forked from gonum/gonum
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decode.go
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/
decode.go
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// Copyright ©2017 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 dot
import (
"fmt"
"strconv"
"strings"
"github.com/ArkaGPL/gonum/graph"
"github.com/ArkaGPL/gonum/graph/encoding"
"github.com/ArkaGPL/gonum/graph/formats/dot"
"github.com/ArkaGPL/gonum/graph/formats/dot/ast"
"github.com/ArkaGPL/gonum/graph/internal/set"
)
// AttributeSetters is implemented by graph values that can set global
// DOT attributes.
type AttributeSetters interface {
// DOTAttributeSetters returns the global attribute setters.
DOTAttributeSetters() (graph, node, edge encoding.AttributeSetter)
}
// DOTIDSetter is implemented by types that can set a DOT ID.
type DOTIDSetter interface {
SetDOTID(id string)
}
// PortSetter is implemented by graph.Edge and graph.Line that can set
// the DOT port and compass directions of an edge.
type PortSetter interface {
// SetFromPort sets the From port and
// compass direction of the receiver.
SetFromPort(port, compass string) error
// SetToPort sets the To port and compass
// direction of the receiver.
SetToPort(port, compass string) error
}
// Unmarshal parses the Graphviz DOT-encoded data and stores the result in dst.
// If the number of graphs encoded in data is not one, an error is returned and
// dst will hold the first graph in data.
//
// Attributes and IDs are unquoted during unmarshalling if appropriate.
func Unmarshal(data []byte, dst encoding.Builder) error {
file, err := dot.ParseBytes(data)
if err != nil {
return err
}
err = copyGraph(dst, file.Graphs[0])
if err == nil && len(file.Graphs) != 1 {
err = fmt.Errorf("invalid number of graphs; expected 1, got %d", len(file.Graphs))
}
return err
}
// UnmarshalMulti parses the Graphviz DOT-encoded data as a multigraph and
// stores the result in dst.
// If the number of graphs encoded in data is not one, an error is returned and
// dst will hold the first graph in data.
//
// Attributes and IDs are unquoted during unmarshalling if appropriate.
func UnmarshalMulti(data []byte, dst encoding.MultiBuilder) error {
file, err := dot.ParseBytes(data)
if err != nil {
return err
}
err = copyMultigraph(dst, file.Graphs[0])
if err == nil && len(file.Graphs) != 1 {
err = fmt.Errorf("invalid number of graphs; expected 1, got %d", len(file.Graphs))
}
return err
}
// copyGraph copies the nodes and edges from the Graphviz AST source graph to
// the destination graph. Edge direction is maintained if present.
func copyGraph(dst encoding.Builder, src *ast.Graph) (err error) {
defer func() {
switch e := recover().(type) {
case nil:
case error:
err = e
default:
panic(e)
}
}()
gen := &simpleGraph{
generator: generator{
directed: src.Directed,
ids: make(map[string]graph.Node),
},
}
if dst, ok := dst.(DOTIDSetter); ok {
dst.SetDOTID(unquoteID(src.ID))
}
if a, ok := dst.(AttributeSetters); ok {
gen.graphAttr, gen.nodeAttr, gen.edgeAttr = a.DOTAttributeSetters()
}
for _, stmt := range src.Stmts {
gen.addStmt(dst, stmt)
}
return err
}
// copyMultigraph copies the nodes and edges from the Graphviz AST source graph to
// the destination graph. Edge direction is maintained if present.
func copyMultigraph(dst encoding.MultiBuilder, src *ast.Graph) (err error) {
defer func() {
switch e := recover().(type) {
case nil:
case error:
err = e
default:
panic(e)
}
}()
gen := &multiGraph{
generator: generator{
directed: src.Directed,
ids: make(map[string]graph.Node),
},
}
if dst, ok := dst.(DOTIDSetter); ok {
dst.SetDOTID(unquoteID(src.ID))
}
if a, ok := dst.(AttributeSetters); ok {
gen.graphAttr, gen.nodeAttr, gen.edgeAttr = a.DOTAttributeSetters()
}
for _, stmt := range src.Stmts {
gen.addStmt(dst, stmt)
}
return err
}
// A generator keeps track of the information required for generating a Gonum
// graph from a dot AST graph.
type generator struct {
// Directed graph.
