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// Copyright ©2020 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 rdf_test
import (
"fmt"
"log"
"os"
"strings"
"text/tabwriter"
"gonum.org/v1/gonum/graph"
"gonum.org/v1/gonum/graph/encoding"
"gonum.org/v1/gonum/graph/encoding/dot"
"gonum.org/v1/gonum/graph/formats/rdf"
"gonum.org/v1/gonum/graph/multi"
)
// dotNode implements graph.Node and dot.Node to allow the
// RDF term value to be given to the DOT encoder.
type dotNode struct {
rdf.Term
}
func (n dotNode) DOTID() string { return n.Term.Value }
// dotLine implements graph.Line and encoding.Attributer to
// allow the line's RDF term value to be given to the DOT
// encoder and for the nodes to be shimmed to the dotNode
// type.
//
// Because the graph here is directed and we are not performing
// any line reversals, it is safe not to implement the
// ReversedLine method on dotLine; it will never be called.
type dotLine struct {
*rdf.Statement
}
func (l dotLine) From() graph.Node { return dotNode{l.Subject} }
func (l dotLine) To() graph.Node { return dotNode{l.Object} }
func (l dotLine) Attributes() []encoding.Attribute {
return []encoding.Attribute{{Key: "label", Value: l.Predicate.Value}}
}
func Example_graph() {
const statements = `
_:alice <http://xmlns.com/foaf/0.1/knows> _:bob .
_:alice <http://xmlns.com/foaf/0.1/givenName> "Alice" .
_:alice <http://xmlns.com/foaf/0.1/familyName> "Smith" .
_:bob <http://xmlns.com/foaf/0.1/knows> _:alice .
_:bob <http://xmlns.com/foaf/0.1/givenName> "Bob" .
_:bob <http://xmlns.com/foaf/0.1/familyName> "Smith" .
`
// Decode the statement stream and insert the lines into a multigraph.
g := multi.NewDirectedGraph()
dec := rdf.NewDecoder(strings.NewReader(statements))
for {
l, err := dec.Unmarshal()
if err != nil {
break
}
// Wrap the line with a shim type to allow the RDF values
// to be passed to the DOT marshaling routine.
g.SetLine(dotLine{l})
}
// Marshal the graph into DOT.
b, err := dot.MarshalMulti(g, "smiths", "", "\t")
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n\n", b)
// Get the ID look-up table.
w := tabwriter.NewWriter(os.Stdout, 0, 4, 1, ' ', 0)
fmt.Fprintln(w, "Term\tID")
for t, id := range dec.Terms() {
fmt.Fprintf(w, "%s\t%d\n", t, id)
}
w.Flush()
// Unordered output:
//
// digraph smiths {
// // Node definitions.
// "_:alice";
// "_:bob";
// "Alice";
// "Smith";
// "Bob";
//
// // Edge definitions.
// "_:alice" -> "_:bob" [label=<http://xmlns.com/foaf/0.1/knows>];
// "_:alice" -> "Alice" [label=<http://xmlns.com/foaf/0.1/givenName>];
// "_:alice" -> "Smith" [label=<http://xmlns.com/foaf/0.1/familyName>];
// "_:bob" -> "_:alice" [label=<http://xmlns.com/foaf/0.1/knows>];
// "_:bob" -> "Smith" [label=<http://xmlns.com/foaf/0.1/familyName>];
// "_:bob" -> "Bob" [label=<http://xmlns.com/foaf/0.1/givenName>];
// }
//
// Term ID
// _:alice 1
// _:bob 2
// <http://xmlns.com/foaf/0.1/knows> 3
// "Alice" 4
// <http://xmlns.com/foaf/0.1/givenName> 5
// "Smith" 6
// <http://xmlns.com/foaf/0.1/familyName> 7
// "Bob" 8
}
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