116 lines
2.6 KiB
Go
116 lines
2.6 KiB
Go
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package rule
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import (
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"fmt"
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"go/ast"
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"go/token"
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"github.com/mgechev/revive/lint"
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)
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// Based on https://github.com/fzipp/gocyclo
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// CyclomaticRule lints given else constructs.
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type CyclomaticRule struct{}
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// Apply applies the rule to given file.
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func (r *CyclomaticRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
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var failures []lint.Failure
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complexity, ok := arguments[0].(int64) // Alt. non panicking version
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if !ok {
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panic("invalid argument for cyclomatic complexity")
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}
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fileAst := file.AST
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walker := lintCyclomatic{
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file: file,
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complexity: int(complexity),
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onFailure: func(failure lint.Failure) {
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failures = append(failures, failure)
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},
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}
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ast.Walk(walker, fileAst)
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return failures
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}
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// Name returns the rule name.
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func (r *CyclomaticRule) Name() string {
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return "cyclomatic"
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}
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type lintCyclomatic struct {
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file *lint.File
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complexity int
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onFailure func(lint.Failure)
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}
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func (w lintCyclomatic) Visit(_ ast.Node) ast.Visitor {
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f := w.file
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for _, decl := range f.AST.Decls {
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if fn, ok := decl.(*ast.FuncDecl); ok {
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c := complexity(fn)
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if c > w.complexity {
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w.onFailure(lint.Failure{
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Confidence: 1,
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Category: "maintenance",
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Failure: fmt.Sprintf("function %s has cyclomatic complexity %d", funcName(fn), c),
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Node: fn,
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})
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}
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}
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}
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return nil
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}
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// funcName returns the name representation of a function or method:
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// "(Type).Name" for methods or simply "Name" for functions.
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func funcName(fn *ast.FuncDecl) string {
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if fn.Recv != nil {
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if fn.Recv.NumFields() > 0 {
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typ := fn.Recv.List[0].Type
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return fmt.Sprintf("(%s).%s", recvString(typ), fn.Name)
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}
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}
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return fn.Name.Name
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}
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// recvString returns a string representation of recv of the
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// form "T", "*T", or "BADRECV" (if not a proper receiver type).
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func recvString(recv ast.Expr) string {
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switch t := recv.(type) {
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case *ast.Ident:
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return t.Name
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case *ast.StarExpr:
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return "*" + recvString(t.X)
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}
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return "BADRECV"
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}
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// complexity calculates the cyclomatic complexity of a function.
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func complexity(fn *ast.FuncDecl) int {
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v := complexityVisitor{}
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ast.Walk(&v, fn)
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return v.Complexity
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}
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type complexityVisitor struct {
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// Complexity is the cyclomatic complexity
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Complexity int
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}
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// Visit implements the ast.Visitor interface.
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func (v *complexityVisitor) Visit(n ast.Node) ast.Visitor {
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switch n := n.(type) {
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case *ast.FuncDecl, *ast.IfStmt, *ast.ForStmt, *ast.RangeStmt, *ast.CaseClause, *ast.CommClause:
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v.Complexity++
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case *ast.BinaryExpr:
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if n.Op == token.LAND || n.Op == token.LOR {
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v.Complexity++
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}
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}
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return v
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}
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