router/pathtree: support a required path segment prefix before :wildcardsv1.4.0

1 files changed, 10 insertions, 7 deletions

diff --git a/router.go b/router.go
index d45a7de..7cf3142 100644
--- a/router.go
+++ b/router.go
@@ -2,6 +2,7 @@ package sliderule
 
 import (
 	"context"
+	"path"
 	"strings"
 
 	"tildegit.org/tjp/sliderule/internal"
@@ -10,9 +11,11 @@ import (
 // Router stores a mapping of request path patterns to handlers.
 //
 // Pattern may begin with "/" and then contain slash-delimited segments.
-//   - Segments beginning with colon (:) are wildcards and will match any path
+//   - Segments containing a colon (:) are wildcards and will match any path
 //     segment at that location. It may optionally have a word after the colon,
-//     which will be the parameter name the path segment is captured into.
+//     which will be the parameter name the path segment is captured into. It
+//     may also optionally have text before the colon, in which case the pattern
+//     will not match unless the request path segment contains that prefix.
 //   - Segments beginning with asterisk (*) are remainder wildcards. This must
 //     come last and will capture any remainder of the path. It may have a name
 //     after the asterisk which will be the parameter name.
@@ -50,7 +53,7 @@ func (r Router) Handle(ctx context.Context, request *Request) *Response {
 		return nil
 	}
 
-	return handler.Handle(context.WithValue(ctx, routeParamsKey, params), request)
+	return handler.Handle(context.WithValue(ctx, RouteParamsKey, params), request)
 }
 
 // Handler builds a Handler
@@ -83,8 +86,8 @@ func (r *Router) Mount(prefix string, subrouter *Router) {
 	prefix = strings.TrimSuffix(prefix, "/")
 
 	for _, subroute := range subrouter.tree.Routes() {
-		r.Route(prefix+"/"+subroute.Pattern, subroute.Value)
-		if subroute.Pattern == "" {
+		r.Route(path.Join(prefix, subroute.Pattern), subroute.Value)
+		if subroute.Pattern == "/" {
 			r.Route(prefix, subroute.Value)
 		}
 	}
@@ -111,7 +114,7 @@ func (r *Router) Use(mw Middleware) {
 // If Router was used but no parameters were captured in the pattern, it
 // returns a non-nil empty map.
 func RouteParams(ctx context.Context) map[string]string {
-	if m, ok := ctx.Value(routeParamsKey).(map[string]string); ok {
+	if m, ok := ctx.Value(RouteParamsKey).(map[string]string); ok {
 		return m
 	}
 	return nil
@@ -119,4 +122,4 @@ func RouteParams(ctx context.Context) map[string]string {
 
 type routeParamsKeyType struct{}
 
-var routeParamsKey = routeParamsKeyType{}
+var RouteParamsKey = routeParamsKeyType{}