tree.go - third_party/julienschmidt/httprouter - Git at Google

 // 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
 						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
 }
	// 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
	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
	}