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: / proc / self / root / proc / 2902 / root / usr / share / node_modules / n3 / lib /
Filename : N3Parser.js
back
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;

var _N3Lexer = _interopRequireDefault(require("./N3Lexer"));

var _N3DataFactory = _interopRequireDefault(require("./N3DataFactory"));

var _IRIs = _interopRequireDefault(require("./IRIs"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

// **N3Parser** parses N3 documents.
let blankNodePrefix = 0; // ## Constructor

class N3Parser {
  constructor(options) {
    this._contextStack = [];
    this._graph = null; // Set the document IRI

    options = options || {};

    this._setBase(options.baseIRI);

    options.factory && initDataFactory(this, options.factory); // Set supported features depending on the format

    const format = typeof options.format === 'string' ? options.format.match(/\w*$/)[0].toLowerCase() : '',
          isTurtle = /turtle/.test(format),
          isTriG = /trig/.test(format),
          isNTriples = /triple/.test(format),
          isNQuads = /quad/.test(format),
          isN3 = this._n3Mode = /n3/.test(format),
          isLineMode = isNTriples || isNQuads;
    if (!(this._supportsNamedGraphs = !(isTurtle || isN3))) this._readPredicateOrNamedGraph = this._readPredicate; // Support triples in other graphs

    this._supportsQuads = !(isTurtle || isTriG || isNTriples || isN3); // Support nesting of triples

    this._supportsRDFStar = format === '' || /star|\*$/.test(format); // Disable relative IRIs in N-Triples or N-Quads mode

    if (isLineMode) this._resolveRelativeIRI = iri => {
      return null;
    };
    this._blankNodePrefix = typeof options.blankNodePrefix !== 'string' ? '' : options.blankNodePrefix.replace(/^(?!_:)/, '_:');
    this._lexer = options.lexer || new _N3Lexer.default({
      lineMode: isLineMode,
      n3: isN3
    }); // Disable explicit quantifiers by default

    this._explicitQuantifiers = !!options.explicitQuantifiers;
  } // ## Static class methods
  // ### `_resetBlankNodePrefix` restarts blank node prefix identification


  static _resetBlankNodePrefix() {
    blankNodePrefix = 0;
  } // ## Private methods
  // ### `_setBase` sets the base IRI to resolve relative IRIs


  _setBase(baseIRI) {
    if (!baseIRI) {
      this._base = '';
      this._basePath = '';
    } else {
      // Remove fragment if present
      const fragmentPos = baseIRI.indexOf('#');
      if (fragmentPos >= 0) baseIRI = baseIRI.substr(0, fragmentPos); // Set base IRI and its components

      this._base = baseIRI;
      this._basePath = baseIRI.indexOf('/') < 0 ? baseIRI : baseIRI.replace(/[^\/?]*(?:\?.*)?$/, '');
      baseIRI = baseIRI.match(/^(?:([a-z][a-z0-9+.-]*:))?(?:\/\/[^\/]*)?/i);
      this._baseRoot = baseIRI[0];
      this._baseScheme = baseIRI[1];
    }
  } // ### `_saveContext` stores the current parsing context
  // when entering a new scope (list, blank node, formula)


  _saveContext(type, graph, subject, predicate, object) {
    const n3Mode = this._n3Mode;

    this._contextStack.push({
      type,
      subject,
      predicate,
      object,
      graph,
      inverse: n3Mode ? this._inversePredicate : false,
      blankPrefix: n3Mode ? this._prefixes._ : '',
      quantified: n3Mode ? this._quantified : null
    }); // The settings below only apply to N3 streams


    if (n3Mode) {
      // Every new scope resets the predicate direction
      this._inversePredicate = false; // In N3, blank nodes are scoped to a formula
      // (using a dot as separator, as a blank node label cannot start with it)

      this._prefixes._ = this._graph ? `${this._graph.id.substr(2)}.` : '.'; // Quantifiers are scoped to a formula

      this._quantified = Object.create(this._quantified);
    }
  } // ### `_restoreContext` restores the parent context
  // when leaving a scope (list, blank node, formula)


  _restoreContext(type, token) {
    // Obtain the previous context
    const context = this._contextStack.pop();

    if (!context || context.type !== type) return this._error(`Unexpected ${token.type}`, token); // Restore the quad of the previous context

    this._subject = context.subject;
    this._predicate = context.predicate;
    this._object = context.object;
    this._graph = context.graph; // Restore N3 context settings

    if (this._n3Mode) {
      this._inversePredicate = context.inverse;
      this._prefixes._ = context.blankPrefix;
      this._quantified = context.quantified;
    }
  } // ### `_readInTopContext` reads a token when in the top context


