684 lines
16 KiB
Go
684 lines
16 KiB
Go
package router
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import (
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"strings"
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"unicode"
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"unicode/utf8"
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)
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func min(a, b int) int {
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if a <= b {
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return a
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}
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return b
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}
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func longestCommonPrefix(a, b string) int {
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i := 0
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max := min(len(a), len(b))
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for i < max && a[i] == b[i] {
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i++
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}
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return i
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}
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// Search for a wildcard segment and check the name for invalid characters.
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// Returns -1 as index, if no wildcard was found.
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func findWildcard(path string) (wilcard string, i int, valid bool) {
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// Find start
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for start, c := range []byte(path) {
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// A wildcard starts with ':' (param) or '*' (catch-all)
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if c != ':' && c != '*' {
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continue
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}
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// Find end and check for invalid characters
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valid = true
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for end, c := range []byte(path[start+1:]) {
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switch c {
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case '/':
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return path[start : start+1+end], start, valid
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case ':', '*':
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valid = false
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}
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}
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return path[start:], start, valid
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}
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return "", -1, false
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}
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func countParams(path string) uint16 {
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var n uint
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for i := range []byte(path) {
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switch path[i] {
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case ':', '*':
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n++
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}
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}
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return uint16(n)
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}
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type nodeType uint8
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const (
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static nodeType = iota // default
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root
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param
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catchAll
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)
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type node struct {
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path string
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indices string
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wildChild bool
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nType nodeType
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priority uint32
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children []*node
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handle Handle
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}
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// Increments priority of the given child and reorders if necessary
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func (n *node) incrementChildPrio(pos int) int {
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cs := n.children
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cs[pos].priority++
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prio := cs[pos].priority
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// Adjust position (move to front)
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newPos := pos
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for ; newPos > 0 && cs[newPos-1].priority < prio; newPos-- {
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// Swap node positions
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cs[newPos-1], cs[newPos] = cs[newPos], cs[newPos-1]
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}
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// Build new index char string
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if newPos != pos {
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n.indices = n.indices[:newPos] + // Unchanged prefix, might be empty
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n.indices[pos:pos+1] + // The index char we move
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n.indices[newPos:pos] + n.indices[pos+1:] // Rest without char at 'pos'
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}
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return newPos
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}
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// addRoute adds a node with the given handle to the path.
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// Not concurrency-safe!
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func (n *node) addRoute(path string, handle Handle, replace bool) {
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fullPath := path
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n.priority++
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// Empty tree
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if n.path == "" && n.indices == "" {
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n.insertChild(path, fullPath, handle)
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n.nType = root
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return
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}
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walk:
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for {
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// Find the longest common prefix.
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// This also implies that the common prefix contains no ':' or '*'
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// since the existing key can't contain those chars.
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i := longestCommonPrefix(path, n.path)
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// Split edge
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if i < len(n.path) {
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child := node{
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path: n.path[i:],
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wildChild: n.wildChild,
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nType: static,
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indices: n.indices,
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children: n.children,
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handle: n.handle,
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priority: n.priority - 1,
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}
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n.children = []*node{&child}
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// []byte for proper unicode char conversion, see #65
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n.indices = string([]byte{n.path[i]})
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n.path = path[:i]
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n.handle = nil
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n.wildChild = false
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}
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// Make new node a child of this node
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if i < len(path) {
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path = path[i:]
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if n.wildChild {
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n = n.children[0]
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n.priority++
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// Check if the wildcard matches
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if len(path) >= len(n.path) && n.path == path[:len(n.path)] &&
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// Adding a child to a catchAll is not possible
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n.nType != catchAll &&
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// Check for longer wildcard, e.g. :name and :names
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(len(n.path) >= len(path) || path[len(n.path)] == '/') {
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continue walk
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} else {
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// Wildcard conflict
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pathSeg := path
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if n.nType != catchAll {
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pathSeg = strings.SplitN(pathSeg, "/", 2)[0]
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}
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prefix := fullPath[:strings.Index(fullPath, pathSeg)] + n.path
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panic("'" + pathSeg +
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"' in new path '" + fullPath +
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"' conflicts with existing wildcard '" + n.path +
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"' in existing prefix '" + prefix +
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"'")
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}
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}
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idxc := path[0]
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// '/' after param
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if n.nType == param && idxc == '/' && len(n.children) == 1 {
