wip

examples/app/go.mod

@@ -2,6 +2,9 @@ module github.com/markbates/pkger/examples/app
 
 go 1.13
 
-require github.com/markbates/pkger v0.0.0
+require (
+	github.com/gobuffalo/buffalo v0.14.10
+	github.com/markbates/pkger v0.0.0
+)
 
 replace github.com/markbates/pkger => ../../

examples/app/main.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 
+	_ "github.com/gobuffalo/buffalo"
 	"github.com/markbates/pkger"
 )
 
@@ -24,7 +25,7 @@ func main() {
 
 	fmt.Printf("Walking files for %s\n", current.ImportPath)
 	// walk the files in this module. "/" is where the `go.mod` for this module is
-	err = pkger.Walk("github.com/markbates/pkger/examples/app:/", func(path string, info os.FileInfo, err error) error {
+	err = pkger.Walk("/", func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}

go.mod

@@ -4,5 +4,6 @@ go 1.13
 
 require (
 	github.com/markbates/errx v1.1.0
+	github.com/markbates/oncer v1.0.0
 	github.com/stretchr/testify v1.4.0
 )

go.sum

@@ -1,10 +1,15 @@
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/markbates/errx v1.1.0 h1:QDFeR+UP95dO12JgW+tgi2UVfo0V8YBHiUIOaeBPiEI=
 github.com/markbates/errx v1.1.0/go.mod h1:PLa46Oex9KNbVDZhKel8v1OT7hD5JZ2eI7AHhA0wswc=
+github.com/markbates/oncer v1.0.0 h1:E83IaVAHygyndzPimgUYJjbshhDTALZyXxvk9FOlQRY=
+github.com/markbates/oncer v1.0.0/go.mod h1:Z59JA581E9GP6w96jai+TGqafHPW+cPfRxz2aSZ0mcI=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=

parser/parser.go

@@ -2,12 +2,11 @@ package parser
 
 import (
 	"fmt"
+	"go/parser"
+	"go/token"
 	"os"
-	"path/filepath"
-	"sort"
-	"strings"
 
-	"github.com/markbates/pkger"
+	"github.com/markbates/oncer"
 	"github.com/markbates/pkger/here"
 	"github.com/markbates/pkger/pkging"
 )
@@ -16,165 +15,117 @@ var DefaultIgnoredFolders = []string{".", "_", "vendor", "node_modules", "_fixtu
 
 func Parse(her here.Info) (Results, error) {
 	var r Results
+	var err error
 
-	name := her.ImportPath
+	oncer.Do(her.ImportPath, func() {
-
+		pwd, err := os.Getwd()
-	pt, err := pkger.Parse(name)
 		if err != nil {
-		return r, err
+			return
 		}
-	r.Path = pt
+		defer os.Chdir(pwd)
 
-	m := map[pkging.Path]bool{}
+		fmt.Println("cd: ", her.Dir, her.ImportPath)
+		os.Chdir(her.Dir)
 
-	root := r.Path.Name
+		// 1. search for .go files in/imported by `her.ImportPath`
-	if !strings.HasPrefix(root, string(filepath.Separator)) {
+		src, err := fromSource(her)
-		root = string(filepath.Separator) + root
-	}
-
-	if !strings.HasPrefix(root, her.Dir) {
-		root = filepath.Join(her.Dir, root)
-	}
-
-	err = filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
-			return err
+			return
 		}
+		fmt.Println(">>>TODO parser/parser.go:30: src ", src)
 
