1 | package validation |
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2 | |||
3 | import ( |
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4 | "errors" |
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5 | "fmt" |
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6 | "math" |
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7 | "strconv" |
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8 | "strings" |
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9 | "unicode" |
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10 | ) |
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11 | |||
12 | // PropertyPathElement is a part of the [PropertyPath]. |
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13 | type PropertyPathElement interface { |
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14 | // IsIndex can be used to determine whether an element is a string (property name) or |
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15 | // an index array. |
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16 | IsIndex() bool |
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17 | fmt.Stringer |
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18 | } |
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19 | |||
20 | // PropertyName holds up property name value under [PropertyPath]. |
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21 | type PropertyName string |
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22 | 1 | ||
23 | // IsIndex on [PropertyName] always returns false. |
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24 | func (p PropertyName) IsIndex() bool { |
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25 | return false |
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26 | } |
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27 | 1 | ||
28 | // String returns property name as is. |
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29 | func (p PropertyName) String() string { |
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30 | return string(p) |
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31 | } |
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32 | |||
33 | // ArrayIndex holds up array index value under [PropertyPath]. |
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34 | type ArrayIndex int |
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35 | 1 | ||
36 | // IsIndex on [ArrayIndex] always returns true. |
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37 | func (a ArrayIndex) IsIndex() bool { |
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38 | return true |
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39 | } |
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40 | 1 | ||
41 | // String returns array index values converted into a string. |
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42 | func (a ArrayIndex) String() string { |
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43 | return strconv.Itoa(int(a)) |
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44 | } |
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45 | |||
46 | // PropertyPath is generated by the validator and indicates how it reached the invalid value |
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47 | // from the root element. Property path is denoted by dots, while array access |
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48 | // is denoted by square brackets. For example, "book.keywords[0]" means that the violation |
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49 | // occurred on the first element of array "keywords" in the "book" object. |
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50 | // |
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51 | // Internally [PropertyPath] is a linked list. You can create a new path using [PropertyPath.WithProperty] |
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52 | // or [PropertyPath.WithIndex] methods. [PropertyPath] should always be used as a pointer value. |
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53 | // Nil value is a valid value that means that the property path is empty. |
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54 | type PropertyPath struct { |
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55 | parent *PropertyPath |
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56 | value PropertyPathElement |
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57 | } |
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58 | |||
59 | 1 | // NewPropertyPath creates a [PropertyPath] from the list of elements. If the list is empty nil will be returned. |
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60 | 1 | // Nil value is a valid value that means that the property path is empty. |
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61 | 1 | func NewPropertyPath(elements ...PropertyPathElement) *PropertyPath { |
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62 | var path *PropertyPath |
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63 | 1 | ||
64 | return path.With(elements...) |
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65 | } |
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66 | |||
67 | // With returns new [PropertyPath] with appended elements to the end of the list. |
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68 | 1 | func (path *PropertyPath) With(elements ...PropertyPathElement) *PropertyPath { |
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69 | current := path |
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70 | for _, element := range elements { |
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71 | current = &PropertyPath{parent: current, value: element} |
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72 | } |
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73 | return current |
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74 | } |
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75 | |||
76 | 1 | // WithProperty returns new [PropertyPath] with appended [PropertyName] to the end of the list. |
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77 | func (path *PropertyPath) WithProperty(name string) *PropertyPath { |
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78 | return &PropertyPath{ |
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79 | parent: path, |
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80 | value: PropertyName(name), |
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81 | } |
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82 | } |
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83 | |||
84 | 1 | // WithIndex returns new [PropertyPath] with appended [ArrayIndex] to the end of the list. |
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85 | 1 | func (path *PropertyPath) WithIndex(index int) *PropertyPath { |
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86 | 1 | return &PropertyPath{ |
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87 | 1 | parent: path, |
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88 | 1 | value: ArrayIndex(index), |
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89 | } |
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90 | 1 | } |
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91 | 1 | ||
92 | 1 | // Elements returns property path as a slice of [PropertyPathElement]. |
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93 | // It returns nil if property path is nil (empty). |
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94 | func (path *PropertyPath) Elements() []PropertyPathElement { |
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95 | 1 | if path == nil || path.value == nil { |
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96 | return nil |
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97 | } |
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98 | 1 | ||
99 | length := path.Len() |
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100 | elements := make([]PropertyPathElement, length) |
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101 | |||
102 | i := length - 1 |
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103 | 1 | element := path |
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104 | for element != nil { |
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105 | elements[i] = element.value |
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106 | element = element.parent |
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107 | i-- |
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108 | } |
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109 | |||
110 | return elements |
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111 | } |
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112 | |||
113 | // Len returns count of property path elements. |
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114 | func (path *PropertyPath) Len() int { |
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115 | length := 0 |
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116 | element := path |
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117 | for element != nil { |
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118 | length++ |
