go web framework gin 路由表的设计

func (engine *Engine) handleHTTPRequest(c *Context) {httpMethod := c.Request.Method //获取Request methodpath := c.Request.URL.Path //获取 Request URL Pathunescape := falseif engine.UseRawPath && len(c.Request.URL.RawPath) > 0 {path = c.Request.URL.RawPathunescape = engine.UnescapePathValues}// Find root of the tree for the given HTTP methodt := engine.treesfor i, tl := 0, len(t); i < tl; i++ { //遍历每一个methord treeif t[i].method != httpMethod {continue}root := t[i].root// Find route in treehandlers, params, tsr := root.getValue(path, c.Params, unescape) //如果找到这个method tree, 那么就从这个tree中根据path，params, unescape 找到对应的handlersif handlers != nil { //执行handlerc.handlers = handlersc.Params = paramsc.Next()c.writermem.WriteHeaderNow()return} ???????????????//异常处理部分if httpMethod != "CONNECT" && path != "/" {if tsr && engine.RedirectTrailingSlash {redirectTrailingSlash(c)return}if engine.RedirectFixedPath && redirectFixedPath(c, root, engine.RedirectFixedPath) {return}}break} ???????//处理不能响应的methodif engine.HandleMethodNotAllowed {for _, tree := range engine.trees {if tree.method == httpMethod {continue}if handlers, _, _ := tree.root.getValue(path, nil, unescape); handlers != nil {c.handlers = engine.allNoMethodserveError(c, http.StatusMethodNotAllowed, default405Body)return}}}c.handlers = engine.allNoRouteserveError(c, http.StatusNotFound, default404Body)}

// getValue returns the handle registered with the given path (key). The values of// wildcards are saved to a map.// If no handle can be found, a TSR (trailing slash redirect) recommendation is// made if a handle exists with an extra (without the) trailing slash for the// given path.func (n *node) getValue(path string, po Params, unescape bool) (handlers HandlersChain, p Params, tsr bool) {p = powalk: // Outer loop for walking the treefor {if len(path) > len(n.path) {if path[:len(n.path)] == n.path {path = path[len(n.path):]// If this node does not have a wildcard (param or catchAll)// child, ?we can just look up the next child node and continue// to walk down the treeif !n.wildChild {c := path[0]for i := 0; i < len(n.indices); i++ {if c == n.indices[i] {n = n.children[i]continue walk}}// Nothing found.// We can recommend to redirect to the same URL without a// trailing slash if a leaf exists for that path.tsr = path == "/" && n.handlers != nilreturn}// handle wildcard childn = n.children[0]switch n.nType {case param:// find param end (either ‘/‘ or path end)end := 0for end < len(path) && path[end] != ‘/‘ {end++}// save param valueif cap(p) < int(n.maxParams) {p = make(Params, 0, n.maxParams)}i := len(p)p = p[:i+1] // expand slice within preallocated capacityp[i].Key = n.path[1:]val := path[:end]if unescape {var err errorif p[i].Value, err = url.QueryUnescape(val); err != nil {p[i].Value = val // fallback, in case of error}} else {p[i].Value = val}// we need to go deeper!if end < len(path) {if len(n.children) > 0 {path = path[end:]n = n.children[0]continue walk}// ... but we can‘ttsr = len(path) == end+1return}if handlers = n.handlers; handlers != nil {return}if len(n.children) == 1 {// No handle found. Check if a handle for this path + a// trailing slash exists for TSR recommendationn = n.children[0]tsr = n.path == "/" && n.handlers != nil}returncase catchAll:// save param valueif cap(p) < int(n.maxParams) {p = make(Params, 0, n.maxParams)}i := len(p)p = p[:i+1] // expand slice within preallocated capacityp[i].Key = n.path[2:]if unescape {var err errorif p[i].Value, err = url.QueryUnescape(path); err != nil {p[i].Value = path // fallback, in case of error}} else {p[i].Value = path}handlers = n.handlersreturndefault:panic("invalid node type")}}} else if path == n.path {// We should have reached the node containing the handle.// Check if this node has a handle registered.if handlers = n.handlers; handlers != nil {return}if path == "/" && n.wildChild && n.nType != root {tsr = truereturn}// No handle found. Check if a handle for this path + a// trailing slash exists for trailing slash recommendationfor i := 0; i < len(n.indices); i++ {if n.indices[i] == ‘/‘ {n = n.children[i]tsr = (len(n.path) == 1 && n.handlers != nil) ||(n.nType == catchAll && n.children[0].handlers != nil)return}}return}// Nothing found. We can recommend to redirect to the same URL with an// extra trailing slash if a leaf exists for that pathtsr = (path == "/") ||(len(n.path) == len(path)+1 && n.path[len(path)] == ‘/‘ &&path == n.path[:len(n.path)-1] && n.handlers != nil)return}}