/**
 * lunr - http://lunrjs.com - A bit like Solr, but much smaller and not as bright - 0.7.1
 * Copyright (C) 2016 Oliver Nightingale
 * @license MIT
 */

;(function(){

/**
 * Convenience function for instantiating a new lunr index and configuring it
 * with the default pipeline functions and the passed config function.
 *
 * When using this convenience function a new index will be created with the
 * following functions already in the pipeline:
 *
 * lunr.StopWordFilter - filters out any stop words before they enter the
 * index
 *
 * lunr.stemmer - stems the tokens before entering the index.
 *
 * Example:
 *
 *     var idx = lunr(function () {
 *       this.field('title', 10)
 *       this.field('tags', 100)
 *       this.field('body')
 *       
 *       this.ref('cid')
 *       
 *       this.pipeline.add(function () {
 *         // some custom pipeline function
 *       })
 *       
 *     })
 *
 * @param {Function} config A function that will be called with the new instance
 * of the lunr.Index as both its context and first parameter. It can be used to
 * customize the instance of new lunr.Index.
 * @namespace
 * @module
 * @returns {lunr.Index}
 *
 */
var lunr = function (config) {
  var idx = new lunr.Index

  idx.pipeline.add(
    lunr.trimmer,
    lunr.stopWordFilter,
    lunr.stemmer
  )

  if (config) config.call(idx, idx)

  return idx
}

lunr.version = "0.7.1"
/*!
 * lunr.utils
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * A namespace containing utils for the rest of the lunr library
 */
lunr.utils = {}

/**
 * Print a warning message to the console.
 *
 * @param {String} message The message to be printed.
 * @memberOf Utils
 */
lunr.utils.warn = (function (global) {
  return function (message) {
    if (global.console && console.warn) {
      console.warn(message)
    }
  }
})(this)

/**
 * Convert an object to a string.
 *
 * In the case of `null` and `undefined` the function returns
 * the empty string, in all other cases the result of calling
 * `toString` on the passed object is returned.
 *
 * @param {Any} obj The object to convert to a string.
 * @return {String} string representation of the passed object.
 * @memberOf Utils
 */
lunr.utils.asString = function (obj) {
  if (obj === void 0 || obj === null) {
    return ""
  } else {
    return obj.toString()
  }
}
/*!
 * lunr.EventEmitter
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.EventEmitter is an event emitter for lunr. It manages adding and removing event handlers and triggering events and their handlers.
 *
 * @constructor
 */
lunr.EventEmitter = function () {
  this.events = {}
}

/**
 * Binds a handler function to a specific event(s).
 *
 * Can bind a single function to many different events in one call.
 *
 * @param {String} [eventName] The name(s) of events to bind this function to.
 * @param {Function} fn The function to call when an event is fired.
 * @memberOf EventEmitter
 */
lunr.EventEmitter.prototype.addListener = function () {
  var args = Array.prototype.slice.call(arguments),
      fn = args.pop(),
      names = args

  if (typeof fn !== "function") throw new TypeError ("last argument must be a function")

  names.forEach(function (name) {
    if (!this.hasHandler(name)) this.events[name] = []
    this.events[name].push(fn)
  }, this)
}

/**
 * Removes a handler function from a specific event.
 *
 * @param {String} eventName The name of the event to remove this function from.
 * @param {Function} fn The function to remove from an event.
 * @memberOf EventEmitter
 */
lunr.EventEmitter.prototype.removeListener = function (name, fn) {
  if (!this.hasHandler(name)) return

  var fnIndex = this.events[name].indexOf(fn)
  this.events[name].splice(fnIndex, 1)

  if (!this.events[name].length) delete this.events[name]
}

/**
 * Calls all functions bound to the given event.
 *
 * Additional data can be passed to the event handler as arguments to `emit`
 * after the event name.
 *
 * @param {String} eventName The name of the event to emit.
 * @memberOf EventEmitter
 */
lunr.EventEmitter.prototype.emit = function (name) {
  if (!this.hasHandler(name)) return

  var args = Array.prototype.slice.call(arguments, 1)

  this.events[name].forEach(function (fn) {
    fn.apply(undefined, args)
  })
}

/**
 * Checks whether a handler has ever been stored against an event.
 *
 * @param {String} eventName The name of the event to check.
 * @private
 * @memberOf EventEmitter
 */
lunr.EventEmitter.prototype.hasHandler = function (name) {
  return name in this.events
}

/*!
 * lunr.tokenizer
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * A function for splitting a string into tokens ready to be inserted into
 * the search index. Uses `lunr.tokenizer.seperator` to split strings, change
 * the value of this property to change how strings are split into tokens.
 *
 * @module
 * @param {String} obj The string to convert into tokens
 * @see lunr.tokenizer.seperator
 * @returns {Array}
 */
lunr.tokenizer = function (obj) {
  if (!arguments.length || obj == null || obj == undefined) return []
  if (Array.isArray(obj)) return obj.map(function (t) { return lunr.utils.asString(t).toLowerCase() })

  return obj.toString().trim().toLowerCase().split(lunr.tokenizer.seperator)
}

/**
 * The sperator used to split a string into tokens. Override this property to change the behaviour of
 * `lunr.tokenizer` behaviour when tokenizing strings. By default this splits on whitespace and hyphens.
 *
 * @static
 * @see lunr.tokenizer
 */
lunr.tokenizer.seperator = /[\s\-]+/

/**
 * Loads a previously serialised tokenizer.
 *
 * A tokenizer function to be loaded must already be registered with lunr.tokenizer.
 * If the serialised tokenizer has not been registered then an error will be thrown.
 *
 * @param {String} label The label of the serialised tokenizer.
 * @returns {Function}
 * @memberOf tokenizer
 */
lunr.tokenizer.load = function (label) {
  var fn = this.registeredFunctions[label]

  if (!fn) {
    throw new Error('Cannot load un-registered function: ' + label)
  }

  return fn
}

lunr.tokenizer.label = 'default'

lunr.tokenizer.registeredFunctions = {
  'default': lunr.tokenizer
}

/**
 * Register a tokenizer function.
 *
 * Functions that are used as tokenizers should be registered if they are to be used with a serialised index.
 *
 * Registering a function does not add it to an index, functions must still be associated with a specific index for them to be used when indexing and searching documents.
 *
 * @param {Function} fn The function to register.
 * @param {String} label The label to register this function with
 * @memberOf tokenizer
 */
lunr.tokenizer.registerFunction = function (fn, label) {
  if (label in this.registeredFunctions) {
    lunr.utils.warn('Overwriting existing tokenizer: ' + label)
  }

