| // 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 = '#' |
| |
| // 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¶mTypeSingle == paramTypeSingle |
| } |
| |
| func (bc baseCheck) IsWildcardParam() bool { |
| return bc¶mTypeWildcard == paramTypeWildcard |
| } |
| |
| func (bc baseCheck) IsAnyParam() bool { |
| return bc¶mTypeAny != 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) { |
| spChars := string([]byte{ParamCharacter, WildcardCharacter}) |
| termChar := string(TerminationCharacter) |
| for _, r := range srcs { |
| if strings.ContainsAny(r.Key, spChars) { |
| 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] |
| } |