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Mini Shell
Mini Shell
# SPDX-License-Identifier: MIT
# SPDX-FileCopyrightText: 2021 Taneli Hukkinen
# Licensed to PSF under a Contributor Agreement.
from __future__ import annotations
from collections.abc import Iterable
import string
from types import MappingProxyType
from typing import Any, BinaryIO, NamedTuple
from ._re import (
RE_DATETIME,
RE_LOCALTIME,
RE_NUMBER,
match_to_datetime,
match_to_localtime,
match_to_number,
)
from ._types import Key, ParseFloat, Pos
ASCII_CTRL = frozenset(chr(i) for i in range(32)) | frozenset(chr(127))
# Neither of these sets include quotation mark or backslash. They are
# currently handled as separate cases in the parser functions.
ILLEGAL_BASIC_STR_CHARS = ASCII_CTRL - frozenset("\t")
ILLEGAL_MULTILINE_BASIC_STR_CHARS = ASCII_CTRL - frozenset("\t\n")
ILLEGAL_LITERAL_STR_CHARS = ILLEGAL_BASIC_STR_CHARS
ILLEGAL_MULTILINE_LITERAL_STR_CHARS = ILLEGAL_MULTILINE_BASIC_STR_CHARS
ILLEGAL_COMMENT_CHARS = ILLEGAL_BASIC_STR_CHARS
TOML_WS = frozenset(" \t")
TOML_WS_AND_NEWLINE = TOML_WS | frozenset("\n")
BARE_KEY_CHARS = frozenset(string.ascii_letters + string.digits + "-_")
KEY_INITIAL_CHARS = BARE_KEY_CHARS | frozenset("\"'")
HEXDIGIT_CHARS = frozenset(string.hexdigits)
BASIC_STR_ESCAPE_REPLACEMENTS = MappingProxyType(
{
"\\b": "\u0008", # backspace
"\\t": "\u0009", # tab
"\\n": "\u000A", # linefeed
"\\f": "\u000C", # form feed
"\\r": "\u000D", # carriage return
'\\"': "\u0022", # quote
"\\\\": "\u005C", # backslash
}
)
class TOMLDecodeError(ValueError):
"""An error raised if a document is not valid TOML."""
def load(fp: BinaryIO, /, *, parse_float: ParseFloat = float) -> dict[str, Any]:
"""Parse TOML from a binary file object."""
b = fp.read()
try:
s = b.decode()
except AttributeError:
raise TypeError(
"File must be opened in binary mode, e.g. use `open('foo.toml', 'rb')`"
) from None
return loads(s, parse_float=parse_float)
def loads(s: str, /, *, parse_float: ParseFloat = float) -> dict[str, Any]: # noqa: C901
"""Parse TOML from a string."""
# The spec allows converting "\r\n" to "\n", even in string
# literals. Let's do so to simplify parsing.
src = s.replace("\r\n", "\n")
pos = 0
out = Output(NestedDict(), Flags())
header: Key = ()
parse_float = make_safe_parse_float(parse_float)
# Parse one statement at a time
# (typically means one line in TOML source)
while True:
# 1. Skip line leading whitespace
pos = skip_chars(src, pos, TOML_WS)
# 2. Parse rules. Expect one of the following:
# - end of file
# - end of line
# - comment
# - key/value pair
# - append dict to list (and move to its namespace)
# - create dict (and move to its namespace)
# Skip trailing whitespace when applicable.
try:
char = src[pos]
except IndexError:
break
if char == "\n":
pos += 1
continue
if char in KEY_INITIAL_CHARS:
pos = key_value_rule(src, pos, out, header, parse_float)
pos = skip_chars(src, pos, TOML_WS)
elif char == "[":
try:
second_char: str | None = src[pos + 1]
except IndexError:
second_char = None
out.flags.finalize_pending()
if second_char == "[":
pos, header = create_list_rule(src, pos, out)
else:
pos, header = create_dict_rule(src, pos, out)
pos = skip_chars(src, pos, TOML_WS)
elif char != "#":
raise suffixed_err(src, pos, "Invalid statement")
# 3. Skip comment
pos = skip_comment(src, pos)
# 4. Expect end of line or end of file
try:
char = src[pos]
except IndexError:
break
if char != "\n":
raise suffixed_err(
src, pos, "Expected newline or end of document after a statement"
)
pos += 1
return out.data.dict
class Flags:
"""Flags that map to parsed keys/namespaces."""
