versioned names (#12)

README.md

@@ -64,6 +64,13 @@ err := GetTag(st, "foo").Fill(&tagInfo)
 // tagInfo.Count will be 9
 ```
 
+## Type names
+
+The `TypeName()` function exists to disambiguate between type names that are
+versioned.  `reflect.Type.String()` will hides package versions.  This doesn't
+matter unless you've, unfortunately, imported multiple versions of the same
+package.  
+
 ## Development status
 
 Reflectutils is used by several packages.  Backwards compatability is expected.

internal/foo/foo.go

@@ -0,0 +1,3 @@
+package foo
+
+type Bar struct {}

internal/foo/v2/foo.go

@@ -0,0 +1,3 @@
+package foo
+
+type Bar struct {}

names.go

@@ -0,0 +1,107 @@
+package reflectutils
+
+import (
+	"path"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var versionRE = regexp.MustCompile(`/v(\d+)$`)
+
+// TypeName is an alternative to reflect.Type's .String() method.  The only
+// expected difference is that if there is a package that is versioned, the
+// version will appear in the package name.
+//
+// For example, if there is a foo/v2 package with a Bar type, and you ask
+// for for the TypeName, you'll get "foo/v2.Bar" instead of the "foo.Bar" that
+// reflect returns.
+func TypeName(t reflect.Type) string {
+	ts := t.String()
+	pkgPath := t.PkgPath()
+	if pkgPath != "" {
+		if versionRE.MatchString(pkgPath) {
+			version := path.Base(pkgPath)
+			pn := path.Base(path.Dir(pkgPath))
+			revised := strings.Replace(ts, pn, pn+"/"+version, 1)
+			if revised != ts {
+				return revised
+			}
+			return "(" + version + ")" + ts
+		}
+		return ts
+	}
+	switch t.Kind() { //nolint:exhaustive // not intended to be exhaustive
+	case reflect.Ptr: // TODO: change to Pointer when go 1.17 support lapses
+		return "*" + TypeName(t.Elem())
+	case reflect.Slice:
+		return "[]" + TypeName(t.Elem())
+	case reflect.Map:
+		return "map[" + TypeName(t.Key()) + "]" + TypeName(t.Elem())
+	case reflect.Array:
+		return "[" + strconv.Itoa(t.Len()) + "]" + TypeName(t.Elem())
+	case reflect.Func:
+		return "func" + fmtFunc(t)
+	case reflect.Chan:
+		switch t.ChanDir() {
+		case reflect.BothDir:
+			return "chan " + TypeName(t.Elem())
+		case reflect.SendDir:
+			return "chan<- " + TypeName(t.Elem())
+		case reflect.RecvDir:
+			return "<-chan " + TypeName(t.Elem())
+		default:
+			return ts
+		}
+	case reflect.Struct:
+		if t.NumField() == 0 {
+			return "struct {}"
+		}
+		fields := make([]string, t.NumField())
+		for i := 0; i < t.NumField(); i++ {
+			f := t.Field(i)
+			if f.Anonymous {
+				fields[i] = TypeName(f.Type)
+			} else {
+				fields[i] = f.Name + " " + TypeName(f.Type)
+			}
+		}
+		return "struct { " + strings.Join(fields, "; ") + " }"
+	case reflect.Interface:
+		n := t.Name()
+		if n != "" {
+			return n
+		}
+		if t.NumMethod() == 0 {
+			return "interface {}"
+		}
+		methods := make([]string, t.NumMethod())
+		for i := 0; i < t.NumMethod(); i++ {