-		base := filepath.Base(path)
+		// 2. parse .go ast's for `pkger.*` calls
-
+		// 3. find path's in those files
-		for _, ig := range DefaultIgnoredFolders {
+		// 4. walk folders in those paths and add to results
-			if strings.HasPrefix(base, ig) {
-				if info.IsDir() {
-					return filepath.SkipDir
-				}
-				return nil
-			}
-		}
-		if info.IsDir() {
-			if _, err := os.Stat(filepath.Join(path, "go.mod")); err == nil {
-				her, err = here.Dir(path)
-				if err != nil {
-					return err
-				}
-			}
-			n := fmt.Sprintf("%s:%s", her.ImportPath, strings.TrimPrefix(path, her.Dir))
-			pt, err := pkger.Parse(n)
-			if err != nil {
-				return err
-			}
-
-			m[pt] = true
-			return nil
-		}
-
-		ext := filepath.Ext(path)
-		if ext != ".go" {
-			return nil
-		}
-
-		v, err := newVisitor(path, her)
-		if err != nil {
-			return err
-		}
-
-		found, err := v.Run()
-		if err != nil {
-			return err
-		}
-
-		for _, p := range found {
-			if p.Pkg == "." {
-				p.Pkg = her.ImportPath
-			}
-			if _, ok := m[p]; ok {
-				continue
-			}
-
-			m[p] = true
-			found, err := sourceFiles(p)
-			if err != nil {
-				return err
-			}
-			for _, pf := range found {
-				pf.Pkg = p.Pkg
-				m[pf] = true
-			}
-		}
-
-		return nil
 	})
 
-	var found []pkging.Path
-
-	for k := range m {
-		if len(k.String()) == 0 {
-			continue
-		}
-		found = append(found, k)
-	}
-	sort.Slice(found, func(a, b int) bool {
-		return found[a].String() <= found[b].String()
-	})
-	r.Paths = found
-
 	return r, err
 }
 
-func sourceFiles(pt pkging.Path) ([]pkging.Path, error) {
+func fromSource(her here.Info) ([]pkging.Path, error) {
-	var res []pkging.Path
+	fmt.Println(">>>TODO parser/parser.go:201: her.ImportPath ", her.ImportPath)
-
+	fmt.Println(her)
-	her, err := pkger.Info(pt.Pkg)
+	root := her.Dir
-
+	fi, err := os.Stat(root)
 	if err != nil {
-		return res, err
+		return nil, err
-	}
-
-	fp := her.FilePath(pt.Name)
-	fi, err := os.Stat(fp)
-	if err != nil {
-		return res, err
 	}
 	if !fi.IsDir() {
-		return res, nil
+		return nil, fmt.Errorf("%q is not a directory", root)
 	}
 
-	err = filepath.Walk(fp, func(p string, info os.FileInfo, err error) error {
+	fset := token.NewFileSet()
+
+	pkgs, err := parser.ParseDir(fset, root, nil, 0)
 	if err != nil {
-			return err
+		return nil, err
 	}
 
-		base := filepath.Base(p)
+	var paths []pkging.Path
+	for _, pkg := range pkgs {
+		for _, pf := range pkg.Files {
+			f := &file{fset: fset, astFile: pf, filename: pf.Name.Name}
+			f.decls = make(map[string]string)
 
-		if base == "." {
+			x, err := f.find()
-			return nil
+			if err != nil {
+				return nil, err
 			}
-
+			for i, pt := range x {
-		for _, ig := range DefaultIgnoredFolders {
+				if pt.Pkg == "/" || pt.Pkg == "" {
-			if strings.HasPrefix(base, ig) {
+					pt.Pkg = her.ImportPath
-				if info.IsDir() {
+					x[i] = pt
-					return filepath.SkipDir
+				}
+				paths = append(paths, x[i])
 			}
-				return nil
 		}
 	}
 
-		if info.IsDir() {
+	for _, i := range her.Imports {
-			return nil
+		fmt.Println(">>>TODO parser/parser.go:237: i ", i)
 	}
 
-		n := strings.TrimPrefix(p, her.Dir)
+	return paths, nil
-		n = strings.Replace(n, "\\", "/", -1)
-		pt := pkging.Path{
-			Name: n,
-		}
-		res = append(res, pt)
-		return nil
-	})
-	return res, err
-
 }
 
