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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#     http://www.apache.org/licenses/LICENSE-2.0
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"Implementation of PEP440 version string normalization"

def mkmethod(self, method):
    """Bind a struct as the first arg to a function.

    This is loosely equivalent to creating a bound method of a class.
    """
    return lambda *args, **kwargs: method(self, *args, **kwargs)

def _isdigit(token):
    return token.isdigit()

def _isalnum(token):
    return token.isalnum()

def _lower(token):
    # PEP 440: Case sensitivity
    return token.lower()

def _is(reference):
    """Predicate testing a token for equality with `reference`."""
    return lambda token: token == reference

def _is_not(reference):
    """Predicate testing a token for inequality with `reference`."""
    return lambda token: token != reference

def _in(reference):
    """Predicate testing if a token is in the list `reference`."""
    return lambda token: token in reference

def _ctx(start):
    return {"norm": "", "start": start}

def _open_context(self):
    """Open an new parsing ctx.

    If the current parsing step succeeds, call self.accept().
    If the current parsing step fails, call self.discard() to
    go back to how it was before we opened a new ctx.

    Args:
      self: The normalizer.
    """
    self.contexts.append(_ctx(_context(self)["start"]))
    return self.contexts[-1]

def _accept(self):
    """Close the current ctx successfully and merge the results."""
    finished = self.contexts.pop()
    self.contexts[-1]["norm"] += finished["norm"]
    self.contexts[-1]["start"] = finished["start"]
    return True

def _context(self):
    return self.contexts[-1]

def _discard(self):
    self.contexts.pop()
    return False

def _new(input):
    """Create a new normalizer"""
    self = struct(
        input = input,
        contexts = [_ctx(0)],
    )

    public = struct(
        # methods: keep sorted
        accept = mkmethod(self, _accept),
        context = mkmethod(self, _context),
        discard = mkmethod(self, _discard),
        open_context = mkmethod(self, _open_context),

        # attributes: keep sorted
        input = self.input,
    )
    return public

def accept(parser, predicate, value):
    """If `predicate` matches the next token, accept the token.

    Accepting the token means adding it (according to `value`) to
    the running results maintained in ctx["norm"] and
    advancing the cursor in ctx["start"] to the next token in
    `version`.

    Args:
      parser: The normalizer.
      predicate: function taking a token and returning a boolean
        saying if we want to accept the token.
      value: the string to add if there's a match, or, if `value`
        is a function, the function to apply to the current token
        to get the string to add.

    Returns:
      whether a token was accepted.
    """

    ctx = parser.context()

    if ctx["start"] >= len(parser.input):
        return False

    token = parser.input[ctx["start"]]

    if predicate(token):
        if type(value) in ["function", "builtin_function_or_method"]:
            value = value(token)

        ctx["norm"] += value
        ctx["start"] += 1
        return True

    return False

def accept_placeholder(parser):
    """Accept a Bazel placeholder.

    Placeholders aren't actually part of PEP 440, but are used for
    stamping purposes. A placeholder might be
    ``{BUILD_TIMESTAMP}``, for instance. We'll accept these as
    they are, assuming they will expand to something that makes
    sense where they appear. Before the stamping has happened, a
    resulting wheel file name containing a placeholder will not
    actually be valid.

    Args:
      parser: The normalizer.

    Returns:
      whether a placeholder was accepted.
    """
    ctx = parser.open_context()

    if not accept(parser, _is("{"), str):
        return parser.discard()

    start = ctx["start"]
    for _ in range(start, len(parser.input) + 1):
        if not accept(parser, _is_not("}"), str):
            break

    if not accept(parser, _is("}"), str):
        return parser.discard()

    return parser.accept()

def accept_digits(parser):
    """Accept multiple digits (or placeholders).

    Args:
      parser: The normalizer.

