text-1.2.1.3: An efficient packed Unicode text type.

Copyright | (c) Bryan O'Sullivan 2009
License | BSD-style
Maintainer | bos@serpentine.com
Stability | experimental
Portability | GHC
Safe Haskell | None
Language | Haskell98

Data.Text.Internal.Search

Description

Fast substring search for `Text`, based on work by Boyer, Moore, Horspool, Sunday, and Lundh.

References:

- R. S. Boyer, J. S. Moore: A Fast String Searching Algorithm. Communications of the ACM, 20, 10, 762-772 (1977)
- R. N. Horspool: Practical Fast Searching in Strings. Software - Practice and Experience 10, 501-506 (1980)
- D. M. Sunday: A Very Fast Substring Search Algorithm. Communications of the ACM, 33, 8, 132-142 (1990)
- F. Lundh: The Fast Search Algorithm. http://effbot.org/zone/stringlib.htm (2006)

Synopsis

- indices :: Text -> Text -> [Int]

# Documentation

indices #

Arguments

:: Text | Substring to search for (`needle`)
-> Text | Text to search in (`haystack`)
-> [Int] |

O(n+m) Find the offsets of all non-overlapping indices of `needle` within `haystack`. The offsets returned represent uncorrected indices in the low-level "needle" array, to which its offset must be added.

In (unlikely) bad cases, this algorithm's complexity degrades towards O(n*m).