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jsr311.go
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jsr311.go
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package restful
// Copyright 2013 Ernest Micklei. All rights reserved.
// Use of this source code is governed by a license
// that can be found in the LICENSE file.
import (
"errors"
"fmt"
"net/http"
"sort"
"strings"
)
// RouterJSR311 implements the flow for matching Requests to Routes (and consequently Resource Functions)
// as specified by the JSR311 http://jsr311.java.net/nonav/releases/1.1/spec/spec.html.
// RouterJSR311 implements the Router interface.
// Concept of locators is not implemented.
type RouterJSR311 struct{}
// SelectRoute is part of the Router interface and returns the best match
// for the WebService and its Route for the given Request.
func (r RouterJSR311) SelectRoute(
webServices []*WebService,
httpRequest *http.Request) (selectedService *WebService, selectedRoute *Route, err error) {
// Identify the root resource class (WebService)
dispatcher, finalMatch, err := r.detectDispatcher(httpRequest.URL.Path, webServices)
if err != nil {
return nil, nil, NewError(http.StatusNotFound, "")
}
// Obtain the set of candidate methods (Routes)
routes := r.selectRoutes(dispatcher, finalMatch)
if len(routes) == 0 {
return dispatcher, nil, NewError(http.StatusNotFound, "404: Page Not Found")
}
// Identify the method (Route) that will handle the request
route, ok := r.detectRoute(routes, httpRequest)
return dispatcher, route, ok
}
// ExtractParameters is used to obtain the path parameters from the route using the same matching
// engine as the JSR 311 router.
func (r RouterJSR311) ExtractParameters(route *Route, webService *WebService, urlPath string) map[string]string {
webServiceExpr := webService.pathExpr
webServiceMatches := webServiceExpr.Matcher.FindStringSubmatch(urlPath)
pathParameters := r.extractParams(webServiceExpr, webServiceMatches)
routeExpr := route.pathExpr
routeMatches := routeExpr.Matcher.FindStringSubmatch(webServiceMatches[len(webServiceMatches)-1])
routeParams := r.extractParams(routeExpr, routeMatches)
for key, value := range routeParams {
pathParameters[key] = value
}
return pathParameters
}
func (RouterJSR311) extractParams(pathExpr *pathExpression, matches []string) map[string]string {
params := map[string]string{}
for i := 1; i < len(matches); i++ {
if len(pathExpr.VarNames) >= i {
params[pathExpr.VarNames[i-1]] = matches[i]
}
}
return params
}
// http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-360003.7.2
func (r RouterJSR311) detectRoute(routes []Route, httpRequest *http.Request) (*Route, error) {
candidates := make([]*Route, 0, 8)
for i, each := range routes {
ok := true
for _, fn := range each.If {
if !fn(httpRequest) {
ok = false
break
}
}
if ok {
candidates = append(candidates, &routes[i])
}
}
if len(candidates) == 0 {
if trace {
traceLogger.Printf("no Route found (from %d) that passes conditional checks", len(routes))
}
return nil, NewError(http.StatusNotFound, "404: Not Found")
}
// http method
previous := candidates
candidates = candidates[:0]
for _, each := range previous {
if httpRequest.Method == each.Method {
candidates = append(candidates, each)
}
}
if len(candidates) == 0 {
if trace {
traceLogger.Printf("no Route found (in %d routes) that matches HTTP method %s\n", len(previous), httpRequest.Method)
}
allowed := []string{}
allowedLoop:
for _, candidate := range previous {
for _, method := range allowed {
if method == candidate.Method {
continue allowedLoop
}
}
allowed = append(allowed, candidate.Method)
}
header := http.Header{"Allow": []string{strings.Join(allowed, ", ")}}
return nil, NewErrorWithHeader(http.StatusMethodNotAllowed, "405: Method Not Allowed", header)
}
// content-type
contentType := httpRequest.Header.Get(HEADER_ContentType)
previous = candidates
candidates = candidates[:0]
for _, each := range previous {
if each.matchesContentType(contentType) {
candidates = append(candidates, each)
}
}
if len(candidates) == 0 {
if trace {
traceLogger.Printf("no Route found (from %d) that matches HTTP Content-Type: %s\n", len(previous), contentType)
}
if httpRequest.ContentLength > 0 {
return nil, NewError(http.StatusUnsupportedMediaType, "415: Unsupported Media Type")
}
}
// accept
previous = candidates
candidates = candidates[:0]
accept := httpRequest.Header.Get(HEADER_Accept)
if len(accept) == 0 {
accept = "*/*"
}
for _, each := range previous {
if each.matchesAccept(accept) {
candidates = append(candidates, each)
}
}
if len(candidates) == 0 {
if trace {
traceLogger.Printf("no Route found (from %d) that matches HTTP Accept: %s\n", len(previous), accept)
}
available := []string{}
for _, candidate := range previous {
available = append(available, candidate.Produces...)
