Merge branch 'master' into performance

src/dinglehopper/align.py

@@ -0,0 +1,65 @@
+import math
+import unicodedata
+from math import ceil
+
+from rapidfuzz.distance import Levenshtein
+
+from .edit_distance import grapheme_clusters
+
+
+def align(t1, t2):
+    """Align text."""
+    s1 = list(grapheme_clusters(unicodedata.normalize("NFC", t1)))
+    s2 = list(grapheme_clusters(unicodedata.normalize("NFC", t2)))
+    return seq_align(s1, s2)
+
+
+def score_hint(er: float, n: int) -> int | None:
+    """Calculate RapidFuzz score hint for a given error rate and count.
+
+    Gives the score hint for the distance functions (= expected distance) or None if
+    the error rate is inf.
+    """
+    assert not math.isnan(er)
+    try:
+        score_hint = int(ceil(er * n))
+    except (OverflowError, ValueError):
+        # ceil(er * n) can be inf or NaN (for n == 0), so int() can throw an
+        # OverflowError and a ValueError.
+        score_hint = None
+    return score_hint
+
+
+def seq_align(s1, s2, score_hint=None):
+    """Align general sequences."""
+    s1 = list(s1)
+    s2 = list(s2)
+    ops = Levenshtein.editops(s1, s2, score_hint=score_hint)
+    i = 0
+    j = 0
+
+    while i < len(s1) or j < len(s2):
+        o = None
+        try:
+            ot = ops[0]
+            if ot[1] == i and ot[2] == j:
+                del ops[0]
+                o = ot
+        except IndexError:
+            pass
+
+        if o:
+            if o[0] == "insert":
+                yield None, s2[j]
+                j += 1
+            elif o[0] == "delete":
+                yield s1[i], None
+                i += 1
+            elif o[0] == "replace":
+                yield s1[i], s2[j]
+                i += 1
+                j += 1
+        else:
+            yield s1[i], s2[j]
+            i += 1
+            j += 1