Clean + switch to bloom filters and bitarrays

* Refactor of the repo structure, for better usability.
* README.md refactored.
* Switch to BloomFilters in python script, to decrease the index file.

TODO:
* Handle binary files in JS to pass the BloomFilters from python to JS.

Note: Current implementations of BloomFilters differ in JS and Python
lib.

README.md

@@ -10,13 +10,31 @@ An index is generated by a Python script, upon generation of the pages, and is d
 
 ## Files
 
+### Index generation (`index_generation/` folder)
+
 * `generate_index.py`: Python script to generate the index (runs only at page generation) in a nice format for Javascript
+* `pybloom.py`: Library to handle bloom filters in Python
+* `stemmer.py`: Implementation of Porter Stemming algorithm in Python, from Vivake Gupta.
+
+### Example html search form
+
+* `index.html`
+* `js/bloom.js`: main JS code
+* `js/bloomfilters.js`: JS library to use BloomFilters
+* `js/jquery-2.0.3.min.js`: jQuery to have convenient functions, will mostly be dropped in the future.
+
+### Examples
+
 * `samples/`: samples for testing purpose (taken from my blog articles)
 
 ## Notes
-I got the idea while reading [this page](http://www.stavros.io/posts/bloom-filter-search-engine/?print) found on [Sebsauvage's shaarli](http://sebsauvage.net/links/). I searched a bit for code doing what I wanted and found these ones :
+* I got the idea while reading [this page](http://www.stavros.io/posts/bloom-filter-search-engine/?print) found on [Sebsauvage's shaarli](http://sebsauvage.net/links/). I searched a bit for code doing what I wanted and found these ones:
 
     * https://github.com/olivernn/lunr.js
     * https://github.com/reyesr/fullproof
 
     But I wasn't fully satisfied by the first one, and I found the second one too heavy and complicated for my purpose, so I ended up coding this.
+
+* This code is mainly a proof of concept. As such, it is not fully optimized (actually, I just tweaked until the resulted files and calculations could be considered "acceptable"). For those looking for more effective solutions, here are a few things I found while looking for information on the web:
+
+    * The stemming algorithm used may not be the most efficient one. People wanting to work with non-English languages or to optimize the overall computation of the index can easily move to a more effective algorithm. See [Wikipedia](http://en.wikipedia.org/wiki/Stemming) and [the stemming library in Python](https://pypi.python.org/pypi/stemming/1.0) which has C wrappers for best performances.

index_generation/generate_index.py

@@ -3,8 +3,8 @@
 import os
 from lxml import html
 import re
-import json
+import stemmer
-from collections import defaultdict
+from pybloom import BloomFilter
 
 
 # List all files in path directory
@@ -22,7 +22,8 @@ def remove_common_words(words):
 
 # =============================================================================
 samples = list_directory("samples/")
-index = defaultdict(list)
+filters = {}
+p = stemmer.PorterStemmer()
 
 for sample in samples:
     with open(sample, 'r') as sample_fh:
@@ -37,10 +38,11 @@ for sample in samples:
     # Remove common words
     words = remove_common_words(words)
     # Stemming to reduce the number of words
-    # TODO : Could use http://tartarus.org/martin/PorterStemmer/
+    words = [p.stem(word, 0, len(word)-1) for word in words]
 
+    filters[sample] = BloomFilter(capacity=len(words), error_rate=0.1)
     for word in words:
-        index[sample].append(word)
+        filters[sample].add(word)
 
