@jahed/sparql-engine
Version:
SPARQL query engine for servers and web browsers.
111 lines • 3.41 kB
JavaScript
import { isIRI } from "../../utils/rdf.js";
const HINT_PREFIX = "http://callidon.github.io/sparql-engine/hints#";
/**
* Build an URI under the <http://www.bigdata.com/queryHints#> namespace
* @param suffix - Suffix append to the HINT namespace
* @return A new URI under the HINT namespace
*/
export function HINT(suffix) {
return HINT_PREFIX + suffix;
}
export const QUERY_HINT_SCOPE = {
QUERY: 0,
BGP: 1,
};
export const QUERY_HINT = {
USE_HASH_JOIN: 0,
USE_SYMMETRIC_HASH_JOIN: 1,
SORTED_TRIPLES: 2,
};
export class QueryHints {
_bgpHints;
constructor() {
this._bgpHints = new Map();
}
/**
* Clone the set of query hints
* @return The cloned set of query hints
*/
clone() {
const res = new QueryHints();
this._bgpHints.forEach((value, key) => res.add(QUERY_HINT_SCOPE.BGP, key));
return res;
}
/**
* Merge the current hints with another set of hints
* @param other - Query hints to merge with
* @return The merged set of query hints
*/
merge(other) {
const res = this.clone();
other._bgpHints.forEach((value, key) => res.add(QUERY_HINT_SCOPE.BGP, key));
return res;
}
/**
* Add a query hint to the set
* @param scope - Scope of the hint (Query, BGP, etc)
* @param hint - Type of hint
*/
add(scope, hint) {
if (scope === QUERY_HINT_SCOPE.BGP) {
this._bgpHints.set(hint, true);
}
}
/**
* Test if a hint exists
* @param scope - Scope of the hint (Query, BGP, etc)
* @param hint - Type of hint
* @return True if the hint exists, False otherwise
*/
has(scope, hint) {
if (scope === QUERY_HINT_SCOPE.BGP) {
return this._bgpHints.has(hint);
}
return false;
}
/**
* Serialize the set of query hints into a string
* @return A string which represents the set of query hints
*/
toString() {
let res = "";
this._bgpHints.forEach((value, key) => {
switch (key) {
case QUERY_HINT.USE_SYMMETRIC_HASH_JOIN:
res += `<${HINT("BGP")}> <${HINT("SymmetricHashJoin")}> "true"^^<http://www.w3.org/2001/XMLSchema#boolean> .\n`;
break;
default:
res += `<${HINT("BGP")}> _:${key} "${value}".\n`;
break;
}
});
return res;
}
}
export function parseHints(bgp, previous) {
let res = new QueryHints();
const regularTriples = [];
bgp.forEach((triple) => {
if (isIRI(triple.subject) &&
triple.subject.value.startsWith(HINT_PREFIX) &&
triple.subject.value === HINT("Group") &&
isIRI(triple.predicate)) {
switch (triple.predicate.value) {
case HINT("HashJoin"):
res.add(QUERY_HINT_SCOPE.BGP, QUERY_HINT.USE_HASH_JOIN);
break;
case HINT("SymmetricHashJoin"):
res.add(QUERY_HINT_SCOPE.BGP, QUERY_HINT.USE_SYMMETRIC_HASH_JOIN);
break;
}
}
else {
regularTriples.push(triple);
}
});
if (previous !== undefined) {
res = res.merge(previous);
}
return [regularTriples, res];
}
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