  _readInTopContext(token) {
    switch (token.type) {
      // If an EOF token arrives in the top context, signal that we're done
      case 'eof':
        if (this._graph !== null) return this._error('Unclosed graph', token);
        delete this._prefixes._;
        return this._callback(null, null, this._prefixes);
      // It could be a prefix declaration

      case 'PREFIX':
        this._sparqlStyle = true;

      case '@prefix':
        return this._readPrefix;
      // It could be a base declaration

      case 'BASE':
        this._sparqlStyle = true;

      case '@base':
        return this._readBaseIRI;
      // It could be a graph

      case '{':
        if (this._supportsNamedGraphs) {
          this._graph = '';
          this._subject = null;
          return this._readSubject;
        }

      case 'GRAPH':
        if (this._supportsNamedGraphs) return this._readNamedGraphLabel;
      // Otherwise, the next token must be a subject

      default:
        return this._readSubject(token);
    }
  } // ### `_readEntity` reads an IRI, prefixed name, blank node, or variable


  _readEntity(token, quantifier) {
    let value;

    switch (token.type) {
      // Read a relative or absolute IRI
      case 'IRI':
      case 'typeIRI':
        const iri = this._resolveIRI(token.value);

        if (iri === null) return this._error('Invalid IRI', token);
        value = this._namedNode(iri);
        break;
      // Read a prefixed name

      case 'type':
      case 'prefixed':
        const prefix = this._prefixes[token.prefix];
        if (prefix === undefined) return this._error(`Undefined prefix "${token.prefix}:"`, token);
        value = this._namedNode(prefix + token.value);
        break;
      // Read a blank node

      case 'blank':
        value = this._blankNode(this._prefixes[token.prefix] + token.value);
        break;
      // Read a variable

      case 'var':
        value = this._variable(token.value.substr(1));
        break;
      // Everything else is not an entity

      default:
        return this._error(`Expected entity but got ${token.type}`, token);
    } // In N3 mode, replace the entity if it is quantified


    if (!quantifier && this._n3Mode && value.id in this._quantified) value = this._quantified[value.id];
    return value;
  } // ### `_readSubject` reads a quad's subject


  _readSubject(token) {
    this._predicate = null;

    switch (token.type) {
      case '[':
        // Start a new quad with a new blank node as subject
        this._saveContext('blank', this._graph, this._subject = this._blankNode(), null, null);

        return this._readBlankNodeHead;

      case '(':
        // Start a new list
        this._saveContext('list', this._graph, this.RDF_NIL, null, null);

        this._subject = null;
        return this._readListItem;

      case '{':
        // Start a new formula
        if (!this._n3Mode) return this._error('Unexpected graph', token);

        this._saveContext('formula', this._graph, this._graph = this._blankNode(), null, null);

        return this._readSubject;

      case '}':
        // No subject; the graph in which we are reading is closed instead
        return this._readPunctuation(token);

      case '@forSome':
        if (!this._n3Mode) return this._error('Unexpected "@forSome"', token);
        this._subject = null;
        this._predicate = this.N3_FORSOME;
        this._quantifier = this._blankNode;
        return this._readQuantifierList;

      case '@forAll':
        if (!this._n3Mode) return this._error('Unexpected "@forAll"', token);
        this._subject = null;
        this._predicate = this.N3_FORALL;
        this._quantifier = this._variable;
        return this._readQuantifierList;

      case 'literal':
        if (!this._n3Mode) return this._error('Unexpected literal', token);

        if (token.prefix.length === 0) {
          this._literalValue = token.value;
          return this._completeSubjectLiteral;
        } else this._subject = this._literal(token.value, this._namedNode(token.prefix));

        break;

      case '<<':
        if (!this._supportsRDFStar) return this._error('Unexpected RDF* syntax', token);

        this._saveContext('<<', this._graph, null, null, null);

        this._graph = null;
        return this._readSubject;

      default:
        // Read the subject entity
        if ((this._subject = this._readEntity(token)) === undefined) return; // In N3 mode, the subject might be a path

        if (this._n3Mode) return this._getPathReader(this._readPredicateOrNamedGraph);
    } // The next token must be a predicate,
    // or, if the subject was actually a graph IRI, a named graph


    return this._readPredicateOrNamedGraph;
  } // ### `_readPredicate` reads a quad's predicate