    Returns:
      whether some digits (or placeholders) were accepted.
    """

    ctx = parser.open_context()
    start = ctx["start"]

    for i in range(start, len(parser.input) + 1):
        if not accept(parser, _isdigit, str) and not accept_placeholder(parser):
            if i - start >= 1:
                if ctx["norm"].isdigit():
                    # PEP 440: Integer Normalization
                    ctx["norm"] = str(int(ctx["norm"]))
                return parser.accept()
            break

    return parser.discard()

def accept_string(parser, string, replacement):
    """Accept a `string` in the input. Output `replacement`.

    Args:
      parser: The normalizer.
      string: The string to search for in the parser input.
      replacement: The normalized string to use if the string was found.

    Returns:
      whether the string was accepted.
    """
    ctx = parser.open_context()

    for character in string.elems():
        if not accept(parser, _in([character, character.upper()]), ""):
            return parser.discard()

    ctx["norm"] = replacement

    return parser.accept()

def accept_alnum(parser):
    """Accept an alphanumeric sequence.

    Args:
      parser: The normalizer.

    Returns:
      whether an alphanumeric sequence was accepted.
    """

    ctx = parser.open_context()
    start = ctx["start"]

    for i in range(start, len(parser.input) + 1):
        if not accept(parser, _isalnum, _lower) and not accept_placeholder(parser):
            if i - start >= 1:
                return parser.accept()
            break

    return parser.discard()

def accept_dot_number(parser):
    """Accept a dot followed by digits.

    Args:
      parser: The normalizer.

    Returns:
      whether a dot+digits pair was accepted.
    """
    parser.open_context()

    if accept(parser, _is("."), ".") and accept_digits(parser):
        return parser.accept()
    else:
        return parser.discard()

def accept_dot_number_sequence(parser):
    """Accept a sequence of dot+digits.

    Args:
      parser: The normalizer.

    Returns:
      whether a sequence of dot+digits pairs was accepted.
    """
    ctx = parser.context()
    start = ctx["start"]
    i = start

    for i in range(start, len(parser.input) + 1):
        if not accept_dot_number(parser):
            break
    return i - start >= 1

def accept_separator_alnum(parser):
    """Accept a separator followed by an alphanumeric string.

    Args:
      parser: The normalizer.

    Returns:
      whether a separator and an alphanumeric string were accepted.
    """
    parser.open_context()

    # PEP 440: Local version segments
    if (
        accept(parser, _in([".", "-", "_"]), ".") and
        (accept_digits(parser) or accept_alnum(parser))
    ):
        return parser.accept()

    return parser.discard()

def accept_separator_alnum_sequence(parser):
    """Accept a sequence of separator+alphanumeric.

    Args:
      parser: The normalizer.

    Returns:
      whether a sequence of separator+alphanumerics was accepted.
    """
    ctx = parser.context()
    start = ctx["start"]
    i = start

    for i in range(start, len(parser.input) + 1):
        if not accept_separator_alnum(parser):
            break

    return i - start >= 1

def accept_epoch(parser):
    """PEP 440: Version epochs.

    Args:
      parser: The normalizer.

    Returns:
      whether a PEP 440 epoch identifier was accepted.
    """
    ctx = parser.open_context()
    if accept_digits(parser) and accept(parser, _is("!"), "!"):
        if ctx["norm"] == "0!":
            ctx["norm"] = ""
        return parser.accept()
    else:
        return parser.discard()

def accept_release(parser):
    """Accept the release segment, numbers separated by dots.

    Args:
      parser: The normalizer.

    Returns:
      whether a release segment was accepted.
    """
    parser.open_context()

    if not accept_digits(parser):
        return parser.discard()

    accept_dot_number_sequence(parser)
    return parser.accept()

def accept_pre_l(parser):
    """PEP 440: Pre-release spelling.

    Args:
      parser: The normalizer.

    Returns:
      whether a prerelease keyword was accepted.
    """
    parser.open_context()

    if (
        accept_string(parser, "alpha", "a") or
        accept_string(parser, "a", "a") or
        accept_string(parser, "beta", "b") or
        accept_string(parser, "b", "b") or
        accept_string(parser, "c", "rc") or
        accept_string(parser, "preview", "rc") or
        accept_string(parser, "pre", "rc") or
        accept_string(parser, "rc", "rc")
    ):
        return parser.accept()
    else:
        return parser.discard()

def accept_prerelease(parser):
    """PEP 440: Pre-releases.