-with open("index.json", 'w') as index_fh:
+print(sum(len(filter.bitarray.tobytes()) for filter in filters.values()) /
-    index_fh.write(json.dumps(index))
+    len(filters))

index_generation/pybloom.py

@@ -0,0 +1,277 @@
+import math
+import hashlib
+from struct import unpack, pack, calcsize
+
+try:
+    import bitarray
+except ImportError:
+    raise ImportError('pybloom requires bitarray >= 0.3.4')
+
+__version__ = '2.0'
+__author__ = "Jay Baird <jay.baird@me.com>, Bob Ippolito <bob@redivi.com>,\
+Marius Eriksen <marius@monkey.org>,\
+Alex Brasetvik <alex@brasetvik.com>"
+
+def make_hashfuncs(num_slices, num_bits):
+    if num_bits >= (1 << 31):
+        fmt_code, chunk_size = 'Q', 8
+    elif num_bits >= (1 << 15):
+        fmt_code, chunk_size = 'I', 4
+    else:
+        fmt_code, chunk_size = 'H', 2
+    total_hash_bits = 8 * num_slices * chunk_size
+    if total_hash_bits > 384:
+        hashfn = hashlib.sha512
+    elif total_hash_bits > 256:
+        hashfn = hashlib.sha384
+    elif total_hash_bits > 160:
+        hashfn = hashlib.sha256
+    elif total_hash_bits > 128:
+        hashfn = hashlib.sha1
+    else:
+        hashfn = hashlib.md5
+    fmt = fmt_code * (hashfn().digest_size // chunk_size)
+    num_salts, extra = divmod(num_slices, len(fmt))
+    if extra:
+        num_salts += 1
+    salts = [hashfn(hashfn(pack('I', i)).digest()) for i in range(num_salts)]
+    def _make_hashfuncs(key):
+        key = str(key)
+        rval = []
+        for salt in salts:
+            h = salt.copy()
+            h.update(key.encode('utf-8'))
+            rval.extend(uint % num_bits for uint in unpack(fmt, h.digest()))
+        del rval[num_slices:]
+        return rval
+    return _make_hashfuncs
+
+
+class BloomFilter(object):
+    FILE_FMT = '<dQQQQ'
+
+    def __init__(self, capacity, error_rate=0.001):
+        if not (0 < error_rate < 1):
+            raise ValueError("Error_Rate must be between 0 and 1.")
+        if not capacity > 0:
+            raise ValueError("Capacity must be > 0")
+        num_slices = int(math.ceil(math.log(1.0 / error_rate, 2)))
+        bits_per_slice = int(math.ceil(
+            (capacity * abs(math.log(error_rate))) /
+            (num_slices * (math.log(2) ** 2))))
+        self._setup(error_rate, num_slices, bits_per_slice, capacity, 0)
+        self.bitarray = bitarray.bitarray(self.num_bits, endian='little')
+        self.bitarray.setall(False)
+
+    def _setup(self, error_rate, num_slices, bits_per_slice, capacity, count):
+        self.error_rate = error_rate
+        self.num_slices = num_slices
+        self.bits_per_slice = bits_per_slice
+        self.capacity = capacity
+        self.num_bits = num_slices * bits_per_slice
+        self.count = count
+        self.make_hashes = make_hashfuncs(self.num_slices, self.bits_per_slice)
+
+    def __contains__(self, key):
+        bits_per_slice = self.bits_per_slice
+        bitarray = self.bitarray
+        if not isinstance(key, list):
+            hashes = self.make_hashes(key)
+        else:
+            hashes = key
+        offset = 0
+        for k in hashes:
+            if not bitarray[offset + k]:
+                return False
+            offset += bits_per_slice
+        return True
+
+    def __len__(self):
+        """Return the number of keys stored by this bloom filter."""
+        return self.count
+