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n = n.children[0]
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n.priority++
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continue walk
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}
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// Check if a child with the next path byte exists
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for i, c := range []byte(n.indices) {
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if c == idxc {
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i = n.incrementChildPrio(i)
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n = n.children[i]
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continue walk
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}
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}
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// Otherwise insert it
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if idxc != ':' && idxc != '*' {
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// []byte for proper unicode char conversion, see #65
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n.indices += string([]byte{idxc})
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child := &node{}
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n.children = append(n.children, child)
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n.incrementChildPrio(len(n.indices) - 1)
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n = child
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}
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n.insertChild(path, fullPath, handle)
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return
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}
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// Otherwise add handle to current node
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if !replace {
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if n.handle != nil {
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panic("a handle is already registered for path '" + fullPath + "'")
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}
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}
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n.handle = handle
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return
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}
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}
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func (n *node) insertChild(path, fullPath string, handle Handle) {
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for {
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// Find prefix until first wildcard
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wildcard, i, valid := findWildcard(path)
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if i < 0 { // No wilcard found
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break
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}
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// The wildcard name must not contain ':' and '*'
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if !valid {
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panic("only one wildcard per path segment is allowed, has: '" +
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wildcard + "' in path '" + fullPath + "'")
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}
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// Check if the wildcard has a name
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if len(wildcard) < 2 {
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panic("wildcards must be named with a non-empty name in path '" + fullPath + "'")
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}
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// Check if this node has existing children which would be
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// unreachable if we insert the wildcard here
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if len(n.children) > 0 {
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panic("wildcard segment '" + wildcard +
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"' conflicts with existing children in path '" + fullPath + "'")
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}
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// param
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if wildcard[0] == ':' {
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if i > 0 {
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// Insert prefix before the current wildcard
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n.path = path[:i]
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path = path[i:]
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}
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n.wildChild = true
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child := &node{
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nType: param,
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path: wildcard,
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}
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n.children = []*node{child}
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n = child
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n.priority++
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// If the path doesn't end with the wildcard, then there
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// will be another non-wildcard subpath starting with '/'
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if len(wildcard) < len(path) {
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path = path[len(wildcard):]
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child := &node{
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priority: 1,
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}
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n.children = []*node{child}
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n = child
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continue
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}
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// Otherwise we're done. Insert the handle in the new leaf
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n.handle = handle
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return
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}
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// catchAll
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if i+len(wildcard) != len(path) {
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panic("catch-all routes are only allowed at the end of the path in path '" + fullPath + "'")
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}
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if len(n.path) > 0 && n.path[len(n.path)-1] == '/' {
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panic("catch-all conflicts with existing handle for the path segment root in path '" + fullPath + "'")
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}
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// Currently fixed width 1 for '/'
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i--
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if path[i] != '/' {
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panic("no / before catch-all in path '" + fullPath + "'")
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}
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n.path = path[:i]
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// First node: catchAll node with empty path
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child := &node{
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wildChild: true,
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nType: catchAll,
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}
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n.children = []*node{child}
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n.indices = string('/')
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n = child
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n.priority++
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// Second node: node holding the variable
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child = &node{
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path: path[i:],
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nType: catchAll,
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handle: handle,
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priority: 1,
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}
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n.children = []*node{child}
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return
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}
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// If no wildcard was found, simply insert the path and handle
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n.path = path
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n.handle = handle
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}
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// Returns the handle registered with the given path (key). The values of
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// wildcards are saved to a map.
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// If no handle can be found, a TSR (trailing slash redirect) recommendation is
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// made if a handle exists with an extra (without the) trailing slash for the
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// given path.
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func (n *node) getValue(path string, params func() *Params) (handle Handle, ps *Params, tsr bool) {
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walk: // Outer loop for walking the tree
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for {
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prefix := n.path
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if len(path) > len(prefix) {
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if path[:len(prefix)] == prefix {
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path = path[len(prefix):]
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// If this node does not have a wildcard (param or catchAll)
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// child, we can just look up the next child node and continue
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// to walk down the tree
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if !n.wildChild {
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idxc := path[0]
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for i, c := range []byte(n.indices) {
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if c == idxc {
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n = n.children[i]
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continue walk
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}
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}
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// Nothing found.
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// We can recommend to redirect to the same URL without a
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// trailing slash if a leaf exists for that path.