  _readPredicate(token) {
    const type = token.type;

    switch (type) {
      case 'inverse':
        this._inversePredicate = true;

      case 'abbreviation':
        this._predicate = this.ABBREVIATIONS[token.value];
        break;

      case '.':
      case ']':
      case '}':
        // Expected predicate didn't come, must have been trailing semicolon
        if (this._predicate === null) return this._error(`Unexpected ${type}`, token);
        this._subject = null;
        return type === ']' ? this._readBlankNodeTail(token) : this._readPunctuation(token);

      case ';':
        // Additional semicolons can be safely ignored
        return this._predicate !== null ? this._readPredicate : this._error('Expected predicate but got ;', token);

      case '[':
        if (this._n3Mode) {
          // Start a new quad with a new blank node as subject
          this._saveContext('blank', this._graph, this._subject, this._subject = this._blankNode(), null);

          return this._readBlankNodeHead;
        }

      case 'blank':
        if (!this._n3Mode) return this._error('Disallowed blank node as predicate', token);

      default:
        if ((this._predicate = this._readEntity(token)) === undefined) return;
    } // The next token must be an object


    return this._readObject;
  } // ### `_readObject` reads a quad's object


  _readObject(token) {
    switch (token.type) {
      case 'literal':
        // Regular literal, can still get a datatype or language
        if (token.prefix.length === 0) {
          this._literalValue = token.value;
          return this._readDataTypeOrLang;
        } // Pre-datatyped string literal (prefix stores the datatype)
        else this._object = this._literal(token.value, this._namedNode(token.prefix));

        break;

      case '[':
        // Start a new quad with a new blank node as subject
        this._saveContext('blank', this._graph, this._subject, this._predicate, this._subject = this._blankNode());

        return this._readBlankNodeHead;

      case '(':
        // Start a new list
        this._saveContext('list', this._graph, this._subject, this._predicate, this.RDF_NIL);

        this._subject = null;
        return this._readListItem;

      case '{':
        // Start a new formula
        if (!this._n3Mode) return this._error('Unexpected graph', token);

        this._saveContext('formula', this._graph, this._subject, this._predicate, this._graph = this._blankNode());

        return this._readSubject;

      case '<<':
        if (!this._supportsRDFStar) return this._error('Unexpected RDF* syntax', token);

        this._saveContext('<<', this._graph, this._subject, this._predicate, null);

        this._graph = null;
        return this._readSubject;

      default:
        // Read the object entity
        if ((this._object = this._readEntity(token)) === undefined) return; // In N3 mode, the object might be a path

        if (this._n3Mode) return this._getPathReader(this._getContextEndReader());
    }

    return this._getContextEndReader();
  } // ### `_readPredicateOrNamedGraph` reads a quad's predicate, or a named graph


  _readPredicateOrNamedGraph(token) {
    return token.type === '{' ? this._readGraph(token) : this._readPredicate(token);
  } // ### `_readGraph` reads a graph


  _readGraph(token) {
    if (token.type !== '{') return this._error(`Expected graph but got ${token.type}`, token); // The "subject" we read is actually the GRAPH's label

    this._graph = this._subject, this._subject = null;
    return this._readSubject;
  } // ### `_readBlankNodeHead` reads the head of a blank node


  _readBlankNodeHead(token) {
    if (token.type === ']') {
      this._subject = null;
      return this._readBlankNodeTail(token);
    } else {
      this._predicate = null;
      return this._readPredicate(token);
    }
  } // ### `_readBlankNodeTail` reads the end of a blank node


  _readBlankNodeTail(token) {
    if (token.type !== ']') return this._readBlankNodePunctuation(token); // Store blank node quad

    if (this._subject !== null) this._emit(this._subject, this._predicate, this._object, this._graph); // Restore the parent context containing this blank node

    const empty = this._predicate === null;

    this._restoreContext('blank', token); // If the blank node was the object, restore previous context and read punctuation


    if (this._object !== null) return this._getContextEndReader(); // If the blank node was the predicate, continue reading the object
    else if (this._predicate !== null) return this._readObject; // If the blank node was the subject, continue reading the predicate
    else // If the blank node was empty, it could be a named graph label
      return empty ? this._readPredicateOrNamedGraph : this._readPredicateAfterBlank;
  } // ### `_readPredicateAfterBlank` reads a predicate after an anonymous blank node


