Since this thing is on the innerwebs I suppose it should have a
[python_utils.git] / unscrambler.py
index d3686d67ed763d9b240b58ee9d43b5151ed31ea8..a40213e2a7fcdb7663b7479ac3979c1ccb485938 100644 (file)
@@ -1,17 +1,22 @@
 #!/usr/bin/env python3
 
+# © Copyright 2021-2022, Scott Gasch
+
+"""A fast word unscrambler library."""
+
 import logging
-from typing import Dict, Mapping
+from typing import Dict, Mapping, Optional
 
 import config
 import decorator_utils
+import file_utils
 import list_utils
 
 cfg = config.add_commandline_args(
-    f'Unscramble! ({__file__})', 'A fast word unscrambler.'
+    f'Unscrambler base library ({__file__})', 'A fast word unscrambler.'
 )
 cfg.add_argument(
-    "--unscramble_indexfile",
+    "--unscrambler_default_indexfile",
     help="Path to a file of signature -> word index.",
     metavar="FILENAME",
     default="/usr/share/dict/sparse_index",
@@ -20,10 +25,10 @@ cfg.add_argument(
 logger = logging.getLogger(__name__)
 
 letters_bits = 32
-letters_mask = 2 ** letters_bits - 1
+letters_mask = 2**letters_bits - 1
 
 fprint_bits = 52
-fprint_mask = (2 ** fprint_bits - 1) << letters_bits
+fprint_mask = (2**fprint_bits - 1) << letters_bits
 
 fprint_feature_bit = {
     'e': 0,
@@ -100,35 +105,40 @@ class Unscrambler(object):
 
     """
 
-    def __init__(self):
+    def __init__(self, indexfile: Optional[str] = None):
         # Cached index per instance.
         self.sigs = []
         self.words = []
 
-        if 'unscramble_indexfile' in config.config:
-            indexfile = config.config['unscramble_indexfile']
-        else:
-            indexfile = "/usr/share/dict/sparse_index"
-
-        with open(indexfile, 'r') as rf:
+        filename = Unscrambler.get_indexfile(indexfile)
+        with open(filename, 'r') as rf:
             lines = rf.readlines()
         for line in lines:
             line = line[:-1]
             (fsig, word) = line.split('+')
-            fsig = int(fsig, 16)
-            self.sigs.append(fsig)
+            isig = int(fsig, 16)
+            self.sigs.append(isig)
             self.words.append(word)
 
+    @staticmethod
+    def get_indexfile(indexfile: Optional[str]) -> str:
+        if indexfile is None:
+            if 'unscrambler_default_indexfile' in config.config:
+                indexfile = config.config['unscramble_indexfile']
+            else:
+                indexfile = "/usr/share/dict/sparse_index"
+        else:
+            assert file_utils.file_is_readable(indexfile), f"Can't read {indexfile}"
+        return indexfile
+
     # 52 bits
     @staticmethod
-    def _compute_word_fingerprint(word: str, population: Mapping[str, int]) -> int:
+    def _compute_word_fingerprint(population: Mapping[str, int]) -> int:
         fp = 0
         for pair in sorted(population.items(), key=lambda x: x[1], reverse=True):
             letter = pair[0]
             if letter in fprint_feature_bit:
-                count = pair[1]
-                if count > 3:
-                    count = 3
+                count = min(pair[1], 3)
                 shift = fprint_feature_bit[letter]
                 s = count << shift
                 fp |= s
@@ -137,25 +147,23 @@ class Unscrambler(object):
     # 32 bits
     @staticmethod
     def _compute_word_letter_sig(
-        letter_sigs: Mapping[str, int],
+        lsigs: Mapping[str, int],
         word: str,
         population: Mapping[str, int],
     ) -> int:
         sig = 0
         for pair in sorted(population.items(), key=lambda x: x[1], reverse=True):
             letter = pair[0]
-            if letter not in letter_sigs:
+            if letter not in lsigs:
                 continue
-            s = letter_sigs[letter]
+            s = lsigs[letter]
             count = pair[1]
             if count > 1:
                 s <<= count
                 s |= count
             s &= letters_mask
             sig ^= s
-        length = len(word)
-        if length > 31:
-            length = 31
+        length = min(len(word), 31)
         sig ^= length << 8
         sig &= letters_mask
         return sig
@@ -182,7 +190,7 @@ class Unscrambler(object):
 
