add SearchSource; refactor search and highlight

* Add SearchSource (SearchSourceBuilder in Elasticsearch)
* Use SearchSource in SearchService to build search body
* Refactor Highlight to represent structure of ES 1.3.0
* Add FetchSourceContext
* Add Rescore and Rescorer
* Move SortInfo into its own file

Author: olivere

fetch_source_context.go

@@ -0,0 +1,49 @@
+package elastic
+
+type FetchSourceContext struct {
+	fetchSource     bool
+	transformSource bool
+	includes        []string
+	excludes        []string
+}
+
+func NewFetchSourceContext(fetchSource bool) *FetchSourceContext {
+	return &FetchSourceContext{
+		fetchSource: fetchSource,
+		includes:    make([]string, 0),
+		excludes:    make([]string, 0),
+	}
+}
+
+func (fsc *FetchSourceContext) FetchSource() bool {
+	return fsc.fetchSource
+}
+
+func (fsc *FetchSourceContext) SetFetchSource(fetchSource bool) {
+	fsc.fetchSource = fetchSource
+}
+
+func (fsc *FetchSourceContext) Include(includes ...string) *FetchSourceContext {
+	fsc.includes = append(fsc.includes, includes...)
+	return fsc
+}
+
+func (fsc *FetchSourceContext) Exclude(excludes ...string) *FetchSourceContext {
+	fsc.excludes = append(fsc.excludes, excludes...)
+	return fsc
+}
+
+func (fsc *FetchSourceContext) TransformSource(transformSource bool) *FetchSourceContext {
+	fsc.transformSource = transformSource
+	return fsc
+}
+
+func (fsc *FetchSourceContext) Source() interface{} {
+	if !fsc.fetchSource {
+		return false
+	}
+	return map[string]interface{}{
+		"includes": fsc.includes,
+		"excludes": fsc.excludes,
+	}
+}

fetch_source_context_test.go

@@ -0,0 +1,58 @@
+package elastic
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestFetchSourceContextNoFetchSource(t *testing.T) {
+	builder := NewFetchSourceContext(false)
+	data, err := json.Marshal(builder.Source())
+	if err != nil {
+		t.Fatalf("marshaling to JSON failed: %v", err)
+	}
+	got := string(data)
+	expected := `false`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}
+
+func TestFetchSourceContextNoFetchSourceIgnoreIncludesAndExcludes(t *testing.T) {
+	builder := NewFetchSourceContext(false).Include("a", "b").Exclude("c")
+	data, err := json.Marshal(builder.Source())
+	if err != nil {
+		t.Fatalf("marshaling to JSON failed: %v", err)
+	}
+	got := string(data)
+	expected := `false`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}
+
+func TestFetchSourceContextFetchSource(t *testing.T) {
+	builder := NewFetchSourceContext(true)
+	data, err := json.Marshal(builder.Source())
+	if err != nil {
+		t.Fatalf("marshaling to JSON failed: %v", err)
+	}
+	got := string(data)
+	expected := `{"excludes":[],"includes":[]}`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}
+
+func TestFetchSourceContextFetchSourceWithIncludesAndExcludes(t *testing.T) {
+	builder := NewFetchSourceContext(true).Include("a", "b").Exclude("c")
+	data, err := json.Marshal(builder.Source())
+	if err != nil {
+		t.Fatalf("marshaling to JSON failed: %v", err)
+	}
+	got := string(data)
+	expected := `{"excludes":["c"],"includes":["a","b"]}`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}