Add page grouping functions

hugolib/pageGroup.go

@@ -0,0 +1,126 @@
+// Copyright © 2014 Steve Francia <spf@spf13.com>.
+//
+// Licensed under the Simple Public License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://opensource.org/licenses/Simple-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package hugolib
+
+import (
+	"errors"
+	"reflect"
+	"sort"
+)
+
+type PageGroup struct {
+	Key  interface{}
+	Data Pages
+}
+
+type mapKeyValues []reflect.Value
+
+func (v mapKeyValues) Len() int      { return len(v) }
+func (v mapKeyValues) Swap(i, j int) { v[i], v[j] = v[j], v[i] }
+
+type mapKeyByInt struct{ mapKeyValues }
+
+func (s mapKeyByInt) Less(i, j int) bool { return s.mapKeyValues[i].Int() < s.mapKeyValues[j].Int() }
+
+type mapKeyByStr struct{ mapKeyValues }
+
+func (s mapKeyByStr) Less(i, j int) bool {
+	return s.mapKeyValues[i].String() < s.mapKeyValues[j].String()
+}
+
+func sortKeys(v []reflect.Value, order string) []reflect.Value {
+	if len(v) <= 1 {
+		return v
+	}
+
+	switch v[0].Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		if order == "desc" {
+			sort.Sort(sort.Reverse(mapKeyByInt{v}))
+		} else {
+			sort.Sort(mapKeyByInt{v})
+		}
+	case reflect.String:
+		if order == "desc" {
+			sort.Sort(sort.Reverse(mapKeyByStr{v}))
+		} else {
+			sort.Sort(mapKeyByStr{v})
+		}
+	}
+	return v
+}
+
+func (p Pages) GroupBy(key, order string) ([]PageGroup, error) {
+	if len(p) < 1 {
+		return nil, nil
+	}
+
+	if order != "asc" && order != "desc" {
+		return nil, errors.New("order argument must be 'asc' or 'desc'")
+	}
+
+	ppt := reflect.TypeOf(&Page{})
+	ft, ok := ppt.Elem().FieldByName(key)
+	if !ok {
+		return nil, errors.New("No such field in Page struct")
+	}
+	tmp := reflect.MakeMap(reflect.MapOf(ft.Type, reflect.SliceOf(ppt)))
+
+	for _, e := range p {
+		ppv := reflect.ValueOf(e)
+		fv := ppv.Elem().FieldByName(key)
+		if !tmp.MapIndex(fv).IsValid() {
+			tmp.SetMapIndex(fv, reflect.MakeSlice(reflect.SliceOf(ppt), 0, 0))
+		}
+		tmp.SetMapIndex(fv, reflect.Append(tmp.MapIndex(fv), ppv))
+	}
+
+	var r []PageGroup
+	for _, k := range sortKeys(tmp.MapKeys(), order) {
+		r = append(r, PageGroup{Key: k.Interface(), Data: tmp.MapIndex(k).Interface().([]*Page)})
+	}
+
+	return r, nil
+}
+
+func (p Pages) GroupByDate(format, order string) ([]PageGroup, error) {
+	if len(p) < 1 {
+		return nil, nil
+	}
+
+	if order != "asc" && order != "desc" {
+		return nil, errors.New("order argument must be 'asc' or 'desc'")
+	}
+
+	sp := p.ByDate()
+	if order == "desc" {
+		sp = sp.Reverse()
+	}
+
+	date := sp[0].Date.Format(format)
+	var r []PageGroup
+	r = append(r, PageGroup{Key: date, Data: make(Pages, 0)})
+	r[0].Data = append(r[0].Data, sp[0])
+
+	i := 0
+	for _, e := range sp[1:] {
+		date = e.Date.Format(format)
+		if r[i].Key.(string) != date {
+			r = append(r, PageGroup{Key: date})
+			i++
+		}
+		r[i].Data = append(r[i].Data, e)
+	}
+	return r, nil
+}