         """
         population = list_utils.population_counts(word)
-        fprint = Unscrambler._compute_word_fingerprint(word, population)
+        fprint = Unscrambler._compute_word_fingerprint(population)
         letter_sig = Unscrambler._compute_word_letter_sig(letter_sigs, word, population)
         assert fprint & letter_sig == 0
         sig = fprint | letter_sig
@@ -190,7 +198,6 @@ class Unscrambler(object):
 
     @staticmethod
     def repopulate(
-        letter_sigs: Dict[str, int],
         dictfile: str = '/usr/share/dict/words',
         indexfile: str = '/usr/share/dict/sparse_index',
     ) -> None:
@@ -198,19 +205,19 @@ class Unscrambler(object):
         unless you want to populate the same exact files.
 
         """
-        words_by_sigs = {}
+        words_by_sigs: Dict[int, str] = {}
         seen = set()
         with open(dictfile, "r") as f:
             for word in f:
                 word = word.replace('\n', '')
                 word = word.lower()
-                sig = Unscrambler.compute_word_sig(letter_sigs, word)
-                logger.debug("%s => 0x%x" % (word, sig))
+                sig = Unscrambler.compute_word_sig(word)
+                logger.debug("%s => 0x%x", word, sig)
                 if word in seen:
                     continue
                 seen.add(word)
                 if sig in words_by_sigs:
-                    words_by_sigs[sig] += ",%s" % word
+                    words_by_sigs[sig] += f",{word}"
                 else:
                     words_by_sigs[sig] = word
         with open(indexfile, 'w') as f:
@@ -218,23 +225,19 @@ class Unscrambler(object):
                 word = words_by_sigs[sig]
                 print(f'0x{sig:x}+{word}', file=f)
 
-    def lookup(
-        self, word: str, *, include_fuzzy_matches: bool = False
-    ) -> Dict[str, bool]:
+    def lookup(self, word: str, *, window_size: int = 5) -> Dict[str, bool]:
         """Looks up a potentially scrambled word optionally including near
         "fuzzy" matches.
 
         >>> u = Unscrambler()
-        >>> u.lookup('eanycleocipd', include_fuzzy_matches=False)
+        >>> u.lookup('eanycleocipd', window_size=0)
         {'encyclopedia': True}
 
         """
         sig = Unscrambler.compute_word_sig(word)
-        return self.lookup_by_sig(sig, include_fuzzy_matches=include_fuzzy_matches)
+        return self.lookup_by_sig(sig, window_size=window_size)
 
-    def lookup_by_sig(
-        self, sig: int, *, include_fuzzy_matches: bool = False
-    ) -> Dict[str, bool]:
+    def lookup_by_sig(self, sig: int, *, window_size: int = 5) -> Dict[str, bool]:
         """Looks up a word that has already been translated into a signature by
         a previous call to Unscrambler.compute_word_sig.  Optionally returns
         near "fuzzy" matches.
@@ -244,23 +247,21 @@ class Unscrambler(object):
         18491949645300288339
 
         >>> u = Unscrambler()
-        >>> u.lookup_by_sig(sig, include_fuzzy_matches=True)
+        >>> u.lookup_by_sig(sig)
         {'pupigerous': False, 'pupigenous': False, 'unpurposing': False, 'superpurgation': False, 'unsupporting': False, 'superseptuaginarian': True, 'purpurogallin': False, 'scuppaug': False, 'purpurigenous': False, 'purpurogenous': False, 'proppage': False}
 
         """
         ret = {}
-        (exact, location) = list_utils.binary_search(self.sigs, sig)
-        start = location - 5
-        if start < 0:
-            start = 0
-        end = location + 6
-        if end > len(self.words):
-            end = len(self.words)
+        (_, location) = list_utils.binary_search(self.sigs, sig)
+        start = location - window_size
+        start = max(start, 0)
+        end = location + 1 + window_size
+        end = min(end, len(self.words))
 
         for x in range(start, end):
             word = self.words[x]
             fsig = self.sigs[x]
-            if include_fuzzy_matches is True or (fsig == sig):
+            if window_size > 0 or (fsig == sig):
                 ret[word] = fsig == sig
         return ret