}
return nil, NewError(
http.StatusNotAcceptable,
fmt.Sprintf("406: Not Acceptable\n\nAvailable representations: %s", strings.Join(available, ", ")),
)
}
// return r.bestMatchByMedia(outputMediaOk, contentType, accept), nil
return candidates[0], nil
}
// http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-360003.7.2
// n/m > n/* > */*
func (r RouterJSR311) bestMatchByMedia(routes []Route, contentType string, accept string) *Route {
// TODO
return &routes[0]
}
// http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-360003.7.2 (step 2)
func (r RouterJSR311) selectRoutes(dispatcher *WebService, pathRemainder string) []Route {
filtered := &sortableRouteCandidates{}
for _, each := range dispatcher.Routes() {
pathExpr := each.pathExpr
matches := pathExpr.Matcher.FindStringSubmatch(pathRemainder)
if matches != nil {
lastMatch := matches[len(matches)-1]
if len(lastMatch) == 0 || lastMatch == "/" { // do not include if value is neither empty nor ‘/’.
filtered.candidates = append(filtered.candidates,
routeCandidate{each, len(matches) - 1, pathExpr.LiteralCount, pathExpr.VarCount})
}
}
}
if len(filtered.candidates) == 0 {
if trace {
traceLogger.Printf("WebService on path %s has no routes that match URL path remainder:%s\n", dispatcher.rootPath, pathRemainder)
}
return []Route{}
}
sort.Sort(sort.Reverse(filtered))
// select other routes from candidates whoes expression matches rmatch
matchingRoutes := []Route{filtered.candidates[0].route}
for c := 1; c < len(filtered.candidates); c++ {
each := filtered.candidates[c]
if each.route.pathExpr.Matcher.MatchString(pathRemainder) {
matchingRoutes = append(matchingRoutes, each.route)
}
}
return matchingRoutes
}
// http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-360003.7.2 (step 1)
func (r RouterJSR311) detectDispatcher(requestPath string, dispatchers []*WebService) (*WebService, string, error) {
filtered := &sortableDispatcherCandidates{}
for _, each := range dispatchers {
matches := each.pathExpr.Matcher.FindStringSubmatch(requestPath)
if matches != nil {
filtered.candidates = append(filtered.candidates,
dispatcherCandidate{each, matches[len(matches)-1], len(matches), each.pathExpr.LiteralCount, each.pathExpr.VarCount})
}
}
if len(filtered.candidates) == 0 {
if trace {
traceLogger.Printf("no WebService was found to match URL path:%s\n", requestPath)
}
return nil, "", errors.New("not found")
}
sort.Sort(sort.Reverse(filtered))
return filtered.candidates[0].dispatcher, filtered.candidates[0].finalMatch, nil
}
// Types and functions to support the sorting of Routes
type routeCandidate struct {
route Route
matchesCount int // the number of capturing groups
literalCount int // the number of literal characters (means those not resulting from template variable substitution)
nonDefaultCount int // the number of capturing groups with non-default regular expressions (i.e. not ‘([^ /]+?)’)
}
func (r routeCandidate) expressionToMatch() string {
return r.route.pathExpr.Source
}
func (r routeCandidate) String() string {
return fmt.Sprintf("(m=%d,l=%d,n=%d)", r.matchesCount, r.literalCount, r.nonDefaultCount)
}
type sortableRouteCandidates struct {
candidates []routeCandidate
}
func (rcs *sortableRouteCandidates) Len() int {
return len(rcs.candidates)
}
func (rcs *sortableRouteCandidates) Swap(i, j int) {
rcs.candidates[i], rcs.candidates[j] = rcs.candidates[j], rcs.candidates[i]
}
func (rcs *sortableRouteCandidates) Less(i, j int) bool {
ci := rcs.candidates[i]
cj := rcs.candidates[j]
// primary key
if ci.literalCount < cj.literalCount {
return true
}
if ci.literalCount > cj.literalCount {
return false
}
// secundary key
if ci.matchesCount < cj.matchesCount {
return true
}
if ci.matchesCount > cj.matchesCount {
return false
}
// tertiary key
if ci.nonDefaultCount < cj.nonDefaultCount {
return true
}
if ci.nonDefaultCount > cj.nonDefaultCount {
return false
}
// quaternary key ("source" is interpreted as Path)
return ci.route.Path < cj.route.Path
}
// Types and functions to support the sorting of Dispatchers
type dispatcherCandidate struct {
dispatcher *WebService
finalMatch string
matchesCount int // the number of capturing groups
literalCount int // the number of literal characters (means those not resulting from template variable substitution)
nonDefaultCount int // the number of capturing groups with non-default regular expressions (i.e. not ‘([^ /]+?)’)
}
type sortableDispatcherCandidates struct {
candidates []dispatcherCandidate
}
func (dc *sortableDispatcherCandidates) Len() int {
return len(dc.candidates)
}
func (dc *sortableDispatcherCandidates) Swap(i, j int) {
dc.candidates[i], dc.candidates[j] = dc.candidates[j], dc.candidates[i]
}
func (dc *sortableDispatcherCandidates) Less(i, j int) bool {
ci := dc.candidates[i]
cj := dc.candidates[j]
// primary key
if ci.matchesCount < cj.matchesCount {
return true
}
if ci.matchesCount > cj.matchesCount {
return false
}
// secundary key
if ci.literalCount < cj.literalCount {
return true
}
if ci.literalCount > cj.literalCount {
return false
}
// tertiary key
return ci.nonDefaultCount < cj.nonDefaultCount
}