go/doc: use regexp for -notes instead of comma-sep. list

-notes="BUG|TODO" instead of -notes="BUG,TODO".
Permits -notes=".*" to see all notes.

R=cnicolaou
CC=golang-dev
https://golang.org/cl/7951043

src/cmd/godoc/doc.go

@@ -67,6 +67,9 @@ The flags are:
 	-maxresults=10000
 		maximum number of full text search results shown
 		(no full text index is built if maxresults <= 0)
+	-notes="BUG"
+		regular expression matching note markers to show
+		(e.g., "BUG|TODO", ".*")
 	-html
 		print HTML in command-line mode
 	-goroot=$GOROOT

src/cmd/godoc/godoc.go

@@ -84,15 +84,11 @@ var (
 	cmdHandler docServer
 	pkgHandler docServer
 
-	// which code 'Notes' to show
-	notes = flag.String("notes", "BUG", "comma separated list of Note markers as per pkg:go/doc")
-	// list of 'Notes' to show
-	notesToShow []string
+	// source code notes
+	notes = flag.String("notes", "BUG", "regular expression matching note markers to show")
 )
 
 func initHandlers() {
-	notesToShow = strings.Split(*notes, ",")
-
 	fileServer = http.FileServer(&httpFS{fs})
 	cmdHandler = docServer{"/cmd/", "/src/cmd"}
 	pkgHandler = docServer{"/pkg/", "/src/pkg"}
@@ -1100,13 +1096,18 @@ func (h *docServer) getPageInfo(abspath, relpath string, mode PageInfoMode) (inf
 
 			// collect any notes that we want to show
 			if info.PDoc.Notes != nil {
+				// could regexp.Compile only once per godoc, but probably not worth it
+				if rx, err := regexp.Compile(*notes); err == nil {
+					for m, n := range info.PDoc.Notes {
+						if rx.MatchString(m) {
+							if info.Notes == nil {
 								info.Notes = make(map[string][]*doc.Note)
-				for _, m := range notesToShow {
-					if n := info.PDoc.Notes[m]; n != nil {
+							}
 							info.Notes[m] = n
 						}
 					}
 				}
+			}
 
 		} else {
 			// show source code