micro/util/http/trie.go
Vasiliy Tolstov 74765b4c5f many lint fixes
Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>
2022-01-10 16:47:37 +03:00

709 lines
16 KiB
Go

package http
// Radix tree implementation below is a based on the original work by
// Armon Dadgar in https://github.com/armon/go-radix/blob/master/radix.go
// (MIT licensed). It's been heavily modified for use as a HTTP routing tree.
// Copied from chi mux tree.go https://raw.githubusercontent.com/go-chi/chi/master/tree.go
// Modified by Unistack LLC to support interface{} type handler and parameters in map[string]string
import (
"fmt"
"net/http"
"regexp"
"sort"
"strconv"
"strings"
)
type methodTyp uint
const (
mSTUB methodTyp = 1 << iota
mCONNECT
mDELETE
mGET
mHEAD
mOPTIONS
mPATCH
mPOST
mPUT
mTRACE
)
var mALL = mCONNECT | mDELETE | mGET | mHEAD |
mOPTIONS | mPATCH | mPOST | mPUT | mTRACE
var methodMap = map[string]methodTyp{
http.MethodConnect: mCONNECT,
http.MethodDelete: mDELETE,
http.MethodGet: mGET,
http.MethodHead: mHEAD,
http.MethodOptions: mOPTIONS,
http.MethodPatch: mPATCH,
http.MethodPost: mPOST,
http.MethodPut: mPUT,
http.MethodTrace: mTRACE,
}
// RegisterMethod adds support for custom HTTP method handlers
func RegisterMethod(method string) error {
if method == "" {
return nil
}
method = strings.ToUpper(method)
if _, ok := methodMap[method]; ok {
return nil
}
n := len(methodMap)
if n > strconv.IntSize-2 {
return fmt.Errorf("max number of methods reached (%d)", strconv.IntSize)
}
mt := methodTyp(2 << n)
methodMap[method] = mt
mALL |= mt
return nil
}
type nodeTyp uint8
const (
ntStatic nodeTyp = iota // /home
ntRegexp // /{id:[0-9]+}
ntParam // /{user}
ntCatchAll // /api/v1/*
)
// NewTrie create new tree
func NewTrie() *Trie {
return &Trie{}
}
// Trie holds nodes for path based tree search
type Trie struct {
// regexp matcher for regexp nodes
rex *regexp.Regexp
// HTTP handler endpoints on the leaf node
endpoints endpoints
// prefix is the common prefix we ignore
prefix string
// child nodes should be stored in-order for iteration,
// in groups of the node type.
children [ntCatchAll + 1]nodes
// first byte of the child prefix
tail byte
// node type: static, regexp, param, catchAll
typ nodeTyp
// first byte of the prefix
label byte
}
// endpoints is a mapping of http method constants to handlers
// for a given route.
type endpoints map[methodTyp]*endpoint
type endpoint struct {
// endpoint handler
handler interface{}
// pattern is the routing pattern for handler nodes
pattern string
// parameters keys recorded on handler nodes
paramKeys []string
}
func (s endpoints) Value(method methodTyp) *endpoint {
mh, ok := s[method]
if !ok {
mh = &endpoint{}
s[method] = mh
}
return mh
}
// Insert add elemenent to tree
func (n *Trie) Insert(methods []string, pattern string, handler interface{}) error {
var err error
for _, method := range methods {
if err = n.insert(methodMap[method], pattern, handler); err != nil {
return err
}
}
return nil
}
func (n *Trie) insert(method methodTyp, pattern string, handler interface{}) error {
var parent *Trie
search := pattern
for {
// Handle key exhaustion
if len(search) == 0 {
// Insert or update the node's leaf handler
return n.setEndpoint(method, handler, pattern)
}
// We're going to be searching for a wild node next,
// in this case, we need to get the tail
label := search[0]
var segTail byte
var segEndIdx int
var segTyp nodeTyp
var segRexpat string
var err error
if label == '{' || label == '*' {
segTyp, _, segRexpat, segTail, _, segEndIdx, err = patNextSegment(search)
}
if err != nil {
return err
}
var prefix string
if segTyp == ntRegexp {
prefix = segRexpat
}
// Look for the edge to attach to
parent = n
n = n.getEdge(segTyp, label, segTail, prefix)
// No edge, create one
if n == nil {
child := &Trie{typ: ntStatic, label: label, tail: segTail, prefix: search}
var hn *Trie
hn, err = parent.addChild(child, search)
if err != nil {
return err
}
return hn.setEndpoint(method, handler, pattern)
}
// Found an edge to match the pattern
if n.typ > ntStatic {
// We found a param node, trim the param from the search path and continue.
