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This code is based on the RDF N-Quad parsing code that I wrote for the Cayley graph database project in 2014. The code here does not include any code that was written by other members of the Cayley project and so is unencumbered by copyright ownership from that project. License addition is for the test suite from [1] linked from [2]. A second more restrictive license is possible if we are claiming spec compliance[3]. [1]https://www.w3.org/Consortium/Legal/2008/03-bsd-license [2]https://www.w3.org/Consortium/Legal/2008/04-testsuite-copyright.html [3]https://www.w3.org/Consortium/Legal/2008/04-testsuite-license.html
116 lines
3.3 KiB
Go
116 lines
3.3 KiB
Go
// Copyright ©2020 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package rdf_test
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import (
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"fmt"
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"log"
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"os"
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"strings"
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"text/tabwriter"
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"gonum.org/v1/gonum/graph"
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"gonum.org/v1/gonum/graph/encoding"
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"gonum.org/v1/gonum/graph/encoding/dot"
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"gonum.org/v1/gonum/graph/formats/rdf"
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"gonum.org/v1/gonum/graph/multi"
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)
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// dotNode implements graph.Node and dot.Node to allow the
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// RDF term value to be given to the DOT encoder.
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type dotNode struct {
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rdf.Term
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}
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func (n dotNode) DOTID() string { return n.Term.Value }
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// dotLine implements graph.Line and encoding.Attributer to
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// allow the line's RDF term value to be given to the DOT
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// encoder and for the nodes to be shimmed to the dotNode
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// type.
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//
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// Because the graph here is directed and we are not performing
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// any line reversals, it is safe not to implement the
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// ReversedLine method on dotLine; it will never be called.
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type dotLine struct {
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*rdf.Statement
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}
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func (l dotLine) From() graph.Node { return dotNode{l.Subject} }
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func (l dotLine) To() graph.Node { return dotNode{l.Object} }
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func (l dotLine) Attributes() []encoding.Attribute {
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return []encoding.Attribute{{Key: "label", Value: l.Predicate.Value}}
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}
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func Example_graph() {
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const statements = `
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_:alice <http://xmlns.com/foaf/0.1/knows> _:bob .
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_:alice <http://xmlns.com/foaf/0.1/givenName> "Alice" .
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_:alice <http://xmlns.com/foaf/0.1/familyName> "Smith" .
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_:bob <http://xmlns.com/foaf/0.1/knows> _:alice .
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_:bob <http://xmlns.com/foaf/0.1/givenName> "Bob" .
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_:bob <http://xmlns.com/foaf/0.1/familyName> "Smith" .
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`
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// Decode the statement stream and insert the lines into a multigraph.
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g := multi.NewDirectedGraph()
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dec := rdf.NewDecoder(strings.NewReader(statements))
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for {
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l, err := dec.Unmarshal()
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if err != nil {
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break
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}
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// Wrap the line with a shim type to allow the RDF values
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// to be passed to the DOT marshaling routine.
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g.SetLine(dotLine{l})
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}
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// Marshal the graph into DOT.
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b, err := dot.MarshalMulti(g, "smiths", "", "\t")
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if err != nil {
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log.Fatal(err)
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}
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fmt.Printf("%s\n\n", b)
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// Get the ID look-up table.
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w := tabwriter.NewWriter(os.Stdout, 0, 4, 1, ' ', 0)
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fmt.Fprintln(w, "Term\tID")
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for t, id := range dec.Terms() {
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fmt.Fprintf(w, "%s\t%d\n", t, id)
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}
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w.Flush()
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// Unordered output:
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//
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// digraph smiths {
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// // Node definitions.
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// "_:alice";
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// "_:bob";
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// "Alice";
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// "Smith";
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// "Bob";
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//
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// // Edge definitions.
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// "_:alice" -> "_:bob" [label=<http://xmlns.com/foaf/0.1/knows>];
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// "_:alice" -> "Alice" [label=<http://xmlns.com/foaf/0.1/givenName>];
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// "_:alice" -> "Smith" [label=<http://xmlns.com/foaf/0.1/familyName>];
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// "_:bob" -> "_:alice" [label=<http://xmlns.com/foaf/0.1/knows>];
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// "_:bob" -> "Smith" [label=<http://xmlns.com/foaf/0.1/familyName>];
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// "_:bob" -> "Bob" [label=<http://xmlns.com/foaf/0.1/givenName>];
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// }
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//
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// Term ID
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// _:alice 1
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// _:bob 2
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// <http://xmlns.com/foaf/0.1/knows> 3
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// "Alice" 4
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// <http://xmlns.com/foaf/0.1/givenName> 5
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// "Smith" 6
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// <http://xmlns.com/foaf/0.1/familyName> 7
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// "Bob" 8
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}
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