"""
String transformers that can split and merge strings.
"""
+import re
+import sys
from abc import ABC, abstractmethod
from collections import defaultdict
from dataclasses import dataclass
-import regex as re
from typing import (
Any,
Callable,
+ ClassVar,
Collection,
Dict,
Iterable,
List,
Optional,
Sequence,
+ Set,
Tuple,
TypeVar,
Union,
)
-from black.rusty import Result, Ok, Err
+if sys.version_info < (3, 8):
+ from typing_extensions import Final, Literal
+else:
+ from typing import Literal, Final
+
+from mypy_extensions import trait
-from black.mode import Feature
-from black.nodes import syms, replace_child, parent_type
-from black.nodes import is_empty_par, is_empty_lpar, is_empty_rpar
-from black.nodes import OPENING_BRACKETS, CLOSING_BRACKETS, STANDALONE_COMMENT
-from black.lines import Line, append_leaves
from black.brackets import BracketMatchError
from black.comments import contains_pragma_comment
-from black.strings import has_triple_quotes, get_string_prefix, assert_is_leaf_string
-from black.strings import normalize_string_quotes
-
-from blib2to3.pytree import Leaf, Node
+from black.lines import Line, append_leaves
+from black.mode import Feature
+from black.nodes import (
+ CLOSING_BRACKETS,
+ OPENING_BRACKETS,
+ STANDALONE_COMMENT,
+ is_empty_lpar,
+ is_empty_par,
+ is_empty_rpar,
+ parent_type,
+ replace_child,
+ syms,
+)
+from black.rusty import Err, Ok, Result
+from black.strings import (
+ assert_is_leaf_string,
+ get_string_prefix,
+ has_triple_quotes,
+ normalize_string_quotes,
+)
from blib2to3.pgen2 import token
+from blib2to3.pytree import Leaf, Node
class CannotTransform(Exception):
return Err(cant_transform)
-@dataclass # type: ignore
+def hug_power_op(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+ """A transformer which normalizes spacing around power operators."""
+
+ # Performance optimization to avoid unnecessary Leaf clones and other ops.
+ for leaf in line.leaves:
+ if leaf.type == token.DOUBLESTAR:
+ break
+ else:
+ raise CannotTransform("No doublestar token was found in the line.")
+
+ def is_simple_lookup(index: int, step: Literal[1, -1]) -> bool:
+ # Brackets and parentheses indicate calls, subscripts, etc. ...
+ # basically stuff that doesn't count as "simple". Only a NAME lookup
+ # or dotted lookup (eg. NAME.NAME) is OK.
+ if step == -1:
+ disallowed = {token.RPAR, token.RSQB}
+ else:
+ disallowed = {token.LPAR, token.LSQB}
+
+ while 0 <= index < len(line.leaves):
+ current = line.leaves[index]
+ if current.type in disallowed:
+ return False
+ if current.type not in {token.NAME, token.DOT} or current.value == "for":
+ # If the current token isn't disallowed, we'll assume this is simple as
+ # only the disallowed tokens are semantically attached to this lookup
+ # expression we're checking. Also, stop early if we hit the 'for' bit
+ # of a comprehension.
+ return True
+
+ index += step
+
+ return True
+
+ def is_simple_operand(index: int, kind: Literal["base", "exponent"]) -> bool:
+ # An operand is considered "simple" if's a NAME, a numeric CONSTANT, a simple
+ # lookup (see above), with or without a preceding unary operator.
+ start = line.leaves[index]
+ if start.type in {token.NAME, token.NUMBER}:
+ return is_simple_lookup(index, step=(1 if kind == "exponent" else -1))
+
+ if start.type in {token.PLUS, token.MINUS, token.TILDE}:
+ if line.leaves[index + 1].type in {token.NAME, token.NUMBER}:
+ # step is always one as bases with a preceding unary op will be checked
+ # for simplicity starting from the next token (so it'll hit the check
+ # above).
