add custom context support

context.go

@@ -187,6 +187,12 @@ type (
 		// with `Echo#AcquireContext()` and `Echo#ReleaseContext()`.
 		// See `Echo#ServeHTTP()`
 		Reset(r *http.Request, w http.ResponseWriter)
+
+		// Underlying returns the underlying context.
+		Underlying() Context
+
+		// release managed resources
+		Free()
 	}
 
 	context struct {
@@ -604,3 +610,9 @@ func (c *context) Reset(r *http.Request, w http.ResponseWriter) {
 	// NOTE: Don't reset because it has to have length c.echo.maxParam at all times
 	// c.pvalues = nil
 }
+
+func (c *context) Underlying() Context {
+	return nil
+}
+
+func (c *context) Free() {}

echo.go

@@ -74,6 +74,7 @@ type (
 		routers          map[string]*Router
 		notFoundHandler  HandlerFunc
 		pool             sync.Pool
+		newCtx           func(r *http.Request, w http.ResponseWriter) Context
 		Server           *http.Server
 		TLSServer        *http.Server
 		Listener         net.Listener
@@ -315,8 +316,19 @@ func New() (e *Echo) {
 	return
 }
 
+func (e *Echo) SetNewContext(newCtx func(r *http.Request, w http.ResponseWriter) Context) {
+	e.newCtx = newCtx
+}
+
 // NewContext returns a Context instance.
 func (e *Echo) NewContext(r *http.Request, w http.ResponseWriter) Context {
+	if e.newCtx != nil {
+		return e.newCtx(r, w)
+	}
+	return e.NewNativeContext(r, w)
+}
+
+func (e *Echo) NewNativeContext(r *http.Request, w http.ResponseWriter) Context {
 	return &context{
 		request:  r,
 		response: NewResponse(w, e),
@@ -587,13 +599,14 @@ func (e *Echo) AcquireContext() Context {
 // ReleaseContext returns the `Context` instance back to the pool.
 // You must call it after `AcquireContext()`.
 func (e *Echo) ReleaseContext(c Context) {
+	c.Free()
 	e.pool.Put(c)
 }
 
 // ServeHTTP implements `http.Handler` interface, which serves HTTP requests.
 func (e *Echo) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Acquire context
-	c := e.pool.Get().(*context)
+	c := e.pool.Get().(Context)
 	c.Reset(r, w)
 
 	h := NotFoundHandler

echo_test.go

@@ -578,3 +578,54 @@ func TestEchoShutdown(t *testing.T) {
 	err := <-errCh
 	assert.Equal(t, err.Error(), "http: Server closed")
 }
+
+type MyContext struct {
+	Context
+
+	MyField1 int
+	MyField2 int
+	MyField3 int
+}
+
+func (ctx *MyContext) Underlying() Context {
+	return ctx.Context
+}
+
+func (ctx *MyContext) Free() {
+	ctx.MyField1 = 0
+	ctx.MyField2 = 0
+	ctx.MyField3 = 0
+}
+
+func TestEchoWrapContext(t *testing.T) {
+	e := New()
+	e.SetNewContext(func(r *http.Request, w http.ResponseWriter) Context {
+		return &MyContext{Context: e.NewNativeContext(r, w)}
+	})
+	toEchoFunc := func(h func(ctx *MyContext) error) HandlerFunc {
+		return func(ctx Context) error {
+			return h(ctx.(*MyContext))
+		}
+	}
+
+	e.Pre(func(next HandlerFunc) HandlerFunc {
+		return func(c Context) error {
+			ctx := c.(*MyContext)
+			ctx.MyField1 = 1
+			ctx.MyField2 = 2
+			ctx.MyField3 = 3
+			return next(c)
+		}
+	})
+
+	e.GET("/users", toEchoFunc(func(c *MyContext) error {
+		assert.Equal(t, c.MyField1, 1)
+		assert.Equal(t, c.MyField2, 2)
+		assert.Equal(t, c.MyField3, 3)
+		return c.String(http.StatusOK, "ok")
+	}))
+
+	c, b := request(http.MethodGet, "/users", e)
+	assert.Equal(t, http.StatusOK, c)
+	assert.Equal(t, "ok", b)
+}

router.go

@@ -1,6 +1,9 @@
 package echo
 
-import "net/http"
+import (
+	"errors"
+	"net/http"
+)
 
 type (
 	// Router is the registry of all registered routes for an `Echo` instance for
@@ -300,7 +303,21 @@ func (n *node) checkMethodNotAllowed() HandlerFunc {
 // - Reset it `Context#Reset()`
 // - Return it `Echo#ReleaseContext()`.
 func (r *Router) Find(method, path string, c Context) {
-	ctx := c.(*context)
+	ctx, isNativeCtx := c.(*context)
+	if !isNativeCtx {
+		for {
+			c = c.Underlying()
+			if c == nil {
+				panic(errors.New("must has underlying native context"))
+			}
+
+			ctx, isNativeCtx = c.(*context)
+			if isNativeCtx {
+				break
+			}
+		}
+	}
+
 	ctx.path = path
 	cn := r.tree // Current node as root