1.根据字符构造trie树 2.构建失败匹配指针 1.根节点的所以一代子孩子失败指针都指向root 2.子节点匹配失败时，找到父节点的失败指针，找不到就一直找，直到找到root还匹配不到，直接指向root 3.文本串匹配 1.如果已经匹配到完整的模式串，根据失败指针切换线路继续向下查找 2.如果还没有匹配完，那么就向下匹配
class ACNode { constructor(data){ this.data = data this.children = new Map() this.isEndingChar = false this.length = 0 this.fail = null } } class ACTree { constructor(){ this.root = new ACNode('/') } insert(text){ let node = this.root for(let char of text){ if(!node.children.get(char)){ node.children.set(char,new ACNode(char)) } node = node.children.get(char) } node.isEndingChar = true node.length = text.length } buildFailurePointer(){ let root = this.root let queue = [] queue.push(root) while(queue.length > 0){ let parentNode = queue.shift() for(let childNode of parentNode.children.values()){ if(!childNode){ continue } //如果现在还在树的第一层 if(parentNode == root){ //所有子节点的失败指针都指向root childNode.fail = root } else { let grandFatherNode = parentNode.fail while(grandFatherNode){ let failNode = grandFatherNode.children.get(childNode.data) if(failNode){ childNode.fail = failNode break } grandFatherNode = grandFatherNode.fail } if(!grandFatherNode){ childNode.fail = root } } queue.push(childNode) } } } match(text){ let root = this.root let len = text.length let currentNode = root for( let i = 0; i < len; i++ ){ let char = text[i] while(!currentNode.children.get(char) && currentNode !== root){ //换线匹配 currentNode = currentNode.fail } currentNode = currentNode.children.get(char) if(!currentNode){ //如果currentNode没有值，就重新回到root节点 currentNode = root } let tmp = currentNode while(tmp != root){ if(tmp.isEndingChar === true){ console.log(`from ${i - tmp.length + 1} length: ${tmp.length} str: ${text.substr(i - currentNode.length + 1,currentNode.length)}`) } tmp = tmp.fail } } } } function match(text,patterns){ let automata = new ACTree(); for(let pattern of patterns){ automata.insert(pattern); } automata.buildFailurePointer(); automata.match(text); } let patterns = ["at", "art", "oars", "soar"]; let text = "soarsoars"; match(text, patterns); let patterns2 = ["Fxtec Pro1", "谷歌Pixel"]; let text2 = "一家总部位于伦敦的公司Fxtex在MWC上就推出了一款名为Fxtec Pro1的手机，该机最大的亮点就是采用了侧滑式全键盘设计。DxOMark年度总榜发布 华为P20 Pro/谷歌Pixel 3争冠"; match(text2, patterns2); 