+    def add(self, key, skip_check=False):
+        bitarray = self.bitarray
+        bits_per_slice = self.bits_per_slice
+        hashes = self.make_hashes(key)
+        if not skip_check and hashes in self:
+            return True
+        if self.count > self.capacity:
+            raise IndexError("BloomFilter is at capacity")
+        offset = 0
+        for k in hashes:
+            self.bitarray[offset + k] = True
+            offset += bits_per_slice
+        self.count += 1
+        return False
+
+    def copy(self):
+        """Return a copy of this bloom filter.
+"""
+        new_filter = BloomFilter(self.capacity, self.error_rate)
+        new_filter.bitarray = self.bitarray.copy()
+        return new_filter
+
+    def union(self, other):
+        """ Calculates the union of the two underlying bitarrays and returns
+a new bloom filter object."""
+        if self.capacity != other.capacity or \
+            self.error_rate != other.error_rate:
+            raise ValueError("Unioning filters requires both filters to have \
+both the same capacity and error rate")
+        new_bloom = self.copy()
+        new_bloom.bitarray = new_bloom.bitarray | other.bitarray
+        return new_bloom
+
+    def __or__(self, other):
+        return self.union(other)
+
+    def intersection(self, other):
+        """ Calculates the intersection of the two underlying bitarrays and returns
+a new bloom filter object."""
+        if self.capacity != other.capacity or \
+            self.error_rate != other.error_rate:
+            raise ValueError("Intersecting filters requires both filters to \
+have equal capacity and error rate")
+        new_bloom = self.copy()
+        new_bloom.bitarray = new_bloom.bitarray & other.bitarray
+        return new_bloom
+
+    def __and__(self, other):
+        return self.intersection(other)
+
+    def tofile(self, f):
+        """Write the bloom filter to file object `f'. Underlying bits
+are written as machine values. This is much more space
+efficient than pickling the object."""
+        f.write(pack(self.FILE_FMT, self.error_rate, self.num_slices,
+                     self.bits_per_slice, self.capacity, self.count))
+        self.bitarray.tofile(f)
+
+    @classmethod
+    def fromfile(cls, f, n=-1):
+        """Read a bloom filter from file-object `f' serialized with
+``BloomFilter.tofile''. If `n' > 0 read only so many bytes."""
+        headerlen = calcsize(cls.FILE_FMT)
+
+        if 0 < n < headerlen:
+            raise ValueError('n too small!')
+
+        filter = cls(1) # Bogus instantiation, we will `_setup'.
+        filter._setup(*unpack(cls.FILE_FMT, f.read(headerlen)))
+        filter.bitarray = bitarray.bitarray(endian='little')
+        if n > 0:
+            filter.bitarray.fromfile(f, n - headerlen)
+        else:
+            filter.bitarray.fromfile(f)
+        if filter.num_bits != filter.bitarray.length() and \
+               (filter.num_bits + (8 - filter.num_bits % 8)
+                != filter.bitarray.length()):
+            raise ValueError('Bit length mismatch!')
+
+        return filter
+
+    def __getstate__(self):
+        d = self.__dict__.copy()
+        del d['make_hashes']
+        return d
+
+    def __setstate__(self, d):
+        self.__dict__.update(d)
+        self.make_hashes = make_hashfuncs(self.num_slices, self.bits_per_slice)
+
+class ScalableBloomFilter(object):