+ return is_simple_lookup(index + 1, step=1)
+
+ return False
+
+ new_line = line.clone()
+ should_hug = False
+ for idx, leaf in enumerate(line.leaves):
+ new_leaf = leaf.clone()
+ if should_hug:
+ new_leaf.prefix = ""
+ should_hug = False
+
+ should_hug = (
+ (0 < idx < len(line.leaves) - 1)
+ and leaf.type == token.DOUBLESTAR
+ and is_simple_operand(idx - 1, kind="base")
+ and line.leaves[idx - 1].value != "lambda"
+ and is_simple_operand(idx + 1, kind="exponent")
+ )
+ if should_hug:
+ new_leaf.prefix = ""
+
+ # We have to be careful to make a new line properly:
+ # - bracket related metadata must be maintained (handled by Line.append)
+ # - comments need to copied over, updating the leaf IDs they're attached to
+ new_line.append(new_leaf, preformatted=True)
+ for comment_leaf in line.comments_after(leaf):
+ new_line.append(comment_leaf, preformatted=True)
+
+ yield new_line
+
+
class StringTransformer(ABC):
"""
An implementation of the Transformer protocol that relies on its
as much as possible.
"""
- line_length: int
- normalize_strings: bool
- __name__ = "StringTransformer"
+ __name__: Final = "StringTransformer"
+
+ # Ideally this would be a dataclass, but unfortunately mypyc breaks when used with
+ # `abc.ABC`.
+ def __init__(self, line_length: int, normalize_strings: bool) -> None:
+ self.line_length = line_length
+ self.normalize_strings = normalize_strings
@abstractmethod
def do_match(self, line: Line) -> TMatchResult:
break_idx: int
+@trait
class CustomSplitMapMixin:
"""
This mixin class is used to map merged strings to a sequence of
the resultant substrings go over the configured max line length.
"""
- _Key = Tuple[StringID, str]
- _CUSTOM_SPLIT_MAP: Dict[_Key, Tuple[CustomSplit, ...]] = defaultdict(tuple)
+ _Key: ClassVar = Tuple[StringID, str]
+ _CUSTOM_SPLIT_MAP: ClassVar[Dict[_Key, Tuple[CustomSplit, ...]]] = defaultdict(
+ tuple
+ )
@staticmethod
def _get_key(string: str) -> "CustomSplitMapMixin._Key":
return key in self._CUSTOM_SPLIT_MAP
-class StringMerger(CustomSplitMapMixin, StringTransformer):
+class StringMerger(StringTransformer, CustomSplitMapMixin):
"""StringTransformer that merges strings together.
Requirements:
is_valid_index = is_valid_index_factory(LL)
- for (i, leaf) in enumerate(LL):
+ for i, leaf in enumerate(LL):
if (
leaf.type == token.STRING
and is_valid_index(i + 1)
and is_valid_index(next_str_idx)
and LL[next_str_idx].type == token.STRING
):
- prefix = get_string_prefix(LL[next_str_idx].value)
+ prefix = get_string_prefix(LL[next_str_idx].value).lower()
next_str_idx += 1
# The next loop merges the string group. The final string will be
num_of_strings += 1
SS = LL[next_str_idx].value
- next_prefix = get_string_prefix(SS)
+ next_prefix = get_string_prefix(SS).lower()
# If this is an f-string group but this substring is not prefixed
# with 'f'...
if "f" in prefix and "f" not in next_prefix:
# Then we must escape any braces contained in this substring.
- SS = re.subf(r"(\{|\})", "{1}{1}", SS)
+ SS = re.sub(r"(\{|\})", r"\1\1", SS)
NSS = make_naked(SS, next_prefix)
next_str_idx += 1
+ # Take a note on the index of the non-STRING leaf.
+ non_string_idx = next_str_idx
+
S_leaf = Leaf(token.STRING, S)
if self.normalize_strings:
S_leaf.value = normalize_string_quotes(S_leaf.value)
string_leaf = Leaf(token.STRING, S_leaf.value.replace(BREAK_MARK, ""))
if atom_node is not None:
- replace_child(atom_node, string_leaf)
+ # If not all children of the atom node are merged (this can happen
+ # when there is a standalone comment in the middle) ...
+ if non_string_idx - string_idx < len(atom_node.children):
+ # We need to replace the old STRING leaves with the new string leaf.
+ first_child_idx = LL[string_idx].remove()
+ for idx in range(string_idx + 1, non_string_idx):
+ LL[idx].remove()
+ if first_child_idx is not None:
+ atom_node.insert_child(first_child_idx, string_leaf)
+ else:
+ # Else replace the atom node with the new string leaf.
