tpl: Add path.Split template func

tpl/path/path.go

@@ -0,0 +1,60 @@
+// Copyright 2018 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 path
+
+import (
+	"fmt"
+	_path "path"
+
+	"github.com/gohugoio/hugo/deps"
+	"github.com/spf13/cast"
+)
+
+// New returns a new instance of the path-namespaced template functions.
+func New(deps *deps.Deps) *Namespace {
+	return &Namespace{
+		deps: deps,
+	}
+}
+
+// Namespace provides template functions for the "os" namespace.
+type Namespace struct {
+	deps *deps.Deps
+}
+
+// DirFile holds the result from path.Split.
+type DirFile struct {
+	Dir  string
+	File string
+}
+
+// Used in test.
+func (df DirFile) String() string {
+	return fmt.Sprintf("%s|%s", df.Dir, df.File)
+}
+
+// Split splits path immediately following the final slash,
+// separating it into a directory and file name component.
+// If there is no slash in path, Split returns an empty dir and
+// file set to path.
+// The returned values have the property that path = dir+file.
+func (ns *Namespace) Split(path interface{}) (DirFile, error) {
+	spath, err := cast.ToStringE(path)
+	if err != nil {
+		return DirFile{}, err
+	}
+	dir, file := _path.Split(spath)
+
+	return DirFile{Dir: dir, File: file}, nil
+}