+// func importName(pkg *ast.File) (string, error) {
+// 	var v visitor
+// 	var name string
+// 	var err error
+// 	v = func(node ast.Node) ast.Visitor {
+// 		if node == nil {
+// 			return v
+// 		}
+// 		switch t := node.(type) {
+// 		case *ast.ImportSpec:
+// 			s, err := strconv.Unquote(t.Path.Value)
+// 			if err != nil {
+// 				err = err
+// 				return nil
+// 			}
+// 			if s != "github.com/markbates/pkger" {
+// 				if t.Name == nil {
+// 					name = "pkger"
+// 					return v
+// 				}
+// 			}
+// 		default:
+// 			// fmt.Printf("%#v\n", node)
+// 		}
+// 		return v
+// 	}
+// 	ast.Walk(v, pkg)
+//
+// 	if err != nil {
+// 		return "", err
+// 	}
+//
+// 	if len(name) == 0 {
+// 		return "", io.EOF
+// 	}
+// 	return name, nil
+// }
+
 type Results struct {
 	Paths []pkging.Path
 	Path  pkging.Path

parser/parser_test.go

@@ -1,7 +1,7 @@
 package parser
 
 import (
-	"fmt"
+	"os"
 	"path/filepath"
 	"sort"
 	"testing"
@@ -13,13 +13,17 @@ import (
 func Test_Parser(t *testing.T) {
 	r := require.New(t)
 
-	ch := filepath.Join("..",
+	pwd, err := os.Getwd()
+	r.NoError(err)
+
+	ch := filepath.Join(pwd, "..",
 		"examples",
 		"app")
 	info := here.Info{
 		Dir:        ch,
 		ImportPath: "github.com/markbates/pkger/examples/app",
 	}
+
 	res, err := Parse(info)
 
 	r.NoError(err)
@@ -41,6 +45,6 @@ func Test_Parser(t *testing.T) {
 	}
 
 	sort.Strings(act)
-	fmt.Printf("%#v\n", act)
+	// fmt.Printf("%#v\n", act)
 	r.Equal(exp, act)
 }

parser/visitor.go

@@ -3,298 +3,248 @@ package parser
 import (
 	"fmt"
 	"go/ast"
+	"go/token"
 	"strconv"
-	"strings"
 
 	"github.com/markbates/pkger"
 	"github.com/markbates/pkger/here"
 	"github.com/markbates/pkger/pkging"
 )
 
-type visitor struct {
+type visitor func(node ast.Node) (w ast.Visitor)
-	File   string
+
-	Found  map[pkging.Path]bool
+func (v visitor) Visit(node ast.Node) ast.Visitor {
-	info   here.Info
+	return v(node)
-	errors []error
 }
 
-func newVisitor(p string, info here.Info) (*visitor, error) {
+// inspired by https://gist.github.com/cryptix/d1b129361cea51a59af2
-	return &visitor{
+type file struct {
-		File:  p,
+	fset     *token.FileSet
-		Found: map[pkging.Path]bool{},
+	astFile  *ast.File
-		info:  info,
+	filename string
-	}, nil
+	decls    map[string]string
+	paths    []pkging.Path
 }
 
-func (v *visitor) Run() ([]pkging.Path, error) {
+func (f *file) walk(fn func(ast.Node) bool) {
-	pf, err := parseFile(v.File)
+	ast.Walk(walker(fn), f.astFile)
-	if err != nil {
-		return nil, fmt.Errorf("%s: %v", v.File, err)
-	}
-
-	ast.Walk(v, pf.Ast)
-
-	var found []pkging.Path
-
-	for k := range v.Found {
-		found = append(found, k)
-	}
-
-	return found, nil
 }
 
-func (v *visitor) addPath(p string) error {
+func (f *file) find() ([]pkging.Path, error) {
-	p, _ = strconv.Unquote(p)
+	if err := f.findDecals(); err != nil {
-	pt, err := pkger.Parse(p)
+		return nil, err
-	if err != nil {
-		return err
 	}
-	if strings.HasPrefix(p, ":") {
+	if err := f.findOpenCalls(); err != nil {
-		pt.Pkg = v.info.ImportPath
+		return nil, err
 	}
 