  fn.label = label
  this.registeredFunctions[label] = fn
}
/*!
 * lunr.Pipeline
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.Pipelines maintain an ordered list of functions to be applied to all
 * tokens in documents entering the search index and queries being ran against
 * the index.
 *
 * An instance of lunr.Index created with the lunr shortcut will contain a
 * pipeline with a stop word filter and an English language stemmer. Extra
 * functions can be added before or after either of these functions or these
 * default functions can be removed.
 *
 * When run the pipeline will call each function in turn, passing a token, the
 * index of that token in the original list of all tokens and finally a list of
 * all the original tokens.
 *
 * The output of functions in the pipeline will be passed to the next function
 * in the pipeline. To exclude a token from entering the index the function
 * should return undefined, the rest of the pipeline will not be called with
 * this token.
 *
 * For serialisation of pipelines to work, all functions used in an instance of
 * a pipeline should be registered with lunr.Pipeline. Registered functions can
 * then be loaded. If trying to load a serialised pipeline that uses functions
 * that are not registered an error will be thrown.
 *
 * If not planning on serialising the pipeline then registering pipeline functions
 * is not necessary.
 *
 * @constructor
 */
lunr.Pipeline = function () {
  this._stack = []
}

lunr.Pipeline.registeredFunctions = {}

/**
 * Register a function with the pipeline.
 *
 * Functions that are used in the pipeline should be registered if the pipeline
 * needs to be serialised, or a serialised pipeline needs to be loaded.
 *
 * Registering a function does not add it to a pipeline, functions must still be
 * added to instances of the pipeline for them to be used when running a pipeline.
 *
 * @param {Function} fn The function to check for.
 * @param {String} label The label to register this function with
 * @memberOf Pipeline
 */
lunr.Pipeline.registerFunction = function (fn, label) {
  if (label in this.registeredFunctions) {
    lunr.utils.warn('Overwriting existing registered function: ' + label)
  }

  fn.label = label
  lunr.Pipeline.registeredFunctions[fn.label] = fn
}

/**
 * Warns if the function is not registered as a Pipeline function.
 *
 * @param {Function} fn The function to check for.
 * @private
 * @memberOf Pipeline
 */
lunr.Pipeline.warnIfFunctionNotRegistered = function (fn) {
  var isRegistered = fn.label && (fn.label in this.registeredFunctions)

  if (!isRegistered) {
    lunr.utils.warn('Function is not registered with pipeline. This may cause problems when serialising the index.\n', fn)
  }
}

/**
 * Loads a previously serialised pipeline.
 *
 * All functions to be loaded must already be registered with lunr.Pipeline.
 * If any function from the serialised data has not been registered then an
 * error will be thrown.
 *
 * @param {Object} serialised The serialised pipeline to load.
 * @returns {lunr.Pipeline}
 * @memberOf Pipeline
 */
lunr.Pipeline.load = function (serialised) {
  var pipeline = new lunr.Pipeline

  serialised.forEach(function (fnName) {
    var fn = lunr.Pipeline.registeredFunctions[fnName]

    if (fn) {
      pipeline.add(fn)
    } else {
      throw new Error('Cannot load un-registered function: ' + fnName)
    }
  })

  return pipeline
}

/**
 * Adds new functions to the end of the pipeline.
 *
 * Logs a warning if the function has not been registered.
 *
 * @param {Function} functions Any number of functions to add to the pipeline.
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.add = function () {
  var fns = Array.prototype.slice.call(arguments)

  fns.forEach(function (fn) {
    lunr.Pipeline.warnIfFunctionNotRegistered(fn)
    this._stack.push(fn)
  }, this)
}

/**
 * Adds a single function after a function that already exists in the
 * pipeline.
 *
 * Logs a warning if the function has not been registered.
 *
 * @param {Function} existingFn A function that already exists in the pipeline.
 * @param {Function} newFn The new function to add to the pipeline.
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.after = function (existingFn, newFn) {
  lunr.Pipeline.warnIfFunctionNotRegistered(newFn)

  var pos = this._stack.indexOf(existingFn)
  if (pos == -1) {
    throw new Error('Cannot find existingFn')
  }

  pos = pos + 1
  this._stack.splice(pos, 0, newFn)
}

/**
 * Adds a single function before a function that already exists in the
 * pipeline.
 *
 * Logs a warning if the function has not been registered.
 *
 * @param {Function} existingFn A function that already exists in the pipeline.
 * @param {Function} newFn The new function to add to the pipeline.
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.before = function (existingFn, newFn) {
  lunr.Pipeline.warnIfFunctionNotRegistered(newFn)

  var pos = this._stack.indexOf(existingFn)
  if (pos == -1) {
    throw new Error('Cannot find existingFn')
  }

  this._stack.splice(pos, 0, newFn)
}

/**
 * Removes a function from the pipeline.
 *
 * @param {Function} fn The function to remove from the pipeline.
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.remove = function (fn) {
  var pos = this._stack.indexOf(fn)
  if (pos == -1) {
    return
  }

  this._stack.splice(pos, 1)
}

/**
 * Runs the current list of functions that make up the pipeline against the
 * passed tokens.
 *
 * @param {Array} tokens The tokens to run through the pipeline.
 * @returns {Array}
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.run = function (tokens) {
  var out = [],
      tokenLength = tokens.length,
      stackLength = this._stack.length

  for (var i = 0; i < tokenLength; i++) {
    var token = tokens[i]

    for (var j = 0; j < stackLength; j++) {
      token = this._stack[j](token, i, tokens)
      if (token === void 0 || token === '') break
    };

    if (token !== void 0 && token !== '') out.push(token)
  };

  return out
}

/**
 * Resets the pipeline by removing any existing processors.
 *
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.reset = function () {
  this._stack = []
}

/**
 * Returns a representation of the pipeline ready for serialisation.
 *
 * Logs a warning if the function has not been registered.
 *
 * @returns {Array}
 * @memberOf Pipeline
 */
lunr.Pipeline.prototype.toJSON = function () {
  return this._stack.map(function (fn) {
    lunr.Pipeline.warnIfFunctionNotRegistered(fn)

    return fn.label
  })
}
/*!
 * lunr.Vector
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.Vectors implement vector related operations for
 * a series of elements.
 *
 * @constructor
 */
lunr.Vector = function () {
  this._magnitude = null
  this.list = undefined
  this.length = 0
}

/**
 * lunr.Vector.Node is a simple struct for each node
 * in a lunr.Vector.
 *
 * @private
 * @param {Number} The index of the node in the vector.
 * @param {Object} The data at this node in the vector.
 * @param {lunr.Vector.Node} The node directly after this node in the vector.
 * @constructor
 * @memberOf Vector
 */
lunr.Vector.Node = function (idx, val, next) {
  this.idx = idx
  this.val = val
  this.next = next
}

