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95
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1 import { Store, Term, NamedNode } from "n3";
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2 import { RDFS } from "./namespaces";
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3
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4 function _singleValue(g: Store, s: Term, p: Term): Term {
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5 const quads = g.getQuads(s, p, null, null);
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6 const objs = new Set(quads.map((q) => q.object));
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7 if (objs.size == 0) {
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8 throw new Error("no value for " + s.value + " " + p.value);
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9 } else if (objs.size == 1) {
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10 const obj = objs.values().next().value;
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11 return obj as Term;
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12 } else {
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13 throw new Error("too many different values: " + JSON.stringify(quads));
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14 }
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15 }
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16
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17 export function stringValue(g: Store, s: Term, p: Term): string {
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18 const ret = _singleValue(g, s, p);
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19 if (ret.termType != "Literal") {
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20 throw new Error(`ret=${ret}`);
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21 }
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22 return ret.value as string;
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23 }
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24
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25 export function uriValue(g: Store, s: Term, p: Term): NamedNode {
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26 const ret = _singleValue(g, s, p);
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27 if (ret.termType != "NamedNode") {
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28 throw new Error(`ret=${ret}`);
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29 }
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30
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31 return ret;
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32 }
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33
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34 export function labelOrTail(g: Store, uri: NamedNode): string {
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35 let ret: string;
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36 try {
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37 ret = stringValue(g, uri, RDFS("label"));
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38 } catch (e) {
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39 const words = uri.value.split("/");
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40 ret = words[words.length - 1];
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41 }
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42 if (!ret) {
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43 ret = uri.value;
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44 }
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45 return ret;
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46 }
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