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1 package tracker |
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2 |
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3 import ( |
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4 "bytes" |
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5 "fmt" |
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6 "sync" |
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7 |
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8 "github.com/pelletier/go-toml/v2/internal/ast" |
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9 ) |
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10 |
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11 type keyKind uint8 |
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12 |
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13 const ( |
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14 invalidKind keyKind = iota |
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15 valueKind |
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16 tableKind |
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17 arrayTableKind |
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18 ) |
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19 |
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20 func (k keyKind) String() string { |
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21 switch k { |
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22 case invalidKind: |
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23 return "invalid" |
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24 case valueKind: |
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25 return "value" |
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26 case tableKind: |
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27 return "table" |
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28 case arrayTableKind: |
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29 return "array table" |
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30 } |
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31 panic("missing keyKind string mapping") |
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32 } |
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33 |
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34 // SeenTracker tracks which keys have been seen with which TOML type to flag |
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35 // duplicates and mismatches according to the spec. |
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36 // |
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37 // Each node in the visited tree is represented by an entry. Each entry has an |
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38 // identifier, which is provided by a counter. Entries are stored in the array |
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39 // entries. As new nodes are discovered (referenced for the first time in the |
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40 // TOML document), entries are created and appended to the array. An entry |
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41 // points to its parent using its id. |
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42 // |
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43 // To find whether a given key (sequence of []byte) has already been visited, |
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44 // the entries are linearly searched, looking for one with the right name and |
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45 // parent id. |
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46 // |
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47 // Given that all keys appear in the document after their parent, it is |
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48 // guaranteed that all descendants of a node are stored after the node, this |
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49 // speeds up the search process. |
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50 // |
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51 // When encountering [[array tables]], the descendants of that node are removed |
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52 // to allow that branch of the tree to be "rediscovered". To maintain the |
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53 // invariant above, the deletion process needs to keep the order of entries. |
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54 // This results in more copies in that case. |
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55 type SeenTracker struct { |
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56 entries []entry |
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57 currentIdx int |
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58 } |
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59 |
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60 var pool sync.Pool |
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61 |
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62 func (s *SeenTracker) reset() { |
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63 // Always contains a root element at index 0. |
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64 s.currentIdx = 0 |
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65 if len(s.entries) == 0 { |
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66 s.entries = make([]entry, 1, 2) |
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67 } else { |
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68 s.entries = s.entries[:1] |
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69 } |
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70 s.entries[0].child = -1 |
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71 s.entries[0].next = -1 |
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72 } |
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73 |
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74 type entry struct { |
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75 // Use -1 to indicate no child or no sibling. |
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76 child int |
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77 next int |
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78 |
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79 name []byte |
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80 kind keyKind |
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81 explicit bool |
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82 kv bool |
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83 } |
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84 |
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85 // Find the index of the child of parentIdx with key k. Returns -1 if |
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86 // it does not exist. |
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87 func (s *SeenTracker) find(parentIdx int, k []byte) int { |
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88 for i := s.entries[parentIdx].child; i >= 0; i = s.entries[i].next { |
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89 if bytes.Equal(s.entries[i].name, k) { |
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90 return i |
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91 } |
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92 } |
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93 return -1 |
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94 } |
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95 |
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96 // Remove all descendants of node at position idx. |
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97 func (s *SeenTracker) clear(idx int) { |
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98 if idx >= len(s.entries) { |
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99 return |
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100 } |
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101 |
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102 for i := s.entries[idx].child; i >= 0; { |
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103 next := s.entries[i].next |
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104 n := s.entries[0].next |
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105 s.entries[0].next = i |
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106 s.entries[i].next = n |
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107 s.entries[i].name = nil |
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108 s.clear(i) |
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109 i = next |
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110 } |
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111 |
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112 s.entries[idx].child = -1 |
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113 } |
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114 |
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115 func (s *SeenTracker) create(parentIdx int, name []byte, kind keyKind, explicit bool, kv bool) int { |
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116 e := entry{ |