/**
 * Inserts a new value at a position in a vector.
 *
 * @param {Number} The index at which to insert a value.
 * @param {Object} The object to insert in the vector.
 * @memberOf Vector.
 */
lunr.Vector.prototype.insert = function (idx, val) {
  this._magnitude = undefined;
  var list = this.list

  if (!list) {
    this.list = new lunr.Vector.Node (idx, val, list)
    return this.length++
  }

  if (idx < list.idx) {
    this.list = new lunr.Vector.Node (idx, val, list)
    return this.length++
  }

  var prev = list,
      next = list.next

  while (next != undefined) {
    if (idx < next.idx) {
      prev.next = new lunr.Vector.Node (idx, val, next)
      return this.length++
    }

    prev = next, next = next.next
  }

  prev.next = new lunr.Vector.Node (idx, val, next)
  return this.length++
}

/**
 * Calculates the magnitude of this vector.
 *
 * @returns {Number}
 * @memberOf Vector
 */
lunr.Vector.prototype.magnitude = function () {
  if (this._magnitude) return this._magnitude
  var node = this.list,
      sumOfSquares = 0,
      val

  while (node) {
    val = node.val
    sumOfSquares += val * val
    node = node.next
  }

  return this._magnitude = Math.sqrt(sumOfSquares)
}

/**
 * Calculates the dot product of this vector and another vector.
 *
 * @param {lunr.Vector} otherVector The vector to compute the dot product with.
 * @returns {Number}
 * @memberOf Vector
 */
lunr.Vector.prototype.dot = function (otherVector) {
  var node = this.list,
      otherNode = otherVector.list,
      dotProduct = 0

  while (node && otherNode) {
    if (node.idx < otherNode.idx) {
      node = node.next
    } else if (node.idx > otherNode.idx) {
      otherNode = otherNode.next
    } else {
      dotProduct += node.val * otherNode.val
      node = node.next
      otherNode = otherNode.next
    }
  }

  return dotProduct
}

/**
 * Calculates the cosine similarity between this vector and another
 * vector.
 *
 * @param {lunr.Vector} otherVector The other vector to calculate the
 * similarity with.
 * @returns {Number}
 * @memberOf Vector
 */
lunr.Vector.prototype.similarity = function (otherVector) {
  return this.dot(otherVector) / (this.magnitude() * otherVector.magnitude())
}
/*!
 * lunr.SortedSet
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.SortedSets are used to maintain an array of uniq values in a sorted
 * order.
 *
 * @constructor
 */
lunr.SortedSet = function () {
  this.length = 0
  this.elements = []
}

/**
 * Loads a previously serialised sorted set.
 *
 * @param {Array} serialisedData The serialised set to load.
 * @returns {lunr.SortedSet}
 * @memberOf SortedSet
 */
lunr.SortedSet.load = function (serialisedData) {
  var set = new this

  set.elements = serialisedData
  set.length = serialisedData.length

  return set
}

/**
 * Inserts new items into the set in the correct position to maintain the
 * order.
 *
 * @param {Object} The objects to add to this set.
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.add = function () {
  var i, element

  for (i = 0; i < arguments.length; i++) {
    element = arguments[i]
    if (~this.indexOf(element)) continue
    this.elements.splice(this.locationFor(element), 0, element)
  }

  this.length = this.elements.length
}

/**
 * Converts this sorted set into an array.
 *
 * @returns {Array}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.toArray = function () {
  return this.elements.slice()
}

/**
 * Creates a new array with the results of calling a provided function on every
 * element in this sorted set.
 *
 * Delegates to Array.prototype.map and has the same signature.
 *
 * @param {Function} fn The function that is called on each element of the
 * set.
 * @param {Object} ctx An optional object that can be used as the context
 * for the function fn.
 * @returns {Array}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.map = function (fn, ctx) {
  return this.elements.map(fn, ctx)
}

/**
 * Executes a provided function once per sorted set element.
 *
 * Delegates to Array.prototype.forEach and has the same signature.
 *
 * @param {Function} fn The function that is called on each element of the
 * set.
 * @param {Object} ctx An optional object that can be used as the context
 * @memberOf SortedSet
 * for the function fn.
 */
lunr.SortedSet.prototype.forEach = function (fn, ctx) {
  return this.elements.forEach(fn, ctx)
}

/**
 * Returns the index at which a given element can be found in the
 * sorted set, or -1 if it is not present.
 *
 * @param {Object} elem The object to locate in the sorted set.
 * @returns {Number}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.indexOf = function (elem) {
  var start = 0,
      end = this.elements.length,
      sectionLength = end - start,
      pivot = start + Math.floor(sectionLength / 2),
      pivotElem = this.elements[pivot]

  while (sectionLength > 1) {
    if (pivotElem === elem) return pivot

    if (pivotElem < elem) start = pivot
    if (pivotElem > elem) end = pivot

    sectionLength = end - start
    pivot = start + Math.floor(sectionLength / 2)
    pivotElem = this.elements[pivot]
  }

  if (pivotElem === elem) return pivot

  return -1
}

/**
 * Returns the position within the sorted set that an element should be
 * inserted at to maintain the current order of the set.
 *
 * This function assumes that the element to search for does not already exist
 * in the sorted set.
 *
 * @param {Object} elem The elem to find the position for in the set
 * @returns {Number}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.locationFor = function (elem) {
  var start = 0,
      end = this.elements.length,
      sectionLength = end - start,
      pivot = start + Math.floor(sectionLength / 2),
      pivotElem = this.elements[pivot]

  while (sectionLength > 1) {
    if (pivotElem < elem) start = pivot
    if (pivotElem > elem) end = pivot

    sectionLength = end - start
    pivot = start + Math.floor(sectionLength / 2)
    pivotElem = this.elements[pivot]
  }

  if (pivotElem > elem) return pivot
  if (pivotElem < elem) return pivot + 1
}

/**
 * Creates a new lunr.SortedSet that contains the elements in the intersection
 * of this set and the passed set.
 *
 * @param {lunr.SortedSet} otherSet The set to intersect with this set.
 * @returns {lunr.SortedSet}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.intersect = function (otherSet) {
  var intersectSet = new lunr.SortedSet,
      i = 0, j = 0,
      a_len = this.length, b_len = otherSet.length,
      a = this.elements, b = otherSet.elements

