add better generate

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

vendor/github.com/docker/distribution/cmd/registry-api-descriptor-template/main.go

@@ -0,0 +1,131 @@
+// registry-api-descriptor-template uses the APIDescriptor defined in the
+// api/v2 package to execute templates passed to the command line.
+//
+// For example, to generate a new API specification, one would execute the
+// following command from the repo root:
+//
+// 	$ registry-api-descriptor-template docs/spec/api.md.tmpl > docs/spec/api.md
+//
+// The templates are passed in the api/v2.APIDescriptor object. Please see the
+// package documentation for fields available on that object. The template
+// syntax is from Go's standard library text/template package. For information
+// on Go's template syntax, please see golang.org/pkg/text/template.
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"regexp"
+	"text/template"
+
+	"github.com/docker/distribution/registry/api/errcode"
+	"github.com/docker/distribution/registry/api/v2"
+)
+
+var spaceRegex = regexp.MustCompile(`\n\s*`)
+
+func main() {
+
+	if len(os.Args) != 2 {
+		log.Fatalln("please specify a template to execute.")
+	}
+
+	path := os.Args[1]
+	filename := filepath.Base(path)
+
+	funcMap := template.FuncMap{
+		"removenewlines": func(s string) string {
+			return spaceRegex.ReplaceAllString(s, " ")
+		},
+		"statustext":    http.StatusText,
+		"prettygorilla": prettyGorillaMuxPath,
+	}
+
+	tmpl := template.Must(template.New(filename).Funcs(funcMap).ParseFiles(path))
+
+	data := struct {
+		RouteDescriptors []v2.RouteDescriptor
+		ErrorDescriptors []errcode.ErrorDescriptor
+	}{
+		RouteDescriptors: v2.APIDescriptor.RouteDescriptors,
+		ErrorDescriptors: append(errcode.GetErrorCodeGroup("registry.api.v2"),
+			// The following are part of the specification but provided by errcode default.
+			errcode.ErrorCodeUnauthorized.Descriptor(),
+			errcode.ErrorCodeDenied.Descriptor(),
+			errcode.ErrorCodeUnsupported.Descriptor()),
+	}
+
+	if err := tmpl.Execute(os.Stdout, data); err != nil {
+		log.Fatalln(err)
+	}
+}
+
+// prettyGorillaMuxPath removes the regular expressions from a gorilla/mux
+// route string, making it suitable for documentation.
+func prettyGorillaMuxPath(s string) string {
+	// Stateful parser that removes regular expressions from gorilla
+	// routes. It correctly handles balanced bracket pairs.
+
+	var output string
+	var label string
+	var level int
+
+start:
+	if s[0] == '{' {
+		s = s[1:]
+		level++
+		goto capture
+	}
+
+	output += string(s[0])
+	s = s[1:]
+
+	goto end
+capture:
+	switch s[0] {
+	case '{':
+		level++
+	case '}':
+		level--
+
+		if level == 0 {
+			s = s[1:]
+			goto label
+		}
+	case ':':
+		s = s[1:]
+		goto skip
+	default:
+		label += string(s[0])
+	}
+	s = s[1:]
+	goto capture
+skip:
+	switch s[0] {
+	case '{':
+		level++
+	case '}':
+		level--
+	}
+	s = s[1:]
+
+	if level == 0 {
+		goto label
+	}
+
+	goto skip
+label:
+	if label != "" {
+		output += "<" + label + ">"
+		label = ""
+	}
+end:
+	if s != "" {
+		goto start
+	}
+
+	return output
+
+}