Source: query.js

/**
 * A lunr.Query provides a programmatic way of defining queries to be performed
 * against a {@link lunr.Index}.
 *
 * Prefer constructing a lunr.Query using the {@link lunr.Index#query} method
 * so the query object is pre-initialized with the right index fields.
 *
 * @constructor
 * @property {lunr.Query~Clause[]} clauses - An array of query clauses.
 * @property {string[]} allFields - An array of all available fields in a lunr.Index.
 */
lunr.Query = function (allFields) {
  this.clauses = []
  this.allFields = allFields
}

/**
 * Constants for indicating what kind of automatic wildcard insertion will be used when constructing a query clause.
 *
 * This allows wildcards to be added to the beginning and end of a term without having to manually do any string
 * concatenation.
 *
 * The wildcard constants can be bitwise combined to select both leading and trailing wildcards.
 *
 * @constant
 * @default
 * @property {number} wildcard.NONE - The term will have no wildcards inserted, this is the default behaviour
 * @property {number} wildcard.LEADING - Prepend the term with a wildcard, unless a leading wildcard already exists
 * @property {number} wildcard.TRAILING - Append a wildcard to the term, unless a trailing wildcard already exists
 * @see lunr.Query~Clause
 * @see lunr.Query#clause
 * @see lunr.Query#term
 * @example <caption>query term with trailing wildcard</caption>
 * query.term('foo', { wildcard: lunr.Query.wildcard.TRAILING })
 * @example <caption>query term with leading and trailing wildcard</caption>
 * query.term('foo', {
 *   wildcard: lunr.Query.wildcard.LEADING | lunr.Query.wildcard.TRAILING
 * })
 */

lunr.Query.wildcard = new String ("*")
lunr.Query.wildcard.NONE = 0
lunr.Query.wildcard.LEADING = 1
lunr.Query.wildcard.TRAILING = 2

/**
 * Constants for indicating what kind of presence a term must have in matching documents.
 *
 * @constant
 * @enum {number}
 * @see lunr.Query~Clause
 * @see lunr.Query#clause
 * @see lunr.Query#term
 * @example <caption>query term with required presence</caption>
 * query.term('foo', { presence: lunr.Query.presence.REQUIRED })
 */
lunr.Query.presence = {
  /**
   * Term's presence in a document is optional, this is the default value.
   */
  OPTIONAL: 1,

  /**
   * Term's presence in a document is required, documents that do not contain
   * this term will not be returned.
   */
  REQUIRED: 2,

  /**
   * Term's presence in a document is prohibited, documents that do contain
   * this term will not be returned.
   */
  PROHIBITED: 3
}

/**
 * A single clause in a {@link lunr.Query} contains a term and details on how to
 * match that term against a {@link lunr.Index}.
 *
 * @typedef {Object} lunr.Query~Clause
 * @property {string[]} fields - The fields in an index this clause should be matched against.
 * @property {number} [boost=1] - Any boost that should be applied when matching this clause.
 * @property {number} [editDistance] - Whether the term should have fuzzy matching applied, and how fuzzy the match should be.
 * @property {boolean} [usePipeline] - Whether the term should be passed through the search pipeline.
 * @property {number} [wildcard=lunr.Query.wildcard.NONE] - Whether the term should have wildcards appended or prepended.
 * @property {number} [presence=lunr.Query.presence.OPTIONAL] - The terms presence in any matching documents.
 */

/**
 * Adds a {@link lunr.Query~Clause} to this query.
 *
 * Unless the clause contains the fields to be matched all fields will be matched. In addition
 * a default boost of 1 is applied to the clause.
 *
 * @param {lunr.Query~Clause} clause - The clause to add to this query.
 * @see lunr.Query~Clause
 * @returns {lunr.Query}
 */
lunr.Query.prototype.clause = function (clause) {
  if (!('fields' in clause)) {
    clause.fields = this.allFields
  }

  if (!('boost' in clause)) {
    clause.boost = 1
  }

  if (!('usePipeline' in clause)) {
    clause.usePipeline = true
  }

  if (!('wildcard' in clause)) {
    clause.wildcard = lunr.Query.wildcard.NONE
  }

  if ((clause.wildcard & lunr.Query.wildcard.LEADING) && (clause.term.charAt(0) != lunr.Query.wildcard)) {
    clause.term = "*" + clause.term
  }

  if ((clause.wildcard & lunr.Query.wildcard.TRAILING) && (clause.term.slice(-1) != lunr.Query.wildcard)) {
    clause.term = "" + clause.term + "*"
  }

  if (!('presence' in clause)) {
    clause.presence = lunr.Query.presence.OPTIONAL
  }

  this.clauses.push(clause)

  return this
}

/**
 * A negated query is one in which every clause has a presence of
 * prohibited. These queries require some special processing to return
 * the expected results.
 *
 * @returns boolean
 */
lunr.Query.prototype.isNegated = function () {
  for (var i = 0; i < this.clauses.length; i++) {
    if (this.clauses[i].presence != lunr.Query.presence.PROHIBITED) {
      return false
    }
  }

  return true
}

/**
 * Adds a term to the current query, under the covers this will create a {@link lunr.Query~Clause}
 * to the list of clauses that make up this query.
 *
 * The term is used as is, i.e. no tokenization will be performed by this method. Instead conversion
 * to a token or token-like string should be done before calling this method.
 *
 * The term will be converted to a string by calling `toString`. Multiple terms can be passed as an
 * array, each term in the array will share the same options.
 *
 * @param {object|object[]} term - The term(s) to add to the query.
 * @param {object} [options] - Any additional properties to add to the query clause.
 * @returns {lunr.Query}
 * @see lunr.Query#clause
 * @see lunr.Query~Clause
 * @example <caption>adding a single term to a query</caption>
 * query.term("foo")
 * @example <caption>adding a single term to a query and specifying search fields, term boost and automatic trailing wildcard</caption>
 * query.term("foo", {
 *   fields: ["title"],
 *   boost: 10,
 *   wildcard: lunr.Query.wildcard.TRAILING
 * })
 * @example <caption>using lunr.tokenizer to convert a string to tokens before using them as terms</caption>
 * query.term(lunr.tokenizer("foo bar"))
 */
lunr.Query.prototype.term = function (term, options) {
  if (Array.isArray(term)) {
    term.forEach(function (t) { this.term(t, lunr.utils.clone(options)) }, this)
    return this
  }

  var clause = options || {}
  clause.term = term.toString()

  this.clause(clause)

  return this
}