1 files changed, 121 insertions, 0 deletions
diff --git a/vendor/github.com/rs/xhandler/chain.go b/vendor/github.com/rs/xhandler/chain.go
new file mode 100644
index 000000000..3e4bd359c
--- /dev/null
+++ b/vendor/github.com/rs/xhandler/chain.go
@@ -0,0 +1,121 @@
+package xhandler
+
+import (
+	"net/http"
+
+	"golang.org/x/net/context"
+)
+
+// Chain is a helper for chaining middleware handlers together for easier
+// management.
+type Chain []func(next HandlerC) HandlerC
+
+// Add appends a variable number of additional middleware handlers
+// to the middleware chain. Middleware handlers can either be
+// context-aware or non-context aware handlers with the appropriate
+// function signatures.
+func (c *Chain) Add(f ...interface{}) {
+	for _, h := range f {
+		switch v := h.(type) {
+		case func(http.Handler) http.Handler:
+			c.Use(v)
+		case func(HandlerC) HandlerC:
+			c.UseC(v)
+		default:
+			panic("Adding invalid handler to the middleware chain")
+		}
+	}
+}
+
+// With creates a new middleware chain from an existing chain,
+// extending it with additional middleware. Middleware handlers
+// can either be context-aware or non-context aware handlers
+// with the appropriate function signatures.
+func (c *Chain) With(f ...interface{}) *Chain {
+	n := make(Chain, len(*c))
+	copy(n, *c)
+	n.Add(f...)
+	return &n
+}
+
+// UseC appends a context-aware handler to the middleware chain.
+func (c *Chain) UseC(f func(next HandlerC) HandlerC) {
+	*c = append(*c, f)
+}
+
+// Use appends a standard http.Handler to the middleware chain without
+// losing track of the context when inserted between two context aware handlers.
+//
+// Caveat: the f function will be called on each request so you are better off putting
+// any initialization sequence outside of this function.
+func (c *Chain) Use(f func(next http.Handler) http.Handler) {
+	xf := func(next HandlerC) HandlerC {
+		return HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+			n := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				next.ServeHTTPC(ctx, w, r)
+			})
+			f(n).ServeHTTP(w, r)
+		})
+	}
+	*c = append(*c, xf)
+}
+
+// Handler wraps the provided final handler with all the middleware appended to
+// the chain and returns a new standard http.Handler instance.
+// The context.Background() context is injected automatically.
+func (c Chain) Handler(xh HandlerC) http.Handler {
+	ctx := context.Background()
+	return c.HandlerCtx(ctx, xh)
+}
+
+// HandlerFC is a helper to provide a function (HandlerFuncC) to Handler().
+//
+// HandlerFC is equivalent to:
+//  c.Handler(xhandler.HandlerFuncC(xhc))
+func (c Chain) HandlerFC(xhf HandlerFuncC) http.Handler {
+	ctx := context.Background()
+	return c.HandlerCtx(ctx, HandlerFuncC(xhf))
+}
+
+// HandlerH is a helper to provide a standard http handler (http.HandlerFunc)
+// to Handler(). Your final handler won't have access to the context though.
+func (c Chain) HandlerH(h http.Handler) http.Handler {
+	ctx := context.Background()
+	return c.HandlerCtx(ctx, HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+		h.ServeHTTP(w, r)
+	}))
+}
+
+// HandlerF is a helper to provide a standard http handler function
+// (http.HandlerFunc) to Handler(). Your final handler won't have access
+// to the context though.
+func (c Chain) HandlerF(hf http.HandlerFunc) http.Handler {
+	ctx := context.Background()
+	return c.HandlerCtx(ctx, HandlerFuncC(func(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+		hf(w, r)
+	}))
+}
+
+// HandlerCtx wraps the provided final handler with all the middleware appended to
+// the chain and returns a new standard http.Handler instance.
+func (c Chain) HandlerCtx(ctx context.Context, xh HandlerC) http.Handler {
+	return New(ctx, c.HandlerC(xh))
+}
+
+// HandlerC wraps the provided final handler with all the middleware appended to
+// the chain and returns a HandlerC instance.
+func (c Chain) HandlerC(xh HandlerC) HandlerC {
+	for i := len(c) - 1; i >= 0; i-- {
+		xh = c[i](xh)
+	}
+	return xh
+}
+
+// HandlerCF wraps the provided final handler func with all the middleware appended to
+// the chain and returns a HandlerC instance.
+//
+// HandlerCF is equivalent to:
+//  c.HandlerC(xhandler.HandlerFuncC(xhc))
+func (c Chain) HandlerCF(xhc HandlerFuncC) HandlerC {
+	return c.HandlerC(HandlerFuncC(xhc))
+}