Support for skipping generated files.

Use `nit -skip-generated <pkgs>`

break_comments.go

@@ -3,27 +3,36 @@ package nit
 import (
 	"go/ast"
 	"go/token"
+	"regexp"
 	"strings"
 )
 
 type (
 	// BreakComments defines all the found break-like comments in the file.
 	BreakComments struct {
-		index    int
-		comments []int
+		index         int
+		comments      []int
+		generatedFile bool
 	}
 )
 
 const (
-	breakComment = "//-"
+	breakComment  = "//-"
+	generatedFile = `^// Code generated .* DO NOT EDIT\.$`
 )
 
 // NewBreakComments returns all the valid break-like comments.
 func NewBreakComments(fset *token.FileSet, comments []*ast.CommentGroup) *BreakComments {
 	r := BreakComments{}
 
+	re, _ := regexp.Compile(generatedFile)
+
 	for _, c := range comments {
 		for _, c1 := range c.List {
+			if re.MatchString(c1.Text) {
+				r.generatedFile = true
+			}
+
 			if strings.HasPrefix(c1.Text, breakComment) {
 				position := fset.PositionFor(c1.Pos(), false)
 				if position.Column == 1 || position.Column == 2 { // left most either nested or not nested group declarations
@@ -35,6 +44,12 @@ func NewBreakComments(fset *token.FileSet, comments []*ast.CommentGroup) *BreakC
 	return &r
 }
 
+// HasGeneratedCode indicates whether the current file contains a "code
+// generated expression".
+func (c *BreakComments) HasGeneratedCode() bool {
+	return c.generatedFile
+}
+
 // Moves current line cursor to the received line.
 func (c *BreakComments) MoveTo(line int) {
 	if c.index >= len(c.comments) {

break_comments_test.go

@@ -10,14 +10,22 @@ import (
 
 func TestBreakComments(t *testing.T) {
 	tests := [...]struct {
-		name     string
-		filename string
-		expected []int
+		name                  string
+		filename              string
+		expected              []int
+		expectedCodegenerated bool
 	}{
 		{
 			"OK",
 			"break_comments1.go",
 			[]int{8, 13, 19},
+			false,
+		},
+		{
+			"OK: code generated",
+			"break_comments2.go",
+			nil,
+			true,
 		},
 	}
 
@@ -40,6 +48,9 @@ func TestBreakComments(t *testing.T) {
 			if !cmp.Equal(tt.expected, actual) {
 				ts.Errorf("expected values do not match: %s", cmp.Diff(tt.expected, actual))
 			}
+			if tt.expectedCodegenerated != bc.HasGeneratedCode() {
+				ts.Errorf("expected %t, got %t", tt.expectedCodegenerated, bc.HasGeneratedCode())
+			}
 		})
 	}
 }

cmd/nit/main.go

@@ -27,17 +27,19 @@ func main() {
 	//-
 
 	localPkg := flag.String("pkg", "", "local package")
+	skipGenerated := flag.Bool("skip-generated", false, "skip generated files")
 	showVersion := flag.Bool("version", false, "prints current version information")
 
 	flag.Parse()
 
 	if *showVersion {
-		fmt.Printf("%v, commit %v, built at %v", version, commit, date)
+		fmt.Printf("%v, commit %v, built at %v\n", version, commit, date)
 		os.Exit(0)
 	}
 
 	if len(flag.Args()) == 0 {
-		fmt.Println("missing packages")
+		fmt.Println("missing `pkg` argument.")
+		flag.Usage()
 		os.Exit(1)
 	}
 
@@ -52,7 +54,10 @@ func main() {
 
 		for _, f := range p.GoFiles {
 			fullpath := filepath.Join(p.Dir, f)
-			v := nit.Nitpicker{LocalPath: *localPkg}
+			v := nit.Nitpicker{
+				LocalPath:         *localPkg,
+				SkipGeneratedFile: *skipGenerated,
+			}
 			if err := v.Validate(fullpath); err != nil {
 				failed = true
 				fmt.Println(err)

nitpicking.go

@@ -11,7 +11,9 @@ import (
 type (
 	// Nitpicker defines the linter.
 	Nitpicker struct {
-		LocalPath  string
+		LocalPath         string
+		SkipGeneratedFile bool
+		//-
 		fset       *token.FileSet
 		fsm        *FileSectionMachine
 		comments   *BreakComments
@@ -30,6 +32,9 @@ func (v *Nitpicker) Validate(filename string) error {
 	}
 
 	v.comments = NewBreakComments(v.fset, f.Comments)
+	if v.comments.HasGeneratedCode() && v.SkipGeneratedFile {
+		return nil
+	}
 
 	for _, s := range f.Decls {
 		// fmt.Printf("%d == %T - %+v -- %t\n", v.fset.PositionFor(s.Pos(), false).Line, s, s, s.End().IsValid())