feat: add ahocorasick filter

Author: StellarisW

README-zh_cn.md

@@ -23,6 +23,7 @@
     - 支持运行过程中动态修改数据源
 - 支持多种过滤算法
     - **DFA** 使用 `trie tree` 数据结构匹配敏感词
+    - **AC 自动机**
 
 ## ⚙ Usage
 

README.md

@@ -14,7 +14,7 @@ English | [中文](README-zh_cn.md)
     - `IsSensitive()` Check whether the text has sensitive word
     - `FindOne()` return first sensitive word that has been found in the text
     - `FindAll()` return all sensitive word that has been found in the text
-    - `FindAllCount()` return all sensitive word with its count that has been found in the text
+    - `FindAllCount()` return all sensitive[README-zh_cn.md](README-zh_cn.md) word with its count that has been found in the text
 - support multiple data sources with dynamic modification
     - support memory storage
     - support mysql storage
@@ -23,7 +23,7 @@ English | [中文](README-zh_cn.md)
     - support dynamic add/del sensitive word while running
 - support multiple filter algorithms
     - **DFA** use `trie tree`  to filter sensitive words
-
+    - **Aho–Corasick algorithm** 
 ## ⚙ Usage
 
 ```go

filter/ahocorasick.go

@@ -0,0 +1,338 @@
+package filter
+
+import (
+	"github.com/sgoware/ds/queue/arrayqueue"
+)
+
+type acNode struct {
+	value    rune
+	children map[rune]*acNode
+	word     *string
+	fail     *acNode
+}
+
+func newAcNode(r rune) *acNode {
+	return &acNode{
+		value:    r,
+		children: make(map[rune]*acNode),
+		word:     nil,
+	}
+}
+
+type AcModel struct {
+	root *acNode
+}
+
+func NewAcModel() *AcModel {
+	return &AcModel{
+		root: newAcNode(0),
+	}
+}
+
+func (m *AcModel) AddWords(words ...string) {
+	for _, word := range words {
+		m.AddWord(word)
+	}
+
+	m.buildFailPointers()
+}
+
+func (m *AcModel) AddWord(word string) {
+	now := m.root
+	runes := []rune(word)
+
+	for _, r := range runes {
+		if next, ok := now.children[r]; ok {
+			now = next
+		} else {
+			next = newAcNode(r)
+			now.children[r] = next
+			now = next
+		}
+	}
+
+	now.word = new(string)
+	*now.word = word
+}
+
+func (m *AcModel) DelWords(words ...string) {
+	for _, word := range words {
+		m.DelWord(word)
+	}
+
+	m.buildFailPointers()
+}
+
+func (m *AcModel) DelWord(word string) {
+	var lastLeaf *acNode
+	var lastLeafNextRune rune
+	now := m.root
+	runes := []rune(word)
+
+	for _, r := range runes {
+		if next, ok := now.children[r]; !ok {
+			return
+		} else {
+			if now.word != nil {
+				lastLeaf = now
+				lastLeafNextRune = r
+			}
+			now = next
+		}
+	}
+
+	delete(lastLeaf.children, lastLeafNextRune)
+}
+
+func (m *AcModel) buildFailPointers() {
+	q := arrayqueue.New(m.root)
+
+	for q.Len() > 0 {
+		temp, _ := q.Top()
+		q.Pop()
+		for _, node := range temp.(*acNode).children {
+			if temp.(*acNode) == m.root {
+				node.fail = m.root
+			} else {
+				p := temp.(*acNode).fail
+				for p != nil {
+					if next, found := p.children[node.value]; found {
+						node.fail = next
+						break
+					}
+					p = p.fail
+				}
+				if p == nil {
+					node.fail = m.root
+				}
+			}
+
+			q.Push(node)
+		}
+	}
+}
+
+func (m *AcModel) Listen(addChan, delChan <-chan string) {
+	go func() {
+		var words []string
+
+		for word := range addChan {
+			words = append(words, word)
+			if len(addChan) == 0 {
+				m.AddWords(words...)
+				word = word[:0]
+			}
+		}
+	}()
+
+	go func() {
+		var words []string
+
+		for word := range delChan {
+			words = append(words, word)
+			if len(delChan) == 0 {
+				m.DelWords(words...)
+				word = word[:0]
+			}
+		}
+	}()
+}
+
+func (m *AcModel) FindAll(text string) []string {
+	var matches []string
+	var found bool
+
+	now := m.root
+	var temp *acNode
+	runes := []rune(text)
+
