1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
package rule
import (
"fmt"
"go/ast"
"go/token"
"github.com/mgechev/revive/lint"
)
// Based on https://github.com/fzipp/gocyclo
// CyclomaticRule lints given else constructs.
type CyclomaticRule struct{}
// Apply applies the rule to given file.
func (r *CyclomaticRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
var failures []lint.Failure
complexity, ok := arguments[0].(int64) // Alt. non panicking version
if !ok {
panic("invalid argument for cyclomatic complexity")
}
fileAst := file.AST
walker := lintCyclomatic{
file: file,
complexity: int(complexity),
onFailure: func(failure lint.Failure) {
failures = append(failures, failure)
},
}
ast.Walk(walker, fileAst)
return failures
}
// Name returns the rule name.
func (r *CyclomaticRule) Name() string {
return "cyclomatic"
}
type lintCyclomatic struct {
file *lint.File
complexity int
onFailure func(lint.Failure)
}
func (w lintCyclomatic) Visit(_ ast.Node) ast.Visitor {
f := w.file
for _, decl := range f.AST.Decls {
if fn, ok := decl.(*ast.FuncDecl); ok {
c := complexity(fn)
if c > w.complexity {
w.onFailure(lint.Failure{
Confidence: 1,
Category: "maintenance",
Failure: fmt.Sprintf("function %s has cyclomatic complexity %d", funcName(fn), c),
Node: fn,
})
}
}
}
return nil
}
// funcName returns the name representation of a function or method:
// "(Type).Name" for methods or simply "Name" for functions.
func funcName(fn *ast.FuncDecl) string {
if fn.Recv != nil {
if fn.Recv.NumFields() > 0 {
typ := fn.Recv.List[0].Type
return fmt.Sprintf("(%s).%s", recvString(typ), fn.Name)
}
}
return fn.Name.Name
}
// recvString returns a string representation of recv of the
// form "T", "*T", or "BADRECV" (if not a proper receiver type).
func recvString(recv ast.Expr) string {
switch t := recv.(type) {
case *ast.Ident:
return t.Name
case *ast.StarExpr:
return "*" + recvString(t.X)
}
return "BADRECV"
}
// complexity calculates the cyclomatic complexity of a function.
func complexity(fn *ast.FuncDecl) int {
v := complexityVisitor{}
ast.Walk(&v, fn)
return v.Complexity
}
type complexityVisitor struct {
// Complexity is the cyclomatic complexity
Complexity int
}
// Visit implements the ast.Visitor interface.
func (v *complexityVisitor) Visit(n ast.Node) ast.Visitor {
switch n := n.(type) {
case *ast.FuncDecl, *ast.IfStmt, *ast.ForStmt, *ast.RangeStmt, *ast.CaseClause, *ast.CommClause:
v.Complexity++
case *ast.BinaryExpr:
if n.Op == token.LAND || n.Op == token.LOR {
v.Complexity++
}
}
return v
}
|
