vendor/github.com/fsouza/go-dockerclient/external/github.com/gorilla/mux/README.md

   1 mux
   2 ===
   3 [![GoDoc](https://godoc.org/github.com/gorilla/mux?status.svg)](https://godoc.org/github.com/gorilla/mux)
   4 [![Build Status](https://travis-ci.org/gorilla/mux.svg?branch=master)](https://travis-ci.org/gorilla/mux)
   5
   6 Package `gorilla/mux` implements a request router and dispatcher.
   7
   8 The name mux stands for "HTTP request multiplexer". Like the standard `http.ServeMux`, `mux.Router` matches incoming requests against a list of registered routes and calls a handler for the route that matches the URL or other conditions. The main features are:
   9
  10 * Requests can be matched based on URL host, path, path prefix, schemes, header and query values, HTTP methods or using custom matchers.
  11 * URL hosts and paths can have variables with an optional regular expression.
  12 * Registered URLs can be built, or "reversed", which helps maintaining references to resources.
  13 * Routes can be used as subrouters: nested routes are only tested if the parent route matches. This is useful to define groups of routes that share common conditions like a host, a path prefix or other repeated attributes. As a bonus, this optimizes request matching.
  14 * It implements the `http.Handler` interface so it is compatible with the standard `http.ServeMux`.
  15
  16 Let's start registering a couple of URL paths and handlers:
  17
  18 ```go
  19 func main() {
  20         r := mux.NewRouter()
  21         r.HandleFunc("/", HomeHandler)
  22         r.HandleFunc("/products", ProductsHandler)
  23         r.HandleFunc("/articles", ArticlesHandler)
  24         http.Handle("/", r)
  25 }
  26 ```
  27
  28 Here we register three routes mapping URL paths to handlers. This is equivalent to how `http.HandleFunc()` works: if an incoming request URL matches one of the paths, the corresponding handler is called passing (`http.ResponseWriter`, `*http.Request`) as parameters.
  29
  30 Paths can have variables. They are defined using the format `{name}` or `{name:pattern}`. If a regular expression pattern is not defined, the matched variable will be anything until the next slash. For example:
  31
  32 ```go
  33 r := mux.NewRouter()
  34 r.HandleFunc("/products/{key}", ProductHandler)
  35 r.HandleFunc("/articles/{category}/", ArticlesCategoryHandler)
  36 r.HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler)
  37 ```
  38
  39 The names are used to create a map of route variables which can be retrieved calling `mux.Vars()`:
  40
  41 ```go
  42 vars := mux.Vars(request)
  43 category := vars["category"]
  44 ```
  45
  46 And this is all you need to know about the basic usage. More advanced options are explained below.
  47
  48 Routes can also be restricted to a domain or subdomain. Just define a host pattern to be matched. They can also have variables:
  49
  50 ```go
  51 r := mux.NewRouter()
  52 // Only matches if domain is "www.example.com".
  53 r.Host("www.example.com")
  54 // Matches a dynamic subdomain.
  55 r.Host("{subdomain:[a-z]+}.domain.com")
  56 ```
  57
  58 There are several other matchers that can be added. To match path prefixes:
  59
  60 ```go
  61 r.PathPrefix("/products/")
  62 ```
  63
  64 ...or HTTP methods:
  65
  66 ```go
  67 r.Methods("GET", "POST")
  68 ```
  69
  70 ...or URL schemes:
  71
  72 ```go
  73 r.Schemes("https")
  74 ```
  75
  76 ...or header values:
  77
  78 ```go
  79 r.Headers("X-Requested-With", "XMLHttpRequest")
  80 ```
  81
  82 ...or query values:
  83
  84 ```go
  85 r.Queries("key", "value")
  86 ```
  87
  88 ...or to use a custom matcher function:
  89
  90 ```go
  91 r.MatcherFunc(func(r *http.Request, rm *RouteMatch) bool {
  92         return r.ProtoMajor == 0
  93 })
  94 ```
  95
  96 ...and finally, it is possible to combine several matchers in a single route:
  97
  98 ```go
  99 r.HandleFunc("/products", ProductsHandler).
 100   Host("www.example.com").
 101   Methods("GET").
 102   Schemes("http")
 103 ```
 104
 105 Setting the same matching conditions again and again can be boring, so we have a way to group several routes that share the same requirements. We call it "subrouting".
