html_file

  $filehandle = html_file($filename, \%options);

This function (exported by default) is the primary entry point. It opens the file specified by $filename for reading, uses "sniff_encoding" to find a suitable encoding layer, and applies it. It also applies the ":crlf" layer. If the file begins with a BOM, the filehandle is positioned just after the BOM.

The optional second argument is a hashref containing options. The possible keys are described under "find_charset_in".

If "sniff_encoding" is unable to determine the encoding, it defaults to $IO::HTML::default_encoding, which is set to "cp1252" (a.k.a. Windows-1252) by default. According to the standard, the default should be locale dependent, but that is not currently implemented.

It dies if the file cannot be opened, or if "sniff_encoding" cannot determine the encoding and $IO::HTML::default_encoding has been set to "undef".

html_file_and_encoding

  ($filehandle, $encoding, $bom)
    = html_file_and_encoding($filename, \%options);

This function (exported only by request) is just like "html_file", but returns more information. In addition to the filehandle, it returns the name of the encoding used, and a flag indicating whether a byte order mark was found (if $bom is true, the file began with a BOM). This may be useful if you want to write the file out again (especially in conjunction with the "html_outfile" function).

The optional second argument is a hashref containing options. The possible keys are described under "find_charset_in".

It dies if the file cannot be opened, or if "sniff_encoding" cannot determine the encoding and $IO::HTML::default_encoding has been set to "undef".

The result of calling "html_file_and_encoding" in scalar context is undefined (in the C sense of there is no guarantee what you'll get).

html_outfile

  $filehandle = html_outfile($filename, $encoding, $bom);

This function (exported only by request) opens $filename for output using $encoding, and writes a BOM to it if $bom is true. If $encoding is "undef", it defaults to $IO::HTML::default_encoding. $encoding may be either an encoding name or an Encode::Encoding object.

It dies if the file cannot be opened, or if both $encoding and $IO::HTML::default_encoding are "undef".

sniff_encoding

  ($encoding, $bom) = sniff_encoding($filehandle, $filename, \%options);

This function (exported only by request) runs the HTML5 encoding sniffing algorithm on $filehandle (which must be seekable, and should have been opened in ":raw" mode). $filename is used only for error messages (if there's a problem using the filehandle), and defaults to "file" if omitted. The optional third argument is a hashref containing options. The possible keys are described under "find_charset_in".

It returns Perl's canonical name for the encoding, which is not necessarily the same as the MIME or IANA charset name. It returns "undef" if the encoding cannot be determined. $bom is true if the file began with a byte order mark. In scalar context, it returns only $encoding.

The filehandle's position is restored to its original position (normally the beginning of the file) unless $bom is true. In that case, the position is immediately after the BOM.

Tip: If you want to run "sniff_encoding" on a file you've already loaded into a string, open an in-memory file on the string, and pass that handle:

  ($encoding, $bom) = do {
    open(my $fh, '<', \$string);  sniff_encoding($fh)
  };

(This only makes sense if $string contains bytes, not characters.)

find_charset_in

  $encoding = find_charset_in($string_containing_HTML, \%options);

This function (exported only by request) looks for charset information in a "<meta>" tag in a possibly-incomplete HTML document using the "two step" algorithm specified by HTML5. It does not look for a BOM. The "<meta>" tag must begin within the first $IO::HTML::bytes_to_check bytes of the string.

It returns Perl's canonical name for the encoding, which is not necessarily the same as the MIME or IANA charset name. It returns "undef" if no charset is specified or if the specified charset is not recognized by the Encode module.

The optional second argument is a hashref containing options. The following keys are recognized:

"encoding"

If true, return the Encode::Encoding object instead of its name. Defaults to false.

"need_pragma"

If true (the default), follow the HTML5 spec and examine the "content" attribute only of "<meta http-equiv="Content-Type"". If set to 0, relax the HTML5 spec, and look for "charset=" in the "content" attribute of every meta tag.