  _readPredicateAfterBlank(token) {
    switch (token.type) {
      case '.':
      case '}':
        // No predicate is coming if the triple is terminated here
        this._subject = null;
        return this._readPunctuation(token);

      default:
        return this._readPredicate(token);
    }
  } // ### `_readListItem` reads items from a list


  _readListItem(token) {
    let item = null,
        // The item of the list
    list = null,
        // The list itself
    next = this._readListItem; // The next function to execute

    const previousList = this._subject,
          // The previous list that contains this list
    stack = this._contextStack,
          // The stack of parent contexts
    parent = stack[stack.length - 1]; // The parent containing the current list

    switch (token.type) {
      case '[':
        // Stack the current list quad and start a new quad with a blank node as subject
        this._saveContext('blank', this._graph, list = this._blankNode(), this.RDF_FIRST, this._subject = item = this._blankNode());

        next = this._readBlankNodeHead;
        break;

      case '(':
        // Stack the current list quad and start a new list
        this._saveContext('list', this._graph, list = this._blankNode(), this.RDF_FIRST, this.RDF_NIL);

        this._subject = null;
        break;

      case ')':
        // Closing the list; restore the parent context
        this._restoreContext('list', token); // If this list is contained within a parent list, return the membership quad here.
        // This will be `<parent list element> rdf:first <this list>.`.


        if (stack.length !== 0 && stack[stack.length - 1].type === 'list') this._emit(this._subject, this._predicate, this._object, this._graph); // Was this list the parent's subject?

        if (this._predicate === null) {
          // The next token is the predicate
          next = this._readPredicate; // No list tail if this was an empty list

          if (this._subject === this.RDF_NIL) return next;
        } // The list was in the parent context's object
        else {
          next = this._getContextEndReader(); // No list tail if this was an empty list

          if (this._object === this.RDF_NIL) return next;
        } // Close the list by making the head nil


        list = this.RDF_NIL;
        break;

      case 'literal':
        // Regular literal, can still get a datatype or language
        if (token.prefix.length === 0) {
          this._literalValue = token.value;
          next = this._readListItemDataTypeOrLang;
        } // Pre-datatyped string literal (prefix stores the datatype)
        else {
          item = this._literal(token.value, this._namedNode(token.prefix));
          next = this._getContextEndReader();
        }

        break;

      case '{':
        // Start a new formula
        if (!this._n3Mode) return this._error('Unexpected graph', token);

        this._saveContext('formula', this._graph, this._subject, this._predicate, this._graph = this._blankNode());

        return this._readSubject;

      default:
        if ((item = this._readEntity(token)) === undefined) return;
    } // Create a new blank node if no item head was assigned yet


    if (list === null) this._subject = list = this._blankNode(); // Is this the first element of the list?

    if (previousList === null) {
      // This list is either the subject or the object of its parent
      if (parent.predicate === null) parent.subject = list;else parent.object = list;
    } else {
      // Continue the previous list with the current list
      this._emit(previousList, this.RDF_REST, list, this._graph);
    } // If an item was read, add it to the list


    if (item !== null) {
      // In N3 mode, the item might be a path
      if (this._n3Mode && (token.type === 'IRI' || token.type === 'prefixed')) {
        // Create a new context to add the item's path
        this._saveContext('item', this._graph, list, this.RDF_FIRST, item);

        this._subject = item, this._predicate = null; // _readPath will restore the context and output the item

        return this._getPathReader(this._readListItem);
      } // Output the item


      this._emit(list, this.RDF_FIRST, item, this._graph);
    }

    return next;
  } // ### `_readDataTypeOrLang` reads an _optional_ datatype or language


  _readDataTypeOrLang(token) {
    return this._completeObjectLiteral(token, false);
  } // ### `_readListItemDataTypeOrLang` reads an _optional_ datatype or language in a list


  _readListItemDataTypeOrLang(token) {
    return this._completeObjectLiteral(token, true);
  } // ### `_completeLiteral` completes a literal with an optional datatype or language


  _completeLiteral(token) {
    // Create a simple string literal by default
    let literal = this._literal(this._literalValue);

    switch (token.type) {
      // Create a datatyped literal
      case 'type':
      case 'typeIRI':
        const datatype = this._readEntity(token);

        if (datatype === undefined) return; // No datatype means an error occurred

        literal = this._literal(this._literalValue, datatype);
        token = null;
        break;
      // Create a language-tagged string

      case 'langcode':
        literal = this._literal(this._literalValue, token.value);
        token = null;
        break;
    }

    return {
      token,
      literal
    };
  } // Completes a literal in subject position


