NewReplacer takes third argument for empty value string

middleware/log/log.go

@@ -33,7 +33,7 @@ func (l Logger) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 				}
 				status = 0
 			}
-			rep := middleware.NewReplacer(r, responseRecorder)
+			rep := middleware.NewReplacer(r, responseRecorder, CommonLogEmptyValue)
 			rule.Log.Println(rep.Replace(rule.Format))
 			return status, err
 		}
@@ -50,8 +50,9 @@ type Rule struct {
 }
 
 const (
-	DefaultLogFilename = "access.log"
-	CommonLogFormat    = `{remote} ` + middleware.EmptyStringReplacer + ` [{when}] "{method} {uri} {proto}" {status} {size}`
-	CombinedLogFormat  = CommonLogFormat + ` "{>Referer}" "{>User-Agent}"`
-	DefaultLogFormat   = CommonLogFormat
+	DefaultLogFilename  = "access.log"
+	CommonLogFormat     = `{remote} ` + CommonLogEmptyValue + ` [{when}] "{method} {uri} {proto}" {status} {size}`
+	CommonLogEmptyValue = "-"
+	CombinedLogFormat   = CommonLogFormat + ` "{>Referer}" "{>User-Agent}"`
+	DefaultLogFormat    = CommonLogFormat
 )

middleware/proxy/proxy.go

@@ -89,7 +89,7 @@ func (p Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
 					if replacer == nil {
 						rHost := r.Host
 						r.Host = requestHost
-						replacer = middleware.NewReplacer(r, nil)
+						replacer = middleware.NewReplacer(r, nil, "")
 						r.Host = rHost
 					}
 					for header, values := range host.ExtraHeaders {

middleware/replacer.go

@@ -16,57 +16,63 @@ type Replacer interface {
 	Replace(string) string
 }
 
-type replacer map[string]string
+type replacer struct {
+	replacements map[string]string
+	emptyValue   string
+}
 
 // NewReplacer makes a new replacer based on r and rr.
 // Do not create a new replacer until r and rr have all
 // the needed values, because this function copies those
 // values into the replacer.
-func NewReplacer(r *http.Request, rr *responseRecorder) Replacer {
+func NewReplacer(r *http.Request, rr *responseRecorder, emptyValue string) Replacer {
 	rep := replacer{
-		"{method}": r.Method,
-		"{scheme}": func() string {
-			if r.TLS != nil {
-				return "https"
-			}
-			return "http"
-		}(),
-		"{host}":     r.Host,
-		"{path}":     r.URL.Path,
-		"{query}":    r.URL.RawQuery,
-		"{fragment}": r.URL.Fragment,
-		"{proto}":    r.Proto,
-		"{remote}": func() string {
-			if fwdFor := r.Header.Get("X-Forwarded-For"); fwdFor != "" {
-				return fwdFor
-			}
-			host, _, err := net.SplitHostPort(r.RemoteAddr)
-			if err != nil {
-				return r.RemoteAddr
-			}
-			return host
-		}(),
-		"{port}": func() string {
-			_, port, err := net.SplitHostPort(r.RemoteAddr)
-			if err != nil {
-				return ""
-			}
-			return port
-		}(),
-		"{uri}": r.RequestURI,
-		"{when}": func() string {
-			return time.Now().Format(timeFormat)
-		}(),
+		replacements: map[string]string{
+			"{method}": r.Method,
+			"{scheme}": func() string {
+				if r.TLS != nil {
+					return "https"
+				}
+				return "http"
+			}(),
+			"{host}":     r.Host,
+			"{path}":     r.URL.Path,
+			"{query}":    r.URL.RawQuery,
+			"{fragment}": r.URL.Fragment,
+			"{proto}":    r.Proto,
+			"{remote}": func() string {
+				if fwdFor := r.Header.Get("X-Forwarded-For"); fwdFor != "" {
+					return fwdFor
+				}
+				host, _, err := net.SplitHostPort(r.RemoteAddr)
+				if err != nil {
+					return r.RemoteAddr
+				}
+				return host
+			}(),
+			"{port}": func() string {
+				_, port, err := net.SplitHostPort(r.RemoteAddr)
+				if err != nil {
+					return ""
+				}
+				return port
+			}(),
+			"{uri}": r.URL.RequestURI(),
+			"{when}": func() string {
+				return time.Now().Format(timeFormat)
+			}(),
+		},
+		emptyValue: emptyValue,
 	}
 	if rr != nil {
-		rep["{status}"] = strconv.Itoa(rr.status)
-		rep["{size}"] = strconv.Itoa(rr.size)
-		rep["{latency}"] = time.Since(rr.start).String()
+		rep.replacements["{status}"] = strconv.Itoa(rr.status)
+		rep.replacements["{size}"] = strconv.Itoa(rr.size)
+		rep.replacements["{latency}"] = time.Since(rr.start).String()
 	}
 
 	// Header placeholders
 	for header, val := range r.Header {
-		rep[headerReplacer+header+"}"] = strings.Join(val, ",")
+		rep.replacements[headerReplacer+header+"}"] = strings.Join(val, ",")
 	}
 
 	return rep
@@ -75,9 +81,9 @@ func NewReplacer(r *http.Request, rr *responseRecorder) Replacer {
 // Replace performs a replacement of values on s and returns
 // the string with the replaced values.
 func (r replacer) Replace(s string) string {
-	for placeholder, replacement := range r {
+	for placeholder, replacement := range r.replacements {
 		if replacement == "" {
-			replacement = EmptyStringReplacer
+			replacement = r.emptyValue
 		}
 		s = strings.Replace(s, placeholder, replacement, -1)
 	}
@@ -88,7 +94,7 @@ func (r replacer) Replace(s string) string {
 		endOffset := idxStart + len(headerReplacer)
 		idxEnd := strings.Index(s[endOffset:], "}")
 		if idxEnd > -1 {
-			s = s[:idxStart] + EmptyStringReplacer + s[endOffset+idxEnd+1:]
+			s = s[:idxStart] + r.emptyValue + s[endOffset+idxEnd+1:]
 		} else {
 			break
 		}
@@ -97,7 +103,6 @@ func (r replacer) Replace(s string) string {
 }
 
 const (
-	timeFormat          = "02/Jan/2006:15:04:05 -0700"
-	headerReplacer      = "{>"
-	EmptyStringReplacer = "-"
+	timeFormat     = "02/Jan/2006:15:04:05 -0700"
+	headerReplacer = "{>"
 )