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119 | element = element.parent |
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120 | } |
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121 | return length |
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122 | } |
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123 | |||
124 | // String is used to format property path to a string. |
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125 | func (path *PropertyPath) String() string { |
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126 | elements := path.Elements() |
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127 | count := 0 |
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128 | for _, element := range elements { |
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129 | if s, ok := element.(PropertyName); ok { |
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130 | count += len(s) |
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131 | } else { |
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132 | count += 2 |
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133 | } |
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134 | } |
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135 | |||
136 | s := strings.Builder{} |
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137 | s.Grow(count) |
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138 | for i, element := range elements { |
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139 | name := element.String() |
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140 | if element.IsIndex() { |
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141 | s.WriteString("[" + name + "]") |
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142 | } else if isIdentifier(name) { |
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143 | if i > 0 { |
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144 | s.WriteString(".") |
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145 | } |
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146 | s.WriteString(name) |
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147 | } else { |
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148 | s.WriteString("['") |
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149 | writePropertyName(&s, name) |
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150 | s.WriteString("']") |
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151 | } |
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152 | } |
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153 | |||
154 | return s.String() |
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155 | } |
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156 | |||
157 | // MarshalText will marshal property path value to a string. |
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158 | func (path *PropertyPath) MarshalText() (text []byte, err error) { |
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159 | return []byte(path.String()), nil |
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160 | } |
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161 | |||
162 | // UnmarshalText unmarshal string representation of property path into [PropertyPath]. |
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163 | func (path *PropertyPath) UnmarshalText(text []byte) error { |
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164 | parser := pathParser{} |
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165 | p, err := parser.Parse(string(text)) |
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166 | if p == nil || err != nil { |
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167 | return err |
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168 | } |
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169 | |||
170 | *path = *p |
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171 | |||
172 | return nil |
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173 | } |
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174 | |||
175 | func isIdentifier(s string) bool { |
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176 | if len(s) == 0 { |
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177 | return false |
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178 | } |
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179 | for i, c := range s { |
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180 | if i == 0 && !isFirstIdentifierChar(c) { |
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181 | return false |
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182 | } |
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183 | if i > 0 && !isIdentifierChar(c) { |
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184 | return false |
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185 | } |
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186 | } |
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187 | |||
188 | return true |
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189 | } |
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190 | |||
191 | func isFirstIdentifierChar(c rune) bool { |
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192 | return unicode.IsLetter(c) || c == '$' || c == '_' |
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193 | } |
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194 | |||
195 | func isIdentifierChar(c rune) bool { |
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196 | return unicode.IsLetter(c) || unicode.IsDigit(c) || c == '$' || c == '_' |
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197 | } |
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198 | |||
199 | func writePropertyName(s *strings.Builder, name string) { |
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200 | for _, c := range name { |
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201 | if c == '\'' || c == '\\' { |
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202 | s.WriteRune('\\') |
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203 | } |
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204 | s.WriteRune(c) |
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205 | } |
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206 | } |
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207 | |||
208 | type parsingState byte |
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209 | |||
210 | const ( |
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211 | initialState parsingState = iota |
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212 | beginIdentifierState |
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213 | identifierState |
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214 | |||
215 | beginIndexState |
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216 | indexState |
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217 | |||
218 | bracketedNameState |
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219 | endBracketedNameState |
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220 | |||
221 | closeBracketState |
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222 | ) |
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223 | |||
224 | type pathParser struct { |
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225 | buffer strings.Builder |
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226 | state parsingState |
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227 | isEscape bool |
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228 | index int |
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229 | pathIndex int |
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230 | path *PropertyPath |
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231 | } |
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232 | |||
233 | func (parser *pathParser) Parse(encodedPath string) (*PropertyPath, error) { |
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234 | if len(encodedPath) == 0 { |
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235 | return nil, nil |
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236 | } |
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237 | for i, c := range encodedPath { |
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238 | parser.index = i |
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239 | if err := parser.handleNext(c); err != nil { |
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240 | return nil, err |
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241 | } |
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242 | } |
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243 | |||
244 | return parser.finish() |
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245 | } |
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246 | |||
247 | func (parser *pathParser) handleNext(c rune) error { |
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248 | var err error |
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249 | |||
250 | switch c { |
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251 | case '[': |
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252 | err = parser.handleOpenBracket(c) |
