1 files changed, 101 insertions, 0 deletions
diff --git a/resources/page/page_lazy_contentprovider.go b/resources/page/page_lazy_contentprovider.go
new file mode 100644
index 000000000..d8d92d7cd
--- /dev/null
+++ b/resources/page/page_lazy_contentprovider.go
@@ -0,0 +1,101 @@
+// 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 (
+	"html/template"
+
+	"github.com/gohugoio/hugo/lazy"
+)
+
+// LazyContentProvider initializes itself when read. Each method of the
+// ContentProvider interface initializes a content provider and shares it
+// with other methods.
+//
+// Used in cases where we cannot guarantee whether the content provider
+// will be needed. Must create via NewLazyContentProvider.
+type LazyContentProvider struct {
+	init *lazy.Init
+	cp   ContentProvider
+}
+
+// NewLazyContentProvider returns a LazyContentProvider initialized with
+// function f. The resulting LazyContentProvider calls f in order to
+// retrieve a ContentProvider
+func NewLazyContentProvider(f func() (ContentProvider, error)) *LazyContentProvider {
+	lcp := LazyContentProvider{
+		init: lazy.New(),
+		cp:   NopPage,
+	}
+	lcp.init.Add(func() (interface{}, error) {
+		cp, err := f()
+		if err != nil {
+			return nil, err
+		}
+		lcp.cp = cp
+		return nil, nil
+	})
+	return &lcp
+}
+
+func (lcp *LazyContentProvider) Content() (interface{}, error) {
+	lcp.init.Do()
+	return lcp.cp.Content()
+}
+
+func (lcp *LazyContentProvider) Plain() string {
+	lcp.init.Do()
+	return lcp.cp.Plain()
+}
+
+func (lcp *LazyContentProvider) PlainWords() []string {
+	lcp.init.Do()
+	return lcp.cp.PlainWords()
+}
+
+func (lcp *LazyContentProvider) Summary() template.HTML {
+	lcp.init.Do()
+	return lcp.cp.Summary()
+
+}
+
+func (lcp *LazyContentProvider) Truncated() bool {
+	lcp.init.Do()
+	return lcp.cp.Truncated()
+
+}
+
+func (lcp *LazyContentProvider) FuzzyWordCount() int {
+	lcp.init.Do()
+	return lcp.cp.FuzzyWordCount()
+
+}
+
+func (lcp *LazyContentProvider) WordCount() int {
+	lcp.init.Do()
+	return lcp.cp.WordCount()
+
+}
+
+func (lcp *LazyContentProvider) ReadingTime() int {
+	lcp.init.Do()
+	return lcp.cp.ReadingTime()
+
+}
+
+func (lcp *LazyContentProvider) Len() int {
+	lcp.init.Do()
+	return lcp.cp.Len()
+
+}