+ replace_child(atom_node, string_leaf)
# Build the final line ('new_line') that this method will later return.
new_line = line.clone()
- for (i, leaf) in enumerate(LL):
+ for i, leaf in enumerate(LL):
if i == string_idx:
new_line.append(string_leaf)
return TErr("StringMerger does NOT merge multiline strings.")
num_of_strings += 1
- prefix = get_string_prefix(leaf.value)
+ prefix = get_string_prefix(leaf.value).lower()
if "r" in prefix:
return TErr("StringMerger does NOT merge raw strings.")
is_valid_index = is_valid_index_factory(LL)
- for (idx, leaf) in enumerate(LL):
+ for idx, leaf in enumerate(LL):
# Should be a string...
if leaf.type != token.STRING:
continue
* The target string is not a multiline (i.e. triple-quote) string.
"""
- STRING_OPERATORS = [
+ STRING_OPERATORS: Final = [
token.EQEQUAL,
token.GREATER,
token.GREATEREQUAL,
max_string_length = self.line_length - offset
return max_string_length
+ @staticmethod
+ def _prefer_paren_wrap_match(LL: List[Leaf]) -> Optional[int]:
+ """
+ Returns:
+ string_idx such that @LL[string_idx] is equal to our target (i.e.
+ matched) string, if this line matches the "prefer paren wrap" statement
+ requirements listed in the 'Requirements' section of the StringParenWrapper
+ class's docstring.
+ OR
+ None, otherwise.
+ """
+ # The line must start with a string.
+ if LL[0].type != token.STRING:
+ return None
+
+ # If the string is surrounded by commas (or is the first/last child)...
+ prev_sibling = LL[0].prev_sibling
+ next_sibling = LL[0].next_sibling
+ if not prev_sibling and not next_sibling and parent_type(LL[0]) == syms.atom:
+ # If it's an atom string, we need to check the parent atom's siblings.
+ parent = LL[0].parent
+ assert parent is not None # For type checkers.
+ prev_sibling = parent.prev_sibling
+ next_sibling = parent.next_sibling
+ if (not prev_sibling or prev_sibling.type == token.COMMA) and (
+ not next_sibling or next_sibling.type == token.COMMA
+ ):
+ return 0
-class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
+ return None
+
+
+def iter_fexpr_spans(s: str) -> Iterator[Tuple[int, int]]:
+ """
+ Yields spans corresponding to expressions in a given f-string.
+ Spans are half-open ranges (left inclusive, right exclusive).
+ Assumes the input string is a valid f-string, but will not crash if the input
+ string is invalid.
+ """
+ stack: List[int] = [] # our curly paren stack
+ i = 0
+ while i < len(s):
+ if s[i] == "{":
+ # if we're in a string part of the f-string, ignore escaped curly braces
+ if not stack and i + 1 < len(s) and s[i + 1] == "{":
+ i += 2
+ continue
+ stack.append(i)
+ i += 1
+ continue
+
+ if s[i] == "}":
+ if not stack:
+ i += 1
+ continue
+ j = stack.pop()
+ # we've made it back out of the expression! yield the span
+ if not stack:
+ yield (j, i + 1)
+ i += 1
+ continue
+
+ # if we're in an expression part of the f-string, fast forward through strings
+ # note that backslashes are not legal in the expression portion of f-strings
+ if stack:
+ delim = None
+ if s[i : i + 3] in ("'''", '"""'):
+ delim = s[i : i + 3]
+ elif s[i] in ("'", '"'):
+ delim = s[i]
+ if delim:
+ i += len(delim)
+ while i < len(s) and s[i : i + len(delim)] != delim:
+ i += 1
+ i += len(delim)
+ continue
+ i += 1
+
+
+def fstring_contains_expr(s: str) -> bool:
+ return any(iter_fexpr_spans(s))
+
+
+class StringSplitter(BaseStringSplitter, CustomSplitMapMixin):
"""
StringTransformer that splits "atom" strings (i.e. strings which exist on
lines by themselves).
CustomSplit objects and add them to the custom split map.
"""
- MIN_SUBSTR_SIZE = 6
- # Matches an "f-expression" (e.g. {var}) that might be found in an f-string.
