search.py

import sys
import re


def iterwords(fh):
    for number, line in enumerate(fh):
        for word in re.split(r'\s+', line.strip()):
            # Preprocess the words here, for example to strip out punctuation
            # (the following example is sloooow, compile this regex if you
            # really want to use it):
            #
            #     word = re.sub(r'[,.:]', '', word)
            #
            word = word.lower()
            yield number, word



def search(fh, query):
    query = re.split(r'\s+', query.strip().lower())
    matches = []
    words = iterwords(fh)

    for line, word in words:
        lines_count = 1
        current_line = line
        for keyword in query:
            if keyword == word:
                next_line, word = next(words)
                if next_line > current_line:
                    lines_count += 1
                    current_line = next_line
            else:
                break
        else:
            matches.append((line, lines_count))

    return tuple(matches)



if __name__ == '__main__':
    query = sys.argv[1]
    fh = open(sys.argv[2])

    matches = search(fh, query)
    
    # Form here on it's only presentation
    fh.seek(0)
    lines = enumerate(fh)
    for lineno, linecount in matches:
        number, line = next(lines)
        while number < lineno:
            number, line = next(lines)
        
        result_lines = [line]
        
        for i in range(linecount-1):
            result_lines.append(next(lines)[1])
        
        print "Match found on line {0} (spawning {1} lines):\n > {2}".format(
            lineno, linecount, ' > '.join(result_lines).strip())