ad2642a8aa
* Implementation for calculating language statistics Impement saving code language statistics to database Implement rendering langauge stats Add primary laguage to show in repository list Implement repository stats indexer queue Add indexer test Refactor to use queue module * Do not timeout for queues
102 lines
2.4 KiB
Go
102 lines
2.4 KiB
Go
// Package trie is an implementation of a trie (prefix tree) data structure over byte slices. It provides a
|
|
// small and simple API for usage as a set as well as a 'Node' API for walking the trie.
|
|
package trie
|
|
|
|
// A Trie is a a prefix tree.
|
|
type Trie struct {
|
|
root *Node
|
|
}
|
|
|
|
// New construct a new, empty Trie ready for use.
|
|
func New() *Trie {
|
|
return &Trie{
|
|
root: &Node{},
|
|
}
|
|
}
|
|
|
|
// Insert puts b into the Trie. It returns true if the element was not previously in t.
|
|
func (t *Trie) Insert(b []byte) bool {
|
|
n := t.root
|
|
for _, c := range b {
|
|
next, ok := n.Walk(c)
|
|
if !ok {
|
|
next = &Node{}
|
|
n.branches[c] = next
|
|
n.hasChildren = true
|
|
}
|
|
n = next
|
|
}
|
|
if n.terminal {
|
|
return false
|
|
}
|
|
n.terminal = true
|
|
return true
|
|
}
|
|
|
|
// Contains checks t for membership of b.
|
|
func (t *Trie) Contains(b []byte) bool {
|
|
n := t.root
|
|
for _, c := range b {
|
|
next, ok := n.Walk(c)
|
|
if !ok {
|
|
return false
|
|
}
|
|
n = next
|
|
}
|
|
return n.terminal
|
|
}
|
|
|
|
// PrefixIndex walks through `b` until a prefix is found (terminal node) or it is exhausted.
|
|
func (t *Trie) PrefixIndex(b []byte) int {
|
|
var idx int
|
|
n := t.root
|
|
for _, c := range b {
|
|
next, ok := n.Walk(c)
|
|
if !ok {
|
|
return -1
|
|
}
|
|
if next.terminal {
|
|
return idx
|
|
}
|
|
n = next
|
|
idx++
|
|
}
|
|
if !n.terminal {
|
|
idx = -1
|
|
}
|
|
return idx
|
|
}
|
|
|
|
// Root returns the root node of a Trie. A valid Trie (i.e., constructed with New), always has a non-nil root
|
|
// node.
|
|
func (t *Trie) Root() *Node {
|
|
return t.root
|
|
}
|
|
|
|
// A Node represents a logical vertex in the trie structure.
|
|
type Node struct {
|
|
branches [256]*Node
|
|
terminal bool
|
|
hasChildren bool
|
|
}
|
|
|
|
// Walk returns the node reached along edge c, if one exists. The ok value indicates whether such a node
|
|
// exist.
|
|
func (n *Node) Walk(c byte) (next *Node, ok bool) {
|
|
next = n.branches[int(c)]
|
|
return next, (next != nil)
|
|
}
|
|
|
|
// Terminal indicates whether n is terminal in the trie (that is, whether the path from the root to n
|
|
// represents an element in the set). For instance, if the root node is terminal, then []byte{} is in the
|
|
// trie.
|
|
func (n *Node) Terminal() bool {
|
|
return n.terminal
|
|
}
|
|
|
|
// Leaf indicates whether n is a leaf node in the trie (that is, whether it has children). A leaf node must be
|
|
// terminal (else it would not exist). Logically, if n is a leaf node then the []byte represented by the path
|
|
// from the root to n is not a proper prefix of any element of the trie.
|
|
func (n *Node) Leaf() bool {
|
|
return !n.hasChildren
|
|
}
|