trout
2016-01-02
Parent:bf38b050b6c4
trout/trie.go
Fix bug in handling of finding closest match for params. We had a bug that finding the closest match for params would only work if the parent was also a param. This lead to problems where multiple methods declared on a single endpoint as follows were treated as multiple endpoints: router.Endpoint("/{id}").Methods("GET").Handler(handleGet) router.Endpoint("/{id}").Methods("POST").Handler(handlePost) This caused erroneous Method Not Allowed errors, as the POST method would be part of an Endpoint that could never be routed to. We also discovered that Method Not Allowed errors weren't returning the required Allow header with a list of acceptable methods, so this has been fixed.
1 package trout
3 import (
4 "net/http"
5 "sort"
6 "sync"
7 )
9 type trie struct {
10 branch *branch
11 sync.RWMutex
12 }
14 func (t *trie) match(input []string) ([]int, bool) {
15 if t.branch == nil {
16 t.branch = &branch{}
17 }
18 b := t.branch
19 path := []int{}
20 offset := 0
21 num := len(input)
22 for i := 0; i < num; i++ {
23 // if we're on a nil branch, we're at the end of our line
24 if b == nil {
25 return path, false
26 }
27 offset = pickNextBranch(b, offset, input[i])
28 if offset == -1 {
29 if len(path) == 0 {
30 // can't find it, bail
31 return path, false
32 }
33 // no match, backup
34 path, offset = backup(path)
35 offset = offset + 1 // we want the next index from the previously matched one
36 b = b.parent // we need to be picking a branch from our parent, again
37 i = i - 2 // back up to the choice before the one that got us here
38 } else {
39 path = append(path, offset)
40 b = b.children[offset]
41 offset = 0
42 }
43 }
44 return path, true
45 }
47 type branch struct {
48 parent *branch
49 children []*branch
50 key string
51 isParam bool
52 methods map[string]http.Handler
53 }
55 func (b *branch) Less(i, j int) bool {
56 if b.children[i].key == b.children[j].key {
57 return b.children[j].isParam && !b.children[i].isParam
58 }
59 return b.children[i].key < b.children[j].key
60 }
62 func (b *branch) Len() int {
63 return len(b.children)
64 }
66 func (b *branch) Swap(i, j int) {
67 b.children[i], b.children[j] = b.children[j], b.children[i]
68 }
70 func (b *branch) addChild(key string, param bool) *branch {
71 child := &branch{key: key, parent: b, isParam: param}
72 if b.children == nil {
73 b.children = []*branch{child}
74 return child
75 }
76 b.children = append(b.children, child)
77 sort.Sort(b)
78 return child
79 }
81 func (b *branch) check(input string) bool {
82 if b.isParam && b.key != "" {
83 return true
84 }
85 if b.key == input {
86 return true
87 }
88 return false
89 }
91 func (b *branch) setHandler(method string, handler http.Handler) {
92 if b.methods == nil {
93 b.methods = map[string]http.Handler{}
94 }
95 b.methods[method] = handler
96 }
98 func pickNextBranch(b *branch, offset int, input string) int {
99 count := len(b.children)
100 for i := offset; i < count; i++ {
101 if b.children[i].check(input) {
102 return i
103 }
104 }
105 return -1
106 }
108 func backup(path []int) ([]int, int) {
109 last := len(path) - 1
110 pos := path[last]
111 path = path[:last]
112 return path, pos
113 }