|
93
|
1 // Load requested view and provide access to it
|
|
94
|
2 import { Store, Parser, Term, NamedNode, DataFactory, Util } from "n3";
|
|
|
3 const Uri = DataFactory.namedNode;
|
|
|
4 const RDFS = Util.prefix("http://www.w3.org/2000/01/rdf-schema#");
|
|
|
5 const RDF = Util.prefix("http://www.w3.org/1999/02/22-rdf-syntax-ns#");
|
|
|
6 const EX = Util.prefix("http://example.com/");
|
|
93
|
7
|
|
|
8 async function fetchAndParse(url: string): Promise<Store> {
|
|
|
9 const store = new Store();
|
|
|
10 const res = await fetch(url);
|
|
|
11 const body = await res.text();
|
|
|
12 const parser = new Parser({ format: "N3" });
|
|
|
13 await new Promise((done, rej) => {
|
|
|
14 parser.parse(body, (err, quad, prefixes) => {
|
|
|
15 if (err) {
|
|
|
16 throw err;
|
|
|
17 }
|
|
|
18 if (quad) {
|
|
|
19 store.addQuad(quad);
|
|
|
20 } else {
|
|
|
21 done(null);
|
|
|
22 }
|
|
|
23 });
|
|
|
24 });
|
|
|
25 return store;
|
|
|
26 }
|
|
|
27
|
|
94
|
28 function _singleValue(g: Store, s: Term, p: Term): Term {
|
|
|
29 const quads = g.getQuads(s, p, null, null);
|
|
|
30 const objs = new Set(quads.map((q) => q.object));
|
|
|
31 if (objs.size == 0) {
|
|
|
32 throw new Error("no value for " + s.value + " " + p.value);
|
|
|
33 } else if (objs.size == 1) {
|
|
|
34 const obj = objs.values().next().value;
|
|
|
35 return obj as Term;
|
|
|
36 } else {
|
|
|
37 throw new Error("too many different values: " + JSON.stringify(quads));
|
|
|
38 }
|
|
|
39 }
|
|
|
40
|
|
|
41 function stringValue(g: Store, s: Term, p: Term): string {
|
|
|
42 const ret = _singleValue(g, s, p);
|
|
|
43 if (ret.termType != "Literal") {
|
|
|
44 throw new Error(`ret=${ret}`);
|
|
|
45 }
|
|
|
46 return ret.value as string;
|
|
|
47 }
|
|
|
48
|
|
|
49 function uriValue(g: Store, s: Term, p: Term): NamedNode {
|
|
|
50 const ret = _singleValue(g, s, p);
|
|
|
51 if (ret.termType != "NamedNode") {
|
|
|
52 throw new Error(`ret=${ret}`);
|
|
|
53 }
|
|
|
54
|
|
|
55 return ret;
|
|
|
56 }
|
|
|
57
|
|
|
58 function labelOrTail(g: Store, uri: NamedNode): string {
|
|
|
59 let ret: string;
|
|
|
60 try {
|
|
|
61 ret = stringValue(g, uri, RDFS("label"));
|
|
|
62 } catch (e) {
|
|
|
63 const words = uri.value.split("/");
|
|
|
64 ret = words[words.length - 1];
|
|
|
65 }
|
|
|
66 if (!ret) {
|
|
|
67 ret = uri.value;
|
|
|
68 }
|
|
|
69 return ret;
|
|
|
70 }
|
|
|
71 function objects(g: Store, subj: NamedNode, pred: NamedNode): Term[] {
|
|
|
72 return g.getObjects(subj, pred, null);
|
|
|
73 }
|
|
|
74 function firstElem<E>(seq: Iterable<E>): E {
|
|
|
75 for (let e of seq) {
|
|
|
76 return e;
|
|
|
77 }
|
|
|
78 throw new Error("no elems");
|
|
|
79 }
|
|
|
80
|
|
93
|
81 export class View {
|
|
|
82 graph: Store;
|
|
|
83 ready: Promise<null>;
|
|
94
|
84 viewRoot!: NamedNode;
|
|
93
|
85 constructor(public url: string | "") {
|
|
94
|
86 (window as any).v = this; //debug
|
|
93
|
87 this.graph = new Store();
|
|
|
88 this.ready = new Promise((res, rej) => {
|
|
|
89 if (url) {
|
|
|
90 fetchAndParse(url).then((s2) => {
|
|
|
91 this.graph = s2;
|
|
|
92 res(null);
|
|
|
93 });
|
|
|
94 } else {
|
|
|
95 res(null);
|
|
|
96 }
|
|
|
97 });
|
|
94
|
98 this.ready.then(() => {
|
|
|
99 this.viewRoot = firstElem(
|
|
|
100 this.graph.getSubjects(RDF("type"), EX("View"), null)
|
|
|
101 ) as NamedNode;
|
|
|
102 });
|
|
93
|
103 }
|
|
|
104 label() {
|
|
94
|
105 return labelOrTail(this.graph, Uri(this.url));
|
|
|
106 }
|
|
|
107 // filtered+ordered list of types to show at the top level
|
|
|
108 typesToShow(typesPresent: NamedNode[]): NamedNode[] {
|
|
|
109 const ret: NamedNode[] = [];
|
|
|
110 for (let table of this.graph.getObjects(this.viewRoot, EX("table"), null)) {
|
|
|
111 const tableType = uriValue(this.graph, table, EX("showsType"));
|
|
|
112 ret.push(tableType);
|
|
|
113 }
|
|
|
114 ret.sort();
|
|
|
115 return ret;
|
|
93
|
116 }
|
|
|
117 }
|