// This param/wild pattern segment would already be on the tree from a previous
// call to addChild when creating a new node.
search = search[segEndIdx:]
continue
}
// Static nodes fall below here.
// Determine longest prefix of the search key on match.
commonPrefix := longestPrefix(search, n.prefix)
if commonPrefix == len(n.prefix) {
// the common prefix is as long as the current node's prefix we're attempting to insert.
// keep the search going.
search = search[commonPrefix:]
continue
}
// Split the node
child := &Trie{
typ: ntStatic,
prefix: search[:commonPrefix],
}
if err = parent.replaceChild(search[0], segTail, child); err != nil {
return err
}
// Restore the existing node
n.label = n.prefix[commonPrefix]
n.prefix = n.prefix[commonPrefix:]
if _, err = child.addChild(n, n.prefix); err != nil {
return err
}
// If the new key is a subset, set the method/handler on this node and finish.
search = search[commonPrefix:]
if len(search) == 0 {
return child.setEndpoint(method, handler, pattern)
}
// Create a new edge for the node
subchild := &Trie{
typ: ntStatic,
label: search[0],
prefix: search,
}
var hn *Trie
hn, err = child.addChild(subchild, search)
if err != nil {
return err
}
return hn.setEndpoint(method, handler, pattern)
}
}
// addChild appends the new `child` node to the tree using the `pattern` as the trie key.
// For a URL router like chi's, we split the static, param, regexp and wildcard segments
// into different nodes. In addition, addChild will recursively call itself until every
// pattern segment is added to the url pattern tree as individual nodes, depending on type.
func (n *Trie) addChild(child *Trie, prefix string) (*Trie, error) {
search := prefix
// handler leaf node added to the tree is the child.
// this may be overridden later down the flow
hn := child
// Parse next segment
segTyp, _, segRexpat, segTail, segStartIdx, segEndIdx, err := patNextSegment(search)
if err != nil {
return nil, err
}
// Add child depending on next up segment
switch segTyp {
case ntStatic:
// Search prefix is all static (that is, has no params in path)
// noop
default:
// Search prefix contains a param, regexp or wildcard
if segTyp == ntRegexp {
rex, err := regexp.Compile(segRexpat)
if err != nil {
return nil, fmt.Errorf("invalid regexp pattern '%s' in route param", segRexpat)
}
child.prefix = segRexpat
child.rex = rex
}
switch {
case segStartIdx == 0:
// Route starts with a param
child.typ = segTyp
if segTyp == ntCatchAll {
segStartIdx = -1
} else {
segStartIdx = segEndIdx
}
if segStartIdx < 0 {
segStartIdx = len(search)
}
child.tail = segTail // for params, we set the tail
if segStartIdx != len(search) {
// add static edge for the remaining part, split the end.
// its not possible to have adjacent param nodes, so its certainly
// going to be a static node next.