  while (true) {
    if (i > a_len - 1 || j > b_len - 1) break

    if (a[i] === b[j]) {
      intersectSet.add(a[i])
      i++, j++
      continue
    }

    if (a[i] < b[j]) {
      i++
      continue
    }

    if (a[i] > b[j]) {
      j++
      continue
    }
  };

  return intersectSet
}

/**
 * Makes a copy of this set
 *
 * @returns {lunr.SortedSet}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.clone = function () {
  var clone = new lunr.SortedSet

  clone.elements = this.toArray()
  clone.length = clone.elements.length

  return clone
}

/**
 * Creates a new lunr.SortedSet that contains the elements in the union
 * of this set and the passed set.
 *
 * @param {lunr.SortedSet} otherSet The set to union with this set.
 * @returns {lunr.SortedSet}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.union = function (otherSet) {
  var longSet, shortSet, unionSet

  if (this.length >= otherSet.length) {
    longSet = this, shortSet = otherSet
  } else {
    longSet = otherSet, shortSet = this
  }

  unionSet = longSet.clone()

  for(var i = 0, shortSetElements = shortSet.toArray(); i < shortSetElements.length; i++){
    unionSet.add(shortSetElements[i])
  }

  return unionSet
}

/**
 * Returns a representation of the sorted set ready for serialisation.
 *
 * @returns {Array}
 * @memberOf SortedSet
 */
lunr.SortedSet.prototype.toJSON = function () {
  return this.toArray()
}
/*!
 * lunr.Index
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.Index is object that manages a search index.  It contains the indexes
 * and stores all the tokens and document lookups.  It also provides the main
 * user facing API for the library.
 *
 * @constructor
 */
lunr.Index = function () {
  this._fields = []
  this._ref = 'id'
  this.pipeline = new lunr.Pipeline
  this.documentStore = new lunr.Store
  this.tokenStore = new lunr.TokenStore
  this.corpusTokens = new lunr.SortedSet
  this.eventEmitter =  new lunr.EventEmitter
  this.tokenizerFn = lunr.tokenizer

  this._idfCache = {}

  this.on('add', 'remove', 'update', (function () {
    this._idfCache = {}
  }).bind(this))
}

/**
 * Bind a handler to events being emitted by the index.
 *
 * The handler can be bound to many events at the same time.
 *
 * @param {String} [eventName] The name(s) of events to bind the function to.
 * @param {Function} fn The serialised set to load.
 * @memberOf Index
 */
lunr.Index.prototype.on = function () {
  var args = Array.prototype.slice.call(arguments)
  return this.eventEmitter.addListener.apply(this.eventEmitter, args)
}

/**
 * Removes a handler from an event being emitted by the index.
 *
 * @param {String} eventName The name of events to remove the function from.
 * @param {Function} fn The serialised set to load.
 * @memberOf Index
 */
lunr.Index.prototype.off = function (name, fn) {
  return this.eventEmitter.removeListener(name, fn)
}

/**
 * Loads a previously serialised index.
 *
 * Issues a warning if the index being imported was serialised
 * by a different version of lunr.
 *
 * @param {Object} serialisedData The serialised set to load.
 * @returns {lunr.Index}
 * @memberOf Index
 */
lunr.Index.load = function (serialisedData) {
  if (serialisedData.version !== lunr.version) {
    lunr.utils.warn('version mismatch: current ' + lunr.version + ' importing ' + serialisedData.version)
  }

  var idx = new this

  idx._fields = serialisedData.fields
  idx._ref = serialisedData.ref

  idx.tokenizer = lunr.tokenizer.load(serialisedData.tokenizer)
  idx.documentStore = lunr.Store.load(serialisedData.documentStore)
  idx.tokenStore = lunr.TokenStore.load(serialisedData.tokenStore)
  idx.corpusTokens = lunr.SortedSet.load(serialisedData.corpusTokens)
  idx.pipeline = lunr.Pipeline.load(serialisedData.pipeline)

  return idx
}

/**
 * Adds a field to the list of fields that will be searchable within documents
 * in the index.
 *
 * An optional boost param can be passed to affect how much tokens in this field
 * rank in search results, by default the boost value is 1.
 *
 * Fields should be added before any documents are added to the index, fields
 * that are added after documents are added to the index will only apply to new
 * documents added to the index.
 *
 * @param {String} fieldName The name of the field within the document that
 * should be indexed
 * @param {Number} boost An optional boost that can be applied to terms in this
 * field.
 * @returns {lunr.Index}
 * @memberOf Index
 */
lunr.Index.prototype.field = function (fieldName, opts) {
  var opts = opts || {},
      field = { name: fieldName, boost: opts.boost || 1 }

  this._fields.push(field)
  return this
}

/**
 * Sets the property used to uniquely identify documents added to the index,
 * by default this property is 'id'.
 *
 * This should only be changed before adding documents to the index, changing
 * the ref property without resetting the index can lead to unexpected results.
 *
 * The value of ref can be of any type but it _must_ be stably comparable and
 * orderable.
 *
 * @param {String} refName The property to use to uniquely identify the
 * documents in the index.
 * @param {Boolean} emitEvent Whether to emit add events, defaults to true
 * @returns {lunr.Index}
 * @memberOf Index
 */
lunr.Index.prototype.ref = function (refName) {
  this._ref = refName
  return this
}

/**
 * Sets the tokenizer used for this index.
 *
 * By default the index will use the default tokenizer, lunr.tokenizer. The tokenizer
 * should only be changed before adding documents to the index. Changing the tokenizer
 * without re-building the index can lead to unexpected results.
 *
 * @param {Function} fn The function to use as a tokenizer.
 * @returns {lunr.Index}
 * @memberOf Index
 */
lunr.Index.prototype.tokenizer = function (fn) {
  var isRegistered = fn.label && (fn.label in lunr.tokenizer.registeredFunctions)

  if (!isRegistered) {
    lunr.utils.warn('Function is not a registered tokenizer. This may cause problems when serialising the index')
  }

  this.tokenizerFn = fn
  return this
}

/**
 * Add a document to the index.
 *
 * This is the way new documents enter the index, this function will run the
 * fields from the document through the index's pipeline and then add it to
 * the index, it will then show up in search results.
 *
 * An 'add' event is emitted with the document that has been added and the index
 * the document has been added to. This event can be silenced by passing false
 * as the second argument to add.
 *
 * @param {Object} doc The document to add to the index.
 * @param {Boolean} emitEvent Whether or not to emit events, default true.
 * @memberOf Index
 */
lunr.Index.prototype.add = function (doc, emitEvent) {
  var docTokens = {},
      allDocumentTokens = new lunr.SortedSet,
      docRef = doc[this._ref],
      emitEvent = emitEvent === undefined ? true : emitEvent

