goahocorasick

README

Aho–Corasick algorithm

Intro

A faster and more effective implement of Aho-Corasick algorithm in golang and supports Both Chinese and English. To improve the performance and reduce memory usage, the program uses Double Array Trie instead of common Linked List Trie. In the benchmark, it is 10 times faster than the most popular AC algorithm implement in golang @ github and tenth of its memory usage. You can find more information in the benchmark parts.

This Project is inspired by hankcs/AhoCorasickDoubleArrayTrie

Besides Multi-Pattern Search using AC algorithm, the program also provides "exact match search" using Double Array Trie

Aho-Corasick algorithm is first presented in the paper below:

Efficient string matching: an aid to bibliographic search

the wikipedia link is: aho-corasick algorithm

Usage

Multi-Pattern Search Example

package main

import (
    "bufio"
    "bytes"
    "fmt"
    "io"
    "os"
 )

import (
	"github.com/anknown/ahocorasick"
)

func ReadRunes(filename string) ([][]rune, error) {
    dict := [][]rune{}

    f, err := os.OpenFile(filename, os.O_RDONLY, 0660)
    if err != nil {
        return nil, err
    }

    r := bufio.NewReader(f)
    for {
        l, err := r.ReadBytes('\n')
        if err != nil || err == io.EOF {
            break
        }
        l = bytes.TrimSpace(l)
        dict = append(dict, bytes.Runes(l))
    }

    return dict, nil
}

func main() {
    dict, err := ReadRunes("your_dict_files")
    if err != nil {
        fmt.Println(err)
        return
    }

    content := []rune("your text")

    m := new(goahocorasick.Machine)
    if err := m.Build(dict); err != nil {
        fmt.Println(err)
        return
    }

    terms := m.MultiPatternSearch(content, false)
    for _, t := range terms {
        fmt.Printf("%d %s\n", t.Pos, string(t.Word))
    }
}

I do not provide read file API because I think your dict may coming form other source

Benchmark

Multi-Pattern Search

compare with cloudflare/ahocorasick who receives most stars and forks in all the implements written in golang

To Run Benchmark, go to test dir

go build benchmark.go

./benchmark

• For Chinese Test

Dictionary contains 153,151 words, Text contains 777,277 words

====================================================================
			cost(million sec)	memory usage(MBytes)
cloudflare/ahocorasick		28926				1911
anknown/ahocorasick		1814				155
====================================================================

• For English Test

Dictionary contains 127,141 words, Text contains 674,669 words

====================================================================
			time(million sec)	memory usage(MBytes)
cloudflare/ahocorasick		19835				1340
anknown/ahocorasick		1619				203
====================================================================

License

MIT License

Documentation

Index

• Constants
• type ExportableMachine
• type Machine
  • func (m *Machine) Build(keywords [][]rune) (err error)
  • func (m *Machine) ExactSearch(content []rune) [](*Term)
  • func (m *Machine) GobDecode(b []byte) error
  • func (m *Machine) GobEncode() ([]byte, error)
  • func (m *Machine) MultiPatternSearch(content []rune, returnImmediately bool) [](*Term)
  • func (m *Machine) PrintFailure()
  • func (m *Machine) PrintOutput()
• type Term

Constants

const FAIL_STATE = -1

const ROOT_STATE = 1

Types

type ExportableMachine

type ExportableMachine struct {
	Trie    *godarts.DoubleArrayTrie
	Failure []int
	Output  map[int]([][]rune)
}

type Machine

type Machine struct {
	// contains filtered or unexported fields
}

func (*Machine) Build

func (m *Machine) Build(keywords [][]rune) (err error)

func (*Machine) ExactSearch

func (m *Machine) ExactSearch(content []rune) [](*Term)

func (*Machine) GobDecode

func (m *Machine) GobDecode(b []byte) error

func (*Machine) GobEncode

func (m *Machine) GobEncode() ([]byte, error)

func (*Machine) MultiPatternSearch

func (m *Machine) MultiPatternSearch(content []rune, returnImmediately bool) [](*Term)

func (*Machine) PrintFailure

func (m *Machine) PrintFailure()

func (*Machine) PrintOutput

func (m *Machine) PrintOutput()

type Term

type Term struct {
	Pos  int
	Word []rune
}