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1 //
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2 // Copyright (c) 2011-2019 Canonical Ltd
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3 //
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4 // Licensed under the Apache License, Version 2.0 (the "License");
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5 // you may not use this file except in compliance with the License.
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6 // You may obtain a copy of the License at
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7 //
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8 // http://www.apache.org/licenses/LICENSE-2.0
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9 //
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10 // Unless required by applicable law or agreed to in writing, software
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11 // distributed under the License is distributed on an "AS IS" BASIS,
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12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 // See the License for the specific language governing permissions and
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14 // limitations under the License.
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15
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16 package yaml
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17
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18 import (
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19 "encoding/base64"
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20 "math"
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21 "regexp"
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22 "strconv"
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23 "strings"
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24 "time"
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25 )
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26
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27 type resolveMapItem struct {
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28 value interface{}
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29 tag string
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30 }
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31
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32 var resolveTable = make([]byte, 256)
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33 var resolveMap = make(map[string]resolveMapItem)
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34
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35 func init() {
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36 t := resolveTable
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37 t[int('+')] = 'S' // Sign
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38 t[int('-')] = 'S'
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39 for _, c := range "0123456789" {
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40 t[int(c)] = 'D' // Digit
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41 }
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42 for _, c := range "yYnNtTfFoO~" {
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43 t[int(c)] = 'M' // In map
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44 }
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45 t[int('.')] = '.' // Float (potentially in map)
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46
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47 var resolveMapList = []struct {
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48 v interface{}
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49 tag string
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50 l []string
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51 }{
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52 {true, boolTag, []string{"true", "True", "TRUE"}},
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53 {false, boolTag, []string{"false", "False", "FALSE"}},
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54 {nil, nullTag, []string{"", "~", "null", "Null", "NULL"}},
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55 {math.NaN(), floatTag, []string{".nan", ".NaN", ".NAN"}},
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56 {math.Inf(+1), floatTag, []string{".inf", ".Inf", ".INF"}},
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57 {math.Inf(+1), floatTag, []string{"+.inf", "+.Inf", "+.INF"}},
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58 {math.Inf(-1), floatTag, []string{"-.inf", "-.Inf", "-.INF"}},
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59 {"<<", mergeTag, []string{"<<"}},
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60 }
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61
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62 m := resolveMap
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63 for _, item := range resolveMapList {
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64 for _, s := range item.l {
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65 m[s] = resolveMapItem{item.v, item.tag}
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66 }
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67 }
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68 }
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69
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70 const (
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71 nullTag = "!!null"
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72 boolTag = "!!bool"
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73 strTag = "!!str"
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74 intTag = "!!int"
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75 floatTag = "!!float"
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76 timestampTag = "!!timestamp"
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77 seqTag = "!!seq"
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78 mapTag = "!!map"
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79 binaryTag = "!!binary"
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80 mergeTag = "!!merge"
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81 )
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82
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83 var longTags = make(map[string]string)
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84 var shortTags = make(map[string]string)
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85
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86 func init() {
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87 for _, stag := range []string{nullTag, boolTag, strTag, intTag, floatTag, timestampTag, seqTag, mapTag, binaryTag, mergeTag} {
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88 ltag := longTag(stag)
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89 longTags[stag] = ltag
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90 shortTags[ltag] = stag
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91 }
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92 }
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93
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94 const longTagPrefix = "tag:yaml.org,2002:"
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95
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96 func shortTag(tag string) string {
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97 if strings.HasPrefix(tag, longTagPrefix) {
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98 if stag, ok := shortTags[tag]; ok {
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99 return stag
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100 }
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101 return "!!" + tag[len(longTagPrefix):]
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102 }
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103 return tag
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104 }
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105
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106 func longTag(tag string) string {
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107 if strings.HasPrefix(tag, "!!") {
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108 if ltag, ok := longTags[tag]; ok {
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109 return ltag
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110 }
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111 return longTagPrefix + tag[2:]
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112 }
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113 return tag
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114 }
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115
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116 func resolvableTag(tag string) bool {
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117 switch tag {
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118 case "", strTag, boolTag, intTag, floatTag, nullTag, timestampTag:
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119 return true
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120 }
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121 return false
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122 }
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123
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124 var yamlStyleFloat = regexp.MustCompile(`^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$`)
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125
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126 func resolve(tag string, in string) (rtag string, out interface{}) {
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127 tag = shortTag(tag)
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128 if !resolvableTag(tag) {
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129 return tag, in
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130 }
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131
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132 defer func() {
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133 switch tag {
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134 case "", rtag, strTag, binaryTag:
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135 return
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136 case floatTag:
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137 if rtag == intTag {
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138 switch v := out.(type) {
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139 case int64:
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140 rtag = floatTag
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141 out = float64(v)
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142 return
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143 case int:
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144 rtag = floatTag
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145 out = float64(v)
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146 return
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147 }
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148 }
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149 }
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150 failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
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151 }()
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152
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153 // Any data is accepted as a !!str or !!binary.
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154 // Otherwise, the prefix is enough of a hint about what it might be.
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155 hint := byte('N')
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156 if in != "" {
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157 hint = resolveTable[in[0]]
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158 }
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159 if hint != 0 && tag != strTag && tag != binaryTag {
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160 // Handle things we can lookup in a map.
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161 if item, ok := resolveMap[in]; ok {
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162 return item.tag, item.value
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163 }
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164
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165 // Base 60 floats are a bad idea, were dropped in YAML 1.2, and
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166 // are purposefully unsupported here. They're still quoted on
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167 // the way out for compatibility with other parser, though.
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168
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169 switch hint {
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170 case 'M':
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171 // We've already checked the map above.
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172
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173 case '.':
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174 // Not in the map, so maybe a normal float.
