
// Alphabetize dependencies
deps := make([]string, 0, targets.Len())
targetNodes := make(map[string]Vertex)
for _, target := range targets.List() {
dep := VertexName(target)
deps = append(deps, dep)
targetNodes[dep] = target
}
sort.Strings(deps)
// Write dependencies
for _, d := range deps {
buf.WriteString(fmt.Sprintf(" %s - %T\n", d, targetNodes[d]))
}
}
return buf.String()
}
// String outputs some human-friendly output for the graph structure.
func (g *Graph) String() string {
var buf bytes.Buffer
// Build the list of node names and a mapping so that we can more
// easily alphabetize the output to remain deterministic.
vertices := g.Vertices()
names := make([]string, 0, len(vertices))
mapping := make(map[string]Vertex, len(vertices))
for _, v := range vertices {
name := VertexName(v)
names = append(names, name)
mapping[name] = v
}
sort.Strings(names)
// Write each node in order...
for _, name := range names {
v := mapping[name]
targets := g.downEdges[hashcode(v)]
buf.WriteString(fmt.Sprintf("%s\n", name))
// Alphabetize dependencies
deps := make([]string, 0, targets.Len())
for _, target := range targets.List() {
deps = append(deps, VertexName(target))
}
sort.Strings(deps)
// Write dependencies
for _, d := range deps {
buf.WriteString(fmt.Sprintf(" %s\n", d))
}
}
return buf.String()
}
func (g *Graph) init() {
if g.vertices == nil {
g.vertices = new(Set)
}
if g.edges == nil {
g.edges = new(Set)
}
if g.downEdges == nil {
g.downEdges = make(map[interface{}]*Set)
}
if g.upEdges == nil {
g.upEdges = make(map[interface{}]*Set)
}
}
// Dot returns a dot-formatted representation of the Graph.
func (g *Graph) Dot(opts *DotOpts) []byte {
return newMarshalGraph("", g).Dot(opts)
}
// MarshalJSON returns a JSON representation of the entire Graph.
func (g *Graph) MarshalJSON() ([]byte, error) {
dg := newMarshalGraph("root", g)
return json.MarshalIndent(dg, "", " ")
}
// SetDebugWriter sets the io.Writer where the Graph will record debug
// information. After this is set, the graph will immediately encode itself to
// the stream, and continue to record all subsequent operations.
func (g *Graph) SetDebugWriter(w io.Writer) {
g.debug = &encoder{w: w}
g.debug.Encode(newMarshalGraph("root", g))
}
// DebugVertexInfo encodes arbitrary information about a vertex in the graph
// debug logs.
func (g *Graph) DebugVertexInfo(v Vertex, info string) {
va := newVertexInfo(typeVertexInfo, v, info)
g.debug.Encode(va)
}
// DebugEdgeInfo encodes arbitrary information about an edge in the graph debug
// logs.
func (g *Graph) DebugEdgeInfo(e Edge, info string) {
ea := newEdgeInfo(typeEdgeInfo, e, info)
g.debug.Encode(ea)
}
// DebugVisitInfo records a visit to a Vertex during a walk operation.
func (g *Graph) DebugVisitInfo(v Vertex, info string) {
vi := newVertexInfo(typeVisitInfo, v, info)
g.debug.Encode(vi)
}
// DebugOperation marks the start of a set of graph transformations in
// the debug log, and returns a DebugOperationEnd func, which marks the end of
// the operation in the log. Additional information can be added to the log via
// the info parameter.
//
// The returned func's End method allows this method to be called from a single
// defer statement:
// defer g.DebugOperationBegin("OpName", "operating").End("")
//
// The returned function must be called to properly close the logical operation
// in the logs.
func (g *Graph) DebugOperation(operation string, info string) DebugOperationEnd {
return g.debug.BeginOperation(operation, info)
}
// VertexName returns the name of a vertex.
func VertexName(raw Vertex) string {
switch v := raw.(type) {
case NamedVertex:
return v.Name()
case fmt.Stringer:
return fmt.Sprintf("%s", v)
default:
return fmt.Sprintf("%v", v)
}
}
