link-rdflib/src/collection.js

an RDF library for node.js, patched for speed.

'use strict'
const BlankNode = require('./blank-node')
const ClassOrder = require('./class-order')
const Node = require('./node')
const Term = require('./term')

class Collection extends Term {
  static mem(coll) {
    if (coll.sI) {
      throw new Error(`Collection ${coll} already registered`)
    }

    coll.sI = ++Term.termIndex
    Term.termMap[coll.sI] = coll

    return coll
  }

  /**
   * To keep the code simple, all collections are instantiated uniquely,
   * so keep track of the proper references.
   */
  constructor (initial) {
    super()
    this.termType = Collection.termType
    this.id = BlankNode.nextId++
    this.elements = []
    this.closed = false
    if (initial && initial.length > 0) {
      initial.forEach(element => {
        this.elements.push(Node.fromValue(element))
      })
    }
    Collection.mem(this)
  }
  append (element) {
    return this.elements.push(element)
  }
  close () {
    this.closed = true
    return this.closed
  }
  shift () {
    return this.elements.shift()
  }
  substitute (bindings) {
    var elementsCopy = this.elements.map(function (ea) {
      ea.substitute(bindings)
    })
    return new Collection(elementsCopy)
  }
  toNT () {
    return BlankNode.NTAnonymousNodePrefix + this.id
  }
  toString () {
    return '(' + this.elements.join(' ') + ')'
  }
  unshift (element) {
    return this.elements.unshift(element)
  }
}
Collection.termType = 'Collection'
Collection.prototype.classOrder = ClassOrder['Collection']
Collection.prototype.compareTerm = BlankNode.prototype.compareTerm
Collection.prototype.isVar = 0

module.exports = Collection