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175 floatv, err := strconv.ParseFloat(in, 64)
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176 if err == nil {
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177 return floatTag, floatv
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178 }
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179
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180 case 'D', 'S':
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181 // Int, float, or timestamp.
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182 // Only try values as a timestamp if the value is unquoted or there's an explicit
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183 // !!timestamp tag.
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184 if tag == "" || tag == timestampTag {
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185 t, ok := parseTimestamp(in)
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186 if ok {
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187 return timestampTag, t
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188 }
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189 }
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190
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191 plain := strings.Replace(in, "_", "", -1)
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192 intv, err := strconv.ParseInt(plain, 0, 64)
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193 if err == nil {
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194 if intv == int64(int(intv)) {
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195 return intTag, int(intv)
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196 } else {
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197 return intTag, intv
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198 }
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199 }
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200 uintv, err := strconv.ParseUint(plain, 0, 64)
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201 if err == nil {
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202 return intTag, uintv
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203 }
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204 if yamlStyleFloat.MatchString(plain) {
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205 floatv, err := strconv.ParseFloat(plain, 64)
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206 if err == nil {
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207 return floatTag, floatv
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208 }
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209 }
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210 if strings.HasPrefix(plain, "0b") {
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211 intv, err := strconv.ParseInt(plain[2:], 2, 64)
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212 if err == nil {
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213 if intv == int64(int(intv)) {
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214 return intTag, int(intv)
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215 } else {
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216 return intTag, intv
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217 }
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218 }
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219 uintv, err := strconv.ParseUint(plain[2:], 2, 64)
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220 if err == nil {
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221 return intTag, uintv
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222 }
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223 } else if strings.HasPrefix(plain, "-0b") {
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224 intv, err := strconv.ParseInt("-"+plain[3:], 2, 64)
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225 if err == nil {
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226 if true || intv == int64(int(intv)) {
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227 return intTag, int(intv)
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228 } else {
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229 return intTag, intv
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230 }
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231 }
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232 }
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233 // Octals as introduced in version 1.2 of the spec.
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234 // Octals from the 1.1 spec, spelled as 0777, are still
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235 // decoded by default in v3 as well for compatibility.
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236 // May be dropped in v4 depending on how usage evolves.
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237 if strings.HasPrefix(plain, "0o") {
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238 intv, err := strconv.ParseInt(plain[2:], 8, 64)
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239 if err == nil {
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240 if intv == int64(int(intv)) {
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241 return intTag, int(intv)
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242 } else {
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243 return intTag, intv
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244 }
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245 }
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246 uintv, err := strconv.ParseUint(plain[2:], 8, 64)
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247 if err == nil {
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248 return intTag, uintv
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249 }
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250 } else if strings.HasPrefix(plain, "-0o") {
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251 intv, err := strconv.ParseInt("-"+plain[3:], 8, 64)
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252 if err == nil {
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253 if true || intv == int64(int(intv)) {
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254 return intTag, int(intv)
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255 } else {
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256 return intTag, intv
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257 }
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258 }
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259 }
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260 default:
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261 panic("internal error: missing handler for resolver table: " + string(rune(hint)) + " (with " + in + ")")
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262 }
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263 }
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264 return strTag, in
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265 }
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266
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267 // encodeBase64 encodes s as base64 that is broken up into multiple lines
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268 // as appropriate for the resulting length.
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269 func encodeBase64(s string) string {
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270 const lineLen = 70
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271 encLen := base64.StdEncoding.EncodedLen(len(s))
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272 lines := encLen/lineLen + 1
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273 buf := make([]byte, encLen*2+lines)
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274 in := buf[0:encLen]
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275 out := buf[encLen:]
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276 base64.StdEncoding.Encode(in, []byte(s))
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277 k := 0
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278 for i := 0; i < len(in); i += lineLen {
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279 j := i + lineLen
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280 if j > len(in) {
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281 j = len(in)
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282 }
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283 k += copy(out[k:], in[i:j])
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284 if lines > 1 {
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285 out[k] = '\n'
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286 k++
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287 }
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288 }
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289 return string(out[:k])
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290 }
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291
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292 // This is a subset of the formats allowed by the regular expression
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293 // defined at http://yaml.org/type/timestamp.html.
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294 var allowedTimestampFormats = []string{
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295 "2006-1-2T15:4:5.999999999Z07:00", // RCF3339Nano with short date fields.
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296 "2006-1-2t15:4:5.999999999Z07:00", // RFC3339Nano with short date fields and lower-case "t".
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297 "2006-1-2 15:4:5.999999999", // space separated with no time zone
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298 "2006-1-2", // date only
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299 // Notable exception: time.Parse cannot handle: "2001-12-14 21:59:43.10 -5"
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300 // from the set of examples.
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301 }
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302
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303 // parseTimestamp parses s as a timestamp string and
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304 // returns the timestamp and reports whether it succeeded.
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305 // Timestamp formats are defined at http://yaml.org/type/timestamp.html
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306 func parseTimestamp(s string) (time.Time, bool) {
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307 // TODO write code to check all the formats supported by
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308 // http://yaml.org/type/timestamp.html instead of using time.Parse.
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309
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310 // Quick check: all date formats start with YYYY-.
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311 i := 0
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312 for ; i < len(s); i++ {
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313 if c := s[i]; c < '0' || c > '9' {
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314 break
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315 }
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316 }
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317 if i != 4 || i == len(s) || s[i] != '-' {
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318 return time.Time{}, false
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319 }
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320 for _, format := range allowedTimestampFormats {
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321 if t, err := time.Parse(format, s); err == nil {
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322 return t, true
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323 }
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324 }
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325 return time.Time{}, false
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326 }
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