Add a page template func

Fixes #9339

tpl/page/init.go

@@ -0,0 +1,49 @@
+// Copyright 2022 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 provides template functions for accessing the current Page object,
+// the entry level context for the current template.
+package page
+
+import (
+	"context"
+
+	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/resources/page"
+	"github.com/gohugoio/hugo/tpl"
+
+	"github.com/gohugoio/hugo/tpl/internal"
+)
+
+const name = "page"
+
+func init() {
+	f := func(d *deps.Deps) *internal.TemplateFuncsNamespace {
+		ns := &internal.TemplateFuncsNamespace{
+			Name: name,
+			Context: func(ctx context.Context, args ...interface{}) (interface{}, error) {
+				v := tpl.GetPageFromContext(ctx)
+				if v == nil {
+					// The multilingual sitemap does not have a page as its context.
+					return nil, nil
+				}
+
+				return v.(page.Page), nil
+			},
+		}
+
+		return ns
+	}
+
+	internal.AddTemplateFuncsNamespace(f)
+}