  _completeSubjectLiteral(token) {
    this._subject = this._completeLiteral(token).literal;
    return this._readPredicateOrNamedGraph;
  } // Completes a literal in object position


  _completeObjectLiteral(token, listItem) {
    const completed = this._completeLiteral(token);

    if (!completed) return;
    this._object = completed.literal; // If this literal was part of a list, write the item
    // (we could also check the context stack, but passing in a flag is faster)

    if (listItem) this._emit(this._subject, this.RDF_FIRST, this._object, this._graph); // If the token was consumed, continue with the rest of the input

    if (completed.token === null) return this._getContextEndReader(); // Otherwise, consume the token now
    else {
      this._readCallback = this._getContextEndReader();
      return this._readCallback(completed.token);
    }
  } // ### `_readFormulaTail` reads the end of a formula


  _readFormulaTail(token) {
    if (token.type !== '}') return this._readPunctuation(token); // Store the last quad of the formula

    if (this._subject !== null) this._emit(this._subject, this._predicate, this._object, this._graph); // Restore the parent context containing this formula

    this._restoreContext('formula', token); // If the formula was the subject, continue reading the predicate.
    // If the formula was the object, read punctuation.


    return this._object === null ? this._readPredicate : this._getContextEndReader();
  } // ### `_readPunctuation` reads punctuation between quads or quad parts


  _readPunctuation(token) {
    let next,
        graph = this._graph;
    const subject = this._subject,
          inversePredicate = this._inversePredicate;

    switch (token.type) {
      // A closing brace ends a graph
      case '}':
        if (this._graph === null) return this._error('Unexpected graph closing', token);
        if (this._n3Mode) return this._readFormulaTail(token);
        this._graph = null;
      // A dot just ends the statement, without sharing anything with the next

      case '.':
        this._subject = null;
        next = this._contextStack.length ? this._readSubject : this._readInTopContext;
        if (inversePredicate) this._inversePredicate = false;
        break;
      // Semicolon means the subject is shared; predicate and object are different

      case ';':
        next = this._readPredicate;
        break;
      // Comma means both the subject and predicate are shared; the object is different

      case ',':
        next = this._readObject;
        break;

      default:
        // An entity means this is a quad (only allowed if not already inside a graph)
        if (this._supportsQuads && this._graph === null && (graph = this._readEntity(token)) !== undefined) {
          next = this._readQuadPunctuation;
          break;
        }

        return this._error(`Expected punctuation to follow "${this._object.id}"`, token);
    } // A quad has been completed now, so return it


    if (subject !== null) {
      const predicate = this._predicate,
            object = this._object;
      if (!inversePredicate) this._emit(subject, predicate, object, graph);else this._emit(object, predicate, subject, graph);
    }

    return next;
  } // ### `_readBlankNodePunctuation` reads punctuation in a blank node


  _readBlankNodePunctuation(token) {
    let next;

    switch (token.type) {
      // Semicolon means the subject is shared; predicate and object are different
      case ';':
        next = this._readPredicate;
        break;
      // Comma means both the subject and predicate are shared; the object is different

      case ',':
        next = this._readObject;
        break;

      default:
        return this._error(`Expected punctuation to follow "${this._object.id}"`, token);
    } // A quad has been completed now, so return it


    this._emit(this._subject, this._predicate, this._object, this._graph);

    return next;
  } // ### `_readQuadPunctuation` reads punctuation after a quad


  _readQuadPunctuation(token) {
    if (token.type !== '.') return this._error('Expected dot to follow quad', token);
    return this._readInTopContext;
  } // ### `_readPrefix` reads the prefix of a prefix declaration


  _readPrefix(token) {
    if (token.type !== 'prefix') return this._error('Expected prefix to follow @prefix', token);
    this._prefix = token.value;
    return this._readPrefixIRI;
  } // ### `_readPrefixIRI` reads the IRI of a prefix declaration


  _readPrefixIRI(token) {
    if (token.type !== 'IRI') return this._error(`Expected IRI to follow prefix "${this._prefix}:"`, token);

    const prefixNode = this._readEntity(token);

    this._prefixes[this._prefix] = prefixNode.value;

    this._prefixCallback(this._prefix, prefixNode);

    return this._readDeclarationPunctuation;
  } // ### `_readBaseIRI` reads the IRI of a base declaration