  this._fields.forEach(function (field) {
    var fieldTokens = this.pipeline.run(this.tokenizerFn(doc[field.name]))

    docTokens[field.name] = fieldTokens

    for (var i = 0; i < fieldTokens.length; i++) {
      var token = fieldTokens[i]
      allDocumentTokens.add(token)
      this.corpusTokens.add(token)
    }
  }, this)

  this.documentStore.set(docRef, allDocumentTokens)

  for (var i = 0; i < allDocumentTokens.length; i++) {
    var token = allDocumentTokens.elements[i]
    var tf = 0;

    for (var j = 0; j < this._fields.length; j++){
      var field = this._fields[j]
      var fieldTokens = docTokens[field.name]
      var fieldLength = fieldTokens.length

      if (!fieldLength) continue

      var tokenCount = 0
      for (var k = 0; k < fieldLength; k++){
        if (fieldTokens[k] === token){
          tokenCount++
        }
      }

      tf += (tokenCount / fieldLength * field.boost)
    }

    this.tokenStore.add(token, { ref: docRef, tf: tf })
  };

  if (emitEvent) this.eventEmitter.emit('add', doc, this)
}

/**
 * Removes a document from the index.
 *
 * To make sure documents no longer show up in search results they can be
 * removed from the index using this method.
 *
 * The document passed only needs to have the same ref property value as the
 * document that was added to the index, they could be completely different
 * objects.
 *
 * A 'remove' event is emitted with the document that has been removed and the index
 * the document has been removed from. This event can be silenced by passing false
 * as the second argument to remove.
 *
 * @param {Object} doc The document to remove from the index.
 * @param {Boolean} emitEvent Whether to emit remove events, defaults to true
 * @memberOf Index
 */
lunr.Index.prototype.remove = function (doc, emitEvent) {
  var docRef = doc[this._ref],
      emitEvent = emitEvent === undefined ? true : emitEvent

  if (!this.documentStore.has(docRef)) return

  var docTokens = this.documentStore.get(docRef)

  this.documentStore.remove(docRef)

  docTokens.forEach(function (token) {
    this.tokenStore.remove(token, docRef)
  }, this)

  if (emitEvent) this.eventEmitter.emit('remove', doc, this)
}

/**
 * Updates a document in the index.
 *
 * When a document contained within the index gets updated, fields changed,
 * added or removed, to make sure it correctly matched against search queries,
 * it should be updated in the index.
 *
 * This method is just a wrapper around `remove` and `add`
 *
 * An 'update' event is emitted with the document that has been updated and the index.
 * This event can be silenced by passing false as the second argument to update. Only
 * an update event will be fired, the 'add' and 'remove' events of the underlying calls
 * are silenced.
 *
 * @param {Object} doc The document to update in the index.
 * @param {Boolean} emitEvent Whether to emit update events, defaults to true
 * @see Index.prototype.remove
 * @see Index.prototype.add
 * @memberOf Index
 */
lunr.Index.prototype.update = function (doc, emitEvent) {
  var emitEvent = emitEvent === undefined ? true : emitEvent

  this.remove(doc, false)
  this.add(doc, false)

  if (emitEvent) this.eventEmitter.emit('update', doc, this)
}

/**
 * Calculates the inverse document frequency for a token within the index.
 *
 * @param {String} token The token to calculate the idf of.
 * @see Index.prototype.idf
 * @private
 * @memberOf Index
 */
lunr.Index.prototype.idf = function (term) {
  var cacheKey = "@" + term
  if (Object.prototype.hasOwnProperty.call(this._idfCache, cacheKey)) return this._idfCache[cacheKey]

  var documentFrequency = this.tokenStore.count(term),
      idf = 1

  if (documentFrequency > 0) {
    idf = 1 + Math.log(this.documentStore.length / documentFrequency)
  }

  return this._idfCache[cacheKey] = idf
}

/**
 * Searches the index using the passed query.
 *
 * Queries should be a string, multiple words are allowed and will lead to an
 * AND based query, e.g. `idx.search('foo bar')` will run a search for
 * documents containing both 'foo' and 'bar'.
 *
 * All query tokens are passed through the same pipeline that document tokens
 * are passed through, so any language processing involved will be run on every
 * query term.
 *
 * Each query term is expanded, so that the term 'he' might be expanded to
 * 'hello' and 'help' if those terms were already included in the index.
 *
 * Matching documents are returned as an array of objects, each object contains
 * the matching document ref, as set for this index, and the similarity score
 * for this document against the query.
 *
 * @param {String} query The query to search the index with.
 * @returns {Object}
 * @see Index.prototype.idf
 * @see Index.prototype.documentVector
 * @memberOf Index
 */
lunr.Index.prototype.search = function (query) {
  var queryTokens = this.pipeline.run(this.tokenizerFn(query)),
      queryVector = new lunr.Vector,
      documentSets = [],
      fieldBoosts = this._fields.reduce(function (memo, f) { return memo + f.boost }, 0)

  var hasSomeToken = queryTokens.some(function (token) {
    return this.tokenStore.has(token)
  }, this)

  if (!hasSomeToken) return []

  queryTokens
    .forEach(function (token, i, tokens) {
      var tf = 1 / tokens.length * this._fields.length * fieldBoosts,
          self = this

      var set = this.tokenStore.expand(token).reduce(function (memo, key) {
        var pos = self.corpusTokens.indexOf(key),
            idf = self.idf(key),
            similarityBoost = 1,
            set = new lunr.SortedSet

        // if the expanded key is not an exact match to the token then
        // penalise the score for this key by how different the key is
        // to the token.
        if (key !== token) {
          var diff = Math.max(3, key.length - token.length)
          similarityBoost = 1 / Math.log(diff)
        }

        // calculate the query tf-idf score for this token
        // applying an similarityBoost to ensure exact matches
        // these rank higher than expanded terms
        if (pos > -1) queryVector.insert(pos, tf * idf * similarityBoost)

        // add all the documents that have this key into a set
        // ensuring that the type of key is preserved
        var matchingDocuments = self.tokenStore.get(key),
            refs = Object.keys(matchingDocuments),
            refsLen = refs.length

        for (var i = 0; i < refsLen; i++) {
          set.add(matchingDocuments[refs[i]].ref)
        }

        return memo.union(set)
      }, new lunr.SortedSet)

      documentSets.push(set)
    }, this)

  var documentSet = documentSets.reduce(function (memo, set) {
    return memo.intersect(set)
  })

  return documentSet
    .map(function (ref) {
      return { ref: ref, score: queryVector.similarity(this.documentVector(ref)) }
    }, this)
    .sort(function (a, b) {
      return b.score - a.score
    })
}

