several bugfixes, add internal.IntLen, round up http-linux example with new router API

http/httphi/mux.go

@@ -0,0 +1,51 @@
+package httphi
+
+import (
+	"strings"
+
+	"github.com/soypat/lneto/internal"
+)
+
+type Mux interface {
+	LookupHandler(get Method, uri []byte) HandlerFunc
+}
+
+type MuxSlice struct {
+	// TODO: binary search worth it?
+	_handlers []struct {
+		method  Method
+		uri     string
+		handler HandlerFunc
+	}
+}
+
+func (sm *MuxSlice) Reset(capacity int) {
+	internal.SliceReuse(&sm._handlers, capacity)
+}
+
+func (sm *MuxSlice) LookupHandler(method Method, uri []byte) HandlerFunc {
+	for _, endpoint := range sm._handlers {
+		if endpoint.method != MethUndefined && endpoint.method != method {
+			continue
+		}
+		// Method matches.
+		if b2s(uri) == endpoint.uri {
+			return endpoint.handler
+		}
+	}
+	return nil
+}
+
+func (sm *MuxSlice) Handle(reg string, handler HandlerFunc) {
+	v := internal.SliceReclaim(&sm._handlers)
+	method := MethUndefined
+	methodOrURL, url, methodFound := strings.Cut(reg, " ")
+	if methodFound {
+		method = MethodFromBytes([]byte(methodOrURL))
+	} else {
+		url = methodOrURL
+	}
+	v.method = method
+	v.uri = url
+	v.handler = handler
+}