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117 child: -1, |
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118 next: s.entries[parentIdx].child, |
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119 |
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120 name: name, |
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121 kind: kind, |
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122 explicit: explicit, |
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123 kv: kv, |
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124 } |
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125 var idx int |
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126 if s.entries[0].next >= 0 { |
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127 idx = s.entries[0].next |
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128 s.entries[0].next = s.entries[idx].next |
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129 s.entries[idx] = e |
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130 } else { |
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131 idx = len(s.entries) |
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132 s.entries = append(s.entries, e) |
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133 } |
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134 |
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135 s.entries[parentIdx].child = idx |
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136 |
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137 return idx |
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138 } |
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139 |
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140 func (s *SeenTracker) setExplicitFlag(parentIdx int) { |
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141 for i := s.entries[parentIdx].child; i >= 0; i = s.entries[i].next { |
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142 if s.entries[i].kv { |
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143 s.entries[i].explicit = true |
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144 s.entries[i].kv = false |
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145 } |
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146 s.setExplicitFlag(i) |
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147 } |
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148 } |
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149 |
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150 // CheckExpression takes a top-level node and checks that it does not contain |
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151 // keys that have been seen in previous calls, and validates that types are |
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152 // consistent. |
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153 func (s *SeenTracker) CheckExpression(node *ast.Node) error { |
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154 if s.entries == nil { |
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155 s.reset() |
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156 } |
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157 switch node.Kind { |
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158 case ast.KeyValue: |
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159 return s.checkKeyValue(node) |
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160 case ast.Table: |
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161 return s.checkTable(node) |
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162 case ast.ArrayTable: |
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163 return s.checkArrayTable(node) |
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164 default: |
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165 panic(fmt.Errorf("this should not be a top level node type: %s", node.Kind)) |
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166 } |
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167 } |
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168 |
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169 func (s *SeenTracker) checkTable(node *ast.Node) error { |
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170 if s.currentIdx >= 0 { |
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171 s.setExplicitFlag(s.currentIdx) |
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172 } |
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173 |
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174 it := node.Key() |
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175 |
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176 parentIdx := 0 |
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177 |
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178 // This code is duplicated in checkArrayTable. This is because factoring |
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179 // it in a function requires to copy the iterator, or allocate it to the |
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180 // heap, which is not cheap. |
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181 for it.Next() { |
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182 if it.IsLast() { |
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183 break |
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184 } |
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185 |
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186 k := it.Node().Data |
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187 |
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188 idx := s.find(parentIdx, k) |
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189 |
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190 if idx < 0 { |
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191 idx = s.create(parentIdx, k, tableKind, false, false) |
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192 } else { |
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193 entry := s.entries[idx] |
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194 if entry.kind == valueKind { |
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195 return fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind) |
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196 } |
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197 } |
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198 parentIdx = idx |
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199 } |
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200 |
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201 k := it.Node().Data |
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202 idx := s.find(parentIdx, k) |
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203 |
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204 if idx >= 0 { |
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205 kind := s.entries[idx].kind |
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206 if kind != tableKind { |
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207 return fmt.Errorf("toml: key %s should be a table, not a %s", string(k), kind) |
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208 } |
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209 if s.entries[idx].explicit { |
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210 return fmt.Errorf("toml: table %s already exists", string(k)) |
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211 } |
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212 s.entries[idx].explicit = true |
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213 } else { |
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214 idx = s.create(parentIdx, k, tableKind, true, false) |
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215 } |
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216 |
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217 s.currentIdx = idx |
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218 |
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219 return nil |
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220 } |
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221 |
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222 func (s *SeenTracker) checkArrayTable(node *ast.Node) error { |
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223 if s.currentIdx >= 0 { |
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224 s.setExplicitFlag(s.currentIdx) |
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225 } |
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226 |
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227 it := node.Key() |
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228 |
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229 parentIdx := 0 |
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230 |
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231 for it.Next() { |
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232 if it.IsLast() { |
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233 break |
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234 } |
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235 |
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236 k := it.Node().Data |
