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gitea/vendor/github.com/go-openapi/runtime/middleware/denco/router.go
2020-09-01 10:01:23 -04:00

457 lines
11 KiB
Go
Vendored

// Package denco provides fast URL router.
package denco
import (
"fmt"
"sort"
"strings"
)
const (
// ParamCharacter is a special character for path parameter.
ParamCharacter = ':'
// WildcardCharacter is a special character for wildcard path parameter.
WildcardCharacter = '*'
// TerminationCharacter is a special character for end of path.
TerminationCharacter = '#'
// SeparatorCharacter separates path segments.
SeparatorCharacter = '/'
// MaxSize is max size of records and internal slice.
MaxSize = (1 << 22) - 1
)
// Router represents a URL router.
type Router struct {
// SizeHint expects the maximum number of path parameters in records to Build.
// SizeHint will be used to determine the capacity of the memory to allocate.
// By default, SizeHint will be determined from given records to Build.
SizeHint int
static map[string]interface{}
param *doubleArray
}
// New returns a new Router.
func New() *Router {
return &Router{
SizeHint: -1,
static: make(map[string]interface{}),
param: newDoubleArray(),
}
}
// Lookup returns data and path parameters that associated with path.
// params is a slice of the Param that arranged in the order in which parameters appeared.
// e.g. when built routing path is "/path/to/:id/:name" and given path is "/path/to/1/alice". params order is [{"id": "1"}, {"name": "alice"}], not [{"name": "alice"}, {"id": "1"}].
func (rt *Router) Lookup(path string) (data interface{}, params Params, found bool) {
if data, found := rt.static[path]; found {
return data, nil, true
}
if len(rt.param.node) == 1 {
return nil, nil, false
}
nd, params, found := rt.param.lookup(path, make([]Param, 0, rt.SizeHint), 1)
if !found {
return nil, nil, false
}
for i := 0; i < len(params); i++ {
params[i].Name = nd.paramNames[i]
}
return nd.data, params, true
}
// Build builds URL router from records.
func (rt *Router) Build(records []Record) error {
statics, params := makeRecords(records)
if len(params) > MaxSize {
return fmt.Errorf("denco: too many records")
}
if rt.SizeHint < 0 {
rt.SizeHint = 0
for _, p := range params {
size := 0
for _, k := range p.Key {
if k == ParamCharacter || k == WildcardCharacter {
size++
}
}
if size > rt.SizeHint {
rt.SizeHint = size
}
}
}
for _, r := range statics {
rt.static[r.Key] = r.Value
}
if err := rt.param.build(params, 1, 0, make(map[int]struct{})); err != nil {
return err
}
return nil
}
// Param represents name and value of path parameter.
type Param struct {
Name string
Value string
}
// Params represents the name and value of path parameters.
type Params []Param
// Get gets the first value associated with the given name.
// If there are no values associated with the key, Get returns "".
func (ps Params) Get(name string) string {
for _, p := range ps {
if p.Name == name {
return p.Value
}
}
return ""
}
type doubleArray struct {
bc []baseCheck
node []*node
}
func newDoubleArray() *doubleArray {
return &doubleArray{
bc: []baseCheck{0},
node: []*node{nil}, // A start index is adjusting to 1 because 0 will be used as a mark of non-existent node.
}
}
// baseCheck contains BASE, CHECK and Extra flags.
// From the top, 22bits of BASE, 2bits of Extra flags and 8bits of CHECK.