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tsr = (path == "/" && n.handle != nil)
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return
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}
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// Handle wildcard child
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n = n.children[0]
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switch n.nType {
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case param:
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// Find param end (either '/' or path end)
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end := 0
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for end < len(path) && path[end] != '/' {
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end++
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}
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// Save param value
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if params != nil {
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if ps == nil {
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ps = params()
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}
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// Expand slice within preallocated capacity
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i := len(*ps)
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*ps = (*ps)[:i+1]
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(*ps)[i] = Param{
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Key: n.path[1:],
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Value: path[:end],
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}
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}
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// We need to go deeper!
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if end < len(path) {
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if len(n.children) > 0 {
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path = path[end:]
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n = n.children[0]
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continue walk
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}
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// ... but we can't
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tsr = (len(path) == end+1)
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return
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}
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if handle = n.handle; handle != nil {
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return
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} else if len(n.children) == 1 {
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// No handle found. Check if a handle for this path + a
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// trailing slash exists for TSR recommendation
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n = n.children[0]
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tsr = (n.path == "/" && n.handle != nil) || (n.path == "" && n.indices == "/")
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}
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return
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case catchAll:
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// Save param value
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if params != nil {
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if ps == nil {
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ps = params()
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}
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// Expand slice within preallocated capacity
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i := len(*ps)
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*ps = (*ps)[:i+1]
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(*ps)[i] = Param{
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Key: n.path[2:],
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Value: path,
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}
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}
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handle = n.handle
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return
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default:
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panic("invalid node type")
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}
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}
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} else if path == prefix {
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// We should have reached the node containing the handle.
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// Check if this node has a handle registered.
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if handle = n.handle; handle != nil {
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return
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}
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// If there is no handle for this route, but this route has a
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// wildcard child, there must be a handle for this path with an
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// additional trailing slash
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if path == "/" && n.wildChild && n.nType != root {
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tsr = true
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return
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}
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if path == "/" && n.nType == static {
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tsr = true
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return
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}
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// No handle found. Check if a handle for this path + a
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// trailing slash exists for trailing slash recommendation
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for i, c := range []byte(n.indices) {
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if c == '/' {
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n = n.children[i]
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tsr = (len(n.path) == 1 && n.handle != nil) ||
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(n.nType == catchAll && n.children[0].handle != nil)
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return
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}
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}
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return
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}
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// Nothing found. We can recommend to redirect to the same URL with an
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// extra trailing slash if a leaf exists for that path
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tsr = (path == "/") ||
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(len(prefix) == len(path)+1 && prefix[len(path)] == '/' &&
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path == prefix[:len(prefix)-1] && n.handle != nil)
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return
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}
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}
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// Makes a case-insensitive lookup of the given path and tries to find a handler.
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// It can optionally also fix trailing slashes.
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// It returns the case-corrected path and a bool indicating whether the lookup
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// was successful.
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func (n *node) findCaseInsensitivePath(path string, fixTrailingSlash bool) (fixedPath string, found bool) {
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const stackBufSize = 128
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// Use a static sized buffer on the stack in the common case.
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// If the path is too long, allocate a buffer on the heap instead.
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buf := make([]byte, 0, stackBufSize)
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if l := len(path) + 1; l > stackBufSize {
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buf = make([]byte, 0, l)
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}
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ciPath := n.findCaseInsensitivePathRec(
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path,
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buf, // Preallocate enough memory for new path
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[4]byte{}, // Empty rune buffer
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fixTrailingSlash,
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)
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return string(ciPath), ciPath != nil
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}
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// Shift bytes in array by n bytes left
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func shiftNRuneBytes(rb [4]byte, n int) [4]byte {
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switch n {
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case 0:
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return rb
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case 1:
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return [4]byte{rb[1], rb[2], rb[3], 0}
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case 2:
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return [4]byte{rb[2], rb[3]}
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case 3:
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return [4]byte{rb[3]}
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default:
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return [4]byte{}
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}
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}
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// Recursive case-insensitive lookup function used by n.findCaseInsensitivePath
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func (n *node) findCaseInsensitivePathRec(path string, ciPath []byte, rb [4]byte, fixTrailingSlash bool) []byte {
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npLen := len(n.path)
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walk: // Outer loop for walking the tree
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for len(path) >= npLen && (npLen == 0 || strings.EqualFold(path[1:npLen], n.path[1:])) {
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// Add common prefix to result
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oldPath := path
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path = path[npLen:]
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ciPath = append(ciPath, n.path...)
