1 files changed, 71 insertions, 0 deletions
diff --git a/tpl/internal/resourcehelpers/helpers.go b/tpl/internal/resourcehelpers/helpers.go
new file mode 100644
index 000000000..4f8b7539a
--- /dev/null
+++ b/tpl/internal/resourcehelpers/helpers.go
@@ -0,0 +1,71 @@
+// Copyright 2020 The Hugo Authors. All rights reserved.
+//
+// Portions Copyright The Go Authors.
+
+// 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 resourcehelpers
+
+import (
+	"errors"
+	"fmt"
+
+	_errors "github.com/pkg/errors"
+
+	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/resources"
+)
+
+// We allow string or a map as the first argument in some cases.
+func ResolveIfFirstArgIsString(args []interface{}) (resources.ResourceTransformer, string, bool) {
+	if len(args) != 2 {
+		return nil, "", false
+	}
+
+	v1, ok1 := args[0].(string)
+	if !ok1 {
+		return nil, "", false
+	}
+	v2, ok2 := args[1].(resources.ResourceTransformer)
+
+	return v2, v1, ok2
+}
+
+// This roundabout way of doing it is needed to get both pipeline behaviour and options as arguments.
+func ResolveArgs(args []interface{}) (resources.ResourceTransformer, map[string]interface{}, error) {
+	if len(args) == 0 {
+		return nil, nil, errors.New("no Resource provided in transformation")
+	}
+
+	if len(args) == 1 {
+		r, ok := args[0].(resources.ResourceTransformer)
+		if !ok {
+			return nil, nil, fmt.Errorf("type %T not supported in Resource transformations", args[0])
+		}
+		return r, nil, nil
+	}
+
+	r, ok := args[1].(resources.ResourceTransformer)
+	if !ok {
+		if _, ok := args[1].(map[string]interface{}); !ok {
+			return nil, nil, fmt.Errorf("no Resource provided in transformation")
+		}
+		return nil, nil, fmt.Errorf("type %T not supported in Resource transformations", args[0])
+	}
+
+	m, err := maps.ToStringMapE(args[0])
+	if err != nil {
+		return nil, nil, _errors.Wrap(err, "invalid options type")
+	}
+
+	return r, m, nil
+}