Sample alternate ServerMux implementation.

- no different functionality, might not be working: the book example is wrong.

ch3/ex2httpex/server.go

@@ -0,0 +1,127 @@
+package httpex
+
+import (
+	"net/http"
+	"path"
+	"sync"
+)
+
+type ServeMux struct {
+	mu    sync.RWMutex
+	m     map[string]muxEntry
+	hosts bool // whether any patterns contain hostnames
+}
+
+type muxEntry struct {
+	explicit bool
+	h        http.Handler
+	pattern  string
+}
+
+// NewServeMux allocates and returns a new ServeMux.
+func NewServeMux() *ServeMux { return &ServeMux{m: make(map[string]muxEntry)} }
+
+// DefaultServeMux is the default ServeMux used by Serve.
+var DefaultServeMux = NewServeMux()
+
+// Does path match pattern?
+func pathMatch(pattern, path string) bool {
+	if len(pattern) == 0 {
+		// should not happen
+		return false
+	}
+	n := len(pattern)
+	if pattern[n-1] != '/' {
+		return pattern == path
+	}
+	return len(path) >= n && path[0:n] == pattern
+}
+
+// Return the canonical path for p, eliminating . and .. elements.
+func cleanPath(p string) string {
+	if p == "" {
+		return "/"
+	}
+	if p[0] != '/' {
+		p = "/" + p
+	}
+	np := path.Clean(p)
+	// path.Clean removes trailing slash except for root;
+	// put the trailing slash back if necessary.
+	if p[len(p)-1] == '/' && np != "/" {
+		np += "/"
+	}
+	return np
+}
+
+// Find a handler on a handler map given a path string
+// Most-specific (longest) pattern wins
+func (mux *ServeMux) match(path string) (h http.Handler, pattern string) {
+	var n = 0
+	for k, v := range mux.m {
+		if !pathMatch(k, path) {
+			continue
+		}
+		if h == nil || len(k) > n {
+			n = len(k)
+			h = v.h
+			pattern = v.pattern
+		}
+	}
+	return
+}
+
+// Handler returns the handler to use for the given request,
+// consulting r.Method, r.Host, and r.URL.Path. It always returns
+// a non-nil handler. If the path is not in its canonical form, the
+// handler will be an internally-generated handler that redirects
+// to the canonical path.
+//
+// Handler also returns the registered pattern that matches the
+// request or, in the case of internally-generated redirects,
+// the pattern that will match after following the redirect.
+//
+// If there is no registered handler that applies to the request,
+// Handler returns a ``page not found'' handler and an empty pattern.
+func (mux *ServeMux) Handler(r *http.Request) (http.Handler, pattern string) {
+	if r.Method != "CONNECT" {
+		if p := cleanPath(r.URL.Path); p != r.URL.Path {
+			_, pattern = mux.handler(r.Host, p)
+			url := *r.URL
+			url.Path = p
+			return http.RedirectHandler(url.String(), http.StatusMovedPermanently), pattern
+		}
+	}
+
+	return mux.handler(r.Host, r.URL.Path)
+}
+
+func (mux *ServeMux) handler(host, path string) (h http.Handler, pattern string) {
+	mux.mu.RLock()
+	defer mux.mu.RUnlock()
+
+	// Host-specific pattern takes precedence over generic ones
+	if mux.hosts {
+		h, pattern = mux.match(host + path)
+	}
+	if h == nil {
+		h, pattern = mux.match(path)
+	}
+	if h == nil {
+		h, pattern = http.NotFoundHandler(), ""
+	}
+	return
+}
+
+// ServeHTTP dispatches the request to the handler whose
+// pattern most closely matches the request URL.
+func (mux *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+}
+
+func (mux *ServeMux) Handle(pattern string, handler http.Handler) {
+}
+
+// HandleFunc registers the handler function for the given pattern.
+func (mux *ServeMux) HandleFunc(pattern string, handler func(http.ResponseWriter, *http.Request)) {
+}
+