cpython_5/solution/solution.patch

diff --git a/Lib/tomllib/__init__.py b/Lib/tomllib/__init__.py
new file mode 100644
index 0000000000..ef91cb9d25
--- /dev/null
+++ b/Lib/tomllib/__init__.py
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2021 Taneli Hukkinen
+# Licensed to PSF under a Contributor Agreement.
+
+__all__ = ("loads", "load", "TOMLDecodeError")
+
+from ._parser import TOMLDecodeError, load, loads
+
+# Pretend this exception was created here.
+TOMLDecodeError.__module__ = __name__
diff --git a/Lib/tomllib/_parser.py b/Lib/tomllib/_parser.py
new file mode 100644
index 0000000000..45ca7a8963
--- /dev/null
+++ b/Lib/tomllib/_parser.py
@@ -0,0 +1,691 @@
+# 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
diff --git a/Lib/tomllib/_re.py b/Lib/tomllib/_re.py
new file mode 100644
index 0000000000..994bb7493f
--- /dev/null
+++ b/Lib/tomllib/_re.py
@@ -0,0 +1,107 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2021 Taneli Hukkinen
+# Licensed to PSF under a Contributor Agreement.
+
+from __future__ import annotations
+
+from datetime import date, datetime, time, timedelta, timezone, tzinfo
+from functools import lru_cache
+import re
+from typing import Any
+
+from ._types import ParseFloat
+
+# E.g.
+# - 00:32:00.999999
+# - 00:32:00
+_TIME_RE_STR = r"([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])(?:\.([0-9]{1,6})[0-9]*)?"
+
+RE_NUMBER = re.compile(
+    r"""
+0
+(?:
+    x[0-9A-Fa-f](?:_?[0-9A-Fa-f])*   # hex
+    |
+    b[01](?:_?[01])*                 # bin
+    |
+    o[0-7](?:_?[0-7])*               # oct
+)
+|
+[+-]?(?:0|[1-9](?:_?[0-9])*)         # dec, integer part
+(?P<floatpart>
+    (?:\.[0-9](?:_?[0-9])*)?         # optional fractional part
+    (?:[eE][+-]?[0-9](?:_?[0-9])*)?  # optional exponent part
+)
+""",
+    flags=re.VERBOSE,
+)
+RE_LOCALTIME = re.compile(_TIME_RE_STR)
+RE_DATETIME = re.compile(
+    rf"""
+([0-9]{{4}})-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])  # date, e.g. 1988-10-27
+(?:
+    [Tt ]
+    {_TIME_RE_STR}
+    (?:([Zz])|([+-])([01][0-9]|2[0-3]):([0-5][0-9]))?  # optional time offset
+)?
+""",
+    flags=re.VERBOSE,
+)
+
+
+def match_to_datetime(match: re.Match) -> datetime | date:
+    """Convert a `RE_DATETIME` match to `datetime.datetime` or `datetime.date`.
+
+    Raises ValueError if the match does not correspond to a valid date
+    or datetime.
+    """
+    (
+        year_str,
+        month_str,
+        day_str,
+        hour_str,
+        minute_str,
+        sec_str,
+        micros_str,
+        zulu_time,
+        offset_sign_str,
+        offset_hour_str,
+        offset_minute_str,
+    ) = match.groups()
+    year, month, day = int(year_str), int(month_str), int(day_str)
+    if hour_str is None:
+        return date(year, month, day)
+    hour, minute, sec = int(hour_str), int(minute_str), int(sec_str)
+    micros = int(micros_str.ljust(6, "0")) if micros_str else 0
+    if offset_sign_str:
+        tz: tzinfo | None = cached_tz(
+            offset_hour_str, offset_minute_str, offset_sign_str
+        )
+    elif zulu_time:
+        tz = timezone.utc
+    else:  # local date-time
+        tz = None
+    return datetime(year, month, day, hour, minute, sec, micros, tzinfo=tz)
+
+
+@lru_cache(maxsize=None)
+def cached_tz(hour_str: str, minute_str: str, sign_str: str) -> timezone:
+    sign = 1 if sign_str == "+" else -1
+    return timezone(
+        timedelta(
+            hours=sign * int(hour_str),
+            minutes=sign * int(minute_str),
+        )
+    )
+
+
+def match_to_localtime(match: re.Match) -> time:
+    hour_str, minute_str, sec_str, micros_str = match.groups()
+    micros = int(micros_str.ljust(6, "0")) if micros_str else 0
+    return time(int(hour_str), int(minute_str), int(sec_str), micros)
+
+
+def match_to_number(match: re.Match, parse_float: ParseFloat) -> Any:
+    if match.group("floatpart"):
+        return parse_float(match.group())
+    return int(match.group(), 0)
diff --git a/Lib/tomllib/_types.py b/Lib/tomllib/_types.py
new file mode 100644
index 0000000000..d949412e03
--- /dev/null
+++ b/Lib/tomllib/_types.py
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2021 Taneli Hukkinen
+# Licensed to PSF under a Contributor Agreement.
+
+from typing import Any, Callable, Tuple
+
+# Type annotations
+ParseFloat = Callable[[str], Any]
+Key = Tuple[str, ...]
+Pos = int
diff --git a/Python/stdlib_module_names.h b/Python/stdlib_module_names.h
index 754fa94e35..553585a76a 100644
--- a/Python/stdlib_module_names.h
+++ b/Python/stdlib_module_names.h
@@ -277,6 +277,7 @@ static const char* _Py_stdlib_module_names[] = {
 "tkinter",
 "token",
 "tokenize",
+"tomllib",
 "trace",
 "traceback",
 "tracemalloc",