github.com/graemephi/kahugo@v0.62.3-0.20211121071557-d78c0423784d/parser/metadecoders/format.go (about)

     1  // Copyright 2018 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package metadecoders
    15  
    16  import (
    17  	"path/filepath"
    18  	"strings"
    19  
    20  	"github.com/gohugoio/hugo/media"
    21  )
    22  
    23  type Format string
    24  
    25  const (
    26  	// These are the supported metdata  formats in Hugo. Most of these are also
    27  	// supported as /data formats.
    28  	ORG  Format = "org"
    29  	JSON Format = "json"
    30  	TOML Format = "toml"
    31  	YAML Format = "yaml"
    32  	CSV  Format = "csv"
    33  )
    34  
    35  // FormatFromString turns formatStr, typically a file extension without any ".",
    36  // into a Format. It returns an empty string for unknown formats.
    37  func FormatFromString(formatStr string) Format {
    38  	formatStr = strings.ToLower(formatStr)
    39  	if strings.Contains(formatStr, ".") {
    40  		// Assume a filename
    41  		formatStr = strings.TrimPrefix(filepath.Ext(formatStr), ".")
    42  	}
    43  	switch formatStr {
    44  	case "yaml", "yml":
    45  		return YAML
    46  	case "json":
    47  		return JSON
    48  	case "toml":
    49  		return TOML
    50  	case "org":
    51  		return ORG
    52  	case "csv":
    53  		return CSV
    54  	}
    55  
    56  	return ""
    57  }
    58  
    59  // FormatFromMediaType gets the Format given a MIME type, empty string
    60  // if unknown.
    61  func FormatFromMediaType(m media.Type) Format {
    62  	for _, suffix := range m.Suffixes() {
    63  		if f := FormatFromString(suffix); f != "" {
    64  			return f
    65  		}
    66  	}
    67  
    68  	return ""
    69  }
    70  
    71  // FormatFromContentString tries to detect the format (JSON, YAML or TOML)
    72  // in the given string.
    73  // It return an empty string if no format could be detected.
    74  func (d Decoder) FormatFromContentString(data string) Format {
    75  	csvIdx := strings.IndexRune(data, d.Delimiter)
    76  	jsonIdx := strings.Index(data, "{")
    77  	yamlIdx := strings.Index(data, ":")
    78  	tomlIdx := strings.Index(data, "=")
    79  
    80  	if isLowerIndexThan(csvIdx, jsonIdx, yamlIdx, tomlIdx) {
    81  		return CSV
    82  	}
    83  
    84  	if isLowerIndexThan(jsonIdx, yamlIdx, tomlIdx) {
    85  		return JSON
    86  	}
    87  
    88  	if isLowerIndexThan(yamlIdx, tomlIdx) {
    89  		return YAML
    90  	}
    91  
    92  	if tomlIdx != -1 {
    93  		return TOML
    94  	}
    95  
    96  	return ""
    97  }
    98  
    99  func isLowerIndexThan(first int, others ...int) bool {
   100  	if first == -1 {
   101  		return false
   102  	}
   103  	for _, other := range others {
   104  		if other != -1 && other < first {
   105  			return false
   106  		}
   107  	}
   108  
   109  	return true
   110  }