directed bool
// Map from dot AST node ID to Gonum node.
ids map[string]graph.Node
// Nodes processed within the context of a subgraph, that is to be used as a
// vertex of an edge.
subNodes []graph.Node
// Stack of start indices into the subgraph node slice. The top element
// corresponds to the start index of the active (or inner-most) subgraph.
subStart []int
// graphAttr, nodeAttr and edgeAttr are global graph attributes.
graphAttr, nodeAttr, edgeAttr encoding.AttributeSetter
}
// node returns the Gonum node corresponding to the given dot AST node ID,
// generating a new such node if none exist.
func (gen *generator) node(dst graph.NodeAdder, id string) graph.Node {
if n, ok := gen.ids[id]; ok {
return n
}
n := dst.NewNode()
if n, ok := n.(DOTIDSetter); ok {
n.SetDOTID(unquoteID(id))
}
dst.AddNode(n)
gen.ids[id] = n
// Check if within the context of a subgraph, that is to be used as a vertex
// of an edge.
if gen.isInSubgraph() {
// Append node processed within the context of a subgraph, that is to be
// used as a vertex of an edge
gen.appendSubgraphNode(n)
}
return n
}
type simpleGraph struct{ generator }
// addStmt adds the given statement to the graph.
func (gen *simpleGraph) addStmt(dst encoding.Builder, stmt ast.Stmt) {
switch stmt := stmt.(type) {
case *ast.NodeStmt:
n, ok := gen.node(dst, stmt.Node.ID).(encoding.AttributeSetter)
if !ok {
return
}
for _, attr := range stmt.Attrs {
a := encoding.Attribute{
Key: unquoteID(attr.Key),
Value: unquoteID(attr.Val),
}
if err := n.SetAttribute(a); err != nil {
panic(fmt.Errorf("unable to unmarshal node DOT attribute (%s=%s): %v", a.Key, a.Value, err))
}
}
case *ast.EdgeStmt:
gen.addEdgeStmt(dst, stmt)
case *ast.AttrStmt:
var n encoding.AttributeSetter
var dst string
switch stmt.Kind {
case ast.GraphKind:
if gen.graphAttr == nil {
return
}
n = gen.graphAttr
dst = "graph"
case ast.NodeKind:
if gen.nodeAttr == nil {
return
}
n = gen.nodeAttr
dst = "node"
case ast.EdgeKind:
if gen.edgeAttr == nil {
return
}
n = gen.edgeAttr
dst = "edge"
default:
panic("unreachable")
}
for _, attr := range stmt.Attrs {
a := encoding.Attribute{
Key: unquoteID(attr.Key),
Value: unquoteID(attr.Val),
}
if err := n.SetAttribute(a); err != nil {
panic(fmt.Errorf("unable to unmarshal global %s DOT attribute (%s=%s): %v", dst, a.Key, a.Value, err))
}
}
case *ast.Attr:
// ignore.
case *ast.Subgraph:
for _, stmt := range stmt.Stmts {
gen.addStmt(dst, stmt)
}
default:
panic(fmt.Sprintf("unknown statement type %T", stmt))
}
}
// basicEdge is an edge without the Reverse method to
// allow satisfaction by both graph.Edge and graph.Line.
type basicEdge interface {
From() graph.Node
To() graph.Node
}
// applyPortsToEdge applies the available port metadata from an ast.Edge
// to a graph.Edge
func applyPortsToEdge(from ast.Vertex, to *ast.Edge, edge basicEdge) {
if ps, isPortSetter := edge.(PortSetter); isPortSetter {
if n, vertexIsNode := from.(*ast.Node); vertexIsNode {
if n.Port != nil {
err := ps.SetFromPort(unquoteID(n.Port.ID), n.Port.CompassPoint.String())
if err != nil {
panic(fmt.Errorf("unable to unmarshal edge port (:%s:%s)", n.Port.ID, n.Port.CompassPoint.String()))
}
}
}
if n, vertexIsNode := to.Vertex.(*ast.Node); vertexIsNode {
if n.Port != nil {
err := ps.SetToPort(unquoteID(n.Port.ID), n.Port.CompassPoint.String())
if err != nil {
panic(fmt.Errorf("unable to unmarshal edge DOT port (:%s:%s)", n.Port.ID, n.Port.CompassPoint.String()))
}
}
}
}
}
// addEdgeStmt adds the given edge statement to the graph.
