// Copyright 2013 Julien Schmidt. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file.
package httprouter
import (
"strings"
"unicode"
"unicode/utf8"
)
func min(a, b int) int {
if a <= b {
return a
}
return b
}
func countParams(path string) uint8 {
var n uint
for i := 0; i < len(path); i++ {
if path[i] != ':' && path[i] != '*' {
continue
}
n++
}
if n >= 255 {
return 255
}
return uint8(n)
}
type nodeType uint8
const (
static nodeType = iota // default
root
param
catchAll
)
type node struct {
path string
wildChild bool
nType nodeType
maxParams uint8
indices string
children []*node
handle Handle
priority uint32
}
// increments priority of the given child and reorders if necessary
func (n *node) incrementChildPrio(pos int) int {
n.children[pos].priority++
prio := n.children[pos].priority
// adjust position (move to front)
newPos := pos
for newPos > 0 && n.children[newPos-1].priority < prio {
// swap node positions
n.children[newPos-1], n.children[newPos] = n.children[newPos], n.children[newPos-1]
newPos--
}
// build new index char string
if newPos != pos {
n.indices = n.indices[:newPos] + // unchanged prefix, might be empty
n.indices[pos:pos+1] + // the index char we move
n.indices[newPos:pos] + n.indices[pos+1:] // rest without char at 'pos'
}
return newPos
}
// addRoute adds a node with the given handle to the path.
// Not concurrency-safe!
func (n *node) addRoute(path string, handle Handle) {
fullPath := path
n.priority++
numParams := countParams(path)
// non-empty tree
if len(n.path) > 0 || len(n.children) > 0 {
walk:
for {
// Update maxParams of the current node
if numParams > n.maxParams {
n.maxParams = numParams
}
// Find the longest common prefix.
// This also implies that the common prefix contains no ':' or '*'
// since the existing key can't contain those chars.
i := 0
max := min(len(path), len(n.path))
for i < max && path[i] == n.path[i] {
i++
}
// Split edge
if i < len(n.path) {
child := node{
path: n.path[i:],
wildChild: n.wildChild,
nType: static,
indices: n.indices,
children: n.children,
handle: n.handle,
priority: n.priority - 1,
}
// Update maxParams (max of all children)
for i := range child.children {
if child.children[i].maxParams > child.maxParams {
child.maxParams = child.children[i].maxParams
}
}
n.children = []*node{&child}
// []byte for proper unicode char conversion, see #65
n.indices = string([]byte{n.path[i]})
n.path = path[:i]
n.handle = nil
n.wildChild = false
}
// Make new node a child of this node
if i < len(path) {
path = path[i:]
if n.wildChild {
n = n.children[0]
n.priority++
// Update maxParams of the child node
if numParams > n.maxParams {
n.maxParams = numParams
}
numParams--
// Check if the wildcard matches
if len(path) >= len(n.path) && n.path == path[:len(n.path)] &&
// Check for longer wildcard, e.g. :name and :names
(len(n.path) >= len(path) || path[len(n.path)] == '/') {
continue walk
} else {
// Wildcard conflict
var pathSeg string
if n.nType == catchAll {
pathSeg = path
} else {
pathSeg = strings.SplitN(path, "/", 2)[0]
}
prefix := fullPath[:strings.Index(fullPath, pathSeg)] + n.path
panic("'" + pathSeg +
"' in new path '" + fullPath +
"' conflicts with existing wildcard '" + n.path +
"' in existing prefix '" + prefix +
"'")
}
}
c := path[0]
// slash after param
if n.nType == param && c == '/' && len(n.children) == 1 {
n = n.children[0]
n.priority++
continue walk
}
// Check if a child with the next path byte exists
for i := 0; i < len(n.indices); i++ {
if c == n.indices[i] {
i = n.incrementChildPrio(i)
n = n.children[i]
continue walk
}
}
// Otherwise insert it
if c != ':' && c != '*' {
// []byte for proper unicode char conversion, see #65