/**
 * Generates a vector containing all the tokens in the document matching the
 * passed documentRef.
 *
 * The vector contains the tf-idf score for each token contained in the
 * document with the passed documentRef.  The vector will contain an element
 * for every token in the indexes corpus, if the document does not contain that
 * token the element will be 0.
 *
 * @param {Object} documentRef The ref to find the document with.
 * @returns {lunr.Vector}
 * @private
 * @memberOf Index
 */
lunr.Index.prototype.documentVector = function (documentRef) {
  var documentTokens = this.documentStore.get(documentRef),
      documentTokensLength = documentTokens.length,
      documentVector = new lunr.Vector

  for (var i = 0; i < documentTokensLength; i++) {
    var token = documentTokens.elements[i],
        tf = this.tokenStore.get(token)[documentRef].tf,
        idf = this.idf(token)

    documentVector.insert(this.corpusTokens.indexOf(token), tf * idf)
  };

  return documentVector
}

/**
 * Returns a representation of the index ready for serialisation.
 *
 * @returns {Object}
 * @memberOf Index
 */
lunr.Index.prototype.toJSON = function () {
  return {
    version: lunr.version,
    fields: this._fields,
    ref: this._ref,
    tokenizer: this.tokenizerFn.label,
    documentStore: this.documentStore.toJSON(),
    tokenStore: this.tokenStore.toJSON(),
    corpusTokens: this.corpusTokens.toJSON(),
    pipeline: this.pipeline.toJSON()
  }
}

/**
 * Applies a plugin to the current index.
 *
 * A plugin is a function that is called with the index as its context.
 * Plugins can be used to customise or extend the behaviour the index
 * in some way. A plugin is just a function, that encapsulated the custom
 * behaviour that should be applied to the index.
 *
 * The plugin function will be called with the index as its argument, additional
 * arguments can also be passed when calling use. The function will be called
 * with the index as its context.
 *
 * Example:
 *
 *     var myPlugin = function (idx, arg1, arg2) {
 *       // `this` is the index to be extended
 *       // apply any extensions etc here.
 *     }
 *
 *     var idx = lunr(function () {
 *       this.use(myPlugin, 'arg1', 'arg2')
 *     })
 *
 * @param {Function} plugin The plugin to apply.
 * @memberOf Index
 */
lunr.Index.prototype.use = function (plugin) {
  var args = Array.prototype.slice.call(arguments, 1)
  args.unshift(this)
  plugin.apply(this, args)
}
/*!
 * lunr.Store
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.Store is a simple key-value store used for storing sets of tokens for
 * documents stored in index.
 *
 * @constructor
 * @module
 */
lunr.Store = function () {
  this.store = {}
  this.length = 0
}

/**
 * Loads a previously serialised store
 *
 * @param {Object} serialisedData The serialised store to load.
 * @returns {lunr.Store}
 * @memberOf Store
 */
lunr.Store.load = function (serialisedData) {
  var store = new this

  store.length = serialisedData.length
  store.store = Object.keys(serialisedData.store).reduce(function (memo, key) {
    memo[key] = lunr.SortedSet.load(serialisedData.store[key])
    return memo
  }, {})

  return store
}

/**
 * Stores the given tokens in the store against the given id.
 *
 * @param {Object} id The key used to store the tokens against.
 * @param {Object} tokens The tokens to store against the key.
 * @memberOf Store
 */
lunr.Store.prototype.set = function (id, tokens) {
  if (!this.has(id)) this.length++
  this.store[id] = tokens
}

/**
 * Retrieves the tokens from the store for a given key.
 *
 * @param {Object} id The key to lookup and retrieve from the store.
 * @returns {Object}
 * @memberOf Store
 */
lunr.Store.prototype.get = function (id) {
  return this.store[id]
}

/**
 * Checks whether the store contains a key.
 *
 * @param {Object} id The id to look up in the store.
 * @returns {Boolean}
 * @memberOf Store
 */
lunr.Store.prototype.has = function (id) {
  return id in this.store
}

/**
 * Removes the value for a key in the store.
 *
 * @param {Object} id The id to remove from the store.
 * @memberOf Store
 */
lunr.Store.prototype.remove = function (id) {
  if (!this.has(id)) return

  delete this.store[id]
  this.length--
}

/**
 * Returns a representation of the store ready for serialisation.
 *
 * @returns {Object}
 * @memberOf Store
 */
lunr.Store.prototype.toJSON = function () {
  return {
    store: this.store,
    length: this.length
  }
}

/*!
 * lunr.stemmer
 * Copyright (C) 2016 Oliver Nightingale
 * Includes code from - http://tartarus.org/~martin/PorterStemmer/js.txt
 */

/**
 * lunr.stemmer is an english language stemmer, this is a JavaScript
 * implementation of the PorterStemmer taken from http://tartarus.org/~martin
 *
 * @module
 * @param {String} str The string to stem
 * @returns {String}
 * @see lunr.Pipeline
 */
lunr.stemmer = (function(){
  var step2list = {
      "ational" : "ate",
      "tional" : "tion",
      "enci" : "ence",
      "anci" : "ance",
      "izer" : "ize",
      "bli" : "ble",
      "alli" : "al",
      "entli" : "ent",
      "eli" : "e",
      "ousli" : "ous",
      "ization" : "ize",
      "ation" : "ate",
      "ator" : "ate",
      "alism" : "al",
      "iveness" : "ive",
      "fulness" : "ful",
      "ousness" : "ous",
      "aliti" : "al",
      "iviti" : "ive",
      "biliti" : "ble",
      "logi" : "log"
    },

    step3list = {
      "icate" : "ic",
      "ative" : "",
      "alize" : "al",
      "iciti" : "ic",
      "ical" : "ic",
      "ful" : "",
      "ness" : ""
    },

    c = "[^aeiou]",          // consonant
    v = "[aeiouy]",          // vowel
    C = c + "[^aeiouy]*",    // consonant sequence
    V = v + "[aeiou]*",      // vowel sequence

    mgr0 = "^(" + C + ")?" + V + C,               // [C]VC... is m>0
    meq1 = "^(" + C + ")?" + V + C + "(" + V + ")?$",  // [C]VC[V] is m=1
    mgr1 = "^(" + C + ")?" + V + C + V + C,       // [C]VCVC... is m>1
    s_v = "^(" + C + ")?" + v;                   // vowel in stem

  var re_mgr0 = new RegExp(mgr0);
  var re_mgr1 = new RegExp(mgr1);
  var re_meq1 = new RegExp(meq1);
  var re_s_v = new RegExp(s_v);