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253 | case ']': |
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254 | err = parser.handleCloseBracket(c) |
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255 | case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': |
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256 | err = parser.handleDigit(c) |
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257 | case '\'': |
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258 | err = parser.handleQuote(c) |
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259 | case '\\': |
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260 | err = parser.handleEscape(c) |
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261 | case '.': |
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262 | err = parser.handlePoint(c) |
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263 | default: |
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264 | err = parser.handleOther(c) |
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265 | } |
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266 | |||
267 | return err |
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268 | } |
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269 | |||
270 | func (parser *pathParser) handleOpenBracket(c rune) error { |
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271 | switch parser.state { |
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272 | case beginIdentifierState, beginIndexState, indexState, endBracketedNameState: |
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273 | return parser.newCharError(c, "unexpected char") |
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274 | case identifierState: |
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275 | if parser.buffer.Len() > 0 { |
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276 | parser.addProperty() |
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277 | } |
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278 | parser.state = beginIndexState |
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279 | case initialState, closeBracketState: |
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280 | parser.state = beginIndexState |
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281 | case bracketedNameState: |
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282 | parser.buffer.WriteRune(c) |
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283 | } |
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284 | |||
285 | return nil |
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286 | } |
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287 | |||
288 | func (parser *pathParser) handleCloseBracket(c rune) error { |
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289 | switch parser.state { |
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290 | case indexState: |
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291 | err := parser.addIndex() |
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292 | if err != nil { |
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293 | return err |
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294 | } |
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295 | parser.state = closeBracketState |
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296 | case bracketedNameState: |
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297 | parser.buffer.WriteRune(c) |
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298 | case endBracketedNameState: |
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299 | parser.addProperty() |
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300 | parser.state = closeBracketState |
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301 | default: |
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302 | return parser.newCharError(c, "unexpected close bracket") |
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303 | } |
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304 | |||
305 | return nil |
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306 | } |
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307 | |||
308 | func (parser *pathParser) handleDigit(c rune) error { |
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309 | switch parser.state { |
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310 | case beginIndexState, indexState: |
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311 | parser.state = indexState |
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312 | case bracketedNameState, identifierState: |
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313 | case initialState, beginIdentifierState: |
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314 | return parser.newCharError(c, "unexpected identifier character") |
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315 | default: |
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316 | return parser.newCharError(c, "invalid array index") |
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317 | } |
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318 | parser.buffer.WriteRune(c) |
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319 | |||
320 | return nil |
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321 | } |
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322 | |||
323 | func (parser *pathParser) handlePoint(c rune) error { |
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324 | switch parser.state { |
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325 | case beginIdentifierState, identifierState: |
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326 | if parser.buffer.Len() == 0 { |
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327 | return parser.newCharError(c, "unexpected point") |
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328 | } |
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329 | parser.addProperty() |
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330 | parser.state = beginIdentifierState |
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331 | case bracketedNameState: |
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332 | parser.buffer.WriteRune(c) |
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333 | case closeBracketState: |
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334 | parser.state = beginIdentifierState |
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335 | default: |
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336 | return parser.newCharError(c, "unexpected point") |
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337 | } |
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338 | |||
339 | return nil |
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340 | } |
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341 | |||
342 | func (parser *pathParser) handleQuote(c rune) error { |
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343 | if parser.isEscape { |
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344 | parser.buffer.WriteRune(c) |
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345 | parser.isEscape = false |
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346 | |||
347 | return nil |
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348 | } |
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349 | |||
350 | switch parser.state { |
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351 | case beginIndexState: |
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352 | parser.state = bracketedNameState |
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353 | case bracketedNameState: |
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354 | parser.state = endBracketedNameState |
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355 | default: |
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356 | return parser.newCharError(c, "unexpected quote") |
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357 | } |
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358 | |||
359 | return nil |
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360 | } |
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361 | |||
362 | func (parser *pathParser) handleEscape(c rune) error { |
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363 | if parser.state != bracketedNameState { |
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364 | return parser.newCharError(c, "unexpected backslash") |
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365 | } |
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366 | |||
367 | if parser.isEscape { |
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368 | parser.buffer.WriteRune(c) |
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369 | parser.isEscape = false |
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370 | } else { |
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371 | parser.isEscape = true |
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372 | } |
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373 | |||
374 | return nil |
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375 | } |
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376 | |||