+	for pos := 0; pos < len(runes); pos++ {
+		_, found = now.children[runes[pos]]
+		if !found && now != m.root {
+			now = now.fail
+			for ; !found && now != m.root; now, found = now.children[runes[pos]] {
+				now = now.fail
+			}
+		}
+
+		// 若找到匹配成功的字符串结点, 则指向那个结点, 否则指向根结点
+		if next, ok := now.children[runes[pos]]; ok {
+			now = next
+		} else {
+			now = m.root
+		}
+
+		temp = now
+
+		for temp != m.root {
+			if temp.word != nil {
+				matches = append(matches, *temp.word)
+			}
+			temp = temp.fail
+		}
+	}
+
+	var res []string
+	set := make(map[string]struct{})
+
+	for _, word := range matches {
+		if _, ok := set[word]; !ok {
+			set[word] = struct{}{}
+			res = append(res, word)
+		}
+	}
+
+	return res
+}
+
+func (m *AcModel) FindAllCount(text string) map[string]int {
+	res := make(map[string]int)
+	var found bool
+	var temp *acNode
+
+	now := m.root
+	runes := []rune(text)
+
+	for pos := 0; pos < len(runes); pos++ {
+		_, found = now.children[runes[pos]]
+		if !found && now != m.root {
+			now = now.fail
+			for ; !found && now != m.root; now, found = now.children[runes[pos]] {
+				now = now.fail
+			}
+		}
+
+		// 若找到匹配成功的字符串结点, 则指向那个结点, 否则指向根结点
+		if next, ok := now.children[runes[pos]]; ok {
+			now = next
+		} else {
+			now = m.root
+		}
+
+		temp = now
+
+		for temp != m.root {
+			if temp.word != nil {
+				res[*temp.word]++
+			}
+			temp = temp.fail
+		}
+	}
+
+	return res
+}
+
+func (m *AcModel) FindOne(text string) string {
+	var found bool
+	var temp *acNode
+
+	now := m.root
+	runes := []rune(text)
+
+	for pos := 0; pos < len(runes); pos++ {
+		_, found = now.children[runes[pos]]
+		if !found && now != m.root {
+			now = now.fail
+			for ; !found && now != m.root; now, found = now.children[runes[pos]] {
+				now = now.fail
+			}
+		}
+
+		// 若找到匹配成功的字符串结点, 则指向那个结点, 否则指向根结点
+		if next, ok := now.children[runes[pos]]; ok {
+			now = next
+		} else {
+			now = m.root
+		}
+
+		temp = now
+
+		for temp != m.root {
+			if temp.word != nil {
+				return *temp.word
+			}
+			temp = temp.fail
+		}
+	}
+
+	return ""
+}
+
+func (m *AcModel) IsSensitive(text string) bool {
+	return m.FindOne(text) != ""
+}
+
+func (m *AcModel) Replace(text string, repl rune) string {
+	var found bool
+	var temp *acNode
+
+	now := m.root
+	runes := []rune(text)
+
+	for pos := 0; pos < len(runes); pos++ {
+		_, found = now.children[runes[pos]]
+		if !found && now != m.root {
+			now = now.fail
+			for ; !found && now != m.root; now, found = now.children[runes[pos]] {
+				now = now.fail
+			}
+		}
+
+		// 若找到匹配成功的字符串结点, 则指向那个结点, 否则指向根结点
+		if next, ok := now.children[runes[pos]]; ok {
+			now = next
+		} else {
+			now = m.root
+		}
+
+		temp = now
+
+		for temp != m.root {
+			if temp.word != nil {
+				for i := pos - len([]rune(*temp.word)) + 1; i <= pos; i++ {
+					runes[i] = repl
+				}
+			}
+			temp = temp.fail
+		}
+	}
+
+	return string(runes)
+}
+
+func (m *AcModel) Remove(text string) string {
+	var found bool
+	var temp *acNode
+
+	now := m.root
+	runes := []rune(text)
+
+	for pos := 0; pos < len(runes); pos++ {
+		_, found = now.children[runes[pos]]
+		if !found && now != m.root {
+			now = now.fail
+			for ; !found && now != m.root; now, found = now.children[runes[pos]] {
+				now = now.fail
+			}
+		}
+
+		// 若找到匹配成功的字符串结点, 则指向那个结点, 否则指向根结点
+		if next, ok := now.children[runes[pos]]; ok {
+			now = next
+		} else {
+			now = m.root
+		}
+
+		temp = now
+
+		for temp != m.root {
+			if temp.word != nil {
+				runes = append(runes[:pos-len([]rune(*temp.word))+1], runes[pos+1:]...)
+				pos -= len([]rune(*temp.word))
+			}
+			temp = temp.fail
+		}
+	}
+
+	return string(runes)
+}