nolan/go-router
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Add PathParams method.

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This commit is contained in:
nolwn
2020-12-06 22:32:39 -08:00
parent dbec3b3e75
commit 1805ac77fe
2 changed files with 161 additions and 52 deletions
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153
router.go
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@ -23,18 +23,30 @@ type Router struct {
routes []route
}
// endpoint is comes at the end of each valid path in the tree. It contains the information you
// need to call the endpoint, including path parameter names.
type endpoint struct {
callback http.HandlerFunc
path string
pathParams []string
}
// route is not part of the tree, but is saved on the router to represent all the available
// routes in the tree.
type route struct {
callback http.HandlerFunc
method string
path string
}
// segment is a tree node. It can have children, or endpoints, or both attached to it. It also
// has a special child called "parameter" which represents a path parameter. If a route string
// doesn't match any of the children, and there is a parameter child present, it will match that
// parameter child.
type segment struct {
children map[string]*segment
methods map[string]http.HandlerFunc
path string
parameter *segment
parameterName string
children map[string]*segment
endpoints map[string]*endpoint
parameter *segment
}
// NotFoundHandler is the default function for handling routes that are not found. If you wish to
@ -49,12 +61,12 @@ var NotFoundHandler http.Handler = http.HandlerFunc(
// method already have a callback registered to them, an error is returned.
func (r *Router) AddRoute(method string, path string, callback http.HandlerFunc) (err error) {
keys := setupKeys(strings.Split(path, "/"))
pathParams := []string{}
if r.root == nil {
r.root = &segment{}
r.root.children = map[string]*segment{}
r.root.methods = map[string]http.HandlerFunc{}
r.root.path = "/"
r.root.endpoints = map[string]*endpoint{}
}
curr := r.root
@ -64,7 +76,12 @@ func (r *Router) AddRoute(method string, path string, callback http.HandlerFunc)
continue
}
if child, ok := curr.children[key]; !ok {
if isParameter(key) {
pathParams = append(pathParams, key[2:])
}
if child, _ := getChild(key, curr); child == nil {
seg := addSegment(curr, key)
curr = seg
} else {
@ -72,18 +89,43 @@ func (r *Router) AddRoute(method string, path string, callback http.HandlerFunc)
}
}
if _, ok := curr.methods[method]; ok {
if _, ok := curr.endpoints[method]; ok {
err = errors.New("path already exists")
return
}
curr.methods[method] = callback
curr.endpoints[method] = &endpoint{callback, path, pathParams}
r.routes = append(r.routes, route{callback, method, path})
return
}
// PathParams takes a path and returns the values for any path parameters
// in the path.
func (r *Router) PathParams(method string, reqPath string) (params map[string]string, err error) {
end, err := r.getEndpoint(method, reqPath)
path := end.path
reqParts := strings.Split(reqPath, "/")
reqKeys := setupKeys(reqParts)
pathParts := strings.Split(path, "/")
pathKeys := setupKeys(pathParts)
params = map[string]string{}
for i, pathKey := range pathKeys {
if isParameter(pathKey) {
name := pathKey[2:]
value := reqKeys[i][1:]
params[name] = value
}
}
return
}
// Get is a convinience method which calls Router.AddRoute with the "GET" method.
func (r *Router) Get(path string, callback http.HandlerFunc) {
r.AddRoute(http.MethodGet, path, callback)
@ -99,33 +141,16 @@ func (r *Router) Get(path string, callback http.HandlerFunc) {
func (r *Router) Handler(req *http.Request) (h http.Handler, pattern string) {
method := req.Method
path := req.URL.Path
root := r.root
curr := root
segments := strings.Split(path, "/")
keys := setupKeys(segments)
if r.NotFoundHandler == nil {
h = NotFoundHandler
}
for _, v := range keys {
if v == "/" {
continue
}
endpoint, err := r.getEndpoint(method, path)
seg := getChild(v, curr)
if seg == nil {
return
}
curr = seg
}
if cb, ok := curr.methods[method]; ok {
h = cb
pattern = curr.path
if err == nil {
h = endpoint.callback
pattern = endpoint.path
}
return
@ -137,25 +162,26 @@ func (r *Router) Handler(req *http.Request) (h http.Handler, pattern string) {
//
// In the case of this router, all it needs to do is lookup the Handler that has been saved at a given
// path and then call its ServeHTTP.
