2026-1-6

venv/Lib/site-packages/whoosh/automata/lev.py

@@ -0,0 +1,30 @@
+from __future__ import print_function
+
+from whoosh.compat import unichr, xrange
+from whoosh.automata.fsa import ANY, EPSILON, NFA, unull
+
+
+def levenshtein_automaton(term, k, prefix=0):
+    nfa = NFA((0, 0))
+    if prefix:
+        for i in xrange(prefix):
+            c = term[i]
+            nfa.add_transition((i, 0), c, (i + 1, 0))
+
+    for i in xrange(prefix, len(term)):
+        c = term[i]
+        for e in xrange(k + 1):
+            # Correct character
+            nfa.add_transition((i, e), c, (i + 1, e))
+            if e < k:
+                # Deletion
+                nfa.add_transition((i, e), ANY, (i, e + 1))
+                # Insertion
+                nfa.add_transition((i, e), EPSILON, (i + 1, e + 1))
+                # Substitution
+                nfa.add_transition((i, e), ANY, (i + 1, e + 1))
+    for e in xrange(k + 1):
+        if e < k:
+            nfa.add_transition((len(term), e), ANY, (len(term), e + 1))
+        nfa.add_final_state((len(term), e))
+    return nfa