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import { DefaultGraph, type RDF } from "../rdf.ts";import xsd from "../namespaces/xsd.ts";import { escape } from "./escape.ts";
export const blankNode = (term: RDF.BlankNode) => {  return `_:${term.value}`;};
export const namedNode = (term: RDF.NamedNode) => {  return `<${term.value}>`;};
export const variable = (term: RDF.Variable) => {  return `?${term.value}`;};
export const literal = (term: RDF.Literal) => {  const datatype = term.datatype.value;  if (    datatype === xsd.integer || datatype === xsd.boolean ||    datatype === xsd.decimal  ) {    return term.value;  }
  const value = `"${escape(term.value)}"`;
  if (term.language) {    return `${value}@${term.language}`;  }
  if (datatype !== xsd.string) {    return `${value}^^${namedNode(term.datatype)}`;  }
  return value;};
const quad = (term: RDF.BaseQuad) => {  const triple = `${stringify(term.subject)} ${stringify(term.predicate)} ${    stringify(term.object)  } .`;
  if (term.graph.equals(DefaultGraph.INSTANCE)) {    return triple;  }
  return `GRAPH ${stringify(term.graph)} { ${triple} }`;};
export const stringify = (term: RDF.Term): string => {  switch (term.termType) {    case "BlankNode":      return blankNode(term);    case "NamedNode":      return namedNode(term);    case "Variable":      return variable(term);    case "Literal":      return literal(term);    case "Quad":      return quad(term);    default:      throw new Error("Unknown RDF type found.");  }};