+    SMALL_SET_GROWTH = 2 # slower, but takes up less memory
+    LARGE_SET_GROWTH = 4 # faster, but takes up more memory faster
+    FILE_FMT = '<idQd'
+
+    def __init__(self, initial_capacity=100, error_rate=0.001,
+                 mode=SMALL_SET_GROWTH):
+        if not error_rate or error_rate < 0:
+            raise ValueError("Error_Rate must be a decimal less than 0.")
+        self._setup(mode, 0.9, initial_capacity, error_rate)
+        self.filters = []
+
+    def _setup(self, mode, ratio, initial_capacity, error_rate):
+        self.scale = mode
+        self.ratio = ratio
+        self.initial_capacity = initial_capacity
+        self.error_rate = error_rate
+
+    def __contains__(self, key):
+        for f in reversed(self.filters):
+            if key in f:
+                return True
+        return False
+
+    def add(self, key):
+        if key in self:
+            return True
+        if not self.filters:
+            filter = BloomFilter(
+                capacity=self.initial_capacity,
+                error_rate=self.error_rate * (1.0 - self.ratio))
+            self.filters.append(filter)
+        else:
+            filter = self.filters[-1]
+            if filter.count >= filter.capacity:
+                filter = BloomFilter(
+                    capacity=filter.capacity * self.scale,
+                    error_rate=filter.error_rate * self.ratio)
+                self.filters.append(filter)
+        filter.add(key, skip_check=True)
+        return False
+
+    @property
+    def capacity(self):
+        """Returns the total capacity for all filters in this SBF"""
+        return sum([f.capacity for f in self.filters])
+
+    @property
+    def count(self):
+        return len(self)
+
+    def tofile(self, f):
+        """Serialize this ScalableBloomFilter into the file-object
+`f'."""
+        f.write(pack(self.FILE_FMT, self.scale, self.ratio,
+                     self.initial_capacity, self.error_rate))
+
+        # Write #-of-filters
+        f.write(pack('<l', len(self.filters)))
+
+        if len(self.filters) > 0:
+            # Then each filter directly, with a header describing
+            # their lengths.
+            headerpos = f.tell()
+            headerfmt = '<' + 'Q'*(len(self.filters))
+            f.write('.' * calcsize(headerfmt))
+            filter_sizes = []
+            for filter in self.filters:
+                begin = f.tell()
+                filter.tofile(f)
+                filter_sizes.append(f.tell() - begin)
+
+            f.seek(headerpos)
+            f.write(pack(headerfmt, *filter_sizes))
+
+    @classmethod
+    def fromfile(cls, f):
+        """Deserialize the ScalableBloomFilter in file object `f'."""
+        filter = cls()
+        filter._setup(*unpack(cls.FILE_FMT, f.read(calcsize(cls.FILE_FMT))))
+        nfilters, = unpack('<l', f.read(calcsize('<l')))
+        if nfilters > 0:
+            header_fmt = '<' + 'Q'*nfilters
+            bytes = f.read(calcsize(header_fmt))
+            filter_lengths = unpack(header_fmt, bytes)
+            for fl in filter_lengths:
+                filter.filters.append(BloomFilter.fromfile(f, fl))
+        else:
+            filter.filters = []
+
+        return filter
+
+    def __len__(self):
+        """Returns the total number of elements stored in this SBF"""
+        return sum([f.count for f in self.filters])

