Standardise newlines after module-level docstrings (#3932)

[etc/vim.git] / src / black / strings.py
diff --git a/src/black/strings.py b/src/black/strings.py

index 9d0e2eb8430e538efcba96582dcfc9ee2d4bc468..0d30f09ed112d28583c9579f82e6221087b5bb01 100644 (file)
--- a/src/black/strings.py
+++ b/src/black/strings.py
@@ -5,19 +5,25 @@ Simple formatting on strings. Further string formatting code is in trans.py.
  import re
  import sys
  from functools import lru_cache
  import re
  import sys
  from functools import lru_cache
-from typing import List, Pattern
-
-if sys.version_info < (3, 8):
-    from typing_extensions import Final
-else:
-    from typing import Final
+from typing import Final, List, Match, Pattern
  
  
+from black._width_table import WIDTH_TABLE
+from blib2to3.pytree import Leaf
  
  STRING_PREFIX_CHARS: Final = "furbFURB"  # All possible string prefix characters.
  STRING_PREFIX_RE: Final = re.compile(
      r"^([" + STRING_PREFIX_CHARS + r"]*)(.*)$", re.DOTALL
  )
  FIRST_NON_WHITESPACE_RE: Final = re.compile(r"\s*\t+\s*(\S)")
  
  STRING_PREFIX_CHARS: Final = "furbFURB"  # All possible string prefix characters.
  STRING_PREFIX_RE: Final = re.compile(
      r"^([" + STRING_PREFIX_CHARS + r"]*)(.*)$", re.DOTALL
  )
  FIRST_NON_WHITESPACE_RE: Final = re.compile(r"\s*\t+\s*(\S)")
+UNICODE_ESCAPE_RE: Final = re.compile(
+    r"(?P<backslashes>\\+)(?P<body>"
+    r"(u(?P<u>[a-fA-F0-9]{4}))"  # Character with 16-bit hex value xxxx
+    r"|(U(?P<U>[a-fA-F0-9]{8}))"  # Character with 32-bit hex value xxxxxxxx
+    r"|(x(?P<x>[a-fA-F0-9]{2}))"  # Character with hex value hh
+    r"|(N\{(?P<N>[a-zA-Z0-9 \-]{2,})\})"  # Character named name in the Unicode database
+    r")",
+    re.VERBOSE,
+)
  
  
  def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
  
  
  def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
@@ -236,3 +242,88 @@ def normalize_string_quotes(s: str) -> str:
          return s  # Prefer double quotes
  
      return f"{prefix}{new_quote}{new_body}{new_quote}"
          return s  # Prefer double quotes
  
      return f"{prefix}{new_quote}{new_body}{new_quote}"
+
+
+def normalize_unicode_escape_sequences(leaf: Leaf) -> None:
+    """Replace hex codes in Unicode escape sequences with lowercase representation."""
+    text = leaf.value
+    prefix = get_string_prefix(text)
+    if "r" in prefix.lower():
+        return
+
+    def replace(m: Match[str]) -> str:
+        groups = m.groupdict()
+        back_slashes = groups["backslashes"]
+
+        if len(back_slashes) % 2 == 0:
+            return back_slashes + groups["body"]
+
+        if groups["u"]:
+            # \u
+            return back_slashes + "u" + groups["u"].lower()
+        elif groups["U"]:
+            # \U
+            return back_slashes + "U" + groups["U"].lower()
+        elif groups["x"]:
+            # \x
+            return back_slashes + "x" + groups["x"].lower()
+        else:
+            assert groups["N"], f"Unexpected match: {m}"
+            # \N{}
+            return back_slashes + "N{" + groups["N"].upper() + "}"
+
+    leaf.value = re.sub(UNICODE_ESCAPE_RE, replace, text)
+
+
+@lru_cache(maxsize=4096)
+def char_width(char: str) -> int:
+    """Return the width of a single character as it would be displayed in a
+    terminal or editor (which respects Unicode East Asian Width).
+
+    Full width characters are counted as 2, while half width characters are
+    counted as 1.  Also control characters are counted as 0.
+    """
+    table = WIDTH_TABLE
+    codepoint = ord(char)
+    highest = len(table) - 1
+    lowest = 0
+    idx = highest // 2
+    while True:
+        start_codepoint, end_codepoint, width = table[idx]
+        if codepoint < start_codepoint:
+            highest = idx - 1
+        elif codepoint > end_codepoint:
+            lowest = idx + 1
+        else:
+            return 0 if width < 0 else width
+        if highest < lowest:
+            break
+        idx = (highest + lowest) // 2
+    return 1
+
+
+def str_width(line_str: str) -> int:
+    """Return the width of `line_str` as it would be displayed in a terminal
+    or editor (which respects Unicode East Asian Width).
+
+    You could utilize this function to determine, for example, if a string
+    is too wide to display in a terminal or editor.
+    """
+    if line_str.isascii():
+        # Fast path for a line consisting of only ASCII characters
+        return len(line_str)
+    return sum(map(char_width, line_str))
+
+
+def count_chars_in_width(line_str: str, max_width: int) -> int:
+    """Count the number of characters in `line_str` that would fit in a
+    terminal or editor of `max_width` (which respects Unicode East Asian
+    Width).
+    """
+    total_width = 0
+    for i, char in enumerate(line_str):
+        width = char_width(char)
+        if width + total_width > max_width:
+            return i
+        total_width += width
+    return len(line_str)