func (gen *simpleGraph) addEdgeStmt(dst encoding.Builder, stmt *ast.EdgeStmt) {
fs := gen.addVertex(dst, stmt.From)
ts := gen.addEdge(dst, stmt.To, stmt.Attrs)
for _, f := range fs {
for _, t := range ts {
edge := dst.NewEdge(f, t)
dst.SetEdge(edge)
applyPortsToEdge(stmt.From, stmt.To, edge)
addEdgeAttrs(edge, stmt.Attrs)
}
}
}
// addVertex adds the given vertex to the graph, and returns its set of nodes.
func (gen *simpleGraph) addVertex(dst encoding.Builder, v ast.Vertex) []graph.Node {
switch v := v.(type) {
case *ast.Node:
n := gen.node(dst, v.ID)
return []graph.Node{n}
case *ast.Subgraph:
gen.pushSubgraph()
for _, stmt := range v.Stmts {
gen.addStmt(dst, stmt)
}
return gen.popSubgraph()
default:
panic(fmt.Sprintf("unknown vertex type %T", v))
}
}
// addEdge adds the given edge to the graph, and returns its set of nodes.
func (gen *simpleGraph) addEdge(dst encoding.Builder, to *ast.Edge, attrs []*ast.Attr) []graph.Node {
if !gen.directed && to.Directed {
panic(fmt.Errorf("directed edge to %v in undirected graph", to.Vertex))
}
fs := gen.addVertex(dst, to.Vertex)
if to.To != nil {
ts := gen.addEdge(dst, to.To, attrs)
for _, f := range fs {
for _, t := range ts {
edge := dst.NewEdge(f, t)
dst.SetEdge(edge)
applyPortsToEdge(to.Vertex, to.To, edge)
addEdgeAttrs(edge, attrs)
}
}
}
return fs
}
// pushSubgraph pushes the node start index of the active subgraph onto the
// stack.
func (gen *generator) pushSubgraph() {
gen.subStart = append(gen.subStart, len(gen.subNodes))
}
// popSubgraph pops the node start index of the active subgraph from the stack,
// and returns the nodes processed since.
func (gen *generator) popSubgraph() []graph.Node {
// Get nodes processed since the subgraph became active.
start := gen.subStart[len(gen.subStart)-1]
// TODO: Figure out a better way to store subgraph nodes, so that duplicates
// may not occur.
nodes := unique(gen.subNodes[start:])
// Remove subgraph from stack.
gen.subStart = gen.subStart[:len(gen.subStart)-1]
if len(gen.subStart) == 0 {
// Remove subgraph nodes when the bottom-most subgraph has been processed.
gen.subNodes = gen.subNodes[:0]
}
return nodes
}
// unique returns the set of unique nodes contained within ns.
func unique(ns []graph.Node) []graph.Node {
var nodes []graph.Node
seen := make(set.Int64s)
for _, n := range ns {
id := n.ID()
if seen.Has(id) {
// skip duplicate node
continue
}
seen.Add(id)
nodes = append(nodes, n)
}
return nodes
}
// isInSubgraph reports whether the active context is within a subgraph, that is
// to be used as a vertex of an edge.
func (gen *generator) isInSubgraph() bool {
return len(gen.subStart) > 0
}
// appendSubgraphNode appends the given node to the slice of nodes processed
// within the context of a subgraph.
func (gen *generator) appendSubgraphNode(n graph.Node) {
gen.subNodes = append(gen.subNodes, n)
}
type multiGraph struct{ generator }
// addStmt adds the given statement to the multigraph.
