Use isGenerated from golang/lint

scanner/generated.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// Taken from https://github.com/golang/lint/blob/85993ffd0a6cd043291f3f63d45d656d97b165bd/lint.go
+
+// Once https://github.com/golang/go/issues/28089 is implemented (proposal is accepted),
+// this can be replaced with the official implementation.
+
+package scanner
+
+import (
+	"bufio"
+	"bytes"
+)
+
+var (
+	genHdr = []byte("// Code generated ")
+	genFtr = []byte(" DO NOT EDIT.")
+)
+
+// isGenerated reports whether the source file is generated code
+// according the rules from https://golang.org/s/generatedcode.
+//
+func isGenerated(src []byte) bool {
+	sc := bufio.NewScanner(bytes.NewReader(src))
+	for sc.Scan() {
+		b := sc.Bytes()
+		if bytes.HasPrefix(b, genHdr) && bytes.HasSuffix(b, genFtr) && len(b) >= len(genHdr)+len(genFtr) {
+			return true
+		}
+	}
+	return false
+}

scanner/generated_test.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2013 The Go Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd.
+
+// Taken from https://github.com/golang/lint/blob/85993ffd0a6cd043291f3f63d45d656d97b165bd/lint_test.go
+
+package scanner
+
+import "testing"
+
+func TestIsGenerated(t *testing.T) {
+	tests := []struct {
+		source    string
+		generated bool
+	}{
+		{"// Code Generated by some tool. DO NOT EDIT.", false},
+		{"// Code generated by some tool. DO NOT EDIT.", true},
+		{"// Code generated by some tool. DO NOT EDIT", false},
+		{"// Code generated  DO NOT EDIT.", true},
+		{"// Code generated DO NOT EDIT.", false},
+		{"\t\t// Code generated by some tool. DO NOT EDIT.\npackage foo\n", false},
+		{"// Code generated by some tool. DO NOT EDIT.\npackage foo\n", true},
+		{"package foo\n// Code generated by some tool. DO NOT EDIT.\ntype foo int\n", true},
+		{"package foo\n // Code generated by some tool. DO NOT EDIT.\ntype foo int\n", false},
+		{"package foo\n// Code generated by some tool. DO NOT EDIT. \ntype foo int\n", false},
+		{"package foo\ntype foo int\n// Code generated by some tool. DO NOT EDIT.\n", true},
+		{"package foo\ntype foo int\n// Code generated by some tool. DO NOT EDIT.", true},
+	}
+
+	for i, test := range tests {
+		got := isGenerated([]byte(test.source))
+		if got != test.generated {
+			t.Errorf("test %d, isGenerated() = %v, want %v", i, got, test.generated)
+		}
+	}
+}

scanner/scanner.go

@@ -8,7 +8,6 @@ import (
 	"go/token"
 	"go/types"
 	"os"
-	"regexp"
 
 	"github.com/dave/astrid"
 	"github.com/dave/brenda"
@@ -119,8 +118,6 @@ func (c *CodeMap) ScanPackages() error {
 	return nil
 }
 
-var doNotEditRe = regexp.MustCompile(`(?m)^// Code generated .* DO NOT EDIT\.$`)
-
 // ScanPackage scans a single package
 func (p *PackageMap) ScanPackage() error {
 	for _, f := range p.pkg.Syntax {
@@ -141,7 +138,7 @@ func (p *PackageMap) ScanPackage() error {
 		if err != nil {
 			return errors.WithStack(err)
 		}
-		if !doNotEditRe.Match(body) {
+		if !isGenerated(body) {
 			continue
 		}
 		for i := range bytes.Split(body, []byte("\n")) {