  _readBaseIRI(token) {
    const iri = token.type === 'IRI' && this._resolveIRI(token.value);

    if (!iri) return this._error('Expected valid IRI to follow base declaration', token);

    this._setBase(iri);

    return this._readDeclarationPunctuation;
  } // ### `_readNamedGraphLabel` reads the label of a named graph


  _readNamedGraphLabel(token) {
    switch (token.type) {
      case 'IRI':
      case 'blank':
      case 'prefixed':
        return this._readSubject(token), this._readGraph;

      case '[':
        return this._readNamedGraphBlankLabel;

      default:
        return this._error('Invalid graph label', token);
    }
  } // ### `_readNamedGraphLabel` reads a blank node label of a named graph


  _readNamedGraphBlankLabel(token) {
    if (token.type !== ']') return this._error('Invalid graph label', token);
    this._subject = this._blankNode();
    return this._readGraph;
  } // ### `_readDeclarationPunctuation` reads the punctuation of a declaration


  _readDeclarationPunctuation(token) {
    // SPARQL-style declarations don't have punctuation
    if (this._sparqlStyle) {
      this._sparqlStyle = false;
      return this._readInTopContext(token);
    }

    if (token.type !== '.') return this._error('Expected declaration to end with a dot', token);
    return this._readInTopContext;
  } // Reads a list of quantified symbols from a @forSome or @forAll statement


  _readQuantifierList(token) {
    let entity;

    switch (token.type) {
      case 'IRI':
      case 'prefixed':
        if ((entity = this._readEntity(token, true)) !== undefined) break;

      default:
        return this._error(`Unexpected ${token.type}`, token);
    } // Without explicit quantifiers, map entities to a quantified entity


    if (!this._explicitQuantifiers) this._quantified[entity.id] = this._quantifier(this._blankNode().value); // With explicit quantifiers, output the reified quantifier
    else {
      // If this is the first item, start a new quantifier list
      if (this._subject === null) this._emit(this._graph || this.DEFAULTGRAPH, this._predicate, this._subject = this._blankNode(), this.QUANTIFIERS_GRAPH); // Otherwise, continue the previous list
      else this._emit(this._subject, this.RDF_REST, this._subject = this._blankNode(), this.QUANTIFIERS_GRAPH); // Output the list item

      this._emit(this._subject, this.RDF_FIRST, entity, this.QUANTIFIERS_GRAPH);
    }
    return this._readQuantifierPunctuation;
  } // Reads punctuation from a @forSome or @forAll statement


  _readQuantifierPunctuation(token) {
    // Read more quantifiers
    if (token.type === ',') return this._readQuantifierList; // End of the quantifier list
    else {
      // With explicit quantifiers, close the quantifier list
      if (this._explicitQuantifiers) {
        this._emit(this._subject, this.RDF_REST, this.RDF_NIL, this.QUANTIFIERS_GRAPH);

        this._subject = null;
      } // Read a dot


      this._readCallback = this._getContextEndReader();
      return this._readCallback(token);
    }
  } // ### `_getPathReader` reads a potential path and then resumes with the given function


  _getPathReader(afterPath) {
    this._afterPath = afterPath;
    return this._readPath;
  } // ### `_readPath` reads a potential path


  _readPath(token) {
    switch (token.type) {
      // Forward path
      case '!':
        return this._readForwardPath;
      // Backward path

      case '^':
        return this._readBackwardPath;
      // Not a path; resume reading where we left off

      default:
        const stack = this._contextStack,
              parent = stack.length && stack[stack.length - 1]; // If we were reading a list item, we still need to output it

        if (parent && parent.type === 'item') {
          // The list item is the remaining subejct after reading the path
          const item = this._subject; // Switch back to the context of the list

          this._restoreContext('item', token); // Output the list item


          this._emit(this._subject, this.RDF_FIRST, item, this._graph);
        }

        return this._afterPath(token);
    }
  } // ### `_readForwardPath` reads a '!' path