index_generation/stemmer.py

@@ -0,0 +1,367 @@
+#!/usr/bin/env python3
+
+"""Porter Stemming Algorithm
+This is the Porter stemming algorithm, ported to Python from the
+version coded up in ANSI C by the author. It may be be regarded
+as canonical, in that it follows the algorithm presented in
+
+Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
+no. 3, pp 130-137,
+
+only differing from it at the points maked --DEPARTURE-- below.
+
+See also http://www.tartarus.org/~martin/PorterStemmer
+
+The algorithm as described in the paper could be exactly replicated
+by adjusting the points of DEPARTURE, but this is barely necessary,
+because (a) the points of DEPARTURE are definitely improvements, and
+(b) no encoding of the Porter stemmer I have seen is anything like
+as exact as this version, even with the points of DEPARTURE!
+
+Vivake Gupta (v@nano.com)
+
+Release 1: January 2001
+
+Further adjustments by Santiago Bruno (bananabruno@gmail.com)
+to allow word input not restricted to one word per line, leading
+to:
+
+release 2: July 2008
+"""
+
+import sys
+
+class PorterStemmer:
+
+    def __init__(self):
+        """The main part of the stemming algorithm starts here.
+        b is a buffer holding a word to be stemmed. The letters are in b[k0],
+        b[k0+1] ... ending at b[k]. In fact k0 = 0 in this demo program. k is
+        readjusted downwards as the stemming progresses. Zero termination is
+        not in fact used in the algorithm.
+
+        Note that only lower case sequences are stemmed. Forcing to lower case
+        should be done before stem(...) is called.
+        """
+
+        self.b = ""  # buffer for word to be stemmed
+        self.k = 0
+        self.k0 = 0
+        self.j = 0   # j is a general offset into the string
+
+    def cons(self, i):
+        """cons(i) is TRUE <=> b[i] is a consonant."""
+        if self.b[i] == 'a' or self.b[i] == 'e' or self.b[i] == 'i' or self.b[i] == 'o' or self.b[i] == 'u':
+            return 0
+        if self.b[i] == 'y':
+            if i == self.k0:
+                return 1
+            else:
+                return (not self.cons(i - 1))
+        return 1
+
+    def m(self):
+        """m() measures the number of consonant sequences between k0 and j.
+        if c is a consonant sequence and v a vowel sequence, and <..>
+        indicates arbitrary presence,
+
+           <c><v>       gives 0
+           <c>vc<v>     gives 1
+           <c>vcvc<v>   gives 2
+           <c>vcvcvc<v> gives 3
+           ....
+        """
+        n = 0
+        i = self.k0
+        while 1:
+            if i > self.j:
+                return n
+            if not self.cons(i):
+                break
+            i = i + 1
+        i = i + 1
+        while 1:
+            while 1:
+                if i > self.j:
+                    return n
+                if self.cons(i):
+                    break
+                i = i + 1
+            i = i + 1
+            n = n + 1
+            while 1:
+                if i > self.j:
+                    return n
+                if not self.cons(i):
+                    break
+                i = i + 1
+            i = i + 1
+
+    def vowelinstem(self):
+        """vowelinstem() is TRUE <=> k0,...j contains a vowel"""
+        for i in range(self.k0, self.j + 1):
+            if not self.cons(i):
+                return 1
+        return 0
+
+    def doublec(self, j):
+        """doublec(j) is TRUE <=> j,(j-1) contain a double consonant."""
+        if j < (self.k0 + 1):
+            return 0
+        if (self.b[j] != self.b[j-1]):
+            return 0
+        return self.cons(j)
+
+    def cvc(self, i):
+        """cvc(i) is TRUE <=> i-2,i-1,i has the form consonant - vowel - consonant
+        and also if the second c is not w,x or y. this is used when trying to
+        restore an e at the end of a short  e.g.
+
+           cav(e), lov(e), hop(e), crim(e), but
+           snow, box, tray.
+        """
+        if i < (self.k0 + 2) or not self.cons(i) or self.cons(i-1) or not self.cons(i-2):
+            return 0
+        ch = self.b[i]
+        if ch == 'w' or ch == 'x' or ch == 'y':
+            return 0
+        return 1
+
+    def ends(self, s):
+        """ends(s) is TRUE <=> k0,...k ends with the string s."""
+        length = len(s)
+        if s[length - 1] != self.b[self.k]: # tiny speed-up
+            return 0
+        if length > (self.k - self.k0 + 1):
+            return 0
+        if self.b[self.k-length+1:self.k+1] != s:
+            return 0