+			m := t.Method(i)
+			methods[i] = m.Name + fmtFunc(m.Type)
+		}
+		return "interface { " + strings.Join(methods, "; ") + " }"
+	default:
+		return ts
+	}
+}
+
+func fmtFunc(t reflect.Type) string {
+	inputs := make([]string, t.NumIn())
+	for i := 0; i < t.NumIn(); i++ {
+		inputs[i] = TypeName(t.In(i))
+	}
+	outputs := make([]string, t.NumOut())
+	for i := 0; i < t.NumOut(); i++ {
+		outputs[i] = TypeName(t.Out(i))
+	}
+	switch t.NumOut() {
+	case 0:
+		return "(" + strings.Join(inputs, ", ") + ")"
+	case 1:
+		return "(" + strings.Join(inputs, ", ") + ") " + outputs[0]
+	default:
+		return "(" + strings.Join(inputs, ", ") + ") (" + strings.Join(outputs, ", ") + ")"
+	}
+}

names_test.go

@@ -0,0 +1,119 @@
+package reflectutils
+
+import (
+	"reflect"
+	"testing"
+
+	v1 "github.com/muir/reflectutils/internal/foo"
+	v2 "github.com/muir/reflectutils/internal/foo/v2"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestVersionedNames(t *testing.T) {
+	type xbar struct {
+		v2.Bar
+	}
+	type ybar struct {
+		xbar
+		v1 v1.Bar //nolint:structcheck,unused // unused and we don't care
+	}
+	cases := []struct {
+		thing interface{}
+		want  string
+	}{
+		{
+			thing: v1.Bar{},
+		},
+		{
+			thing: v2.Bar{},
+			want:  "foo/v2.Bar",
+		},
+		{
+			thing: &v1.Bar{},
+			want:  "*foo.Bar",
+		},
+		{
+			thing: &v2.Bar{},
+			want:  "*foo/v2.Bar",
+		},
+		{
+			thing: []v2.Bar{},
+			want:  "[]foo/v2.Bar",
+		},
+		{
+			thing: (func(*v1.Bar, *v2.Bar) (string, error))(nil),
+			want:  "func(*foo.Bar, *foo/v2.Bar) (string, error)",
+		},
+		{
+			thing: [8]v2.Bar{},
+			want:  "[8]foo/v2.Bar",
+		},
+		{
+			thing: make(chan *v2.Bar),
+			want:  "chan *foo/v2.Bar",
+		},
+		{
+			thing: make(chan *v1.Bar),
+			want:  "chan *foo.Bar",
+		},
+		{
+			thing: (chan<- *v1.Bar)(nil),
+			want:  "chan<- *foo.Bar",
+		},
+		{
+			thing: (chan<- *v2.Bar)(nil),
+			want:  "chan<- *foo/v2.Bar",
+		},
+		{
+			thing: (<-chan *v2.Bar)(nil),
+			want:  "<-chan *foo/v2.Bar",
+		},
+		{
+			thing: (<-chan *v1.Bar)(nil),
+			want:  "<-chan *foo.Bar",
+		},
+		{
+			thing: (func(interface {
+				V1() v1.Bar
+				V2() v2.Bar
+			}))(nil),
+			want: "func(interface { V1() foo.Bar; V2() foo/v2.Bar })",
+		},
+		{
+			thing: (func(interface{}))(nil),
+		},
+		{
+			thing: struct {
+				v1 v1.Bar
+				v2 v2.Bar
+			}{},
+			want: "struct { v1 foo.Bar; v2 foo/v2.Bar }",
+		},
+		{
+			thing: struct{}{},
+		},
+		{
+			thing: struct {
+				v2.Bar
+				v1 v1.Bar
+			}{},
+			want: "struct { foo/v2.Bar; v1 foo.Bar }",
+		},
+		{
+			thing: struct {
+				ybar
+			}{},
+			// want: "struct { reflectutils.ybar }",
+		},
+	}
+
+	for _, tc := range cases {
+		want := tc.want
+		if want == "" {
+			want = reflect.TypeOf(tc.thing).String()
+		}
+		t.Logf("%+v wanting %s", tc.thing, want)
+		assert.Equal(t, want, TypeName(reflect.TypeOf(tc.thing)))
+	}
+}