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237 |
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238 idx := s.find(parentIdx, k) |
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239 |
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240 if idx < 0 { |
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241 idx = s.create(parentIdx, k, tableKind, false, false) |
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242 } else { |
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243 entry := s.entries[idx] |
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244 if entry.kind == valueKind { |
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245 return fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind) |
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246 } |
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247 } |
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248 |
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249 parentIdx = idx |
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250 } |
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251 |
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252 k := it.Node().Data |
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253 idx := s.find(parentIdx, k) |
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254 |
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255 if idx >= 0 { |
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256 kind := s.entries[idx].kind |
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257 if kind != arrayTableKind { |
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258 return fmt.Errorf("toml: key %s already exists as a %s, but should be an array table", kind, string(k)) |
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259 } |
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260 s.clear(idx) |
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261 } else { |
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262 idx = s.create(parentIdx, k, arrayTableKind, true, false) |
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263 } |
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264 |
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265 s.currentIdx = idx |
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266 |
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267 return nil |
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268 } |
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269 |
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270 func (s *SeenTracker) checkKeyValue(node *ast.Node) error { |
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271 parentIdx := s.currentIdx |
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272 it := node.Key() |
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273 |
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274 for it.Next() { |
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275 k := it.Node().Data |
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276 |
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277 idx := s.find(parentIdx, k) |
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278 |
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279 if idx < 0 { |
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280 idx = s.create(parentIdx, k, tableKind, false, true) |
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281 } else { |
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282 entry := s.entries[idx] |
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283 if it.IsLast() { |
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284 return fmt.Errorf("toml: key %s is already defined", string(k)) |
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285 } else if entry.kind != tableKind { |
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286 return fmt.Errorf("toml: expected %s to be a table, not a %s", string(k), entry.kind) |
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287 } else if entry.explicit { |
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288 return fmt.Errorf("toml: cannot redefine table %s that has already been explicitly defined", string(k)) |
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289 } |
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290 } |
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291 |
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292 parentIdx = idx |
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293 } |
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294 |
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295 s.entries[parentIdx].kind = valueKind |
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296 |
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297 value := node.Value() |
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298 |
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299 switch value.Kind { |
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300 case ast.InlineTable: |
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301 return s.checkInlineTable(value) |
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302 case ast.Array: |
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303 return s.checkArray(value) |
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304 } |
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305 |
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306 return nil |
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307 } |
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308 |
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309 func (s *SeenTracker) checkArray(node *ast.Node) error { |
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310 it := node.Children() |
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311 for it.Next() { |
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312 n := it.Node() |
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313 switch n.Kind { |
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314 case ast.InlineTable: |
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315 err := s.checkInlineTable(n) |
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316 if err != nil { |
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317 return err |
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318 } |
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319 case ast.Array: |
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320 err := s.checkArray(n) |
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321 if err != nil { |
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322 return err |
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323 } |
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324 } |
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325 } |
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326 return nil |
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327 } |
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328 |
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329 func (s *SeenTracker) checkInlineTable(node *ast.Node) error { |
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330 if pool.New == nil { |
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331 pool.New = func() interface{} { |
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332 return &SeenTracker{} |
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333 } |
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334 } |
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335 |
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336 s = pool.Get().(*SeenTracker) |
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337 s.reset() |
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338 |
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339 it := node.Children() |
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340 for it.Next() { |
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341 n := it.Node() |
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342 err := s.checkKeyValue(n) |
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343 if err != nil { |
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344 return err |
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345 } |
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346 } |
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347 |
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348 // As inline tables are self-contained, the tracker does not |
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349 // need to retain the details of what they contain. The |
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350 // keyValue element that creates the inline table is kept to |
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351 // mark the presence of the inline table and prevent |
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352 // redefinition of its keys: check* functions cannot walk into |
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353 // a value. |
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354 pool.Put(s) |
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355 return nil |
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356 } |