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Diffstat (limited to 'vendor/github.com/rs/xhandler/chain.go')
-rw-r--r-- | vendor/github.com/rs/xhandler/chain.go | 121 |
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)) +} |