//
// BASE (22bit) | Extra flags (2bit) | CHECK (8bit)
// |----------------------|--|--------|
// 32 10 8 0
type baseCheck uint32
func (bc baseCheck) Base() int {
return int(bc >> 10)
}
func (bc *baseCheck) SetBase(base int) {
*bc |= baseCheck(base) << 10
}
func (bc baseCheck) Check() byte {
return byte(bc)
}
func (bc *baseCheck) SetCheck(check byte) {
*bc |= baseCheck(check)
}
func (bc baseCheck) IsEmpty() bool {
return bc&0xfffffcff == 0
}
func (bc baseCheck) IsSingleParam() bool {
return bc&paramTypeSingle == paramTypeSingle
}
func (bc baseCheck) IsWildcardParam() bool {
return bc&paramTypeWildcard == paramTypeWildcard
}
func (bc baseCheck) IsAnyParam() bool {
return bc&paramTypeAny != 0
}
func (bc *baseCheck) SetSingleParam() {
*bc |= (1 << 8)
}
func (bc *baseCheck) SetWildcardParam() {
*bc |= (1 << 9)
}
const (
paramTypeSingle = 0x0100
paramTypeWildcard = 0x0200
paramTypeAny = 0x0300
)
func (da *doubleArray) lookup(path string, params []Param, idx int) (*node, []Param, bool) {
indices := make([]uint64, 0, 1)
for i := 0; i < len(path); i++ {
if da.bc[idx].IsAnyParam() {
indices = append(indices, (uint64(i)<<32)|(uint64(idx)&0xffffffff))
}
c := path[i]
if idx = nextIndex(da.bc[idx].Base(), c); idx >= len(da.bc) || da.bc[idx].Check() != c {
goto BACKTRACKING
}
}
if next := nextIndex(da.bc[idx].Base(), TerminationCharacter); next < len(da.bc) && da.bc[next].Check() == TerminationCharacter {
return da.node[da.bc[next].Base()], params, true
}
BACKTRACKING:
for j := len(indices) - 1; j >= 0; j-- {
i, idx := int(indices[j]>>32), int(indices[j]&0xffffffff)
if da.bc[idx].IsSingleParam() {
idx := nextIndex(da.bc[idx].Base(), ParamCharacter)
if idx >= len(da.bc) {
break
}
next := NextSeparator(path, i)
params := append(params, Param{Value: path[i:next]})
if nd, params, found := da.lookup(path[next:], params, idx); found {
return nd, params, true
}
}
if da.bc[idx].IsWildcardParam() {
idx := nextIndex(da.bc[idx].Base(), WildcardCharacter)
params := append(params, Param{Value: path[i:]})
return da.node[da.bc[idx].Base()], params, true
}
}
return nil, nil, false
}
// build builds double-array from records.
func (da *doubleArray) build(srcs []*record, idx, depth int, usedBase map[int]struct{}) error {
sort.Stable(recordSlice(srcs))
base, siblings, leaf, err := da.arrange(srcs, idx, depth, usedBase)
if err != nil {
return err
}
if leaf != nil {
nd, err := makeNode(leaf)
if err != nil {
return err
}
da.bc[idx].SetBase(len(da.node))
da.node = append(da.node, nd)
}
for _, sib := range siblings {
da.setCheck(nextIndex(base, sib.c), sib.c)
}
for _, sib := range siblings {
records := srcs[sib.start:sib.end]
switch sib.c {
case ParamCharacter:
for _, r := range records {
next := NextSeparator(r.Key, depth+1)
name := r.Key[depth+1 : next]
r.paramNames = append(r.paramNames, name)
r.Key = r.Key[next:]
}
da.bc[idx].SetSingleParam()
if err := da.build(records, nextIndex(base, sib.c), 0, usedBase); err != nil {
return err
}
case WildcardCharacter:
r := records[0]
name := r.Key[depth+1 : len(r.Key)-1]
r.paramNames = append(r.paramNames, name)
r.Key = ""
da.bc[idx].SetWildcardParam()
if err := da.build(records, nextIndex(base, sib.c), 0, usedBase); err != nil {
return err
}
default:
if err := da.build(records, nextIndex(base, sib.c), depth+1, usedBase); err != nil {
return err
}
}
}
return nil
}
// setBase sets BASE.
func (da *doubleArray) setBase(i, base int) {
da.bc[i].SetBase(base)
}
// setCheck sets CHECK.
func (da *doubleArray) setCheck(i int, check byte) {
da.bc[i].SetCheck(check)
}
// findEmptyIndex returns an index of unused BASE/CHECK node.
func (da *doubleArray) findEmptyIndex(start int) int {
i := start
for ; i < len(da.bc); i++ {
if da.bc[i].IsEmpty() {
break
}
}
return i
}
// findBase returns good BASE.
func (da *doubleArray) findBase(siblings []sibling, start int, usedBase map[int]struct{}) (base int) {
for idx, firstChar := start+1, siblings[0].c; ; idx = da.findEmptyIndex(idx + 1) {
base = nextIndex(idx, firstChar)
if _, used := usedBase[base]; used {
continue
}
i := 0
for ; i < len(siblings); i++ {
next := nextIndex(base, siblings[i].c)
if len(da.bc) <= next {
da.bc = append(da.bc, make([]baseCheck, next-len(da.bc)+1)...)