- RE_FEXPR = r"""
- (?<!\{) (?:\{\{)* \{ (?!\{)
- (?:
- [^\{\}]
- | \{\{
- | \}\}
- | (?R)
- )+
- \}
- """
+ MIN_SUBSTR_SIZE: Final = 6
def do_splitter_match(self, line: Line) -> TMatchResult:
LL = line.leaves
+ if self._prefer_paren_wrap_match(LL) is not None:
+ return TErr("Line needs to be wrapped in parens first.")
+
is_valid_index = is_valid_index_factory(LL)
idx = 0
is_valid_index = is_valid_index_factory(LL)
insert_str_child = insert_str_child_factory(LL[string_idx])
- prefix = get_string_prefix(LL[string_idx].value)
+ prefix = get_string_prefix(LL[string_idx].value).lower()
# We MAY choose to drop the 'f' prefix from substrings that don't
# contain any f-expressions, but ONLY if the original f-string
# contains at least one f-expression. Otherwise, we will alter the AST
# of the program.
- drop_pointless_f_prefix = ("f" in prefix) and re.search(
- self.RE_FEXPR, LL[string_idx].value, re.VERBOSE
+ drop_pointless_f_prefix = ("f" in prefix) and fstring_contains_expr(
+ LL[string_idx].value
)
first_string_line = True
string_op_leaves = self._get_string_operator_leaves(LL)
string_op_leaves_length = (
- sum([len(str(prefix_leaf)) for prefix_leaf in string_op_leaves]) + 1
+ sum(len(str(prefix_leaf)) for prefix_leaf in string_op_leaves) + 1
if string_op_leaves
else 0
)
last_line.comments = line.comments.copy()
yield Ok(last_line)
+ def _iter_nameescape_slices(self, string: str) -> Iterator[Tuple[Index, Index]]:
+ """
+ Yields:
+ All ranges of @string which, if @string were to be split there,
+ would result in the splitting of an \\N{...} expression (which is NOT
+ allowed).
+ """
+ # True - the previous backslash was unescaped
+ # False - the previous backslash was escaped *or* there was no backslash
+ previous_was_unescaped_backslash = False
+ it = iter(enumerate(string))
+ for idx, c in it:
+ if c == "\\":
+ previous_was_unescaped_backslash = not previous_was_unescaped_backslash
+ continue
+ if not previous_was_unescaped_backslash or c != "N":
+ previous_was_unescaped_backslash = False
+ continue
+ previous_was_unescaped_backslash = False
+
+ begin = idx - 1 # the position of backslash before \N{...}
+ for idx, c in it:
+ if c == "}":
+ end = idx
+ break
+ else:
+ # malformed nameescape expression?
+ # should have been detected by AST parsing earlier...
+ raise RuntimeError(f"{self.__class__.__name__} LOGIC ERROR!")
+ yield begin, end
+
+ def _iter_fexpr_slices(self, string: str) -> Iterator[Tuple[Index, Index]]:
+ """
+ Yields:
+ All ranges of @string which, if @string were to be split there,
+ would result in the splitting of an f-expression (which is NOT
+ allowed).
+ """
+ if "f" not in get_string_prefix(string).lower():
+ return
+ yield from iter_fexpr_spans(string)
+
+ def _get_illegal_split_indices(self, string: str) -> Set[Index]:
+ illegal_indices: Set[Index] = set()
+ iterators = [
+ self._iter_fexpr_slices(string),
+ self._iter_nameescape_slices(string),
+ ]
+ for it in iterators:
+ for begin, end in it:
+ illegal_indices.update(range(begin, end + 1))
+ return illegal_indices
+
def _get_break_idx(self, string: str, max_break_idx: int) -> Optional[int]:
"""
This method contains the algorithm that StringSplitter uses to
assert is_valid_index(max_break_idx)
assert_is_leaf_string(string)
- _fexpr_slices: Optional[List[Tuple[Index, Index]]] = None
+ _illegal_split_indices = self._get_illegal_split_indices(string)
- def fexpr_slices() -> Iterator[Tuple[Index, Index]]:
- """
- Yields:
- All ranges of @string which, if @string were to be split there,
- would result in the splitting of an f-expression (which is NOT
- allowed).
