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Module

x/ldkit/library/encoder.ts

LDkit - Linked Data query toolkit for TypeScript developers
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import type { Options } from "./options.ts";import { DataFactory, type IRI, type RDF, toRdf } from "./rdf.ts";import type { ExpandedProperty, ExpandedSchema } from "./schema/mod.ts";import { xsd } from "../namespaces/xsd.ts";import { rdf } from "../namespaces/rdf.ts";import { ldkit } from "../namespaces/ldkit.ts";
type DecodedNode = Record<string, unknown>;
type NodeId = RDF.NamedNode | RDF.BlankNode;
export const encode = ( node: DecodedNode, schema: ExpandedSchema, options: Options, includeType = true, variableInitCounter = 0,) => { return Encoder.encode( node, schema, options, includeType, variableInitCounter, );};
export const encodeValue = ( value: unknown, datatype: string, df: DataFactory,) => { if (datatype === ldkit.IRI) { return df.namedNode(value as string); } return toRdf(value, { datatype: df.namedNode(datatype), });};
class Encoder { private readonly options: Options; private readonly includeType: boolean;
private df: DataFactory = new DataFactory({ blankNodePrefix: "b", });
private variableCounter: number;
private output: RDF.Quad[] = [];
private constructor( options: Options, includeType: boolean, variableInitCounter: number, ) { this.options = options; this.includeType = includeType; this.variableCounter = variableInitCounter; }
static encode( node: DecodedNode, schema: ExpandedSchema, options: Options, includeType: boolean, variableInitCounter: number, ) { return new Encoder(options, includeType, variableInitCounter).encode( node, schema, ); }
encode(node: DecodedNode, schema: ExpandedSchema) { const nodeId = this.getNodeId(node); this.encodeNode(node, schema, nodeId);
return this.output; }
push( s: RDF.Quad_Subject, p: RDF.Quad_Predicate, o: RDF.Quad_Object, ) { this.output.push(this.df.quad(s, p, o)); }
getNodeId(node: DecodedNode) { return node.$id ? this.df.namedNode(node.$id as string) : this.df.blankNode(); }
getNodeTypes(node: DecodedNode) { if (Array.isArray(node.$type)) { return node.$type; }
return node.$type ? [node.$type] : []; }
encodeNode(node: DecodedNode, schema: ExpandedSchema, nodeId: NodeId) { if (this.includeType) { this.encodeNodeType(node, schema["@type"], nodeId); }
Object.keys(schema).forEach((key) => { if (key === "@type") { return; } this.encodeNodeProperty( node[key], schema[key] as ExpandedProperty, nodeId, ); }); }
encodeNodeType(node: DecodedNode, requiredTypes: IRI[], nodeId: NodeId) { const finalTypes = new Set([...this.getNodeTypes(node), ...requiredTypes]);
finalTypes.forEach((type) => { this.push(nodeId, this.df.namedNode(rdf.type), this.df.namedNode(type)); }); }
encodeNodeProperty( value: unknown, property: ExpandedProperty, nodeId: NodeId, ) { if (value === undefined) { return; }
const propertyId = this.df.namedNode(property["@id"]);
if (value === null) { // TODO this.push( nodeId, propertyId, this.df.variable(`v${this.variableCounter++}`), ); return; }
if (property["@multilang"]) { const multiValue = value as unknown as Record<string, unknown>; Object.keys(multiValue).forEach((language) => { const languageValue: string[] = Array.isArray(multiValue[language]) ? multiValue[language] as string[] : [multiValue[language]] as string[]; languageValue.forEach((singleValue) => { this.push( nodeId, propertyId, this.df.literal( singleValue, language.length > 0 ? language : undefined, ), ); }); }); return; }
const values = Array.isArray(value) ? value : [value];
values.forEach((val) => { if (property["@schema"]) { const subNodeId = this.getNodeId(val); this.encodeNode(val, property["@schema"], subNodeId); this.push(nodeId, propertyId, subNodeId); return; }
const propertyType = property["@type"] ? property["@type"] : xsd.string;
if (typeof val === "string" && this.options.language) { if (propertyType === xsd.string || propertyType === rdf.langString) { this.push( nodeId, propertyId, this.df.literal(val, this.options.language), ); return; } }
const rdfValue = encodeValue(val, propertyType, this.df); this.push(nodeId, propertyId, rdfValue); }); }}