vendor/gopkg.in/yaml.v2/resolve.go

   1 package yaml
   2
   3 import (
   4         "encoding/base64"
   5         "math"
   6         "regexp"
   7         "strconv"
   8         "strings"
   9         "unicode/utf8"
  10 )
  11
  12 type resolveMapItem struct {
  13         value interface{}
  14         tag   string
  15 }
  16
  17 var resolveTable = make([]byte, 256)
  18 var resolveMap = make(map[string]resolveMapItem)
  19
  20 func init() {
  21         t := resolveTable
  22         t[int('+')] = 'S' // Sign
  23         t[int('-')] = 'S'
  24         for _, c := range "0123456789" {
  25                 t[int(c)] = 'D' // Digit
  26         }
  27         for _, c := range "yYnNtTfFoO~" {
  28                 t[int(c)] = 'M' // In map
  29         }
  30         t[int('.')] = '.' // Float (potentially in map)
  31
  32         var resolveMapList = []struct {
  33                 v   interface{}
  34                 tag string
  35                 l   []string
  36         }{
  37                 {true, yaml_BOOL_TAG, []string{"y", "Y", "yes", "Yes", "YES"}},
  38                 {true, yaml_BOOL_TAG, []string{"true", "True", "TRUE"}},
  39                 {true, yaml_BOOL_TAG, []string{"on", "On", "ON"}},
  40                 {false, yaml_BOOL_TAG, []string{"n", "N", "no", "No", "NO"}},
  41                 {false, yaml_BOOL_TAG, []string{"false", "False", "FALSE"}},
  42                 {false, yaml_BOOL_TAG, []string{"off", "Off", "OFF"}},
  43                 {nil, yaml_NULL_TAG, []string{"", "~", "null", "Null", "NULL"}},
  44                 {math.NaN(), yaml_FLOAT_TAG, []string{".nan", ".NaN", ".NAN"}},
  45                 {math.Inf(+1), yaml_FLOAT_TAG, []string{".inf", ".Inf", ".INF"}},
  46                 {math.Inf(+1), yaml_FLOAT_TAG, []string{"+.inf", "+.Inf", "+.INF"}},
  47                 {math.Inf(-1), yaml_FLOAT_TAG, []string{"-.inf", "-.Inf", "-.INF"}},
  48                 {"<<", yaml_MERGE_TAG, []string{"<<"}},
  49         }
  50
  51         m := resolveMap
  52         for _, item := range resolveMapList {
  53                 for _, s := range item.l {
  54                         m[s] = resolveMapItem{item.v, item.tag}
  55                 }
  56         }
  57 }
  58
  59 const longTagPrefix = "tag:yaml.org,2002:"
  60
  61 func shortTag(tag string) string {
  62         // TODO This can easily be made faster and produce less garbage.
  63         if strings.HasPrefix(tag, longTagPrefix) {
  64                 return "!!" + tag[len(longTagPrefix):]
  65         }
  66         return tag
  67 }
  68
  69 func longTag(tag string) string {
  70         if strings.HasPrefix(tag, "!!") {
  71                 return longTagPrefix + tag[2:]
  72         }
  73         return tag
  74 }
  75
  76 func resolvableTag(tag string) bool {
  77         switch tag {
  78         case "", yaml_STR_TAG, yaml_BOOL_TAG, yaml_INT_TAG, yaml_FLOAT_TAG, yaml_NULL_TAG:
  79                 return true
  80         }
  81         return false
  82 }
  83
  84 var yamlStyleFloat = regexp.MustCompile(`^[-+]?[0-9]*\.?[0-9]+([eE][-+][0-9]+)?$`)
  85
  86 func resolve(tag string, in string) (rtag string, out interface{}) {
  87         if !resolvableTag(tag) {
  88                 return tag, in
  89         }
  90
  91         defer func() {
  92                 switch tag {
  93                 case "", rtag, yaml_STR_TAG, yaml_BINARY_TAG:
  94                         return
  95                 }
  96                 failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
  97         }()
  98
  99         // Any data is accepted as a !!str or !!binary.
 100         // Otherwise, the prefix is enough of a hint about what it might be.
