github.com/go-kivik/kivik/v4@v4.3.2/x/fsdb/cdb/decode/decode.go (about)

     1  // Licensed under the Apache License, Version 2.0 (the "License"); you may not
     2  // use this file except in compliance with the License. You may obtain a copy of
     3  // the License at
     4  //
     5  //  http://www.apache.org/licenses/LICENSE-2.0
     6  //
     7  // Unless required by applicable law or agreed to in writing, software
     8  // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
     9  // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    10  // License for the specific language governing permissions and limitations under
    11  // the License.
    12  
    13  // Package decode assists in document decoding.
    14  package decode
    15  
    16  import (
    17  	"fmt"
    18  	"io"
    19  	"os"
    20  	"path/filepath"
    21  	"sort"
    22  	"strings"
    23  
    24  	"github.com/go-kivik/kivik/v4/x/fsdb/filesystem"
    25  )
    26  
    27  type decoder interface {
    28  	Decode(io.Reader, interface{}) error
    29  }
    30  
    31  var decoders = map[string]decoder{
    32  	"json": &jsonDecoder{},
    33  	"yaml": &yamlDecoder{},
    34  	"yml":  &yamlDecoder{},
    35  }
    36  
    37  var extensions = func() []string {
    38  	exts := make([]string, 0, len(decoders))
    39  	for ext := range decoders {
    40  		exts = append(exts, ext)
    41  	}
    42  	sort.Strings(exts)
    43  	return exts
    44  }()
    45  
    46  // OpenAny attempts to open base + any supported extension. It returns the open
    47  // file, the matched extension, or an error.
    48  func OpenAny(fs filesystem.Filesystem, base string) (f filesystem.File, ext string, err error) {
    49  	for ext = range decoders {
    50  		f, err = fs.Open(base + "." + ext)
    51  		if err == nil || !os.IsNotExist(err) {
    52  			return
    53  		}
    54  	}
    55  	return
    56  }
    57  
    58  // Decode decodes r according to ext's registered decoder, into i.
    59  func Decode(r io.Reader, ext string, i interface{}) error {
    60  	ext = strings.TrimPrefix(ext, ".")
    61  	dec, ok := decoders[ext]
    62  	if !ok {
    63  		return fmt.Errorf("No decoder for %s", ext)
    64  	}
    65  	return dec.Decode(r, i)
    66  }
    67  
    68  // ExplodeFilename returns the base name, extension, and a boolean indicating
    69  // whether the extension is decodable.
    70  func ExplodeFilename(filename string) (basename, ext string, ok bool) {
    71  	dotExt := filepath.Ext(filename)
    72  	basename = strings.TrimSuffix(filename, dotExt)
    73  	ext = strings.TrimPrefix(dotExt, ".")
    74  	_, ok = decoders[ext]
    75  	return basename, ext, ok
    76  }
    77  
    78  // Extensions returns a list of supported extensions.
    79  func Extensions() []string {
    80  	return extensions
    81  }