Replace pkger with embed.FS compatibility

kyaml/fn/framework/parser/parser.go

@@ -0,0 +1,95 @@
+// Copyright 2021 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package parser
+
+import (
+	iofs "io/fs"
+	"io/ioutil"
+	"path"
+	"strings"
+
+	"sigs.k8s.io/kustomize/kyaml/errors"
+)
+
+type parser struct {
+	fs        iofs.FS
+	paths     []string
+	extension string
+}
+
+type contentProcessor func(content []byte, name string) error
+
+func (l parser) parse(processContent contentProcessor) error {
+	for _, path := range l.paths {
+		if err := l.readPath(path, processContent); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (l parser) readPath(path string, processContent contentProcessor) error {
+	f, err := l.fs.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	info, err := f.Stat()
+	if err != nil {
+		return err
+	}
+
+	// File is directory -- read templates among its immediate children
+	if info.IsDir() {
+		dir, ok := f.(iofs.ReadDirFile)
+		if !ok {
+			return errors.Errorf("%s is a directory but could not be opened as one", path)
+		}
+		return l.readDir(dir, path, processContent)
+	}
+
+	// Path is a file -- check extension and read it
+	if !strings.HasSuffix(path, l.extension) {
+		return errors.Errorf("file %s did not have required extension %s", path, l.extension)
+	}
+	b, err := ioutil.ReadAll(f)
+	if err != nil {
+		return err
+	}
+	return processContent(b, path)
+}
+
+func (l parser) readDir(dir iofs.ReadDirFile, dirname string, processContent contentProcessor) error {
+	entries, err := dir.ReadDir(0)
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() || !strings.HasSuffix(entry.Name(), l.extension) {
+			continue
+		}
+		// Note: using filepath.Join will break Windows, because io/fs.FS implementations require slashes on all OS.
+		// See https://golang.org/pkg/io/fs/#ValidPath
+		b, err := l.readFile(path.Join(dirname, entry.Name()))
+		if err != nil {
+			return err
+		}
+		if err := processContent(b, entry.Name()); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (l parser) readFile(path string) ([]byte, error) {
+	f, err := l.fs.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	return ioutil.ReadAll(f)
+}