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Aho–Corasick string matching algorithm in C#

The Aho–Corasick string matching algorithm is a string searching algorithm. It's useful in NLP when you have a dictionary with words and you need to tell if a text contains any of the words.

AhoCorasick.Trie trie = new AhoCorasick.Trie();

// add words
trie.Add("hello");
trie.Add("world");

// build search tree
trie.Build();

string text = "hello and welcome to this beautiful world!";

// find words
foreach (string word in trie.Find(text)) {
  Console.WriteLine(word);
}

You can associate other data with the words (like an ID or line number).

AhoCorasick.Trie<int> trie = new AhoCorasick.Trie<int>();

// add words
trie.Add("hello", 123);
trie.Add("world", 456);

// build search tree
trie.Build();

// retrieve IDs
foreach (int id in trie.Find(text)) {
  Console.WriteLine(id);
}

Use IEnumerable<T>.Any() to check if the text contains a match without retrieving all of them.

If you want to match whole words, you can use Trie<string, T>.

string[] text = "hello world i say to you".Split(' ');
            
AhoCorasick.Trie<string, bool> trie = new AhoCorasick.Trie<string, bool>();
trie.Add("hello world".Split(' '), true);
trie.Build();
bool containsHelloWorld = trie.Find(text).Any();

License

MIT