suffixarray

Documentation

Overview

Package suffixarray implements substring search in logarithmic time using an in-memory suffix array.

Example use:

// create index for some data
index := suffixarray.New(data)

// lookup byte slice s
offsets1 := index.Lookup(s, -1) // the list of all indices where s occurs in data
offsets2 := index.Lookup(s, 3)  // the list of at most 3 indices where s occurs in data

Index

• type Index
  • func New(data []byte) *Index
  • func (x *Index) Bytes() []byte
  • func (x *Index) FindAllIndex(r *regexp.Regexp, n int) (result [][]int)
  • func (x *Index) Lookup(s []byte, n int) (result []int)
  • func (x *Index) Read(r io.Reader) error
  • func (x *Index) Write(w io.Writer) error

Examples

• Index.Lookup

Types

type Index

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

Index implements a suffix array for fast substring search.

func New

func New(data []byte) *Index

New creates a new Index for data. Index creation time is O(N*log(N)) for N = len(data).

func (*Index) Bytes

func (x *Index) Bytes() []byte

Bytes returns the data over which the index was created. It must not be modified.

func (*Index) FindAllIndex

func (x *Index) FindAllIndex(r *regexp.Regexp, n int) (result [][]int)

FindAllIndex returns a sorted list of non-overlapping matches of the regular expression r, where a match is a pair of indices specifying the matched slice of x.Bytes(). If n < 0, all matches are returned in successive order. Otherwise, at most n matches are returned and they may not be successive. The result is nil if there are no matches, or if n == 0.

func (*Index) Lookup

func (x *Index) Lookup(s []byte, n int) (result []int)

Lookup returns an unsorted list of at most n indices where the byte string s occurs in the indexed data. If n < 0, all occurrences are returned. The result is nil if s is empty, s is not found, or n == 0. Lookup time is O(log(N)*len(s) + len(result)) where N is the size of the indexed data.

Example

package main

import (
	"fmt"
	"index/suffixarray"
)

func main() {
	index := suffixarray.New([]byte("banana"))
	offsets := index.Lookup([]byte("ana"), -1)
	for _, off := range offsets {
		fmt.Println(off)
	}

}

Output:

1
3

func (*Index) Read

func (x *Index) Read(r io.Reader) error

Read reads the index from r into x; x must not be nil.

func (*Index) Write

func (x *Index) Write(w io.Writer) error

Write writes the index x to w.