 106
 107 For example, let's say we have several URLs that should only match when the host is `www.example.com`. Create a route for that host and get a "subrouter" from it:
 108
 109 ```go
 110 r := mux.NewRouter()
 111 s := r.Host("www.example.com").Subrouter()
 112 ```
 113
 114 Then register routes in the subrouter:
 115
 116 ```go
 117 s.HandleFunc("/products/", ProductsHandler)
 118 s.HandleFunc("/products/{key}", ProductHandler)
 119 s.HandleFunc("/articles/{category}/{id:[0-9]+}"), ArticleHandler)
 120 ```
 121
 122 The three URL paths we registered above will only be tested if the domain is `www.example.com`, because the subrouter is tested first. This is not only convenient, but also optimizes request matching. You can create subrouters combining any attribute matchers accepted by a route.
 123
 124 Subrouters can be used to create domain or path "namespaces": you define subrouters in a central place and then parts of the app can register its paths relatively to a given subrouter.
 125
 126 There's one more thing about subroutes. When a subrouter has a path prefix, the inner routes use it as base for their paths:
 127
 128 ```go
 129 r := mux.NewRouter()
 130 s := r.PathPrefix("/products").Subrouter()
 131 // "/products/"
 132 s.HandleFunc("/", ProductsHandler)
 133 // "/products/{key}/"
 134 s.HandleFunc("/{key}/", ProductHandler)
 135 // "/products/{key}/details"
 136 s.HandleFunc("/{key}/details", ProductDetailsHandler)
 137 ```
 138
 139 Now let's see how to build registered URLs.
 140
 141 Routes can be named. All routes that define a name can have their URLs built, or "reversed". We define a name calling `Name()` on a route. For example:
 142
 143 ```go
 144 r := mux.NewRouter()
 145 r.HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler).
 146   Name("article")
 147 ```
 148
 149 To build a URL, get the route and call the `URL()` method, passing a sequence of key/value pairs for the route variables. For the previous route, we would do:
 150
 151 ```go
 152 url, err := r.Get("article").URL("category", "technology", "id", "42")
 153 ```
 154
 155 ...and the result will be a `url.URL` with the following path:
 156
 157 ```
 158 "/articles/technology/42"
 159 ```
 160
 161 This also works for host variables:
 162
 163 ```go
 164 r := mux.NewRouter()
 165 r.Host("{subdomain}.domain.com").
 166   Path("/articles/{category}/{id:[0-9]+}").
 167   HandlerFunc(ArticleHandler).
 168   Name("article")
 169
 170 // url.String() will be "http://news.domain.com/articles/technology/42"
 171 url, err := r.Get("article").URL("subdomain", "news",
 172                                  "category", "technology",
 173                                  "id", "42")
 174 ```
 175
 176 All variables defined in the route are required, and their values must conform to the corresponding patterns. These requirements guarantee that a generated URL will always match a registered route -- the only exception is for explicitly defined "build-only" routes which never match.
 177
 178 Regex support also exists for matching Headers within a route. For example, we could do:
 179
 180 ```go
 181 r.HeadersRegexp("Content-Type", "application/(text|json)")
 182 ```
 183
 184 ...and the route will match both requests with a Content-Type of `application/json` as well as `application/text`
 185
 186 There's also a way to build only the URL host or path for a route: use the methods `URLHost()` or `URLPath()` instead. For the previous route, we would do:
 187
 188 ```go
 189 // "http://news.domain.com/"
 190 host, err := r.Get("article").URLHost("subdomain", "news")
 191
 192 // "/articles/technology/42"
 193 path, err := r.Get("article").URLPath("category", "technology", "id", "42")
 194 ```
 195
 196 And if you use subrouters, host and path defined separately can be built as well:
 197
 198 ```go
 199 r := mux.NewRouter()
 200 s := r.Host("{subdomain}.domain.com").Subrouter()
 201 s.Path("/articles/{category}/{id:[0-9]+}").
 202   HandlerFunc(ArticleHandler).
 203   Name("article")
 204
 205 // "http://news.domain.com/articles/technology/42"
 206 url, err := r.Get("article").URL("subdomain", "news",
 207                                  "category", "technology",
 208                                  "id", "42")
 209 ```
 210
 211 ## Full Example
 212
 213 Here's a complete, runnable example of a small `mux` based server:
 214
 215 ```go
 216 package main
 217
 218 import (
 219         "net/http"
 220
 221         "github.com/gorilla/mux"
 222 )
 223
 224 func YourHandler(w http.ResponseWriter, r *http.Request) {
 225         w.Write([]byte("Gorilla!\n"))
 226 }
 227
 228 func main() {
 229         r := mux.NewRouter()
 230         // Routes consist of a path and a handler function.
 231         r.HandleFunc("/", YourHandler)
 232
 233         // Bind to a port and pass our router in
 234         http.ListenAndServe(":8000", r)
 235 }
 236 ```
 237
 238 ## License
 239
 240 BSD licensed. See the LICENSE file for details.