Check strings in jupyter notebooks

pre_commit_hooks/util_string_fixer.py

@@ -0,0 +1,52 @@
+from __future__ import annotations
+
+import io
+import re
+import tokenize
+
+
+def handle_match(token_text: str) -> str:
+    if '"""' in token_text or "'''" in token_text:
+        return token_text
+
+    match = START_QUOTE_RE.match(token_text)
+    if match is not None:
+        meat = token_text[match.end():-1]
+        if '"' in meat or "'" in meat:
+            return token_text
+        else:
+            return match.group().replace('"', "'") + meat + "'"
+    else:
+        return token_text
+
+
+def get_line_offsets_by_line_no(src: str) -> list[int]:
+    # Padded so we can index with line number
+    offsets = [-1, 0]
+    for line in src.splitlines(True):
+        offsets.append(offsets[-1] + len(line))
+    return offsets
+
+
+def fix_strings_in_file_contents(contents: str) -> str:
+    line_offsets = get_line_offsets_by_line_no(contents)
+
+    # Basically a mutable string
+    splitcontents = list(contents)
+
+    # Iterate in reverse so the offsets are always correct
+    tokens_l = list(tokenize.generate_tokens(io.StringIO(contents).readline))
+    tokens = reversed(tokens_l)
+    for token_type, token_text, (srow, scol), (erow, ecol), _ in tokens:
+        if token_type == tokenize.STRING:
+            new_text = handle_match(token_text)
+            splitcontents[
+                line_offsets[srow] + scol:
+                line_offsets[erow] + ecol
+            ] = new_text
+
+    new_contents = ''.join(splitcontents)
+    return new_contents
+
+
+START_QUOTE_RE = re.compile('^[a-zA-Z]*"')