func (r Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
handler, _ := r.Handler(req)
handler.ServeHTTP(w, req)
return
}
// addSegment create a new segment either as a child or as a parameter depending on whether the key
// qualifies as a parameter. A pointer to the created segment is then returned.
func addSegment(curr *segment, key string) (seg *segment) {
if curr.parameterName == key {
if curr.parameter != nil {
seg = curr.parameter
} else if child, ok := curr.children[key]; !ok { // child does not match...
var isParam bool
seg, isParam = newSegment(curr.path, key)
seg, isParam = newSegment(key)
if isParam {
curr.parameter = seg
curr.parameterName = key[2:]
} else {
curr.children[key] = seg
@ -170,33 +196,60 @@ func addSegment(curr *segment, key string) (seg *segment) {
return
}
func getChild(key string, curr *segment) (child *segment) {
// getChild takes a path part and finds the appropriate segment child for it. If it is an exact match to a
// child on the segment, then that child segment is returned. If it is not a match, then the parameter child
// is returned. If there is no parameter child, nil is returned. isParam is true if the parameter child is
// being returned.
func getChild(key string, curr *segment) (child *segment, isParam bool) {
if seg, ok := curr.children[key]; ok { // is there an exact match?
child = seg
} else if curr.parameter != nil { // could this be a parameter?
child = curr.parameter
isParam = true
}
return
}
func newSegment(parentPath string, key string) (seg *segment, isParam bool) {
var path string
// getEndpoint takes a path and traverses the tree until it finds the endpoint associated with that path.
// If no endpoint if found, an error is returned.
func (r *Router) getEndpoint(method string, path string) (end *endpoint, err error) {
curr := r.root
segments := strings.Split(path, "/")
keys := setupKeys(segments)
if parentPath == "/" {
path = key
for _, v := range keys {
if v == "/" {
continue
}
} else {
path = parentPath + key
seg, _ := getChild(v, curr)
if seg == nil {
return
}
curr = seg
}
if _, ok := curr.endpoints[method]; !ok {
err = errors.New("route not found")
}
end = curr.endpoints[method]
return
}
// TODO: refactor out newSegment as it's not longer needed.
// newSegment constructs a new, empty segment and reports back if the key is a parameter.
func newSegment(key string) (seg *segment, isParam bool) {
seg = &segment{}
seg.children = map[string]*segment{}
seg.methods = map[string]http.HandlerFunc{}
seg.path = path
seg.endpoints = map[string]*endpoint{}
if isParameter(key) {
isParam = true
@ -205,6 +258,8 @@ func newSegment(parentPath string, key string) (seg *segment, isParam bool) {
return
}
// setupKeys takes an array of strings representing the parts of a path, and returns a new slice
// made up of the parts with "/" prepended to each.
func setupKeys(slice []string) (keys []string) {
keys = append(keys, "/")
for _, v := range slice {
@ -217,8 +272,8 @@ func setupKeys(slice []string) (keys []string) {
}
// isParameter returns true if the key is more than one character long and starts with a ':'
func isParameter(key string) (isVar bool) {
if len([]rune(key)) <= 2 {
func isParameter(key string) (isParam bool) {
if len([]rune(key)) <= 1 {
return // avoid empty variables, i.e. /somepath/:/someotherpath
}
@ -226,7 +281,7 @@ func isParameter(key string) (isVar bool) {
return
}
isVar = true
isParam = true
return
}