search = search[segStartIdx:] // advance search position
nn := &Trie{
typ: ntStatic,
label: search[0],
prefix: search,
}
var err error
hn, err = child.addChild(nn, search)
if err != nil {
return nil, err
}
}
case segStartIdx > 0:
// Route has some param
// starts with a static segment
child.typ = ntStatic
child.prefix = search[:segStartIdx]
child.rex = nil
// add the param edge node
search = search[segStartIdx:]
nn := &Trie{
typ: segTyp,
label: search[0],
tail: segTail,
}
var err error
hn, err = child.addChild(nn, search)
if err != nil {
return nil, err
}
}
}
n.children[child.typ] = append(n.children[child.typ], child)
n.children[child.typ].Sort()
return hn, nil
}
func (n *Trie) replaceChild(label, tail byte, child *Trie) error {
for i := 0; i < len(n.children[child.typ]); i++ {
if n.children[child.typ][i].label == label && n.children[child.typ][i].tail == tail {
n.children[child.typ][i] = child
n.children[child.typ][i].label = label
n.children[child.typ][i].tail = tail
return nil
}
}
return fmt.Errorf("replacing missing child")
}
func (n *Trie) getEdge(ntyp nodeTyp, label, tail byte, prefix string) *Trie {
nds := n.children[ntyp]
for i := 0; i < len(nds); i++ {
if nds[i].label == label && nds[i].tail == tail {
if ntyp == ntRegexp && nds[i].prefix != prefix {
continue
}
return nds[i]
}
}
return nil
}
func (n *Trie) setEndpoint(method methodTyp, handler interface{}, pattern string) error {
// Set the handler for the method type on the node
if n.endpoints == nil {
n.endpoints = make(endpoints)
}
paramKeys, err := patParamKeys(pattern)
if err != nil {
return err
}
if method&mSTUB == mSTUB {
n.endpoints.Value(mSTUB).handler = handler
}
if method&mALL == mALL {
h := n.endpoints.Value(mALL)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
for _, m := range methodMap {
h := n.endpoints.Value(m)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
}
} else {
h := n.endpoints.Value(method)
h.handler = handler
h.pattern = pattern
h.paramKeys = paramKeys
}
return nil
}
// Search try to find element in tree with path and method
func (n *Trie) Search(method string, path string) (interface{}, map[string]string, bool) {
params := &routeParams{}
// Find the routing handlers for the path
rn := n.findRoute(params, methodMap[method], path)
if rn == nil {
return nil, nil, false
}
ep, ok := rn.endpoints[methodMap[method]]
if !ok {
return nil, nil, false
}
eparams := make(map[string]string, len(params.keys))
for idx, key := range params.keys {
eparams[key] = params.vals[idx]
}
return ep.handler, eparams, true
}
type routeParams struct {
keys []string
vals []string
}
// Recursive edge traversal by checking all nodeTyp groups along the way.
// It's like searching through a multi-dimensional radix trie.
func (n *Trie) findRoute(params *routeParams, method methodTyp, path string) *Trie {
nn := n
search := path
for t, nds := range nn.children {
ntyp := nodeTyp(t)
if len(nds) == 0 {
continue
}
var xn *Trie
xsearch := search
var label byte
if search != "" {
label = search[0]
}
switch ntyp {
case ntStatic:
xn = nds.findEdge(label)
if xn == nil || !strings.HasPrefix(xsearch, xn.prefix) {
continue
}
xsearch = xsearch[len(xn.prefix):]
case ntParam, ntRegexp:
// short-circuit and return no matching route for empty param values
if xsearch == "" {
continue
}
// serially loop through each node grouped by the tail delimiter
for idx := 0; idx < len(nds); idx++ {
xn = nds[idx]
// label for param nodes is the delimiter byte
p := strings.IndexByte(xsearch, xn.tail)
if p < 0 {
if xn.tail == '/' {
p = len(xsearch)
} else {
continue
}
} else if ntyp == ntRegexp && p == 0 {
continue
}
if ntyp == ntRegexp && xn.rex != nil {
if !xn.rex.MatchString(xsearch[:p]) {
continue
}
} else if strings.IndexByte(xsearch[:p], '/') != -1 {
// avoid a match across path segments
continue
}
prevlen := len(params.vals)
params.vals = append(params.vals, xsearch[:p])
xsearch = xsearch[p:]
if len(xsearch) == 0 {
if xn.isLeaf() {
h := xn.endpoints[method]
if h != nil && h.handler != nil {
params.keys = append(params.keys, h.paramKeys...)
return xn
}
}
}
// recursively find the next node on this branch
fin := xn.findRoute(params, method, xsearch)
if fin != nil {
return fin
}
// not found on this branch, reset vars
params.vals = params.vals[:prevlen]
xsearch = search
}
params.vals = append(params.vals, "")
default:
// catch-all nodes
params.vals = append(params.vals, search)
xn = nds[0]
xsearch = ""
}
if xn == nil {
continue
}
// did we find it yet?
if len(xsearch) == 0 {
if xn.isLeaf() {
h := xn.endpoints[method]
if h != nil && h.handler != nil {
params.keys = append(params.keys, h.paramKeys...)
return xn
}
}
}
// recursively find the next node..
