pybmoore

Python/Cython implementation of Boyer-Moore string-search algorithm.

Installing

Install and update using pip:

pip install pybmoore

notice: gcc must be available on the system.

Usage

Single term

The search method in the pybmoore module will return a list of tuples with all occurrences, where the tuple have the initial and final position. For example:

import pybmoore


TEXT = """The Boyer–Moore string-search algorithm is 
an efficient string-searching algorithm that is the 
standard benchmark for practical string-search literature.
"""

matches = pybmoore.search('string', TEXT)
print(f"Occurrences: {len(matches)}")
# output: Occurrences: 3

print(matches)
# output: [(16, 22), (57, 63), (130, 136)]

for x, y in matches:
    print(f"({x},{y}) - {TEXT[x:y]}")

notice: search method it's case sensitive.

import pybmoore


TEXT = """The algorithm preprocesses the string being searched for (the pattern), 
but not the string being searched in (the text). It is thus well-suited for 
applications in which the pattern is much shorter than the text or where it 
persists across multiple searches.
"""

pybmoore.search('algorithm', TEXT)
# output: [(4, 13)]

pybmoore.search('Algorithm', TEXT)
# output: []

Multiple terms

from concurrent.futures import ProcessPoolExecutor, ThreadPoolExecutor

import pybmoore


TEXT = """The Boyer-Moore algorithm searches for occurrences of P in T by 
performing explicit character comparisons at different alignments. Instead of a 
brute-force search of all alignments (of which there are m − n + 1, Boyer-Moore 
uses information gained by preprocessing P to skip as many alignments as possible.
"""

# Using a list of patterns
pybmoore.search_m(['brute-force', 'Boyer-Moore'], TEXT, ProcessPoolExecutor)
# output: {'brute-force': [(146, 157)], 'Boyer-Moore': [(4, 15), (214, 225)]}

# Using a set of patterns
pybmoore.search_m({'brute-force', 'Boyer-Moore'}, TEXT, ThreadPoolExecutor)
# output: {'brute-force': [(146, 157)], 'Boyer-Moore': [(4, 15), (214, 225)]}

# Using a tuple of patterns
pybmoore.search_m(('brute-force', 'Boyer-Moore'), TEXT, ThreadPoolExecutor, max_workers=4)
# output: {'brute-force': [(146, 157)], 'Boyer-Moore': [(4, 15), (214, 225)]}

Details

For granular control of the pool, use the parameters listed in the module documentation. For example:

Development

To build pybmoore locally first install requirements-dev.txt dependencies and run:

make build # without Cython

make build USE_CYTHON=1 # with Cython

in some cases it's necesary run make clean before make build.

Type make in the command line to see all available targets.

Links

• License: Apache License
• Code: https://github.com/amenezes/pybmoore
• Issue tracker: https://github.com/amenezes/pybmoore/issues