  _readForwardPath(token) {
    let subject, predicate;

    const object = this._blankNode(); // The next token is the predicate


    if ((predicate = this._readEntity(token)) === undefined) return; // If we were reading a subject, replace the subject by the path's object

    if (this._predicate === null) subject = this._subject, this._subject = object; // If we were reading an object, replace the subject by the path's object
    else subject = this._object, this._object = object; // Emit the path's current quad and read its next section

    this._emit(subject, predicate, object, this._graph);

    return this._readPath;
  } // ### `_readBackwardPath` reads a '^' path


  _readBackwardPath(token) {
    const subject = this._blankNode();

    let predicate, object; // The next token is the predicate

    if ((predicate = this._readEntity(token)) === undefined) return; // If we were reading a subject, replace the subject by the path's subject

    if (this._predicate === null) object = this._subject, this._subject = subject; // If we were reading an object, replace the subject by the path's subject
    else object = this._object, this._object = subject; // Emit the path's current quad and read its next section

    this._emit(subject, predicate, object, this._graph);

    return this._readPath;
  } // ### `_readRDFStarTailOrGraph` reads the graph of a nested RDF* quad or the end of a nested RDF* triple


  _readRDFStarTailOrGraph(token) {
    if (token.type !== '>>') {
      // An entity means this is a quad (only allowed if not already inside a graph)
      if (this._supportsQuads && this._graph === null && (this._graph = this._readEntity(token)) !== undefined) return this._readRDFStarTail;
      return this._error(`Expected >> to follow "${this._object.id}"`, token);
    }

    return this._readRDFStarTail(token);
  } // ### `_readRDFStarTail` reads the end of a nested RDF* triple


  _readRDFStarTail(token) {
    if (token.type !== '>>') return this._error(`Expected >> but got ${token.type}`, token); // Read the quad and restore the previous context

    const quad = this._quad(this._subject, this._predicate, this._object, this._graph || this.DEFAULTGRAPH);

    this._restoreContext('<<', token); // If the triple was the subject, continue by reading the predicate.


    if (this._subject === null) {
      this._subject = quad;
      return this._readPredicate;
    } // If the triple was the object, read context end.
    else {
      this._object = quad;
      return this._getContextEndReader();
    }
  } // ### `_getContextEndReader` gets the next reader function at the end of a context


  _getContextEndReader() {
    const contextStack = this._contextStack;
    if (!contextStack.length) return this._readPunctuation;

    switch (contextStack[contextStack.length - 1].type) {
      case 'blank':
        return this._readBlankNodeTail;

      case 'list':
        return this._readListItem;

      case 'formula':
        return this._readFormulaTail;

      case '<<':
        return this._readRDFStarTailOrGraph;
    }
  } // ### `_emit` sends a quad through the callback


  _emit(subject, predicate, object, graph) {
    this._callback(null, this._quad(subject, predicate, object, graph || this.DEFAULTGRAPH));
  } // ### `_error` emits an error message through the callback


  _error(message, token) {
    const err = new Error(`${message} on line ${token.line}.`);
    err.context = {
      token: token,
      line: token.line,
      previousToken: this._lexer.previousToken
    };

    this._callback(err);

    this._callback = noop;
  } // ### `_resolveIRI` resolves an IRI against the base path


  _resolveIRI(iri) {
    return /^[a-z][a-z0-9+.-]*:/i.test(iri) ? iri : this._resolveRelativeIRI(iri);
  } // ### `_resolveRelativeIRI` resolves an IRI against the base path,
  // assuming that a base path has been set and that the IRI is indeed relative


  _resolveRelativeIRI(iri) {
    // An empty relative IRI indicates the base IRI
    if (!iri.length) return this._base; // Decide resolving strategy based in the first character

    switch (iri[0]) {
      // Resolve relative fragment IRIs against the base IRI
      case '#':
        return this._base + iri;
      // Resolve relative query string IRIs by replacing the query string

      case '?':
        return this._base.replace(/(?:\?.*)?$/, iri);
      // Resolve root-relative IRIs at the root of the base IRI

      case '/':
        // Resolve scheme-relative IRIs to the scheme
        return (iri[1] === '/' ? this._baseScheme : this._baseRoot) + this._removeDotSegments(iri);
      // Resolve all other IRIs at the base IRI's path

      default:
        // Relative IRIs cannot contain a colon in the first path segment
        return /^[^/:]*:/.test(iri) ? null : this._removeDotSegments(this._basePath + iri);
    }
  } // ### `_removeDotSegments` resolves './' and '../' path segments in an IRI as per RFC3986