fin := xn.findRoute(params, method, xsearch)
if fin != nil {
return fin
}
// Did not find final handler, let's remove the param here if it was set
if xn.typ > ntStatic {
if len(params.vals) > 0 {
params.vals = params.vals[:len(params.vals)-1]
}
}
}
return nil
}
func (n *Trie) isLeaf() bool {
return n.endpoints != nil
}
// patNextSegment returns the next segment details from a pattern:
// node type, param key, regexp string, param tail byte, param starting index, param ending index
func patNextSegment(pattern string) (nodeTyp, string, string, byte, int, int, error) {
ps := strings.Index(pattern, "{")
ws := strings.Index(pattern, "*")
if ps < 0 && ws < 0 {
return ntStatic, "", "", 0, 0, len(pattern), nil // we return the entire thing
}
// Sanity check
if ps >= 0 && ws >= 0 && ws < ps {
return ntStatic, "", "", 0, 0, 0, fmt.Errorf("wildcard '*' must be the last pattern in a route, otherwise use a '{param}'")
}
var tail byte = '/' // Default endpoint tail to / byte
if ps < 0 {
// Wildcard pattern as finale
if ws < len(pattern)-1 {
return ntStatic, "", "", 0, 0, 0, fmt.Errorf("wildcard '*' must be the last value in a route. trim trailing text or use a '{param}' instead")
}
return ntCatchAll, "*", "", 0, ws, len(pattern), nil
}
// Param/Regexp pattern is next
nt := ntParam
// Read to closing } taking into account opens and closes in curl count (cc)
cc := 0
pe := ps
for i, c := range pattern[ps:] {
if c == '{' {
cc++
} else if c == '}' {
cc--
if cc == 0 {
pe = ps + i
break
}
}
}
if pe == ps {
return ntStatic, "", "", 0, 0, 0, fmt.Errorf("route param closing delimiter '}' is missing")
}
key := pattern[ps+1 : pe]
pe++ // set end to next position
if pe < len(pattern) {
tail = pattern[pe]
}
var rexpat string
if idx := strings.Index(key, ":"); idx >= 0 {
nt = ntRegexp
rexpat = key[idx+1:]
key = key[:idx]
}
if len(rexpat) > 0 {
if rexpat[0] != '^' {
rexpat = "^" + rexpat
}
if rexpat[len(rexpat)-1] != '$' {
rexpat += "$"
}
}
return nt, key, rexpat, tail, ps, pe, nil
}
func patParamKeys(pattern string) ([]string, error) {
pat := pattern
paramKeys := []string{}
for {
ptyp, paramKey, _, _, _, e, err := patNextSegment(pat)
if err != nil {
return nil, err
}
if ptyp == ntStatic {
return paramKeys, nil
}
for i := 0; i < len(paramKeys); i++ {
if paramKeys[i] == paramKey {
return nil, fmt.Errorf("routing pattern '%s' contains duplicate param key, '%s'", pattern, paramKey)
}
}
paramKeys = append(paramKeys, paramKey)
pat = pat[e:]
}
}
// longestPrefix finds the length of the shared prefix
// of two strings
func longestPrefix(k1, k2 string) int {
max := len(k1)
if l := len(k2); l < max {
max = l
}
var i int
for i = 0; i < max; i++ {
if k1[i] != k2[i] {
break
}
}
return i
}
type nodes []*Trie
// Sort the list of nodes by label
func (ns nodes) Sort() { sort.Sort(ns); ns.tailSort() }
func (ns nodes) Len() int { return len(ns) }
func (ns nodes) Swap(i, j int) { ns[i], ns[j] = ns[j], ns[i] }
func (ns nodes) Less(i, j int) bool { return ns[i].label < ns[j].label }
// tailSort pushes nodes with '/' as the tail to the end of the list for param nodes.
// The list order determines the traversal order.
func (ns nodes) tailSort() {
for i := len(ns) - 1; i >= 0; i-- {
if ns[i].typ > ntStatic && ns[i].tail == '/' {
ns.Swap(i, len(ns)-1)
return
}
}
}
func (ns nodes) findEdge(label byte) *Trie {
num := len(ns)
idx := 0
i, j := 0, num-1
for i <= j {
idx = i + (j-i)/2
if label > ns[idx].label {
i = idx + 1
} else if label < ns[idx].label {
j = idx - 1
} else {
i = num // breaks cond
}
}
if ns[idx].label != label {
return nil
}
return ns[idx]
}