+        self.j = self.k - length
+        return 1
+
+    def setto(self, s):
+        """setto(s) sets (j+1),...k to the characters in the string s, readjusting k."""
+        length = len(s)
+        self.b = self.b[:self.j+1] + s + self.b[self.j+length+1:]
+        self.k = self.j + length
+
+    def r(self, s):
+        """r(s) is used further down."""
+        if self.m() > 0:
+            self.setto(s)
+
+    def step1ab(self):
+        """step1ab() gets rid of plurals and -ed or -ing. e.g.
+
+           caresses  ->  caress
+           ponies    ->  poni
+           ties      ->  ti
+           caress    ->  caress
+           cats      ->  cat
+
+           feed      ->  feed
+           agreed    ->  agree
+           disabled  ->  disable
+
+           matting   ->  mat
+           mating    ->  mate
+           meeting   ->  meet
+           milling   ->  mill
+           messing   ->  mess
+
+           meetings  ->  meet
+        """
+        if self.b[self.k] == 's':
+            if self.ends("sses"):
+                self.k = self.k - 2
+            elif self.ends("ies"):
+                self.setto("i")
+            elif self.b[self.k - 1] != 's':
+                self.k = self.k - 1
+        if self.ends("eed"):
+            if self.m() > 0:
+                self.k = self.k - 1
+        elif (self.ends("ed") or self.ends("ing")) and self.vowelinstem():
+            self.k = self.j
+            if self.ends("at"):   self.setto("ate")
+            elif self.ends("bl"): self.setto("ble")
+            elif self.ends("iz"): self.setto("ize")
+            elif self.doublec(self.k):
+                self.k = self.k - 1
+                ch = self.b[self.k]
+                if ch == 'l' or ch == 's' or ch == 'z':
+                    self.k = self.k + 1
+            elif (self.m() == 1 and self.cvc(self.k)):
+                self.setto("e")
+
+    def step1c(self):
+        """step1c() turns terminal y to i when there is another vowel in the stem."""
+        if (self.ends("y") and self.vowelinstem()):
+            self.b = self.b[:self.k] + 'i' + self.b[self.k+1:]
+
+    def step2(self):
+        """step2() maps double suffices to single ones.
+        so -ization ( = -ize plus -ation) maps to -ize etc. note that the
+        string before the suffix must give m() > 0.
+        """
+        if self.b[self.k - 1] == 'a':
+            if self.ends("ational"):   self.r("ate")
+            elif self.ends("tional"):  self.r("tion")
+        elif self.b[self.k - 1] == 'c':
+            if self.ends("enci"):      self.r("ence")
+            elif self.ends("anci"):    self.r("ance")
+        elif self.b[self.k - 1] == 'e':
+            if self.ends("izer"):      self.r("ize")
+        elif self.b[self.k - 1] == 'l':
+            if self.ends("bli"):       self.r("ble") # --DEPARTURE--
+            # To match the published algorithm, replace this phrase with
+            #   if self.ends("abli"):      self.r("able")
+            elif self.ends("alli"):    self.r("al")
+            elif self.ends("entli"):   self.r("ent")
+            elif self.ends("eli"):     self.r("e")
+            elif self.ends("ousli"):   self.r("ous")
+        elif self.b[self.k - 1] == 'o':
+            if self.ends("ization"):   self.r("ize")
+            elif self.ends("ation"):   self.r("ate")
+            elif self.ends("ator"):    self.r("ate")
+        elif self.b[self.k - 1] == 's':
+            if self.ends("alism"):     self.r("al")
+            elif self.ends("iveness"): self.r("ive")
+            elif self.ends("fulness"): self.r("ful")
+            elif self.ends("ousness"): self.r("ous")
+        elif self.b[self.k - 1] == 't':
+            if self.ends("aliti"):     self.r("al")
+            elif self.ends("iviti"):   self.r("ive")
+            elif self.ends("biliti"):  self.r("ble")
+        elif self.b[self.k - 1] == 'g': # --DEPARTURE--
+            if self.ends("logi"):      self.r("log")
+        # To match the published algorithm, delete this phrase
+
+    def step3(self):
+        """step3() dels with -ic-, -full, -ness etc. similar strategy to step2."""
+        if self.b[self.k] == 'e':
+            if self.ends("icate"):     self.r("ic")
+            elif self.ends("ative"):   self.r("")
+            elif self.ends("alize"):   self.r("al")
+        elif self.b[self.k] == 'i':
+            if self.ends("iciti"):     self.r("ic")
+        elif self.b[self.k] == 'l':
+            if self.ends("ical"):      self.r("ic")