# Marks an immutable namespace (inline array or inline table).
FROZEN = 0
# Marks a nest that has been explicitly created and can no longer
# be opened using the "[table]" syntax.
EXPLICIT_NEST = 1
def __init__(self) -> None:
self._flags: dict[str, dict] = {}
self._pending_flags: set[tuple[Key, int]] = set()
def add_pending(self, key: Key, flag: int) -> None:
self._pending_flags.add((key, flag))
def finalize_pending(self) -> None:
for key, flag in self._pending_flags:
self.set(key, flag, recursive=False)
self._pending_flags.clear()
def unset_all(self, key: Key) -> None:
cont = self._flags
for k in key[:-1]:
if k not in cont:
return
cont = cont[k]["nested"]
cont.pop(key[-1], None)
def set(self, key: Key, flag: int, *, recursive: bool) -> None: # noqa: A003
cont = self._flags
key_parent, key_stem = key[:-1], key[-1]
for k in key_parent:
if k not in cont:
cont[k] = {"flags": set(), "recursive_flags": set(), "nested": {}}
cont = cont[k]["nested"]
if key_stem not in cont:
cont[key_stem] = {"flags": set(), "recursive_flags": set(), "nested": {}}
cont[key_stem]["recursive_flags" if recursive else "flags"].add(flag)
def is_(self, key: Key, flag: int) -> bool:
if not key:
return False # document root has no flags
cont = self._flags
for k in key[:-1]:
if k not in cont:
return False
inner_cont = cont[k]
if flag in inner_cont["recursive_flags"]:
return True
cont = inner_cont["nested"]
key_stem = key[-1]
if key_stem in cont:
cont = cont[key_stem]
return flag in cont["flags"] or flag in cont["recursive_flags"]
return False
class NestedDict:
def __init__(self) -> None:
# The parsed content of the TOML document
self.dict: dict[str, Any] = {}
def get_or_create_nest(
self,
key: Key,
*,
access_lists: bool = True,
) -> dict:
cont: Any = self.dict
for k in key:
if k not in cont:
cont[k] = {}
cont = cont[k]
if access_lists and isinstance(cont, list):
cont = cont[-1]
if not isinstance(cont, dict):
raise KeyError("There is no nest behind this key")
return cont
def append_nest_to_list(self, key: Key) -> None:
cont = self.get_or_create_nest(key[:-1])
last_key = key[-1]
if last_key in cont:
list_ = cont[last_key]
if not isinstance(list_, list):
raise KeyError("An object other than list found behind this key")
list_.append({})
else:
cont[last_key] = [{}]
class Output(NamedTuple):
data: NestedDict
flags: Flags
def skip_chars(src: str, pos: Pos, chars: Iterable[str]) -> Pos:
try:
while src[pos] in chars:
pos += 1
except IndexError:
pass
return pos
def skip_until(
src: str,
pos: Pos,
expect: str,
*,
error_on: frozenset[str],
error_on_eof: bool,
) -> Pos:
try:
new_pos = src.index(expect, pos)
except ValueError:
new_pos = len(src)
if error_on_eof:
raise suffixed_err(src, new_pos, f"Expected {expect!r}") from None
if not error_on.isdisjoint(src[pos:new_pos]):
while src[pos] not in error_on:
pos += 1
raise suffixed_err(src, pos, f"Found invalid character {src[pos]!r}")
return new_pos
def skip_comment(src: str, pos: Pos) -> Pos:
try:
char: str | None = src[pos]
except IndexError:
char = None
if char == "#":
return skip_until(
src, pos + 1, "\n", error_on=ILLEGAL_COMMENT_CHARS, error_on_eof=False
)
return pos
def skip_comments_and_array_ws(src: str, pos: Pos) -> Pos:
while True:
pos_before_skip = pos
pos = skip_chars(src, pos, TOML_WS_AND_NEWLINE)
pos = skip_comment(src, pos)
if pos == pos_before_skip:
return pos
def create_dict_rule(src: str, pos: Pos, out: Output) -> tuple[Pos, Key]:
pos += 1 # Skip "["
pos = skip_chars(src, pos, TOML_WS)
pos, key = parse_key(src, pos)
if out.flags.is_(key, Flags.EXPLICIT_NEST) or out.flags.is_(key, Flags.FROZEN):
raise suffixed_err(src, pos, f"Cannot declare {key} twice")
out.flags.set(key, Flags.EXPLICIT_NEST, recursive=False)
try:
out.data.get_or_create_nest(key)
except KeyError:
raise suffixed_err(src, pos, "Cannot overwrite a value") from None
if not src.startswith("]", pos):
raise suffixed_err(src, pos, "Expected ']' at the end of a table declaration")
return pos + 1, key
def create_list_rule(src: str, pos: Pos, out: Output) -> tuple[Pos, Key]:
pos += 2 # Skip "[["
pos = skip_chars(src, pos, TOML_WS)
pos, key = parse_key(src, pos)
if out.flags.is_(key, Flags.FROZEN):
raise suffixed_err(src, pos, f"Cannot mutate immutable namespace {key}")