n.indices += string([]byte{c})
child := &node{
maxParams: numParams,
}
n.children = append(n.children, child)
n.incrementChildPrio(len(n.indices) - 1)
n = child
}
n.insertChild(numParams, path, fullPath, handle)
return
} else if i == len(path) { // Make node a (in-path) leaf
if n.handle != nil {
panic("a handle is already registered for path '" + fullPath + "'")
}
n.handle = handle
}
return
}
} else { // Empty tree
n.insertChild(numParams, path, fullPath, handle)
n.nType = root
}
}
func (n *node) insertChild(numParams uint8, path, fullPath string, handle Handle) {
var offset int // already handled bytes of the path
// find prefix until first wildcard (beginning with ':'' or '*'')
for i, max := 0, len(path); numParams > 0; i++ {
c := path[i]
if c != ':' && c != '*' {
continue
}
// find wildcard end (either '/' or path end)
end := i + 1
for end < max && path[end] != '/' {
switch path[end] {
// the wildcard name must not contain ':' and '*'
case ':', '*':
panic("only one wildcard per path segment is allowed, has: '" +
path[i:] + "' in path '" + fullPath + "'")
default:
end++
}
}
// check if this Node existing children which would be
// unreachable if we insert the wildcard here
if len(n.children) > 0 {
panic("wildcard route '" + path[i:end] +
"' conflicts with existing children in path '" + fullPath + "'")
}
// check if the wildcard has a name
if end-i < 2 {
panic("wildcards must be named with a non-empty name in path '" + fullPath + "'")
}
if c == ':' { // param
// split path at the beginning of the wildcard
if i > 0 {
n.path = path[offset:i]
offset = i
}
child := &node{
nType: param,
maxParams: numParams,
}
n.children = []*node{child}
n.wildChild = true
n = child
n.priority++
numParams--
// if the path doesn't end with the wildcard, then there
// will be another non-wildcard subpath starting with '/'
if end < max {
n.path = path[offset:end]
offset = end
child := &node{
maxParams: numParams,
priority: 1,
}
n.children = []*node{child}
n = child
}
} else { // catchAll
if end != max || numParams > 1 {
panic("catch-all routes are only allowed at the end of the path in path '" + fullPath + "'")
}
if len(n.path) > 0 && n.path[len(n.path)-1] == '/' {
panic("catch-all conflicts with existing handle for the path segment root in path '" + fullPath + "'")
}
// currently fixed width 1 for '/'
i--
if path[i] != '/' {
panic("no / before catch-all in path '" + fullPath + "'")
}
n.path = path[offset:i]
// first node: catchAll node with empty path
child := &node{
wildChild: true,
nType: catchAll,
maxParams: 1,
}
n.children = []*node{child}
n.indices = string(path[i])
n = child
n.priority++
// second node: node holding the variable
child = &node{
path: path[i:],
nType: catchAll,
maxParams: 1,
handle: handle,
priority: 1,
}
n.children = []*node{child}
return
}
}
// insert remaining path part and handle to the leaf
n.path = path[offset:]
n.handle = handle
}
// Returns the handle registered with the given path (key). The values of
// wildcards are saved to a map.
// If no handle can be found, a TSR (trailing slash redirect) recommendation is
// made if a handle exists with an extra (without the) trailing slash for the
// given path.
func (n *node) getValue(path string) (handle Handle, p Params, tsr bool) {
walk: // outer loop for walking the tree
for {
if len(path) > len(n.path) {
if path[:len(n.path)] == n.path {
path = path[len(n.path):]
// If this node does not have a wildcard (param or catchAll)
// child, we can just look up the next child node and continue
// to walk down the tree
if !n.wildChild {
c := path[0]
for i := 0; i < len(n.indices); i++ {
if c == n.indices[i] {
n = n.children[i]
continue walk
}
}
// Nothing found.
