Function Score Query

Added function score query and its score functions.

Author: olivere

README.md

@@ -200,6 +200,7 @@ Here's the current API status.
 * `filtered` (ok)
 * `flt` (missing)
 * `flt_field` (missing)
+* `function_score` (ok)
 * `fuzzy` (missing)
 * `has_child` (ok)
 * `has_parent` (ok)

search_queries_fsq.go

@@ -0,0 +1,117 @@
+// Copyright 2012 Oliver Eilhard. All rights reserved.
+// Use of this source code is governed by a MIT-license.
+// See http://olivere.mit-license.org/license.txt for details.
+
+package elastic
+
+// The function_score allows you to modify the score of documents that
+// are retrieved by a query. This can be useful if, for example,
+// a score function is computationally expensive and it is sufficient
+// to compute the score on a filtered set of documents.
+// For more details, see
+// http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-function-score-query.html
+type FunctionScoreQuery struct {
+	query      Query
+	filter     Filter
+	boost      *float32
+	maxBoost   *float32
+	scoreMode  string
+	boostMode  string
+	filters    []Filter
+	scoreFuncs []ScoreFunction
+}
+
+// NewFunctionScoreQuery creates a new function score query.
+func NewFunctionScoreQuery() FunctionScoreQuery {
+	return FunctionScoreQuery{
+		filters:    make([]Filter, 0),
+		scoreFuncs: make([]ScoreFunction, 0),
+	}
+}
+
+func (q FunctionScoreQuery) Query(query Query) FunctionScoreQuery {
+	q.query = query
+	q.filter = nil
+	return q
+}
+
+func (q FunctionScoreQuery) Filter(filter Filter) FunctionScoreQuery {
+	q.query = nil
+	q.filter = filter
+	return q
+}
+
+func (q FunctionScoreQuery) Add(filter Filter, scoreFunc ScoreFunction) FunctionScoreQuery {
+	q.filters = append(q.filters, filter)
+	q.scoreFuncs = append(q.scoreFuncs, scoreFunc)
+	return q
+}
+
+func (q FunctionScoreQuery) AddScoreFunc(scoreFunc ScoreFunction) FunctionScoreQuery {
+	q.filters = append(q.filters, nil)
+	q.scoreFuncs = append(q.scoreFuncs, scoreFunc)
+	return q
+}
+
+func (q FunctionScoreQuery) ScoreMode(scoreMode string) FunctionScoreQuery {
+	q.scoreMode = scoreMode
+	return q
+}
+
+func (q FunctionScoreQuery) BoostMode(boostMode string) FunctionScoreQuery {
+	q.boostMode = boostMode
+	return q
+}
+
+func (q FunctionScoreQuery) MaxBoost(maxBoost float32) FunctionScoreQuery {
+	q.maxBoost = &maxBoost
+	return q
+}
+
+func (q FunctionScoreQuery) Boost(boost float32) FunctionScoreQuery {
+	q.boost = &boost
+	return q
+}
+
+// Source returns JSON for the function score query.
+func (q FunctionScoreQuery) Source() interface{} {
+	source := make(map[string]interface{})
+	query := make(map[string]interface{})
+	source["function_score"] = query
+
+	if q.query != nil {
+		query["query"] = q.query.Source()
+	} else if q.filter != nil {
+		query["filter"] = q.filter.Source()
+	}
+
+	if len(q.filters) == 1 && q.filters[0] == nil {
+		query[q.scoreFuncs[0].Name()] = q.scoreFuncs[0].Source()
+	} else {
+		funcs := make([]interface{}, len(q.filters))
+		for i, filter := range q.filters {
+			hsh := make(map[string]interface{})
+			if filter != nil {
+				hsh["filter"] = filter.Source()
+			}
+			hsh[q.scoreFuncs[i].Name()] = q.scoreFuncs[i].Source()
+			funcs[i] = hsh
+		}
+		query["functions"] = funcs
+	}
+
+	if q.scoreMode != "" {
+		query["score_mode"] = q.scoreMode
+	}
+	if q.boostMode != "" {
+		query["boost_mode"] = q.boostMode
+	}
+	if q.maxBoost != nil {
+		query["max_boost"] = *q.maxBoost
+	}
+	if q.boost != nil {
+		query["boost"] = *q.boost
+	}
+
+	return source
+}