-	v.Found[pt] = true
+	if err := f.findWalkCalls(); err != nil {
+		return nil, err
+	}
+
+	if err := f.findImportCalls(); err != nil {
+		return nil, err
+	}
+
+	return f.paths, nil
+}
+
+func (f *file) findDecals() error {
+	// iterate over all declarations
+	for _, d := range f.astFile.Decls {
+
+		// log.Printf("#%d Decl: %+v\n", i, d)
+
+		// only interested in generic declarations
+		if genDecl, ok := d.(*ast.GenDecl); ok {
+
+			// handle const's and vars
+			if genDecl.Tok == token.CONST || genDecl.Tok == token.VAR {
+
+				// there may be multiple
+				// i.e. const ( ... )
+				for _, cDecl := range genDecl.Specs {
+
+					// havn't find another kind of spec then value but better check
+					if vSpec, ok := cDecl.(*ast.ValueSpec); ok {
+						// log.Printf("const ValueSpec: %+v\n", vSpec)
+
+						// iterate over Name/Value pair
+						for i := 0; i < len(vSpec.Names); i++ {
+							// TODO: only basic literals work currently
+							if i > len(vSpec.Values) || len(vSpec.Values) == 0 {
+								break
+							}
+							switch v := vSpec.Values[i].(type) {
+							case *ast.BasicLit:
+								f.decls[vSpec.Names[i].Name] = v.Value
+							default:
+								// log.Printf("Name: %s - Unsupported ValueSpec: %+v\n", vSpec.Names[i].Name, v)
+							}
+						}
+					}
+				}
+			}
+
+		}
+	}
 
 	return nil
 }
 
-func (v *visitor) Visit(node ast.Node) ast.Visitor {
+func (f *file) findOpenCalls() error {
-	if node == nil {
+	var err error
-		return v
+	f.walk(func(node ast.Node) bool {
-	}
+		ce, ok := node.(*ast.CallExpr)
-	if err := v.eval(node); err != nil {
-		v.errors = append(v.errors, err)
-	}
-
-	return v
-}
-
-func (v *visitor) eval(node ast.Node) error {
-	switch t := node.(type) {
-	case *ast.CallExpr:
-		return v.evalExpr(t)
-	case *ast.Ident:
-		return v.evalIdent(t)
-	case *ast.GenDecl:
-		for _, n := range t.Specs {
-			if err := v.eval(n); err != nil {
-				return err
-			}
-		}
-	case *ast.FuncDecl:
-		if t.Body == nil {
-			return nil
-		}
-		for _, b := range t.Body.List {
-			if err := v.evalStmt(b); err != nil {
-				return err
-			}
-		}
-		return nil
-	case *ast.ValueSpec:
-		for _, e := range t.Values {
-			if err := v.evalExpr(e); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-func (v *visitor) evalStmt(stmt ast.Stmt) error {
-	switch t := stmt.(type) {
-	case *ast.ExprStmt:
-		return v.evalExpr(t.X)
-	case *ast.AssignStmt:
-		for _, e := range t.Rhs {
-			if err := v.evalArgs(e); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-func (v *visitor) evalExpr(expr ast.Expr) error {
-	switch t := expr.(type) {
-	case *ast.CallExpr:
-		if t.Fun == nil {
-			return nil
-		}
-		for _, a := range t.Args {
-			switch at := a.(type) {
-			case *ast.CallExpr:
-				if sel, ok := t.Fun.(*ast.SelectorExpr); ok {
-					return v.evalSelector(at, sel)
-				}
-
-				if err := v.evalArgs(at); err != nil {
-					return err
-				}
-			case *ast.CompositeLit:
-				for _, e := range at.Elts {
-					if err := v.evalExpr(e); err != nil {
-						return err
-					}
-				}
-			}
-		}
-		if ft, ok := t.Fun.(*ast.SelectorExpr); ok {
-			return v.evalSelector(t, ft)
-		}
-	case *ast.KeyValueExpr:
-		return v.evalExpr(t.Value)
-	}
-	return nil
-}
-
-func (v *visitor) evalArgs(expr ast.Expr) error {
-	switch at := expr.(type) {
-	case *ast.CompositeLit:
-		for _, e := range at.Elts {
-			if err := v.evalExpr(e); err != nil {
-				return err
-			}
-		}
-	case *ast.CallExpr:
-		if at.Fun == nil {
-			return nil
-		}
-		switch st := at.Fun.(type) {
-		case *ast.SelectorExpr:
-			if err := v.evalSelector(at, st); err != nil {
-				return err
-			}
-		case *ast.Ident:
-			return v.evalIdent(st)
-		}
-		for _, a := range at.Args {
-			if err := v.evalArgs(a); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-func (v *visitor) evalSelector(expr *ast.CallExpr, sel *ast.SelectorExpr) error {
-	x, ok := sel.X.(*ast.Ident)
 		if !ok {
-		return nil
+			return true
-	}
-	if x.Name == "pkger" {
-		switch sel.Sel.Name {
-		case "Walk":
-			if len(expr.Args) != 2 {
-				return fmt.Errorf("`Walk` requires two arguments")
 		}
 