func (gen *multiGraph) addStmt(dst encoding.MultiBuilder, stmt ast.Stmt) {
switch stmt := stmt.(type) {
case *ast.NodeStmt:
n, ok := gen.node(dst, stmt.Node.ID).(encoding.AttributeSetter)
if !ok {
return
}
for _, attr := range stmt.Attrs {
a := encoding.Attribute{
Key: unquoteID(attr.Key),
Value: unquoteID(attr.Val),
}
if err := n.SetAttribute(a); err != nil {
panic(fmt.Errorf("unable to unmarshal node DOT attribute (%s=%s): %v", a.Key, a.Value, err))
}
}
case *ast.EdgeStmt:
gen.addEdgeStmt(dst, stmt)
case *ast.AttrStmt:
var n encoding.AttributeSetter
var dst string
switch stmt.Kind {
case ast.GraphKind:
if gen.graphAttr == nil {
return
}
n = gen.graphAttr
dst = "graph"
case ast.NodeKind:
if gen.nodeAttr == nil {
return
}
n = gen.nodeAttr
dst = "node"
case ast.EdgeKind:
if gen.edgeAttr == nil {
return
}
n = gen.edgeAttr
dst = "edge"
default:
panic("unreachable")
}
for _, attr := range stmt.Attrs {
a := encoding.Attribute{
Key: unquoteID(attr.Key),
Value: unquoteID(attr.Val),
}
if err := n.SetAttribute(a); err != nil {
panic(fmt.Errorf("unable to unmarshal global %s DOT attribute (%s=%s): %v", dst, a.Key, a.Value, err))
}
}
case *ast.Attr:
// ignore.
case *ast.Subgraph:
for _, stmt := range stmt.Stmts {
gen.addStmt(dst, stmt)
}
default:
panic(fmt.Sprintf("unknown statement type %T", stmt))
}
}
// addEdgeStmt adds the given edge statement to the multigraph.
func (gen *multiGraph) addEdgeStmt(dst encoding.MultiBuilder, stmt *ast.EdgeStmt) {
fs := gen.addVertex(dst, stmt.From)
ts := gen.addLine(dst, stmt.To, stmt.Attrs)
for _, f := range fs {
for _, t := range ts {
edge := dst.NewLine(f, t)
dst.SetLine(edge)
applyPortsToEdge(stmt.From, stmt.To, edge)
addEdgeAttrs(edge, stmt.Attrs)
}
}
}
// addVertex adds the given vertex to the multigraph, and returns its set of nodes.
func (gen *multiGraph) addVertex(dst encoding.MultiBuilder, v ast.Vertex) []graph.Node {
switch v := v.(type) {
case *ast.Node:
n := gen.node(dst, v.ID)
return []graph.Node{n}
case *ast.Subgraph:
gen.pushSubgraph()
for _, stmt := range v.Stmts {
gen.addStmt(dst, stmt)
}
return gen.popSubgraph()
default:
panic(fmt.Sprintf("unknown vertex type %T", v))
}
}
// addLine adds the given edge to the multigraph, and returns its set of nodes.
func (gen *multiGraph) addLine(dst encoding.MultiBuilder, to *ast.Edge, attrs []*ast.Attr) []graph.Node {
if !gen.directed && to.Directed {
panic(fmt.Errorf("directed edge to %v in undirected graph", to.Vertex))
}
fs := gen.addVertex(dst, to.Vertex)
if to.To != nil {
ts := gen.addLine(dst, to.To, attrs)
for _, f := range fs {
for _, t := range ts {
edge := dst.NewLine(f, t)
dst.SetLine(edge)
applyPortsToEdge(to.Vertex, to.To, edge)
addEdgeAttrs(edge, attrs)
}
}
}
return fs
}
// addEdgeAttrs adds the attributes to the given edge.
func addEdgeAttrs(edge basicEdge, attrs []*ast.Attr) {
e, ok := edge.(encoding.AttributeSetter)
if !ok {
return
}
for _, attr := range attrs {
a := encoding.Attribute{
Key: unquoteID(attr.Key),
Value: unquoteID(attr.Val),
}
if err := e.SetAttribute(a); err != nil {
panic(fmt.Errorf("unable to unmarshal edge DOT attribute (%s=%s): %v", a.Key, a.Value, err))
}
}
}
// unquoteID unquotes the given string if needed in the context of an ID. If s
// is not already quoted the original string is returned.
func unquoteID(s string) string {
// To make round-trips idempotent, don't unquote quoted HTML-like strings
//
// /^"<.*>"$/
if len(s) >= 4 && strings.HasPrefix(s, `"<`) && strings.HasSuffix(s, `>"`) {
return s
}
// Unquote quoted string if possible.
if t, err := strconv.Unquote(s); err == nil {
return t
}
// On error, either s is not quoted or s is quoted but contains invalid
// characters, in both cases we return the original string rather than
// panicking.
return s
}