1package js
  2
  3// IVisitor represents the AST Visitor
  4// Each INode encountered by `Walk` is passed to `Enter`, children nodes will be ignored if the returned IVisitor is nil
  5// `Exit` is called upon the exit of a node
  6type IVisitor interface {
  7	Enter(n INode) IVisitor
  8	Exit(n INode)
  9}
 10
 11// Walk traverses an AST in depth-first order
 12func Walk(v IVisitor, n INode) {
 13	if n == nil {
 14		return
 15	}
 16
 17	if v = v.Enter(n); v == nil {
 18		return
 19	}
 20
 21	defer v.Exit(n)
 22
 23	switch n := n.(type) {
 24	case *AST:
 25		Walk(v, &n.BlockStmt)
 26	case *Var:
 27		return
 28	case *BlockStmt:
 29		if n.List != nil {
 30			for i := 0; i < len(n.List); i++ {
 31				Walk(v, n.List[i])
 32			}
 33		}
 34	case *EmptyStmt:
 35		return
 36	case *ExprStmt:
 37		Walk(v, n.Value)
 38	case *IfStmt:
 39		Walk(v, n.Body)
 40		Walk(v, n.Else)
 41		Walk(v, n.Cond)
 42	case *DoWhileStmt:
 43		Walk(v, n.Body)
 44		Walk(v, n.Cond)
 45	case *WhileStmt:
 46		Walk(v, n.Body)
 47		Walk(v, n.Cond)
 48	case *ForStmt:
 49		if n.Body != nil {
 50			Walk(v, n.Body)
 51		}
 52
 53		Walk(v, n.Init)
 54		Walk(v, n.Cond)
 55		Walk(v, n.Post)
 56	case *ForInStmt:
 57		if n.Body != nil {
 58			Walk(v, n.Body)
 59		}
 60
 61		Walk(v, n.Init)
 62		Walk(v, n.Value)
 63	case *ForOfStmt:
 64		if n.Body != nil {
 65			Walk(v, n.Body)
 66		}
 67
 68		Walk(v, n.Init)
 69		Walk(v, n.Value)
 70	case *CaseClause:
 71		if n.List != nil {
 72			for i := 0; i < len(n.List); i++ {
 73				Walk(v, n.List[i])
 74			}
 75		}
 76
 77		Walk(v, n.Cond)
 78	case *SwitchStmt:
 79		if n.List != nil {
 80			for i := 0; i < len(n.List); i++ {
 81				Walk(v, &n.List[i])
 82			}
 83		}
 84
 85		Walk(v, n.Init)
 86	case *BranchStmt:
 87		return
 88	case *ReturnStmt:
 89		Walk(v, n.Value)
 90	case *WithStmt:
 91		Walk(v, n.Body)
 92		Walk(v, n.Cond)
 93	case *LabelledStmt:
 94		Walk(v, n.Value)
 95	case *ThrowStmt:
 96		Walk(v, n.Value)
 97	case *TryStmt:
 98		if n.Body != nil {
 99			Walk(v, n.Body)
100		}
101
102		if n.Catch != nil {
103			Walk(v, n.Catch)
104		}
105
106		if n.Finally != nil {
107			Walk(v, n.Finally)
108		}
109
110		Walk(v, n.Binding)
111	case *DebuggerStmt:
112		return
113	case *Alias:
114		return
115	case *ImportStmt:
116		if n.List != nil {
117			for i := 0; i < len(n.List); i++ {
118				Walk(v, &n.List[i])
119			}
120		}
121	case *ExportStmt:
122		if n.List != nil {
123			for i := 0; i < len(n.List); i++ {
124				Walk(v, &n.List[i])
125			}
126		}
127
128		Walk(v, n.Decl)
129	case *DirectivePrologueStmt:
130		return
131	case *PropertyName:
132		Walk(v, &n.Literal)
133		Walk(v, n.Computed)
134	case *BindingArray:
135		if n.List != nil {
136			for i := 0; i < len(n.List); i++ {
137				Walk(v, &n.List[i])
138			}
139		}
140
141		Walk(v, n.Rest)
142	case *BindingObjectItem:
143		if n.Key != nil {
144			Walk(v, n.Key)
145		}
146
147		Walk(v, &n.Value)
148	case *BindingObject:
149		if n.List != nil {
150			for i := 0; i < len(n.List); i++ {
151				Walk(v, &n.List[i])
152			}
153		}
154
155		if n.Rest != nil {
156			Walk(v, n.Rest)
157		}
158	case *BindingElement:
159		Walk(v, n.Binding)
160		Walk(v, n.Default)
161	case *VarDecl:
162		if n.List != nil {
163			for i := 0; i < len(n.List); i++ {
164				Walk(v, &n.List[i])
165			}
166		}
167	case *Params:
168		if n.List != nil {
169			for i := 0; i < len(n.List); i++ {
170				Walk(v, &n.List[i])
171			}
172		}
173
174		Walk(v, n.Rest)
175	case *FuncDecl:
176		Walk(v, &n.Body)
177		Walk(v, &n.Params)
178
179		if n.Name != nil {
180			Walk(v, n.Name)
181		}
182	case *MethodDecl:
183		Walk(v, &n.Body)
184		Walk(v, &n.Params)
185		Walk(v, &n.Name)
186	case *Field:
187		Walk(v, &n.Name)
188		Walk(v, n.Init)
189	case *ClassDecl:
190		if n.Name != nil {
191			Walk(v, n.Name)
192		}
193
194		Walk(v, n.Extends)
195
196		for _, item := range n.List {
197			if item.StaticBlock != nil {
198				Walk(v, item.StaticBlock)
199			} else if item.Method != nil {
200				Walk(v, item.Method)
201			} else {
202				Walk(v, &item.Field)
203			}
204		}
205	case *LiteralExpr:
206		return
207	case *Element:
208		Walk(v, n.Value)
209	case *ArrayExpr:
210		if n.List != nil {
211			for i := 0; i < len(n.List); i++ {
212				Walk(v, &n.List[i])
213			}
214		}
215	case *Property:
216		if n.Name != nil {
217			Walk(v, n.Name)
218		}
219
220		Walk(v, n.Value)
221		Walk(v, n.Init)
222	case *ObjectExpr:
223		if n.List != nil {
224			for i := 0; i < len(n.List); i++ {
225				Walk(v, &n.List[i])
226			}
227		}
228	case *TemplatePart:
229		Walk(v, n.Expr)
230	case *TemplateExpr:
231		if n.List != nil {
232			for i := 0; i < len(n.List); i++ {
233				Walk(v, &n.List[i])
234			}
235		}
236
237		Walk(v, n.Tag)
238	case *GroupExpr:
239		Walk(v, n.X)
240	case *IndexExpr:
241		Walk(v, n.X)
242		Walk(v, n.Y)
243	case *DotExpr:
244		Walk(v, n.X)
245		Walk(v, &n.Y)
246	case *NewTargetExpr:
247		return
248	case *ImportMetaExpr:
249		return
250	case *Arg:
251		Walk(v, n.Value)
252	case *Args:
253		if n.List != nil {
254			for i := 0; i < len(n.List); i++ {
255				Walk(v, &n.List[i])
256			}
257		}
258	case *NewExpr:
259		if n.Args != nil {
260			Walk(v, n.Args)
261		}
262
263		Walk(v, n.X)
264	case *CallExpr:
265		Walk(v, &n.Args)
266		Walk(v, n.X)
267	case *UnaryExpr:
268		Walk(v, n.X)
269	case *BinaryExpr:
270		Walk(v, n.X)
271		Walk(v, n.Y)
272	case *CondExpr:
273		Walk(v, n.Cond)
274		Walk(v, n.X)
275		Walk(v, n.Y)
276	case *YieldExpr:
277		Walk(v, n.X)
278	case *ArrowFunc:
279		Walk(v, &n.Body)
280		Walk(v, &n.Params)
281	case *CommaExpr:
282		for _, item := range n.List {
283			Walk(v, item)
284		}
285	default:
286		return
287	}
288}