DFA算法以及ios中OC实现DFA
DFA不同于苹果手机的idfa
DFA全称为:Deterministic Finite Automaton,即确定有穷自动机。其特征为:有一个有限状态集合和一些从一个状态通向另一个状态的边,每条边上标记有一个符号,其中一个状态是初态,某些状态是终态。但不同于不确定的有限自动机,DFA中不会有从同一状态出发的两条边标志有相同的符号。
ios oc 代码如下
#import "WordFilter.h"
#define EXIST @"isExists"
@interface WordFilter()
@property (nonatomic,strong) NSMutableDictionary *root;
@property (nonatomic,assign) BOOL isFilterClose;
@end
@implementation WordFilter
static WordFilter *instance;
+ (instancetype)sharedInstance{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc]init];
});
return instance;
}
- (void)initFilter:(NSString *)filepath{
self.root = [NSMutableDictionary dictionary];
char word[1024];
FILE *fp;
char *p;
//打开文件
fp = fopen([filepath UTF8String], "r");
//按行读取内容
while (fgets(word, sizeof(word), fp)) {
p = word;
while (*p != 0) {
if (*p == '\r' || *p == '\n' || *p == ' ') {
*p = 0;
break;
}
p++;
}
//插入字符,构造节点
[self insertWords:[NSString stringWithUTF8String:word]];
}
}
-(void)insertWords:(NSString *)words{
NSMutableDictionary *node = self.root;
for (int i = 0; i < words.length; i ++) {
NSString *word = [words substringWithRange:NSMakeRange(i, 1)];
if (node[word] == nil) {
node[word] = [NSMutableDictionary dictionary];
}
node = node[word];
}
//敏感词最后一个字符标识
node[EXIST] = [NSNumber numberWithInt:1];
}
- (NSString *)filter:(NSString *)str{
if (self.isFilterClose || !self.root) {
return str;
}
NSMutableString *result = result = [str mutableCopy];
for (int i = 0; i < str.length; i ++) {
NSString *subString = [str substringFromIndex:i];
NSMutableDictionary *node = [self.root mutableCopy] ;
int num = 0;
for (int j = 0; j < subString.length; j ++) {
NSString *word = [subString substringWithRange:NSMakeRange(j, 1)];
if (node[word] == nil) {
break;
}else{
num ++;
node = node[word];
}
//敏感词匹配成功
if ([node[EXIST]integerValue] == 1) {
NSMutableString *symbolStr = [NSMutableString string];
for (int k = 0; k < num; k ++) {
[symbolStr appendString:@"*"];
}
[result replaceCharactersInRange:NSMakeRange(i, num) withString:symbolStr];
i += j;
break;
}
}
}
return result;
}
- (void)freeFilter{
self.root = nil;
}
- (void)stopFilter:(BOOL)b{
self.isFilterClose = b;
}
参考链接:
https://www.cnblogs.com/myvic/p/8671991.html
https://blog.csdn.net/Jali_li/article/details/52843576(代码主要是这个亲的,赞一个)
posted on 2015-11-22 17:20 🌞Bob 阅读(349) 评论(0) 编辑 收藏 举报