+            elif self.ends("ful"):     self.r("")
+        elif self.b[self.k] == 's':
+            if self.ends("ness"):      self.r("")
+
+    def step4(self):
+        """step4() takes off -ant, -ence etc., in context <c>vcvc<v>."""
+        if self.b[self.k - 1] == 'a':
+            if self.ends("al"): pass
+            else: return
+        elif self.b[self.k - 1] == 'c':
+            if self.ends("ance"): pass
+            elif self.ends("ence"): pass
+            else: return
+        elif self.b[self.k - 1] == 'e':
+            if self.ends("er"): pass
+            else: return
+        elif self.b[self.k - 1] == 'i':
+            if self.ends("ic"): pass
+            else: return
+        elif self.b[self.k - 1] == 'l':
+            if self.ends("able"): pass
+            elif self.ends("ible"): pass
+            else: return
+        elif self.b[self.k - 1] == 'n':
+            if self.ends("ant"): pass
+            elif self.ends("ement"): pass
+            elif self.ends("ment"): pass
+            elif self.ends("ent"): pass
+            else: return
+        elif self.b[self.k - 1] == 'o':
+            if self.ends("ion") and (self.b[self.j] == 's' or self.b[self.j] == 't'): pass
+            elif self.ends("ou"): pass
+            # takes care of -ous
+            else: return
+        elif self.b[self.k - 1] == 's':
+            if self.ends("ism"): pass
+            else: return
+        elif self.b[self.k - 1] == 't':
+            if self.ends("ate"): pass
+            elif self.ends("iti"): pass
+            else: return
+        elif self.b[self.k - 1] == 'u':
+            if self.ends("ous"): pass
+            else: return
+        elif self.b[self.k - 1] == 'v':
+            if self.ends("ive"): pass
+            else: return
+        elif self.b[self.k - 1] == 'z':
+            if self.ends("ize"): pass
+            else: return
+        else:
+            return
+        if self.m() > 1:
+            self.k = self.j
+
+    def step5(self):
+        """step5() removes a final -e if m() > 1, and changes -ll to -l if
+        m() > 1.
+        """
+        self.j = self.k
+        if self.b[self.k] == 'e':
+            a = self.m()
+            if a > 1 or (a == 1 and not self.cvc(self.k-1)):
+                self.k = self.k - 1
+        if self.b[self.k] == 'l' and self.doublec(self.k) and self.m() > 1:
+            self.k = self.k -1
+
+    def stem(self, p, i, j):
+        """In stem(p,i,j), p is a char pointer, and the string to be stemmed
+        is from p[i] to p[j] inclusive. Typically i is zero and j is the
+        offset to the last character of a string, (p[j+1] == '\0'). The
+        stemmer adjusts the characters p[i] ... p[j] and returns the new
+        end-point of the string, k. Stemming never increases word length, so
+        i <= k <= j. To turn the stemmer into a module, declare 'stem' as
+        extern, and delete the remainder of this file.
+        """
+        # copy the parameters into statics
+        self.b = p
+        self.k = j
+        self.k0 = i
+        if self.k <= self.k0 + 1:
+            return self.b # --DEPARTURE--
+
+        # With this line, strings of length 1 or 2 don't go through the
+        # stemming process, although no mention is made of this in the
+        # published algorithm. Remove the line to match the published
+        # algorithm.
+
+        self.step1ab()
+        self.step1c()
+        self.step2()
+        self.step3()
+        self.step4()
+        self.step5()
+        return self.b[self.k0:self.k+1]
+
+
+if __name__ == '__main__':
+    p = PorterStemmer()
+    if len(sys.argv) > 1:
+        for f in sys.argv[1:]:
+            infile = open(f, 'r')
+            while 1:
+                output = ''
+                word = ''
+                line = infile.readline()
+                if line == '':
+                    break
+                for c in line:
+                    if c.isalpha():
+                        word += c.lower()
+                    else:
+                        if word:
+                            output += p.stem(word, 0,len(word)-1)
+                            word = ''
+                        output += c.lower()
+                print(output)
+            infile.close()

js/bloom.js

@@ -44,6 +44,9 @@ function callback_change() {
             $("#results").append("<p>"+key+"</p>");
         }
     }
+    if(!$("#results p").length) {
+        $("#results").append("<p>No results...</p>");
+    }
 }
 
 $("#search").on('input', callback_change);