  var re_1a = /^(.+?)(ss|i)es$/;
  var re2_1a = /^(.+?)([^s])s$/;
  var re_1b = /^(.+?)eed$/;
  var re2_1b = /^(.+?)(ed|ing)$/;
  var re_1b_2 = /.$/;
  var re2_1b_2 = /(at|bl|iz)$/;
  var re3_1b_2 = new RegExp("([^aeiouylsz])\\1$");
  var re4_1b_2 = new RegExp("^" + C + v + "[^aeiouwxy]$");

  var re_1c = /^(.+?[^aeiou])y$/;
  var re_2 = /^(.+?)(ational|tional|enci|anci|izer|bli|alli|entli|eli|ousli|ization|ation|ator|alism|iveness|fulness|ousness|aliti|iviti|biliti|logi)$/;

  var re_3 = /^(.+?)(icate|ative|alize|iciti|ical|ful|ness)$/;

  var re_4 = /^(.+?)(al|ance|ence|er|ic|able|ible|ant|ement|ment|ent|ou|ism|ate|iti|ous|ive|ize)$/;
  var re2_4 = /^(.+?)(s|t)(ion)$/;

  var re_5 = /^(.+?)e$/;
  var re_5_1 = /ll$/;
  var re3_5 = new RegExp("^" + C + v + "[^aeiouwxy]$");

  var porterStemmer = function porterStemmer(w) {
    var   stem,
      suffix,
      firstch,
      re,
      re2,
      re3,
      re4;

    if (w.length < 3) { return w; }

    firstch = w.substr(0,1);
    if (firstch == "y") {
      w = firstch.toUpperCase() + w.substr(1);
    }

    // Step 1a
    re = re_1a
    re2 = re2_1a;

    if (re.test(w)) { w = w.replace(re,"$1$2"); }
    else if (re2.test(w)) { w = w.replace(re2,"$1$2"); }

    // Step 1b
    re = re_1b;
    re2 = re2_1b;
    if (re.test(w)) {
      var fp = re.exec(w);
      re = re_mgr0;
      if (re.test(fp[1])) {
        re = re_1b_2;
        w = w.replace(re,"");
      }
    } else if (re2.test(w)) {
      var fp = re2.exec(w);
      stem = fp[1];
      re2 = re_s_v;
      if (re2.test(stem)) {
        w = stem;
        re2 = re2_1b_2;
        re3 = re3_1b_2;
        re4 = re4_1b_2;
        if (re2.test(w)) {  w = w + "e"; }
        else if (re3.test(w)) { re = re_1b_2; w = w.replace(re,""); }
        else if (re4.test(w)) { w = w + "e"; }
      }
    }

    // Step 1c - replace suffix y or Y by i if preceded by a non-vowel which is not the first letter of the word (so cry -> cri, by -> by, say -> say)
    re = re_1c;
    if (re.test(w)) {
      var fp = re.exec(w);
      stem = fp[1];
      w = stem + "i";
    }

    // Step 2
    re = re_2;
    if (re.test(w)) {
      var fp = re.exec(w);
      stem = fp[1];
      suffix = fp[2];
      re = re_mgr0;
      if (re.test(stem)) {
        w = stem + step2list[suffix];
      }
    }

    // Step 3
    re = re_3;
    if (re.test(w)) {
      var fp = re.exec(w);
      stem = fp[1];
      suffix = fp[2];
      re = re_mgr0;
      if (re.test(stem)) {
        w = stem + step3list[suffix];
      }
    }

    // Step 4
    re = re_4;
    re2 = re2_4;
    if (re.test(w)) {
      var fp = re.exec(w);
      stem = fp[1];
      re = re_mgr1;
      if (re.test(stem)) {
        w = stem;
      }
    } else if (re2.test(w)) {
      var fp = re2.exec(w);
      stem = fp[1] + fp[2];
      re2 = re_mgr1;
      if (re2.test(stem)) {
        w = stem;
      }
    }

    // Step 5
    re = re_5;
    if (re.test(w)) {
      var fp = re.exec(w);
      stem = fp[1];
      re = re_mgr1;
      re2 = re_meq1;
      re3 = re3_5;
      if (re.test(stem) || (re2.test(stem) && !(re3.test(stem)))) {
        w = stem;
      }
    }

    re = re_5_1;
    re2 = re_mgr1;
    if (re.test(w) && re2.test(w)) {
      re = re_1b_2;
      w = w.replace(re,"");
    }

    // and turn initial Y back to y

    if (firstch == "y") {
      w = firstch.toLowerCase() + w.substr(1);
    }

    return w;
  };

  return porterStemmer;
})();

lunr.Pipeline.registerFunction(lunr.stemmer, 'stemmer')
/*!
 * lunr.stopWordFilter
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.generateStopWordFilter builds a stopWordFilter function from the provided
 * list of stop words.
 *
 * The built in lunr.stopWordFilter is built using this generator and can be used
 * to generate custom stopWordFilters for applications or non English languages.
 *
 * @module
 * @param {Array} token The token to pass through the filter
 * @returns {Function}
 * @see lunr.Pipeline
 * @see lunr.stopWordFilter
 */
lunr.generateStopWordFilter = function (stopWords) {
  var words = stopWords.reduce(function (memo, stopWord) {
    memo[stopWord] = stopWord
    return memo
  }, {})

  return function (token) {
    if (token && words[token] !== token) return token
  }
}

/**
 * lunr.stopWordFilter is an English language stop word list filter, any words
 * contained in the list will not be passed through the filter.
 *
 * This is intended to be used in the Pipeline. If the token does not pass the
 * filter then undefined will be returned.
 *
 * @module
 * @param {String} token The token to pass through the filter
 * @returns {String}
 * @see lunr.Pipeline
 */
lunr.stopWordFilter = lunr.generateStopWordFilter([
  'a',
  'able',
  'about',
  'across',
  'after',
  'all',
  'almost',
  'also',
  'am',
  'among',
  'an',
  'and',
  'any',
  'are',
  'as',
  'at',
  'be',
  'because',
  'been',
  'but',
  'by',
  'can',
  'cannot',
  'could',
  'dear',
  'did',
  'do',
  'does',
  'either',
  'else',
  'ever',
  'every',
  'for',
  'from',
  'get',
  'got',
  'had',
  'has',
  'have',
  'he',
  'her',
  'hers',
  'him',
  'his',
  'how',
  'however',
  'i',
  'if',
  'in',
  'into',
  'is',
  'it',
  'its',
  'just',
  'least',
  'let',
  'like',
  'likely',
  'may',
  'me',
  'might',
  'most',
  'must',
  'my',
  'neither',
  'no',
  'nor',
  'not',
  'of',
  'off',
  'often',
  'on',
  'only',
  'or',
  'other',
  'our',
  'own',
  'rather',
  'said',
  'say',
  'says',
  'she',
  'should',
  'since',
  'so',
  'some',
  'than',
  'that',
  'the',
  'their',
  'them',
  'then',
  'there',
  'these',
  'they',
  'this',
  'tis',
  'to',
  'too',
  'twas',
  'us',
  'wants',
  'was',
  'we',
  'were',
  'what',
  'when',
  'where',
  'which',
  'while',
  'who',
  'whom',
  'why',
  'will',
  'with',
  'would',
  'yet',
  'you',
  'your'
])