377 | func (parser *pathParser) handleOther(c rune) error { |
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378 | switch parser.state { |
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379 | case beginIndexState, indexState: |
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380 | return parser.newCharError(c, "unexpected array index character") |
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381 | case initialState, beginIdentifierState, identifierState: |
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382 | if !isFirstIdentifierChar(c) { |
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383 | return parser.newCharError(c, "unexpected identifier char") |
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384 | } |
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385 | parser.state = identifierState |
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386 | case closeBracketState, endBracketedNameState: |
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387 | return parser.newCharError(c, "unexpected char") |
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388 | } |
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389 | parser.buffer.WriteRune(c) |
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390 | |||
391 | return nil |
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392 | } |
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393 | |||
394 | func (parser *pathParser) addProperty() { |
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395 | parser.path = parser.path.WithProperty(parser.buffer.String()) |
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396 | parser.pathIndex++ |
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397 | parser.buffer.Reset() |
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398 | } |
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399 | |||
400 | func (parser *pathParser) addIndex() error { |
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401 | s := parser.buffer.String() |
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402 | |||
403 | u, err := strconv.ParseUint(s, 10, 0) |
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404 | if err != nil { |
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405 | if errors.Is(err, strconv.ErrRange) { |
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406 | return parser.newProcessingError("value out of range: " + s) |
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407 | } |
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408 | return parser.newProcessingError("invalid array index: " + s) |
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409 | } |
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410 | if u > math.MaxInt { |
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411 | return parser.newProcessingError("value out of range: " + s) |
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412 | } |
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413 | |||
414 | parser.path = parser.path.WithIndex(int(u)) |
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415 | parser.pathIndex++ |
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416 | parser.buffer.Reset() |
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417 | |||
418 | return nil |
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419 | } |
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420 | |||
421 | func (parser *pathParser) finish() (*PropertyPath, error) { |
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422 | switch parser.state { |
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423 | case beginIdentifierState, identifierState: |
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424 | if parser.buffer.Len() == 0 { |
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425 | return nil, parser.newError("incomplete property name") |
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426 | } |
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427 | parser.path = parser.path.WithProperty(parser.buffer.String()) |
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428 | case beginIndexState, indexState: |
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429 | return nil, parser.newError("incomplete array index") |
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430 | case bracketedNameState, endBracketedNameState: |
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431 | return nil, parser.newError("incomplete bracketed property name") |
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432 | case closeBracketState: |
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433 | default: |
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434 | return nil, parser.newError("unexpected parsing state") |
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435 | } |
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436 | |||
437 | return parser.path, nil |
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438 | } |
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439 | |||
440 | func (parser *pathParser) newError(message string) *pathParsingError { |
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441 | return &pathParsingError{ |
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442 | pathIndex: parser.pathIndex, |
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443 | message: message, |
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444 | } |
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445 | } |
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446 | |||
447 | func (parser *pathParser) newCharError(char rune, message string) *pathParsingCharError { |
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448 | return &pathParsingCharError{ |
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449 | index: parser.index, |
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450 | pathIndex: parser.pathIndex, |
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451 | char: char, |
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452 | message: message, |
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453 | } |
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454 | } |
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455 | |||
456 | func (parser *pathParser) newProcessingError(message string) *pathParsingProcessingError { |
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457 | return &pathParsingProcessingError{ |
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458 | pathIndex: parser.pathIndex, |
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459 | message: message, |
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460 | } |
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461 | } |
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462 | |||
463 | type pathParsingError struct { |
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464 | pathIndex int |
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465 | message string |
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466 | } |
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467 | |||
468 | func (err *pathParsingError) Error() string { |
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469 | return fmt.Sprintf("parsing path element #%d: %s", err.pathIndex, err.message) |
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470 | } |
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471 | |||
472 | type pathParsingCharError struct { |
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473 | index int |
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474 | pathIndex int |
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475 | char rune |
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476 | message string |
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477 | } |
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478 | |||
479 | func (err *pathParsingCharError) Error() string { |
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480 | return fmt.Sprintf( |
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481 | "parsing path element #%d at char #%d %q: %s", |
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482 | err.pathIndex, |
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483 | err.index, |
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484 | err.char, |
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485 | err.message, |
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486 | ) |
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487 | } |
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488 | |||
489 | type pathParsingProcessingError struct { |
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490 | pathIndex int |
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491 | message string |
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492 | } |
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493 | |||
494 | func (err *pathParsingProcessingError) Error() string { |
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495 | return fmt.Sprintf("parsing path element #%d: %s", err.pathIndex, err.message) |
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496 | } |
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497 |