    Args:
      parser: The normalizer.

    Returns:
      whether a prerelease identifier was accepted.
    """
    ctx = parser.open_context()

    # PEP 440: Pre-release separators
    accept(parser, _in(["-", "_", "."]), "")

    if not accept_pre_l(parser):
        return parser.discard()

    accept(parser, _in(["-", "_", "."]), "")

    if not accept_digits(parser):
        # PEP 440: Implicit pre-release number
        ctx["norm"] += "0"

    return parser.accept()

def accept_implicit_postrelease(parser):
    """PEP 440: Implicit post releases.

    Args:
      parser: The normalizer.

    Returns:
      whether an implicit postrelease identifier was accepted.
    """
    ctx = parser.open_context()

    if accept(parser, _is("-"), "") and accept_digits(parser):
        ctx["norm"] = ".post" + ctx["norm"]
        return parser.accept()

    return parser.discard()

def accept_explicit_postrelease(parser):
    """PEP 440: Post-releases.

    Args:
      parser: The normalizer.

    Returns:
      whether an explicit postrelease identifier was accepted.
    """
    ctx = parser.open_context()

    # PEP 440: Post release separators
    if not accept(parser, _in(["-", "_", "."]), "."):
        ctx["norm"] += "."

    # PEP 440: Post release spelling
    if (
        accept_string(parser, "post", "post") or
        accept_string(parser, "rev", "post") or
        accept_string(parser, "r", "post")
    ):
        accept(parser, _in(["-", "_", "."]), "")

        if not accept_digits(parser):
            # PEP 440: Implicit post release number
            ctx["norm"] += "0"

        return parser.accept()

    return parser.discard()

def accept_postrelease(parser):
    """PEP 440: Post-releases.

    Args:
      parser: The normalizer.

    Returns:
      whether a postrelease identifier was accepted.
    """
    parser.open_context()

    if accept_implicit_postrelease(parser) or accept_explicit_postrelease(parser):
        return parser.accept()

    return parser.discard()

def accept_devrelease(parser):
    """PEP 440: Developmental releases.

    Args:
      parser: The normalizer.

    Returns:
      whether a developmental release identifier was accepted.
    """
    ctx = parser.open_context()

    # PEP 440: Development release separators
    if not accept(parser, _in(["-", "_", "."]), "."):
        ctx["norm"] += "."

    if accept_string(parser, "dev", "dev"):
        accept(parser, _in(["-", "_", "."]), "")

        if not accept_digits(parser):
            # PEP 440: Implicit development release number
            ctx["norm"] += "0"

        return parser.accept()

    return parser.discard()

def accept_local(parser):
    """PEP 440: Local version identifiers.

    Args:
      parser: The normalizer.

    Returns:
      whether a local version identifier was accepted.
    """
    parser.open_context()

    if accept(parser, _is("+"), "+") and accept_alnum(parser):
        accept_separator_alnum_sequence(parser)
        return parser.accept()

    return parser.discard()

def normalize_pep440(version):
    """Escape the version component of a filename.

    See https://packaging.python.org/en/latest/specifications/binary-distribution-format/#escaping-and-unicode
    and https://peps.python.org/pep-0440/

    Args:
      version: version string to be normalized according to PEP 440.

    Returns:
      string containing the normalized version.
    """
    parser = _new(version.strip())  # PEP 440: Leading and Trailing Whitespace
    accept(parser, _is("v"), "")  # PEP 440: Preceding v character
    accept_epoch(parser)
    accept_release(parser)
    accept_prerelease(parser)
    accept_postrelease(parser)
    accept_devrelease(parser)
    accept_local(parser)
    if parser.input[parser.context()["start"]:]:
        fail(
            "Failed to parse PEP 440 version identifier '%s'." % parser.input,
            "Parse error at '%s'" % parser.input[parser.context()["start"]:],
        )
    return parser.context()["norm"]