Rewrite: Use middleware.Replacer.

Bug fix for regexps starting with '/'.

middleware/replacer.go

@@ -3,6 +3,7 @@ package middleware
 import (
 	"net"
 	"net/http"
+	"path"
 	"strconv"
 	"strings"
 	"time"
@@ -40,6 +41,7 @@ func NewReplacer(r *http.Request, rr *responseRecorder, emptyValue string) Repla
 			"{host}":     r.Host,
 			"{path}":     r.URL.Path,
 			"{query}":    r.URL.RawQuery,
+			"{frag}":     r.URL.Fragment,
 			"{fragment}": r.URL.Fragment,
 			"{proto}":    r.Proto,
 			"{remote}": func() string {
@@ -63,6 +65,14 @@ func NewReplacer(r *http.Request, rr *responseRecorder, emptyValue string) Repla
 			"{when}": func() string {
 				return time.Now().Format(timeFormat)
 			}(),
+			"{file}": func() string {
+				_, file := path.Split(r.URL.Path)
+				return file
+			}(),
+			"{dir}": func() string {
+				dir, _ := path.Split(r.URL.Path)
+				return dir
+			}(),
 		},
 		emptyValue: emptyValue,
 	}

middleware/rewrite/rewrite.go

@@ -3,9 +3,8 @@
 package rewrite
 
 import (
-	"net/http"
-
 	"fmt"
+	"net/http"
 	"net/url"
 	"path"
 	"path/filepath"
@@ -96,15 +95,6 @@ func NewRegexpRule(base, pattern, to string, ext []string) (*RegexpRule, error)
 	}, nil
 }
 
-// regexpVars are variables that can be used for To (rewrite destination path).
-var regexpVars = []string{
-	"{path}",
-	"{query}",
-	"{file}",
-	"{dir}",
-	"{frag}",
-}
-
 // Rewrite rewrites the internal location of the current request.
 func (r *RegexpRule) Rewrite(req *http.Request) bool {
 	rPath := req.URL.Path
@@ -119,32 +109,19 @@ func (r *RegexpRule) Rewrite(req *http.Request) bool {
 		return false
 	}
 
+	// include trailing slash in regexp if present
+	start := len(r.Base)
+	if strings.HasSuffix(r.Base, "/") {
+		start -= 1
+	}
+
 	// validate regexp
-	if !r.MatchString(rPath[len(r.Base):]) {
+	if !r.MatchString(rPath[start:]) {
 		return false
 	}
 
-	to := r.To
-
-	// check variables
-	for _, v := range regexpVars {
-		if strings.Contains(r.To, v) {
-			switch v {
-			case "{path}":
-				to = strings.Replace(to, v, req.URL.Path[1:], -1)
-			case "{query}":
-				to = strings.Replace(to, v, req.URL.RawQuery, -1)
-			case "{frag}":
-				to = strings.Replace(to, v, req.URL.Fragment, -1)
-			case "{file}":
-				_, file := path.Split(req.URL.Path)
-				to = strings.Replace(to, v, file, -1)
-			case "{dir}":
-				dir, _ := path.Split(req.URL.Path)
-				to = path.Clean(strings.Replace(to, v, dir, -1))
-			}
-		}
-	}
+	// replace variables
+	to := path.Clean(middleware.NewReplacer(req, nil, "").Replace(r.To))
 
 	// validate resulting path
 	url, err := url.Parse(to)