-			zz := func(e ast.Expr) (string, error) {
+		exists := isPkgDot(ce.Fun, "pkger", "Open")
-				switch at := e.(type) {
+		if !(exists) || len(ce.Args) != 1 {
-				case *ast.Ident:
+			return true
-					switch at.Obj.Kind {
-					case ast.Var:
-						if as, ok := at.Obj.Decl.(*ast.AssignStmt); ok {
-							return v.fromVariable(as)
 		}
-					case ast.Con:
+
-						if vs, ok := at.Obj.Decl.(*ast.ValueSpec); ok {
+		switch x := ce.Args[0].(type) {
-							return v.fromConstant(vs)
+
-						}
-					}
-					return "", v.evalIdent(at)
 		case *ast.BasicLit:
-					return at.Value, nil
+			s, err := strconv.Unquote(x.Value)
-				case *ast.CallExpr:
-					return "", v.evalExpr(at)
-				}
-				return "", fmt.Errorf("can't handle %T", e)
-			}
-
-			k1, err := zz(expr.Args[0])
 			if err != nil {
-				return err
+				err = nil
+				return false
 			}
-			if err := v.addPath(k1); err != nil {
+			pt, err := pkger.Parse(s)
-				return err
+			if err != nil {
+				err = err
+				return false
 			}
-
+			f.paths = append(f.paths, pt)
-			return nil
-		case "Open":
-			for _, e := range expr.Args {
-				switch at := e.(type) {
 		case *ast.Ident:
-					switch at.Obj.Kind {
+			val, ok := f.decls[x.Name]
-					case ast.Var:
+			if !ok {
-						if as, ok := at.Obj.Decl.(*ast.AssignStmt); ok {
+				//TODO: Add ERRORs list to file type and return after iteration!
-							v.addVariable("", as)
+				// log.Printf("Could not find identifier[%s] in decls map\n", x.Name)
+				return true
 			}
-					case ast.Con:
+			s, err := strconv.Unquote(val)
-						if vs, ok := at.Obj.Decl.(*ast.ValueSpec); ok {
-							v.addConstant("", vs)
-						}
-					}
-					return v.evalIdent(at)
-				case *ast.BasicLit:
-					return v.addPath(at.Value)
-				case *ast.CallExpr:
-					return v.evalExpr(at)
-				}
-			}
-		}
-	}
-
-	return nil
-}
-
-func (v *visitor) evalIdent(i *ast.Ident) error {
-	if i.Obj == nil {
-		return nil
-	}
-	if s, ok := i.Obj.Decl.(*ast.AssignStmt); ok {
-		return v.evalStmt(s)
-	}
-	return nil
-}
-
-func (v *visitor) fromVariable(as *ast.AssignStmt) (string, error) {
-	if len(as.Rhs) == 1 {
-		if bs, ok := as.Rhs[0].(*ast.BasicLit); ok {
-			return bs.Value, nil
-		}
-	}
-	return "", fmt.Errorf("unable to find value from variable %v", as)
-}
-
-func (v *visitor) addVariable(bn string, as *ast.AssignStmt) error {
-	bv, err := v.fromVariable(as)
 			if err != nil {
-		return nil
+				err = nil
+				return false
 			}
-	if len(bn) == 0 {
+			pt, err := pkger.Parse(s)
-		bn = bv
+			if err != nil {
+				err = err
+				return false
 			}
-	return v.addPath(bn)
+			f.paths = append(f.paths, pt)
+
+		default:
+		}
+
+		return true
+	})
+	return err
 }
 
