Add Pattern-based request multiplexer

runtime/mux.go

@@ -0,0 +1,79 @@
+package runtime
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/golang/glog"
+)
+
+// A HandlerFunc handles a specific pair of path pattern and HTTP method.
+type HandlerFunc func(w http.ResponseWriter, r *http.Request, pathParams map[string]string)
+
+// ServeMux is a request multiplexer for grpc-gateway.
+// It matches http requests to patterns and invokes the corresponding handler.
+type ServeMux struct {
+	// handlers maps HTTP method to a list of handlers.
+	handlers map[string][]handler
+}
+
+// NewServeMux returns a new MuxHandler whose internal mapping is empty.
+func NewServeMux() *ServeMux {
+	return &ServeMux{
+		handlers: make(map[string][]handler),
+	}
+}
+
+// Handle associates "h" to the pair of HTTP method and path pattern.
+func (s *ServeMux) Handle(meth string, pat Pattern, h HandlerFunc) {
+	s.handlers[meth] = append(s.handlers[meth], handler{pat: pat, h: h})
+}
+
+// ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.Path.
+func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	path := r.URL.Path
+	if !strings.HasPrefix(path, "/") {
+		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+		return
+	}
+
+	components := strings.Split(path[1:], "/")
+	l := len(components)
+	var verb string
+	if idx := strings.LastIndex(components[l-1], ":"); idx == 0 {
+		http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+		return
+	} else if idx > 0 {
+		c := components[l-1]
+		verb, components[l-1] = c[:idx], c[idx+1:]
+	}
+
+	for _, h := range s.handlers[r.Method] {
+		pathParams, err := h.pat.Match(components, verb)
+		if err != nil {
+			glog.V(3).Infof("path mismatch: %q to %q", path, h.pat)
+			continue
+		}
+		h.h(w, r, pathParams)
+		return
+	}
+
+	// lookup other methods to determine if it is MethodNotAllowed
+	for m, handlers := range s.handlers {
+		if m == r.Method {
+			continue
+		}
+		for _, h := range handlers {
+			if _, err := h.pat.Match(components, verb); err == nil {
+				http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+				return
+			}
+		}
+	}
+	http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+}
+
+type handler struct {
+	pat Pattern
+	h   HandlerFunc
+}