// We can recommend to redirect to the same URL without a
// trailing slash if a leaf exists for that path.
tsr = (path == "/" && n.handle != nil)
return
}
// handle wildcard child
n = n.children[0]
switch n.nType {
case param:
// find param end (either '/' or path end)
end := 0
for end < len(path) && path[end] != '/' {
end++
}
// save param value
if p == nil {
// lazy allocation
p = make(Params, 0, n.maxParams)
}
i := len(p)
p = p[:i+1] // expand slice within preallocated capacity
p[i].Key = n.path[1:]
p[i].Value = path[:end]
// we need to go deeper!
if end < len(path) {
if len(n.children) > 0 {
path = path[end:]
n = n.children[0]
continue walk
}
// ... but we can't
tsr = (len(path) == end+1)
return
}
if handle = n.handle; handle != nil {
return
} else if len(n.children) == 1 {
// No handle found. Check if a handle for this path + a
// trailing slash exists for TSR recommendation
n = n.children[0]
tsr = (n.path == "/" && n.handle != nil)
}
return
case catchAll:
// save param value
if p == nil {
// lazy allocation
p = make(Params, 0, n.maxParams)
}
i := len(p)
p = p[:i+1] // expand slice within preallocated capacity
p[i].Key = n.path[2:]
p[i].Value = path
handle = n.handle
return
default:
panic("invalid node type")
}
}
} else if path == n.path {
// We should have reached the node containing the handle.
// Check if this node has a handle registered.
if handle = n.handle; handle != nil {
return
}
if path == "/" && n.wildChild && n.nType != root {
tsr = true
return
}
// No handle found. Check if a handle for this path + a
// trailing slash exists for trailing slash recommendation
for i := 0; i < len(n.indices); i++ {
if n.indices[i] == '/' {
n = n.children[i]
tsr = (len(n.path) == 1 && n.handle != nil) ||
(n.nType == catchAll && n.children[0].handle != nil)
return
}
}
return
}
// Nothing found. We can recommend to redirect to the same URL with an
// extra trailing slash if a leaf exists for that path
tsr = (path == "/") ||
(len(n.path) == len(path)+1 && n.path[len(path)] == '/' &&
path == n.path[:len(n.path)-1] && n.handle != nil)
return
}
}
// Makes a case-insensitive lookup of the given path and tries to find a handler.
// It can optionally also fix trailing slashes.
// It returns the case-corrected path and a bool indicating whether the lookup
// was successful.
func (n *node) findCaseInsensitivePath(path string, fixTrailingSlash bool) (ciPath []byte, found bool) {
return n.findCaseInsensitivePathRec(
path,
strings.ToLower(path),
make([]byte, 0, len(path)+1), // preallocate enough memory for new path
[4]byte{}, // empty rune buffer
fixTrailingSlash,
)
}
// shift bytes in array by n bytes left
func shiftNRuneBytes(rb [4]byte, n int) [4]byte {
switch n {
case 0:
return rb
case 1:
return [4]byte{rb[1], rb[2], rb[3], 0}
case 2:
return [4]byte{rb[2], rb[3]}
case 3:
return [4]byte{rb[3]}
default:
return [4]byte{}
}
}
// recursive case-insensitive lookup function used by n.findCaseInsensitivePath
func (n *node) findCaseInsensitivePathRec(path, loPath string, ciPath []byte, rb [4]byte, fixTrailingSlash bool) ([]byte, bool) {
loNPath := strings.ToLower(n.path)
walk: // outer loop for walking the tree
for len(loPath) >= len(loNPath) && (len(loNPath) == 0 || loPath[1:len(loNPath)] == loNPath[1:]) {
// add common path to result
ciPath = append(ciPath, n.path...)