# Free the namespace now that it points to another empty list item...
out.flags.unset_all(key)
# ...but this key precisely is still prohibited from table declaration
out.flags.set(key, Flags.EXPLICIT_NEST, recursive=False)
try:
out.data.append_nest_to_list(key)
except KeyError:
raise suffixed_err(src, pos, "Cannot overwrite a value") from None
if not src.startswith("]]", pos):
raise suffixed_err(src, pos, "Expected ']]' at the end of an array declaration")
return pos + 2, key
def key_value_rule(
src: str, pos: Pos, out: Output, header: Key, parse_float: ParseFloat
) -> Pos:
pos, key, value = parse_key_value_pair(src, pos, parse_float)
key_parent, key_stem = key[:-1], key[-1]
abs_key_parent = header + key_parent
relative_path_cont_keys = (header + key[:i] for i in range(1, len(key)))
for cont_key in relative_path_cont_keys:
# Check that dotted key syntax does not redefine an existing table
if out.flags.is_(cont_key, Flags.EXPLICIT_NEST):
raise suffixed_err(src, pos, f"Cannot redefine namespace {cont_key}")
# Containers in the relative path can't be opened with the table syntax or
# dotted key/value syntax in following table sections.
out.flags.add_pending(cont_key, Flags.EXPLICIT_NEST)
if out.flags.is_(abs_key_parent, Flags.FROZEN):
raise suffixed_err(
src, pos, f"Cannot mutate immutable namespace {abs_key_parent}"
)
try:
nest = out.data.get_or_create_nest(abs_key_parent)
except KeyError:
raise suffixed_err(src, pos, "Cannot overwrite a value") from None
if key_stem in nest:
raise suffixed_err(src, pos, "Cannot overwrite a value")
# Mark inline table and array namespaces recursively immutable
if isinstance(value, (dict, list)):
out.flags.set(header + key, Flags.FROZEN, recursive=True)
nest[key_stem] = value
return pos
def parse_key_value_pair(
src: str, pos: Pos, parse_float: ParseFloat
) -> tuple[Pos, Key, Any]:
pos, key = parse_key(src, pos)
try:
char: str | None = src[pos]
except IndexError:
char = None
if char != "=":
raise suffixed_err(src, pos, "Expected '=' after a key in a key/value pair")
pos += 1
pos = skip_chars(src, pos, TOML_WS)
pos, value = parse_value(src, pos, parse_float)
return pos, key, value
def parse_key(src: str, pos: Pos) -> tuple[Pos, Key]:
pos, key_part = parse_key_part(src, pos)
key: Key = (key_part,)
pos = skip_chars(src, pos, TOML_WS)
while True:
try:
char: str | None = src[pos]
except IndexError:
char = None
if char != ".":
return pos, key
pos += 1
pos = skip_chars(src, pos, TOML_WS)
pos, key_part = parse_key_part(src, pos)
key += (key_part,)
pos = skip_chars(src, pos, TOML_WS)
def parse_key_part(src: str, pos: Pos) -> tuple[Pos, str]:
try:
char: str | None = src[pos]
except IndexError:
char = None
if char in BARE_KEY_CHARS:
start_pos = pos
pos = skip_chars(src, pos, BARE_KEY_CHARS)
return pos, src[start_pos:pos]
if char == "'":
return parse_literal_str(src, pos)
if char == '"':
return parse_one_line_basic_str(src, pos)
raise suffixed_err(src, pos, "Invalid initial character for a key part")
def parse_one_line_basic_str(src: str, pos: Pos) -> tuple[Pos, str]:
pos += 1
return parse_basic_str(src, pos, multiline=False)
def parse_array(src: str, pos: Pos, parse_float: ParseFloat) -> tuple[Pos, list]:
pos += 1
array: list = []
pos = skip_comments_and_array_ws(src, pos)
if src.startswith("]", pos):
return pos + 1, array
while True:
pos, val = parse_value(src, pos, parse_float)