}
if !da.bc[next].IsEmpty() {
break
}
}
if i == len(siblings) {
break
}
}
usedBase[base] = struct{}{}
return base
}
func (da *doubleArray) arrange(records []*record, idx, depth int, usedBase map[int]struct{}) (base int, siblings []sibling, leaf *record, err error) {
siblings, leaf, err = makeSiblings(records, depth)
if err != nil {
return -1, nil, nil, err
}
if len(siblings) < 1 {
return -1, nil, leaf, nil
}
base = da.findBase(siblings, idx, usedBase)
if base > MaxSize {
return -1, nil, nil, fmt.Errorf("denco: too many elements of internal slice")
}
da.setBase(idx, base)
return base, siblings, leaf, err
}
// node represents a node of Double-Array.
type node struct {
data interface{}
// Names of path parameters.
paramNames []string
}
// makeNode returns a new node from record.
func makeNode(r *record) (*node, error) {
dups := make(map[string]bool)
for _, name := range r.paramNames {
if dups[name] {
return nil, fmt.Errorf("denco: path parameter `%v' is duplicated in the key `%v'", name, r.Key)
}
dups[name] = true
}
return &node{data: r.Value, paramNames: r.paramNames}, nil
}
// sibling represents an intermediate data of build for Double-Array.
type sibling struct {
// An index of start of duplicated characters.
start int
// An index of end of duplicated characters.
end int
// A character of sibling.
c byte
}
// nextIndex returns a next index of array of BASE/CHECK.
func nextIndex(base int, c byte) int {
return base ^ int(c)
}
// makeSiblings returns slice of sibling.
func makeSiblings(records []*record, depth int) (sib []sibling, leaf *record, err error) {
var (
pc byte
n int
)
for i, r := range records {
if len(r.Key) <= depth {
leaf = r
continue
}
c := r.Key[depth]
switch {
case pc < c:
sib = append(sib, sibling{start: i, c: c})
case pc == c:
continue
default:
return nil, nil, fmt.Errorf("denco: BUG: routing table hasn't been sorted")
}
if n > 0 {
sib[n-1].end = i
}
pc = c
n++
}
if n == 0 {
return nil, leaf, nil
}
sib[n-1].end = len(records)
return sib, leaf, nil
}
// Record represents a record data for router construction.
type Record struct {
// Key for router construction.
Key string
// Result value for Key.
Value interface{}
}
// NewRecord returns a new Record.
func NewRecord(key string, value interface{}) Record {
return Record{
Key: key,
Value: value,
}
}
// record represents a record that use to build the Double-Array.
type record struct {
Record
paramNames []string
}
// makeRecords returns the records that use to build Double-Arrays.
func makeRecords(srcs []Record) (statics, params []*record) {
termChar := string(TerminationCharacter)
paramPrefix := string(SeparatorCharacter) + string(ParamCharacter)
wildcardPrefix := string(SeparatorCharacter) + string(WildcardCharacter)
for _, r := range srcs {
if strings.Contains(r.Key, paramPrefix) || strings.Contains(r.Key, wildcardPrefix) {
r.Key += termChar
params = append(params, &record{Record: r})
} else {
statics = append(statics, &record{Record: r})
}
}
return statics, params
}
// recordSlice represents a slice of Record for sort and implements the sort.Interface.
type recordSlice []*record
// Len implements the sort.Interface.Len.
func (rs recordSlice) Len() int {
return len(rs)
}
// Less implements the sort.Interface.Less.
func (rs recordSlice) Less(i, j int) bool {
return rs[i].Key < rs[j].Key
}
// Swap implements the sort.Interface.Swap.
func (rs recordSlice) Swap(i, j int) {
rs[i], rs[j] = rs[j], rs[i]
}