 101         hint := byte('N')
 102         if in != "" {
 103                 hint = resolveTable[in[0]]
 104         }
 105         if hint != 0 && tag != yaml_STR_TAG && tag != yaml_BINARY_TAG {
 106                 // Handle things we can lookup in a map.
 107                 if item, ok := resolveMap[in]; ok {
 108                         return item.tag, item.value
 109                 }
 110
 111                 // Base 60 floats are a bad idea, were dropped in YAML 1.2, and
 112                 // are purposefully unsupported here. They're still quoted on
 113                 // the way out for compatibility with other parser, though.
 114
 115                 switch hint {
 116                 case 'M':
 117                         // We've already checked the map above.
 118
 119                 case '.':
 120                         // Not in the map, so maybe a normal float.
 121                         floatv, err := strconv.ParseFloat(in, 64)
 122                         if err == nil {
 123                                 return yaml_FLOAT_TAG, floatv
 124                         }
 125
 126                 case 'D', 'S':
 127                         // Int, float, or timestamp.
 128                         plain := strings.Replace(in, "_", "", -1)
 129                         intv, err := strconv.ParseInt(plain, 0, 64)
 130                         if err == nil {
 131                                 if intv == int64(int(intv)) {
 132                                         return yaml_INT_TAG, int(intv)
 133                                 } else {
 134                                         return yaml_INT_TAG, intv
 135                                 }
 136                         }
 137                         uintv, err := strconv.ParseUint(plain, 0, 64)
 138                         if err == nil {
 139                                 return yaml_INT_TAG, uintv
 140                         }
 141                         if yamlStyleFloat.MatchString(plain) {
 142                                 floatv, err := strconv.ParseFloat(plain, 64)
 143                                 if err == nil {
 144                                         return yaml_FLOAT_TAG, floatv
 145                                 }
 146                         }
 147                         if strings.HasPrefix(plain, "0b") {
 148                                 intv, err := strconv.ParseInt(plain[2:], 2, 64)
 149                                 if err == nil {
 150                                         if intv == int64(int(intv)) {
 151                                                 return yaml_INT_TAG, int(intv)
 152                                         } else {
 153                                                 return yaml_INT_TAG, intv
 154                                         }
 155                                 }
 156                                 uintv, err := strconv.ParseUint(plain[2:], 2, 64)
 157                                 if err == nil {
 158                                         return yaml_INT_TAG, uintv
 159                                 }
 160                         } else if strings.HasPrefix(plain, "-0b") {
 161                                 intv, err := strconv.ParseInt(plain[3:], 2, 64)
 162                                 if err == nil {
 163                                         if intv == int64(int(intv)) {
 164                                                 return yaml_INT_TAG, -int(intv)
 165                                         } else {
 166                                                 return yaml_INT_TAG, -intv
 167                                         }
 168                                 }
 169                         }
 170                         // XXX Handle timestamps here.
 171
 172                 default:
 173                         panic("resolveTable item not yet handled: " + string(rune(hint)) + " (with " + in + ")")
 174                 }
 175         }
 176         if tag == yaml_BINARY_TAG {
 177                 return yaml_BINARY_TAG, in
 178         }
 179         if utf8.ValidString(in) {
 180                 return yaml_STR_TAG, in
 181         }
 182         return yaml_BINARY_TAG, encodeBase64(in)
 183 }
 184
 185 // encodeBase64 encodes s as base64 that is broken up into multiple lines
 186 // as appropriate for the resulting length.
 187 func encodeBase64(s string) string {
 188         const lineLen = 70
 189         encLen := base64.StdEncoding.EncodedLen(len(s))
 190         lines := encLen/lineLen + 1
 191         buf := make([]byte, encLen*2+lines)
 192         in := buf[0:encLen]
 193         out := buf[encLen:]
 194         base64.StdEncoding.Encode(in, []byte(s))
 195         k := 0
 196         for i := 0; i < len(in); i += lineLen {
 197                 j := i + lineLen
 198                 if j > len(in) {
 199                         j = len(in)
 200                 }
 201                 k += copy(out[k:], in[i:j])
 202                 if lines > 1 {
 203                         out[k] = '\n'
 204                         k++
 205                 }
 206         }
 207         return string(out[:k])
 208 }