  _removeDotSegments(iri) {
    // Don't modify the IRI if it does not contain any dot segments
    if (!/(^|\/)\.\.?($|[/#?])/.test(iri)) return iri; // Start with an imaginary slash before the IRI in order to resolve trailing './' and '../'

    const length = iri.length;
    let result = '',
        i = -1,
        pathStart = -1,
        segmentStart = 0,
        next = '/';

    while (i < length) {
      switch (next) {
        // The path starts with the first slash after the authority
        case ':':
          if (pathStart < 0) {
            // Skip two slashes before the authority
            if (iri[++i] === '/' && iri[++i] === '/') // Skip to slash after the authority
              while ((pathStart = i + 1) < length && iri[pathStart] !== '/') i = pathStart;
          }

          break;
        // Don't modify a query string or fragment

        case '?':
        case '#':
          i = length;
          break;
        // Handle '/.' or '/..' path segments

        case '/':
          if (iri[i + 1] === '.') {
            next = iri[++i + 1];

            switch (next) {
              // Remove a '/.' segment
              case '/':
                result += iri.substring(segmentStart, i - 1);
                segmentStart = i + 1;
                break;
              // Remove a trailing '/.' segment

              case undefined:
              case '?':
              case '#':
                return result + iri.substring(segmentStart, i) + iri.substr(i + 1);
              // Remove a '/..' segment

              case '.':
                next = iri[++i + 1];

                if (next === undefined || next === '/' || next === '?' || next === '#') {
                  result += iri.substring(segmentStart, i - 2); // Try to remove the parent path from result

                  if ((segmentStart = result.lastIndexOf('/')) >= pathStart) result = result.substr(0, segmentStart); // Remove a trailing '/..' segment

                  if (next !== '/') return `${result}/${iri.substr(i + 1)}`;
                  segmentStart = i + 1;
                }

            }
          }

      }

      next = iri[++i];
    }

    return result + iri.substring(segmentStart);
  } // ## Public methods
  // ### `parse` parses the N3 input and emits each parsed quad through the callback


  parse(input, quadCallback, prefixCallback) {
    // The read callback is the next function to be executed when a token arrives.
    // We start reading in the top context.
    this._readCallback = this._readInTopContext;
    this._sparqlStyle = false;
    this._prefixes = Object.create(null);
    this._prefixes._ = this._blankNodePrefix ? this._blankNodePrefix.substr(2) : `b${blankNodePrefix++}_`;
    this._prefixCallback = prefixCallback || noop;
    this._inversePredicate = false;
    this._quantified = Object.create(null); // Parse synchronously if no quad callback is given

    if (!quadCallback) {
      const quads = [];
      let error;

      this._callback = (e, t) => {
        e ? error = e : t && quads.push(t);
      };

      this._lexer.tokenize(input).every(token => {
        return this._readCallback = this._readCallback(token);
      });

      if (error) throw error;
      return quads;
    } // Parse asynchronously otherwise, executing the read callback when a token arrives


    this._callback = quadCallback;

    this._lexer.tokenize(input, (error, token) => {
      if (error !== null) this._callback(error), this._callback = noop;else if (this._readCallback) this._readCallback = this._readCallback(token);
    });
  }

} // The empty function


exports.default = N3Parser;

function noop() {} // Initializes the parser with the given data factory


function initDataFactory(parser, factory) {
  // Set factory methods
  const namedNode = factory.namedNode;
  parser._namedNode = namedNode;
  parser._blankNode = factory.blankNode;
  parser._literal = factory.literal;
  parser._variable = factory.variable;
  parser._quad = factory.quad;
  parser.DEFAULTGRAPH = factory.defaultGraph(); // Set common named nodes

  parser.RDF_FIRST = namedNode(_IRIs.default.rdf.first);
  parser.RDF_REST = namedNode(_IRIs.default.rdf.rest);
  parser.RDF_NIL = namedNode(_IRIs.default.rdf.nil);
  parser.N3_FORALL = namedNode(_IRIs.default.r.forAll);
  parser.N3_FORSOME = namedNode(_IRIs.default.r.forSome);
  parser.ABBREVIATIONS = {
    'a': namedNode(_IRIs.default.rdf.type),
    '=': namedNode(_IRIs.default.owl.sameAs),
    '>': namedNode(_IRIs.default.log.implies)
  };
  parser.QUANTIFIERS_GRAPH = namedNode('urn:n3:quantifiers');
}

initDataFactory(N3Parser.prototype, _N3DataFactory.default);