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if len(path) > 0 {
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// If this node does not have a wildcard (param or catchAll) child,
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// we can just look up the next child node and continue to walk down
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// the tree
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if !n.wildChild {
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// Skip rune bytes already processed
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rb = shiftNRuneBytes(rb, npLen)
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if rb[0] != 0 {
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// Old rune not finished
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idxc := rb[0]
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for i, c := range []byte(n.indices) {
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if c == idxc {
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// continue with child node
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n = n.children[i]
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npLen = len(n.path)
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continue walk
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}
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}
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} else {
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// Process a new rune
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var rv rune
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// Find rune start.
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// Runes are up to 4 byte long,
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// -4 would definitely be another rune.
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var off int
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for max := min(npLen, 3); off < max; off++ {
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if i := npLen - off; utf8.RuneStart(oldPath[i]) {
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// read rune from cached path
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rv, _ = utf8.DecodeRuneInString(oldPath[i:])
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break
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}
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}
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// Calculate lowercase bytes of current rune
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lo := unicode.ToLower(rv)
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utf8.EncodeRune(rb[:], lo)
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// Skip already processed bytes
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rb = shiftNRuneBytes(rb, off)
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idxc := rb[0]
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for i, c := range []byte(n.indices) {
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// Lowercase matches
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if c == idxc {
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// must use a recursive approach since both the
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// uppercase byte and the lowercase byte might exist
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// as an index
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if out := n.children[i].findCaseInsensitivePathRec(
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path, ciPath, rb, fixTrailingSlash,
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); out != nil {
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return out
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}
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break
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}
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}
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// If we found no match, the same for the uppercase rune,
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// if it differs
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if up := unicode.ToUpper(rv); up != lo {
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utf8.EncodeRune(rb[:], up)
|
|
rb = shiftNRuneBytes(rb, off)
|
|
|
|
idxc := rb[0]
|
|
for i, c := range []byte(n.indices) {
|
|
// Uppercase matches
|
|
if c == idxc {
|
|
// Continue with child node
|
|
n = n.children[i]
|
|
npLen = len(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
|
|
if fixTrailingSlash && path == "/" && n.handle != nil {
|
|
return ciPath
|
|
}
|
|
return nil
|
|
}
|
|
|
|
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++
|
|
}
|
|
|
|
// Add param value to case insensitive path
|
|
ciPath = append(ciPath, path[:end]...)
|
|
|
|
// We need to go deeper!
|
|
if end < len(path) {
|
|
if len(n.children) > 0 {
|
|
// Continue with child node
|
|
n = n.children[0]
|
|
npLen = len(n.path)
|
|
path = path[end:]
|
|
continue
|
|
}
|
|
|
|
// ... but we can't
|
|
if fixTrailingSlash && len(path) == end+1 {
|
|
return ciPath
|
|
}
|
|
return nil
|
|
}
|
|
|
|
if n.handle != nil {
|
|
return ciPath
|
|
} 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, '/')
|
|
}
|
|
}
|
|
return nil
|
|
|
|
case catchAll:
|
|
return append(ciPath, path...)
|
|
|
|
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
|
|
}
|
|
|
|
// No handle found.
|
|
// Try to fix the path by adding a trailing slash
|
|
if fixTrailingSlash {
|
|
for i, c := range []byte(n.indices) {
|
|
if c == '/' {
|
|
n = n.children[i]
|
|
if (len(n.path) == 1 && n.handle != nil) ||
|
|
(n.nType == catchAll && n.children[0].handle != nil) {
|
|
return append(ciPath, '/')
|
|
}
|
|
return nil
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
}
|
|
|
|
// Nothing found.
|
|
// Try to fix the path by adding / removing a trailing slash
|
|
if fixTrailingSlash {
|
|
if path == "/" {
|
|
return ciPath
|
|
}
|
|
if len(path)+1 == npLen && n.path[len(path)] == '/' &&
|
|
strings.EqualFold(path[1:], n.path[1:len(path)]) && n.handle != nil {
|
|
return append(ciPath, n.path...)
|
|
}
|
|
}
|
|
return nil
|
|
}
|