hugo/resources/page/pages_related.go

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// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache 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://www.apache.org/licenses/LICENSE-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 page
import (
"sync"
"github.com/gohugoio/hugo/common/types"
"github.com/gohugoio/hugo/related"
"github.com/pkg/errors"
"github.com/spf13/cast"
)
var (
// Assert that Pages and PageGroup implements the PageGenealogist interface.
_ PageGenealogist = (Pages)(nil)
_ PageGenealogist = PageGroup{}
)
// A PageGenealogist finds related pages in a page collection. This interface is implemented
// by Pages and PageGroup, which makes it available as `{{ .RegularRelated . }}` etc.
type PageGenealogist interface {
// Template example:
// {{ $related := .RegularPages.Related . }}
Related(doc related.Document) (Pages, error)
// Template example:
// {{ $related := .RegularPages.RelatedIndices . "tags" "date" }}
RelatedIndices(doc related.Document, indices ...interface{}) (Pages, error)
// Template example:
// {{ $related := .RegularPages.RelatedTo ( keyVals "tags" "hugo", "rocks") ( keyVals "date" .Date ) }}
RelatedTo(args ...types.KeyValues) (Pages, error)
}
// Related searches all the configured indices with the search keywords from the
// supplied document.
func (p Pages) Related(doc related.Document) (Pages, error) {
result, err := p.searchDoc(doc)
if err != nil {
return nil, err
}
if page, ok := doc.(Page); ok {
return result.removeFirstIfFound(page), nil
}
return result, nil
}
// RelatedIndices searches the given indices with the search keywords from the
// supplied document.
func (p Pages) RelatedIndices(doc related.Document, indices ...interface{}) (Pages, error) {
indicesStr, err := cast.ToStringSliceE(indices)
if err != nil {
return nil, err
}
result, err := p.searchDoc(doc, indicesStr...)
if err != nil {
return nil, err
}
if page, ok := doc.(Page); ok {
return result.removeFirstIfFound(page), nil
}
return result, nil
}
// RelatedTo searches the given indices with the corresponding values.
func (p Pages) RelatedTo(args ...types.KeyValues) (Pages, error) {
if len(p) == 0 {
return nil, nil
}
return p.search(args...)
}
func (p Pages) search(args ...types.KeyValues) (Pages, error) {
return p.withInvertedIndex(func(idx *related.InvertedIndex) ([]related.Document, error) {
return idx.SearchKeyValues(args...)
})
}
func (p Pages) searchDoc(doc related.Document, indices ...string) (Pages, error) {
return p.withInvertedIndex(func(idx *related.InvertedIndex) ([]related.Document, error) {
return idx.SearchDoc(doc, indices...)
})
}
func (p Pages) withInvertedIndex(search func(idx *related.InvertedIndex) ([]related.Document, error)) (Pages, error) {
if len(p) == 0 {
return nil, nil
}
d, ok := p[0].(InternalDependencies)
if !ok {
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return nil, errors.Errorf("invalid type %T in related search", p[0])
}
cache := d.GetRelatedDocsHandler()
searchIndex, err := cache.getOrCreateIndex(p)
if err != nil {
return nil, err
}
result, err := search(searchIndex)
if err != nil {
return nil, err
}
if len(result) > 0 {
mp := make(Pages, len(result))
for i, match := range result {
mp[i] = match.(Page)
}
return mp, nil
}
return nil, nil
}
type cachedPostingList struct {
p Pages
postingList *related.InvertedIndex
}
type RelatedDocsHandler struct {
cfg related.Config
postingLists []*cachedPostingList
mu sync.RWMutex
}
func NewRelatedDocsHandler(cfg related.Config) *RelatedDocsHandler {
return &RelatedDocsHandler{cfg: cfg}
}
func (s *RelatedDocsHandler) Clone() *RelatedDocsHandler {
return NewRelatedDocsHandler(s.cfg)
}
// This assumes that a lock has been acquired.
func (s *RelatedDocsHandler) getIndex(p Pages) *related.InvertedIndex {
for _, ci := range s.postingLists {
if pagesEqual(p, ci.p) {
return ci.postingList
}
}
return nil
}
func (s *RelatedDocsHandler) getOrCreateIndex(p Pages) (*related.InvertedIndex, error) {
s.mu.RLock()
cachedIndex := s.getIndex(p)
if cachedIndex != nil {
s.mu.RUnlock()
return cachedIndex, nil
}
s.mu.RUnlock()
s.mu.Lock()
defer s.mu.Unlock()
if cachedIndex := s.getIndex(p); cachedIndex != nil {
return cachedIndex, nil
}
searchIndex := related.NewInvertedIndex(s.cfg)
for _, page := range p {
if err := searchIndex.Add(page); err != nil {
return nil, err
}
}
s.postingLists = append(s.postingLists, &cachedPostingList{p: p, postingList: searchIndex})
return searchIndex, nil
}