array.append(val)
pos = skip_comments_and_array_ws(src, pos)
c = src[pos : pos + 1]
if c == "]":
return pos + 1, array
if c != ",":
raise suffixed_err(src, pos, "Unclosed array")
pos += 1
pos = skip_comments_and_array_ws(src, pos)
if src.startswith("]", pos):
return pos + 1, array
def parse_inline_table(src: str, pos: Pos, parse_float: ParseFloat) -> tuple[Pos, dict]:
pos += 1
nested_dict = NestedDict()
flags = Flags()
pos = skip_chars(src, pos, TOML_WS)
if src.startswith("}", pos):
return pos + 1, nested_dict.dict
while True:
pos, key, value = parse_key_value_pair(src, pos, parse_float)
key_parent, key_stem = key[:-1], key[-1]
if flags.is_(key, Flags.FROZEN):
raise suffixed_err(src, pos, f"Cannot mutate immutable namespace {key}")
try:
nest = nested_dict.get_or_create_nest(key_parent, access_lists=False)
except KeyError:
raise suffixed_err(src, pos, "Cannot overwrite a value") from None
if key_stem in nest:
raise suffixed_err(src, pos, f"Duplicate inline table key {key_stem!r}")
nest[key_stem] = value
pos = skip_chars(src, pos, TOML_WS)
c = src[pos : pos + 1]
if c == "}":
return pos + 1, nested_dict.dict
if c != ",":
raise suffixed_err(src, pos, "Unclosed inline table")
if isinstance(value, (dict, list)):
flags.set(key, Flags.FROZEN, recursive=True)
pos += 1
pos = skip_chars(src, pos, TOML_WS)
def parse_basic_str_escape(
src: str, pos: Pos, *, multiline: bool = False
) -> tuple[Pos, str]:
escape_id = src[pos : pos + 2]
pos += 2
if multiline and escape_id in {"\\ ", "\\\t", "\\\n"}:
# Skip whitespace until next non-whitespace character or end of
# the doc. Error if non-whitespace is found before newline.
if escape_id != "\\\n":
pos = skip_chars(src, pos, TOML_WS)
try:
char = src[pos]
except IndexError:
return pos, ""
if char != "\n":
raise suffixed_err(src, pos, "Unescaped '\\' in a string")
pos += 1
pos = skip_chars(src, pos, TOML_WS_AND_NEWLINE)
return pos, ""
if escape_id == "\\u":
return parse_hex_char(src, pos, 4)
if escape_id == "\\U":
return parse_hex_char(src, pos, 8)
try:
return pos, BASIC_STR_ESCAPE_REPLACEMENTS[escape_id]
except KeyError:
raise suffixed_err(src, pos, "Unescaped '\\' in a string") from None
def parse_basic_str_escape_multiline(src: str, pos: Pos) -> tuple[Pos, str]:
return parse_basic_str_escape(src, pos, multiline=True)
def parse_hex_char(src: str, pos: Pos, hex_len: int) -> tuple[Pos, str]:
hex_str = src[pos : pos + hex_len]
if len(hex_str) != hex_len or not HEXDIGIT_CHARS.issuperset(hex_str):
raise suffixed_err(src, pos, "Invalid hex value")
pos += hex_len
hex_int = int(hex_str, 16)
if not is_unicode_scalar_value(hex_int):
raise suffixed_err(src, pos, "Escaped character is not a Unicode scalar value")
return pos, chr(hex_int)
def parse_literal_str(src: str, pos: Pos) -> tuple[Pos, str]:
pos += 1 # Skip starting apostrophe
start_pos = pos
pos = skip_until(
src, pos, "'", error_on=ILLEGAL_LITERAL_STR_CHARS, error_on_eof=True
)
return pos + 1, src[start_pos:pos] # Skip ending apostrophe
def parse_multiline_str(src: str, pos: Pos, *, literal: bool) -> tuple[Pos, str]:
pos += 3
if src.startswith("\n", pos):
pos += 1
if literal:
delim = "'"
end_pos = skip_until(
src,
pos,
"'''",
error_on=ILLEGAL_MULTILINE_LITERAL_STR_CHARS,
error_on_eof=True,
)
result = src[pos:end_pos]
pos = end_pos + 3
else:
delim = '"'
pos, result = parse_basic_str(src, pos, multiline=True)
