InvertedIndex

constructor

elasticlunr.InvertedIndex()

elasticlunr.InvertedIndex is used for efficiently storing and
lookup of documents that contain a given token.

elasticlunr.InvertedIndex = function () {
  this.root = { docs: {}, df: 0 };
};

load

method

elasticlunr.InvertedIndex.load()

Option name	Type	Description
serialisedData	Object	The serialised inverted index to load.
return	elasticlunr.InvertedIndex

Loads a previously serialised inverted index.

elasticlunr.InvertedIndex.load = function (serialisedData) {
  var idx = new this;
  idx.root = serialisedData.root;

  return idx;
};

addToken

method

elasticlunr.InvertedIndex.prototype.addToken()

Option name	Type	Description
token	String
tokenInfo	Object	format: { ref: 1, tf: 2}
root	Object	An optional node at which to start looking for the correct place to enter the doc, by default the root of this elasticlunr.InvertedIndex is used.

Adds a {token: tokenInfo} pair to the inverted index.
If the token already exist, then update the tokenInfo.

tokenInfo format: { ref: 1, tf: 2}
tokenInfor should contains the document's ref and the tf(token frequency) of that token in
the document.

By default this function starts at the root of the current inverted index, however
it can start at any node of the inverted index if required.

elasticlunr.InvertedIndex.prototype.addToken = function (token, tokenInfo, root) {
  var root = root || this.root,
      idx = 0;

  while (idx <= token.length - 1) {
    var key = token[idx];

    if (!(key in root)) root[key] = {docs: {}, df: 0};
    idx += 1;
    root = root[key];
  }

  var docRef = tokenInfo.ref;
  if (!root.docs[docRef]) {
    // if this doc not exist, then add this doc
    root.docs[docRef] = {tf: tokenInfo.tf};
    root.df += 1;
  } else {
    // if this doc already exist, then update tokenInfo
    root.docs[docRef] = {tf: tokenInfo.tf};
  }
};

hasToken

method

elasticlunr.InvertedIndex.prototype.hasToken()

Option name	Type	Description
token	String	The token to be checked
return	Boolean

Checks whether a token is in this elasticlunr.InvertedIndex.

elasticlunr.InvertedIndex.prototype.hasToken = function (token) {
  if (!token) return false;

  var node = this.root;

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

  return true;
};

getNode

method

elasticlunr.InvertedIndex.prototype.getNode()

Option name	Type	Description
token	String	The token to get the node for.
return	Object

Retrieve a node from the inverted index for a given token.
If token not found in this InvertedIndex, return null.

elasticlunr.InvertedIndex.prototype.getNode = function (token) {
  if (!token) return null;

  var node = this.root;

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

  return node;
};

getDocs

method

elasticlunr.InvertedIndex.prototype.getDocs()

Option name	Type	Description
token	String	The token to get the documents for.
return	Object

Retrieve the documents of a given token.
If token not found, return {}.

elasticlunr.InvertedIndex.prototype.getDocs = function (token) {
  var node = this.getNode(token);
  if (node == null) {
    return {};
  }

  return node.docs;
};

getTermFrequency

method

elasticlunr.InvertedIndex.prototype.getTermFrequency()

Option name	Type	Description
token	String	The token to get the documents for.
docRef	String,Integer
return	Integer

Retrieve term frequency of given token in given docRef.
If token or docRef not found, return 0.

elasticlunr.InvertedIndex.prototype.getTermFrequency = function (token, docRef) {
  var node = this.getNode(token);

  if (node == null) {
    return 0;
  }

  if (!(docRef in node.docs)) {
    return 0;
  }

  return node.docs[docRef].tf;
};

getDocFreq

method

elasticlunr.InvertedIndex.prototype.getDocFreq()

Option name	Type	Description
token	String	The token to get the documents for.
return	Object

Retrieve the document frequency of given token.
If token not found, return 0.

elasticlunr.InvertedIndex.prototype.getDocFreq = function (token) {
  var node = this.getNode(token);

  if (node == null) {
    return 0;
  }

  return node.df;
};

removeToken

method

elasticlunr.InvertedIndex.prototype.removeToken()

Option name	Type	Description
token	String	Remove the document from which token.
ref	String	The ref of the document to remove from given token.

Remove the document identified by document's ref from the token in the inverted index.

elasticlunr.InvertedIndex.prototype.removeToken = function (token, ref) {
  if (!token) return;
  var node = this.getNode(token);

  if (node == null) return;

  if (ref in node.docs) {
    delete node.docs[ref];
    node.df -= 1;
  }
};

expandToken

method

elasticlunr.InvertedIndex.prototype.expandToken()

Option name	Type	Description
token	String	The token to expand.
return	Array

Find all the possible suffixes of given token using tokens currently in the inverted index.
If token not found, return empty Array.

elasticlunr.InvertedIndex.prototype.expandToken = function (token, memo, root) {
  if (token == null || token == '') return [];
  var memo = memo || [];

  if (root == void 0) {
    root = this.getNode(token);
    if (root == null) return memo;
  }

  if (root.df > 0) memo.push(token);

  for (var key in root) {
    if (key === 'docs') continue;
    if (key === 'df') continue;
    this.expandToken(token + key, memo, root[key]);
  }

  return memo;
};

toJSON

method

elasticlunr.InvertedIndex.prototype.toJSON()

Returns a representation of the inverted index ready for serialisation.

elasticlunr.InvertedIndex.prototype.toJSON = function () {
  return {
    root: this.root
  };
};