- """
- nonlocal _fexpr_slices
-
- if _fexpr_slices is None:
- _fexpr_slices = []
- for match in re.finditer(self.RE_FEXPR, string, re.VERBOSE):
- _fexpr_slices.append(match.span())
-
- yield from _fexpr_slices
-
- is_fstring = "f" in get_string_prefix(string)
-
- def breaks_fstring_expression(i: Index) -> bool:
+ def breaks_unsplittable_expression(i: Index) -> bool:
"""
Returns:
True iff returning @i would result in the splitting of an
- f-expression (which is NOT allowed).
+ unsplittable expression (which is NOT allowed).
"""
- if not is_fstring:
- return False
-
- for (start, end) in fexpr_slices():
- if start <= i < end:
- return True
-
- return False
+ return i in _illegal_split_indices
def passes_all_checks(i: Index) -> bool:
"""
is_space
and is_not_escaped
and is_big_enough
- and not breaks_fstring_expression(i)
+ and not breaks_unsplittable_expression(i)
)
# First, we check all indices BELOW @max_break_idx.
"""
assert_is_leaf_string(string)
- if "f" in prefix and not re.search(self.RE_FEXPR, string, re.VERBOSE):
+ if "f" in prefix and not fstring_contains_expr(string):
new_prefix = prefix.replace("f", "")
temp = string[len(prefix) :]
return string_op_leaves
-class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter):
+class StringParenWrapper(BaseStringSplitter, CustomSplitMapMixin):
"""
- StringTransformer that splits non-"atom" strings (i.e. strings that do not
- exist on lines by themselves).
+ StringTransformer that wraps strings in parens and then splits at the LPAR.
Requirements:
All of the requirements listed in BaseStringSplitter's docstring in
OR
* The line is a dictionary key assignment where some valid key is being
assigned the value of some string.
+ OR
+ * The line starts with an "atom" string that prefers to be wrapped in
+ parens. It's preferred to be wrapped when the string is surrounded by
+ commas (or is the first/last child).
Transformations:
The chosen string is wrapped in parentheses and then split at the LPAR.
changed such that it no longer needs to be given its own line,
StringParenWrapper relies on StringParenStripper to clean up the
parentheses it created.
+
+ For "atom" strings that prefers to be wrapped in parens, it requires
+ StringSplitter to hold the split until the string is wrapped in parens.
"""
def do_splitter_match(self, line: Line) -> TMatchResult:
or self._assert_match(LL)
or self._assign_match(LL)
or self._dict_match(LL)
+ or self._prefer_paren_wrap_match(LL)
)
if string_idx is not None:
if parent_type(LL[0]) == syms.assert_stmt and LL[0].value == "assert":
is_valid_index = is_valid_index_factory(LL)
- for (i, leaf) in enumerate(LL):
+ for i, leaf in enumerate(LL):
# We MUST find a comma...
if leaf.type == token.COMMA:
idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
):
is_valid_index = is_valid_index_factory(LL)
- for (i, leaf) in enumerate(LL):
+ for i, leaf in enumerate(LL):
# We MUST find either an '=' or '+=' symbol...
if leaf.type in [token.EQUAL, token.PLUSEQUAL]:
idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
if syms.dictsetmaker in [parent_type(LL[0]), parent_type(LL[0].parent)]:
is_valid_index = is_valid_index_factory(LL)
- for (i, leaf) in enumerate(LL):
+ for i, leaf in enumerate(LL):
# We MUST find a colon...
if leaf.type == token.COLON:
idx = i + 2 if is_empty_par(LL[i + 1]) else i + 1
```
"""
- DEFAULT_TOKEN = -1
+ DEFAULT_TOKEN: Final = 20210605
# String Parser States
- START = 1
- DOT = 2
- NAME = 3
- PERCENT = 4
- SINGLE_FMT_ARG = 5
- LPAR = 6
- RPAR = 7
- DONE = 8
+ START: Final = 1
+ DOT: Final = 2
+ NAME: Final = 3
+ PERCENT: Final = 4
+ SINGLE_FMT_ARG: Final = 5
+ LPAR: Final = 6
+ RPAR: Final = 7
+ DONE: Final = 8
# Lookup Table for Next State
- _goto: Dict[Tuple[ParserState, NodeType], ParserState] = {
+ _goto: Final[Dict[Tuple[ParserState, NodeType], ParserState]] = {
# A string trailer may start with '.' OR '%'.
(START, token.DOT): DOT,
(START, token.PERCENT): PERCENT,
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