NAME
    Mail::SpamAssassin::Pyzor::Digest::Pieces - Pyzor backend logic module

DESCRIPTION
    This module houses backend logic for Mail::SpamAssassin::Pyzor::Digest.

    It reimplements logic found in pyzor's digest.py module
    (<https://github.com/SpamExperts/pyzor/blob/master/pyzor/digest.py>).

FUNCTIONS
  $strings_ar = digest_payloads( $EMAIL_MIME )
    This imitates the corresponding object method in digest.py. It returns a
    reference to an array of strings. Each string can be either a byte
    string or a character string (e.g., UTF-8 decoded).

    NB: RFC 2822 stipulates that message bodies should use CRLF line breaks,
    not plain LF (nor plain CR). We will thus convert any plain CRs in a
    quoted-printable message body into CRLF. Python, though, doesn't do
    this, so the output of our implementation of "digest_payloads()"
    diverges from that of the Python original. It doesn't ultimately make a
    difference since the line-ending whitespace gets trimmed regardless, but
    it's necessary to factor in when comparing the output of our
    implementation with the Python output.

  normalize( $STRING )
    This imitates the corresponding object method in digest.py. It modifies
    $STRING in-place.

    As with the original implementation, if $STRING contains (decoded)
    Unicode characters, those characters will be parsed accordingly. So:

        $str = "123\xc2\xa0";   # [ c2 a0 ] == \u00a0, non-breaking space

        normalize($str);

    The above will leave $str alone, but this:

        utf8::decode($str);

        normalize($str);

    ... will trim off the last two bytes from $str.

  $yn = should_handle_line( $STRING )
    This imitates the corresponding object method in digest.py. It returns a
    boolean.

  $sr = assemble_lines( \@LINES )
    This assembles a string buffer out of @LINES. The string is the buffer
    of octets that will be hashed to produce the message digest.

    Each member of @LINES is expected to be an octet string, not a character
    string.

  ($main, $sub, $encoding, $checkval) = parse_content_type( $CONTENT_TYPE )
  @lines = splitlines( $TEXT )
    Imitates "str.splitlines()". (cf. "pydoc str")

    Returns a plain list in list context. Returns the number of items to be
    returned in scalar context.