Merge pull request #144 from tumdum/regexp-speedup

[refactor] Only wrap regexp in group if not already in a group + perf. gains.

- Addresses https://github.com/gorilla/mux/issues/62
- ~27% less allocs/~15% speedup (ns/op)

bench_test.go

@@ -6,6 +6,7 @@ package mux
 
 import (
 	"net/http"
+	"net/http/httptest"
 	"testing"
 )
 
@@ -19,3 +20,30 @@ func BenchmarkMux(b *testing.B) {
 		router.ServeHTTP(nil, request)
 	}
 }
+
+func BenchmarkMuxAlternativeInRegexp(b *testing.B) {
+	router := new(Router)
+	handler := func(w http.ResponseWriter, r *http.Request) {}
+	router.HandleFunc("/v1/{v1:(a|b)}", handler)
+
+	requestA, _ := http.NewRequest("GET", "/v1/a", nil)
+	requestB, _ := http.NewRequest("GET", "/v1/b", nil)
+	for i := 0; i < b.N; i++ {
+		router.ServeHTTP(nil, requestA)
+		router.ServeHTTP(nil, requestB)
+	}
+}
+
+func BenchmarkManyPathVariables(b *testing.B) {
+	router := new(Router)
+	handler := func(w http.ResponseWriter, r *http.Request) {}
+	router.HandleFunc("/v1/{v1}/{v2}/{v3}/{v4}/{v5}", handler)
+
+	matchingRequest, _ := http.NewRequest("GET", "/v1/1/2/3/4/5", nil)
+	notMatchingRequest, _ := http.NewRequest("GET", "/v1/1/2/3/4", nil)
+	recorder := httptest.NewRecorder()
+	for i := 0; i < b.N; i++ {
+		router.ServeHTTP(nil, matchingRequest)
+		router.ServeHTTP(recorder, notMatchingRequest)
+	}
+}

regexp.go

@@ -73,14 +73,17 @@ func newRouteRegexp(tpl string, matchHost, matchPrefix, matchQuery, strictSlash
 				tpl[idxs[i]:end])
 		}
 		// Build the regexp pattern.
-		varIdx := i / 2
+		if patt[0] == '(' && patt[len(patt)-1] == ')' {
-		fmt.Fprintf(pattern, "%s(?P<%s>%s)", regexp.QuoteMeta(raw), varGroupName(varIdx), patt)
+			fmt.Fprintf(pattern, "%s%s", regexp.QuoteMeta(raw), patt)
+		} else {
+			fmt.Fprintf(pattern, "%s(%s)", regexp.QuoteMeta(raw), patt)
+		}
 		// Build the reverse template.
 		fmt.Fprintf(reverse, "%s%%s", raw)
 
 		// Append variable name and compiled pattern.
-		varsN[varIdx] = name
+		varsN[i/2] = name
-		varsR[varIdx], err = regexp.Compile(fmt.Sprintf("^%s$", patt))
+		varsR[i/2], err = regexp.Compile(fmt.Sprintf("^%s$", patt))
 		if err != nil {
 			return nil, err
 		}
@@ -246,30 +249,17 @@ type routeRegexpGroup struct {
 func (v *routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route) {
 	// Store host variables.
 	if v.host != nil {
-		hostVars := v.host.regexp.FindStringSubmatch(getHost(req))
+		host := getHost(req)
-		if hostVars != nil {
+		matches := v.host.regexp.FindStringSubmatchIndex(host)
-			subexpNames := v.host.regexp.SubexpNames()
+		if len(matches) > 0 {
-			varName := 0
+			extractVars(host, matches, v.host.varsN, m.Vars)
-			for i, name := range subexpNames[1:] {
-				if name != "" && name == varGroupName(varName) {
-					m.Vars[v.host.varsN[varName]] = hostVars[i+1]
-					varName++
-				}
-			}
 		}
 	}
 	// Store path variables.
 	if v.path != nil {
-		pathVars := v.path.regexp.FindStringSubmatch(req.URL.Path)
+		matches := v.path.regexp.FindStringSubmatchIndex(req.URL.Path)
-		if pathVars != nil {
+		if len(matches) > 0 {
-			subexpNames := v.path.regexp.SubexpNames()
+			extractVars(req.URL.Path, matches, v.path.varsN, m.Vars)
-			varName := 0
-			for i, name := range subexpNames[1:] {
-				if name != "" && name == varGroupName(varName) {
-					m.Vars[v.path.varsN[varName]] = pathVars[i+1]
-					varName++
-				}
-			}
 			// Check if we should redirect.
 			if v.path.strictSlash {
 				p1 := strings.HasSuffix(req.URL.Path, "/")
@@ -288,16 +278,10 @@ func (v *routeRegexpGroup) setMatch(req *http.Request, m *RouteMatch, r *Route)
 	}
 	// Store query string variables.
 	for _, q := range v.queries {
-		queryVars := q.regexp.FindStringSubmatch(q.getUrlQuery(req))
+		queryUrl := q.getUrlQuery(req)
-		if queryVars != nil {
+		matches := q.regexp.FindStringSubmatchIndex(queryUrl)
-			subexpNames := q.regexp.SubexpNames()
+		if len(matches) > 0 {
-			varName := 0
+			extractVars(queryUrl, matches, q.varsN, m.Vars)
-			for i, name := range subexpNames[1:] {
-				if name != "" && name == varGroupName(varName) {
-					m.Vars[q.varsN[varName]] = queryVars[i+1]
-					varName++
-				}
-			}
 		}
 	}
 }
@@ -315,3 +299,16 @@ func getHost(r *http.Request) string {
 	return host
 
 }
+
+func extractVars(input string, matches []int, names []string, output map[string]string) {
+	matchesCount := 0
+	prevEnd := -1
+	for i := 2; i < len(matches) && matchesCount < len(names); i += 2 {
+		if prevEnd < matches[i+1] {
+			value := input[matches[i]:matches[i+1]]
+			output[names[matchesCount]] = value
+			prevEnd = matches[i+1]
+			matchesCount++
+		}
+	}
+}