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102
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1 // Load requested view (rdf data) and provide access to it
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2 import { DataFactory, NamedNode, Store } from "n3";
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3 import { fetchAndParse, n3Graph } from "./fetchAndParse";
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4 import { EX, RDF } from "./namespaces";
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95
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5 import { labelOrTail, uriValue } from "./rdf_value";
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94
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6 const Uri = DataFactory.namedNode;
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93
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7
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94
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8 function firstElem<E>(seq: Iterable<E>): E {
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9 for (let e of seq) {
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10 return e;
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11 }
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12 throw new Error("no elems");
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13 }
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14
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97
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15 export interface TableDesc {
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16 uri: NamedNode;
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17 primary: NamedNode;
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18 joins: NamedNode[];
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19 }
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20
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102
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21 export class ViewConfig {
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93
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22 graph: Store;
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94
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23 viewRoot!: NamedNode;
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102
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24 url?: string;
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25 tables: TableDesc[] = [];
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95
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26
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102
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27 constructor() {
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93
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28 this.graph = new Store();
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29 }
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95
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30
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102
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31 async readFromUrl(url: string | "") {
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32 if (!url) {
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33 return;
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34 }
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35 await fetchAndParse(url, this.graph);
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36
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37 this._read();
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94
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38 }
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95
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39
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102
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40 async readFromGraph(n3: string) {
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41 this.graph = await n3Graph(n3);
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42 this._read();
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43 }
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44
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45 _read() {
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46 this.viewRoot = firstElem(
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47 this.graph.getSubjects(RDF("type"), EX("View"), null)
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48 ) as NamedNode;
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94
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49 for (let table of this.graph.getObjects(this.viewRoot, EX("table"), null)) {
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97
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50 const tableType = uriValue(this.graph, table, EX("primaryType"));
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51 const joins: NamedNode[] = [];
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52 for (let joinType of this.graph.getObjects(table, EX("joinType"), null)) {
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53 joins.push(joinType as NamedNode);
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54 }
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55 joins.sort();
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102
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56 this.tables.push({
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57 uri: table as NamedNode,
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58 primary: tableType,
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59 joins: joins,
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60 });
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94
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61 }
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102
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62 this.tables.sort();
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63 }
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64
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65 label(): string {
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66 return this.url !== undefined
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67 ? labelOrTail(this.graph, Uri(this.url))
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68 : "unnamed";
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93
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69 }
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70 }
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