-func (v *visitor) fromConstant(vs *ast.ValueSpec) (string, error) {
+func (f *file) findWalkCalls() error {
-	if len(vs.Values) == 1 {
+	var err error
-		if bs, ok := vs.Values[0].(*ast.BasicLit); ok {
+	f.walk(func(node ast.Node) bool {
-			return bs.Value, nil
+		ce, ok := node.(*ast.CallExpr)
+		if !ok {
+			return true
 		}
+
+		exists := isPkgDot(ce.Fun, "pkger", "Walk")
+		if !(exists) || len(ce.Args) != 2 {
+			return true
 		}
-	return "", fmt.Errorf("unable to find value from constant %v", vs)
+
+		switch x := ce.Args[0].(type) {
+
+		case *ast.BasicLit:
+			s, err := strconv.Unquote(x.Value)
+			if err != nil {
+				err = nil
+				return false
+			}
+			pt, err := pkger.Parse(s)
+			if err != nil {
+				err = err
+				return false
+			}
+			f.paths = append(f.paths, pt)
+		case *ast.Ident:
+			val, ok := f.decls[x.Name]
+			if !ok {
+				//TODO: Add ERRORs list to file type and return after iteration!
+				// log.Printf("Could not find identifier[%s] in decls map\n", x.Name)
+				return true
+			}
+			s, err := strconv.Unquote(val)
+			if err != nil {
+				err = nil
+				return false
+			}
+			pt, err := pkger.Parse(s)
+			if err != nil {
+				err = err
+				return false
+			}
+			f.paths = append(f.paths, pt)
+
+		default:
+		}
+
+		return true
+	})
+	return err
 }
 
-func (v *visitor) addConstant(bn string, vs *ast.ValueSpec) error {
+func (f *file) findImportCalls() error {
-	if len(vs.Values) == 1 {
+	var err error
-		if bs, ok := vs.Values[0].(*ast.BasicLit); ok {
+	f.walk(func(node ast.Node) bool {
-			bv := bs.Value
+		ce, ok := node.(*ast.ImportSpec)
-			if len(bn) == 0 {
+		if !ok {
-				bn = bv
+			return true
 		}
-			return v.addPath(bn)
+
+		s, err := strconv.Unquote(ce.Path.Value)
+		if err != nil {
+			return false
 		}
+		info, err := here.Package(s)
+		if err != nil {
+			return false
+		}
+		fmt.Println(">>>TODO parser/visitor.go:216: info ", info)
+		res, err := Parse(info)
+		if err != nil {
+			return false
+		}
+		fmt.Println(">>>TODO parser/visitor.go:224: res ", res)
+		return true
+	})
+	return err
+}
+
+// helpers
+// =======
+func isPkgDot(expr ast.Expr, pkg, name string) bool {
+	sel, ok := expr.(*ast.SelectorExpr)
+	return ok && isIdent(sel.X, pkg) && isIdent(sel.Sel, name)
+}
+
+func isIdent(expr ast.Expr, ident string) bool {
+	id, ok := expr.(*ast.Ident)
+	return ok && id.Name == ident
+}
+
+// wrap a function to fulfill ast.Visitor interface
+type walker func(ast.Node) bool
+
+func (w walker) Visit(node ast.Node) ast.Visitor {
+	if w(node) {
+		return w
 	}
 	return nil
 }