# Add at maximum two extra apostrophes/quotes if the end sequence
# is 4 or 5 chars long instead of just 3.
if not src.startswith(delim, pos):
return pos, result
pos += 1
if not src.startswith(delim, pos):
return pos, result + delim
pos += 1
return pos, result + (delim * 2)
def parse_basic_str(src: str, pos: Pos, *, multiline: bool) -> tuple[Pos, str]:
if multiline:
error_on = ILLEGAL_MULTILINE_BASIC_STR_CHARS
parse_escapes = parse_basic_str_escape_multiline
else:
error_on = ILLEGAL_BASIC_STR_CHARS
parse_escapes = parse_basic_str_escape
result = ""
start_pos = pos
while True:
try:
char = src[pos]
except IndexError:
raise suffixed_err(src, pos, "Unterminated string") from None
if char == '"':
if not multiline:
return pos + 1, result + src[start_pos:pos]
if src.startswith('"""', pos):
return pos + 3, result + src[start_pos:pos]
pos += 1
continue
if char == "\\":
result += src[start_pos:pos]
pos, parsed_escape = parse_escapes(src, pos)
result += parsed_escape
start_pos = pos
continue
if char in error_on:
raise suffixed_err(src, pos, f"Illegal character {char!r}")
pos += 1
def parse_value( # noqa: C901
src: str, pos: Pos, parse_float: ParseFloat
) -> tuple[Pos, Any]:
try:
char: str | None = src[pos]
except IndexError:
char = None
# IMPORTANT: order conditions based on speed of checking and likelihood
# Basic strings
if char == '"':
if src.startswith('"""', pos):
return parse_multiline_str(src, pos, literal=False)
return parse_one_line_basic_str(src, pos)
# Literal strings
if char == "'":
if src.startswith("'''", pos):
return parse_multiline_str(src, pos, literal=True)
return parse_literal_str(src, pos)
# Booleans
if char == "t":
if src.startswith("true", pos):
return pos + 4, True
if char == "f":
if src.startswith("false", pos):
return pos + 5, False
# Arrays
if char == "[":
return parse_array(src, pos, parse_float)
# Inline tables
if char == "{":
return parse_inline_table(src, pos, parse_float)
# Dates and times
datetime_match = RE_DATETIME.match(src, pos)
if datetime_match:
try:
datetime_obj = match_to_datetime(datetime_match)
except ValueError as e:
raise suffixed_err(src, pos, "Invalid date or datetime") from e
return datetime_match.end(), datetime_obj
localtime_match = RE_LOCALTIME.match(src, pos)
if localtime_match:
return localtime_match.end(), match_to_localtime(localtime_match)
# Integers and "normal" floats.
# The regex will greedily match any type starting with a decimal
# char, so needs to be located after handling of dates and times.
number_match = RE_NUMBER.match(src, pos)
if number_match:
return number_match.end(), match_to_number(number_match, parse_float)
# Special floats
first_three = src[pos : pos + 3]
if first_three in {"inf", "nan"}:
return pos + 3, parse_float(first_three)
first_four = src[pos : pos + 4]
if first_four in {"-inf", "+inf", "-nan", "+nan"}:
return pos + 4, parse_float(first_four)
raise suffixed_err(src, pos, "Invalid value")
def suffixed_err(src: str, pos: Pos, msg: str) -> TOMLDecodeError:
"""Return a `TOMLDecodeError` where error message is suffixed with
coordinates in source."""
def coord_repr(src: str, pos: Pos) -> str:
if pos >= len(src):
return "end of document"
line = src.count("\n", 0, pos) + 1
if line == 1:
column = pos + 1
else:
column = pos - src.rindex("\n", 0, pos)
return f"line {line}, column {column}"
return TOMLDecodeError(f"{msg} (at {coord_repr(src, pos)})")
def is_unicode_scalar_value(codepoint: int) -> bool:
return (0 <= codepoint <= 55295) or (57344 <= codepoint <= 1114111)
def make_safe_parse_float(parse_float: ParseFloat) -> ParseFloat:
"""A decorator to make `parse_float` safe.
`parse_float` must not return dicts or lists, because these types
would be mixed with parsed TOML tables and arrays, thus confusing
the parser. The returned decorated callable raises `ValueError`
instead of returning illegal types.
"""
# The default `float` callable never returns illegal types. Optimize it.
if parse_float is float: # type: ignore[comparison-overlap]
return float
def safe_parse_float(float_str: str) -> Any:
float_value = parse_float(float_str)
if isinstance(float_value, (dict, list)):
raise ValueError("parse_float must not return dicts or lists")
return float_value
return safe_parse_float
Zerion Mini Shell 1.0