lunr.Pipeline.registerFunction(lunr.stopWordFilter, 'stopWordFilter')
/*!
 * lunr.trimmer
 * Copyright (C) 2016 Oliver Nightingale
 */

/**
 * lunr.trimmer is a pipeline function for trimming non word
 * characters from the begining and end of tokens before they
 * enter the index.
 *
 * This implementation may not work correctly for non latin
 * characters and should either be removed or adapted for use
 * with languages with non-latin characters.
 *
 * @module
 * @param {String} token The token to pass through the filter
 * @returns {String}
 * @see lunr.Pipeline
 */
lunr.trimmer = function (token) {
  return token.replace(/^\W+/, '').replace(/\W+$/, '')
}

lunr.Pipeline.registerFunction(lunr.trimmer, 'trimmer')
/*!
 * lunr.stemmer
 * Copyright (C) 2016 Oliver Nightingale
 * Includes code from - http://tartarus.org/~martin/PorterStemmer/js.txt
 */

/**
 * lunr.TokenStore is used for efficient storing and lookup of the reverse
 * index of token to document ref.
 *
 * @constructor
 */
lunr.TokenStore = function () {
  this.root = { docs: {} }
  this.length = 0
}

/**
 * Loads a previously serialised token store
 *
 * @param {Object} serialisedData The serialised token store to load.
 * @returns {lunr.TokenStore}
 * @memberOf TokenStore
 */
lunr.TokenStore.load = function (serialisedData) {
  var store = new this

  store.root = serialisedData.root
  store.length = serialisedData.length

  return store
}

/**
 * Adds a new token doc pair to the store.
 *
 * By default this function starts at the root of the current store, however
 * it can start at any node of any token store if required.
 *
 * @param {String} token The token to store the doc under
 * @param {Object} doc The doc to store against the token
 * @param {Object} root An optional node at which to start looking for the
 * correct place to enter the doc, by default the root of this lunr.TokenStore
 * is used.
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.add = function (token, doc, root) {
  var root = root || this.root,
      key = token.charAt(0),
      rest = token.slice(1)

  if (!(key in root)) root[key] = {docs: {}}

  if (rest.length === 0) {
    root[key].docs[doc.ref] = doc
    this.length += 1
    return
  } else {
    return this.add(rest, doc, root[key])
  }
}

/**
 * Checks whether this key is contained within this lunr.TokenStore.
 *
 * By default this function starts at the root of the current store, however
 * it can start at any node of any token store if required.
 *
 * @param {String} token The token to check for
 * @param {Object} root An optional node at which to start
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.has = function (token) {
  if (!token) return false

  var node = this.root

  for (var i = 0; i < token.length; i++) {
    if (!node[token.charAt(i)]) return false

    node = node[token.charAt(i)]
  }

  return true
}

/**
 * Retrieve a node from the token store for a given token.
 *
 * By default this function starts at the root of the current store, however
 * it can start at any node of any token store if required.
 *
 * @param {String} token The token to get the node for.
 * @param {Object} root An optional node at which to start.
 * @returns {Object}
 * @see TokenStore.prototype.get
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.getNode = function (token) {
  if (!token) return {}

  var node = this.root

  for (var i = 0; i < token.length; i++) {
    if (!node[token.charAt(i)]) return {}

    node = node[token.charAt(i)]
  }

  return node
}

/**
 * Retrieve the documents for a node for the given token.
 *
 * By default this function starts at the root of the current store, however
 * it can start at any node of any token store if required.
 *
 * @param {String} token The token to get the documents for.
 * @param {Object} root An optional node at which to start.
 * @returns {Object}
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.get = function (token, root) {
  return this.getNode(token, root).docs || {}
}

lunr.TokenStore.prototype.count = function (token, root) {
  return Object.keys(this.get(token, root)).length
}

/**
 * Remove the document identified by ref from the token in the store.
 *
 * By default this function starts at the root of the current store, however
 * it can start at any node of any token store if required.
 *
 * @param {String} token The token to get the documents for.
 * @param {String} ref The ref of the document to remove from this token.
 * @param {Object} root An optional node at which to start.
 * @returns {Object}
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.remove = function (token, ref) {
  if (!token) return
  var node = this.root

  for (var i = 0; i < token.length; i++) {
    if (!(token.charAt(i) in node)) return
    node = node[token.charAt(i)]
  }

  delete node.docs[ref]
}

/**
 * Find all the possible suffixes of the passed token using tokens
 * currently in the store.
 *
 * @param {String} token The token to expand.
 * @returns {Array}
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.expand = function (token, memo) {
  var root = this.getNode(token),
      docs = root.docs || {},
      memo = memo || []

  if (Object.keys(docs).length) memo.push(token)

  Object.keys(root)
    .forEach(function (key) {
      if (key === 'docs') return

      memo.concat(this.expand(token + key, memo))
    }, this)

  return memo
}

/**
 * Returns a representation of the token store ready for serialisation.
 *
 * @returns {Object}
 * @memberOf TokenStore
 */
lunr.TokenStore.prototype.toJSON = function () {
  return {
    root: this.root,
    length: this.length
  }
}

  /**
   * export the module via AMD, CommonJS or as a browser global
   * Export code from https://github.com/umdjs/umd/blob/master/returnExports.js
   */
  ;(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
      // AMD. Register as an anonymous module.
      define(factory)
    } else if (typeof exports === 'object') {
      /**
       * Node. Does not work with strict CommonJS, but
       * only CommonJS-like enviroments that support module.exports,
       * like Node.
       */
      module.exports = factory()
    } else {
      // Browser globals (root is window)
      root.lunr = factory()
    }
  }(this, function () {
    /**
     * Just return a value to define the module export.
     * This example returns an object, but the module
     * can return a function as the exported value.
     */
    return lunr
  }))
})();