if path = path[len(n.path):]; len(path) > 0 {
loOld := loPath
loPath = loPath[len(loNPath):]
// If this node does not have a wildcard (param or catchAll) child,
// we can just look up the next child node and continue to walk down
// the tree
if !n.wildChild {
// skip rune bytes already processed
rb = shiftNRuneBytes(rb, len(loNPath))
if rb[0] != 0 {
// old rune not finished
for i := 0; i < len(n.indices); i++ {
if n.indices[i] == rb[0] {
// continue with child node
n = n.children[i]
loNPath = strings.ToLower(n.path)
continue walk
}
}
} else {
// process a new rune
var rv rune
// find rune start
// runes are up to 4 byte long,
// -4 would definitely be another rune
var off int
for max := min(len(loNPath), 3); off < max; off++ {
if i := len(loNPath) - off; utf8.RuneStart(loOld[i]) {
// read rune from cached lowercase path
rv, _ = utf8.DecodeRuneInString(loOld[i:])
break
}
}
// calculate lowercase bytes of current rune
utf8.EncodeRune(rb[:], rv)
// skipp already processed bytes
rb = shiftNRuneBytes(rb, off)
for i := 0; i < len(n.indices); i++ {
// lowercase matches
if n.indices[i] == rb[0] {
// must use a recursive approach since both the
// uppercase byte and the lowercase byte might exist
// as an index
if out, found := n.children[i].findCaseInsensitivePathRec(
path, loPath, ciPath, rb, fixTrailingSlash,
); found {
return out, true
}
break
}
}
// same for uppercase rune, if it differs
if up := unicode.ToUpper(rv); up != rv {
utf8.EncodeRune(rb[:], up)
rb = shiftNRuneBytes(rb, off)
for i := 0; i < len(n.indices); i++ {
// uppercase matches
if n.indices[i] == rb[0] {
// continue with child node
n = n.children[i]
loNPath = strings.ToLower(n.path)
continue walk
}
}
}
}
// Nothing found. We can recommend to redirect to the same URL
// without a trailing slash if a leaf exists for that path
return ciPath, (fixTrailingSlash && path == "/" && n.handle != nil)
}
n = n.children[0]
switch n.nType {
case param:
// find param end (either '/' or path end)
k := 0
for k < len(path) && path[k] != '/' {
k++
}
// add param value to case insensitive path
ciPath = append(ciPath, path[:k]...)
// we need to go deeper!
if k < len(path) {
if len(n.children) > 0 {
// continue with child node
n = n.children[0]
loNPath = strings.ToLower(n.path)
loPath = loPath[k:]
path = path[k:]
continue
}
// ... but we can't
if fixTrailingSlash && len(path) == k+1 {
return ciPath, true
}
return ciPath, false
}
if n.handle != nil {
return ciPath, true
} else if fixTrailingSlash && len(n.children) == 1 {
// No handle found. Check if a handle for this path + a
// trailing slash exists
n = n.children[0]
if n.path == "/" && n.handle != nil {
return append(ciPath, '/'), true
}
}
return ciPath, false
case catchAll:
return append(ciPath, path...), true
default:
panic("invalid node type")
}
} else {
// We should have reached the node containing the handle.
// Check if this node has a handle registered.
if n.handle != nil {
return ciPath, true
}
// No handle found.
// Try to fix the path by adding a trailing slash
if fixTrailingSlash {
for i := 0; i < len(n.indices); i++ {
if n.indices[i] == '/' {
n = n.children[i]
if (len(n.path) == 1 && n.handle != nil) ||
(n.nType == catchAll && n.children[0].handle != nil) {
return append(ciPath, '/'), true
}
return ciPath, false
}
}
}
return ciPath, false
}
}
// Nothing found.
// Try to fix the path by adding / removing a trailing slash
if fixTrailingSlash {
if path == "/" {
return ciPath, true
}
if len(loPath)+1 == len(loNPath) && loNPath[len(loPath)] == '/' &&
loPath[1:] == loNPath[1:len(loPath)] && n.handle != nil {
return append(ciPath, n.path...), true
}
}
return ciPath, false
}