
=head1 NAME

Mail::Message::Field::Full - one line of a message header


=head1 INHERITANCE

 Mail::Message::Field::Full
   is a Mail::Message::Field
   is a Mail::Reporter

 Mail::Message::Field::Full is extended by
   Mail::Message::Field::Addresses
   Mail::Message::Field::Unstructured


=head1 SYNOPSIS

 !! UNDER CONSTRUCTION !!
 !! THE DETAILS OF THIS MODULE ARE NOT FINISHED YET!!

 # Getting to understand the complexity of a header field ...

 my $fast = $msg->head->get('subject');
 my $full = Mail::Message::Field::Full->from($fast);

 my $full = $msg->head->get('subject')->study;  # same
 my $full = $msg->head->study('subject');       # same
 my $full = $msg->get('subject');               # same

 # ... or build a complex header field yourself

 my @encode = (charset => 'jp', use_continuations => 1);

 my $f = Mail::Message::Field::Full
            ->new('Content-Type' => 'text/html');
 $f->addExtra(" and more", @encode);

 $f->addPhrase("text ", @encode);
 $f->addPhrase(" and more text", language => 'en-GB' );

 $f->addAttribute('filename=passwd');
 $f->addAttribute(filename => 'passwd', @encode);

 my $attr = Mail::Message::Field::Attribute->new(...);
 $f->addAttribute($attr);

 $f->addComment('just me', $encode);


=head1 DESCRIPTION

This is the full implementation of a header field: it will be quite slow,
because header fields can be very complex.  Of course, this class delivers
the optimal result, but for a quite large penalty in performance and
memory consumption.

This class supports the common header description from RFC2822 (formerly
RFC822), the extensions with respect to character-set encodings as specified
in RFC2047, and the extensions on language specification and long parameter
wrapping from RFC2231.  If you do not need the latter two, then the
L<Mail::Message::Field::Fast|Mail::Message::Field::Fast> and L<Mail::Message::Field::Flex|Mail::Message::Field::Flex>
are enough for your application.

=head2 Header fields


=head2 Folding


=head2 Performance consideration



=head1 OVERLOADED


overload: B<"">

=over 4

See L<Mail::Message::Field/"OVERLOADED">

=back

overload: B<+0>

=over 4

See L<Mail::Message::Field/"OVERLOADED">

=back

overload: B<<=>>

=over 4

See L<Mail::Message::Field/"OVERLOADED">

=back

overload: B<bool>

=over 4

See L<Mail::Message::Field/"OVERLOADED">

=back

overload: B<cmp>

=over 4

See L<Mail::Message::Field/"OVERLOADED">

=back


=head1 METHODS


=head2 Constructors


$obj-E<gt>B<clone>

=over 4

See L<Mail::Message::Field/"Constructors">

=back

Mail::Message::Field::Full-E<gt>B<from>(FIELD, OPTIONS)

=over 4

Convert any FIELD (a L<Mail::Message::Field|Mail::Message::Field> object) into a new
L<Mail::Message::Field::Full|Mail::Message::Field::Full> object.  This conversion is done the hard
way: the string which is produced by the original object is parsed
again.  Usually, the string which is parsed is exactly the line (or lines)
as found in the original input source, which is a good thing because Full
fields are much more carefull with the actual content.

OPTIONS are passed to the constructor (see L<new()|"METHODS">).  In any case, some
extensions of this Full field class is returned.  It depends on which
field is created what kind of class we get.

I<Example:> 

 my $fast = $msg->head->get('subject');
 my $full = Mail::Message::Field::Full->from($fast);

 my $full = $msg->head->get('subject')->study;  # same
 my $full = $msg->head->study('subject');       # same
 my $full = $msg->get('subject');               # same

=back

Mail::Message::Field::Full-E<gt>B<new>(DATA)

=over 4

Creating a new field object the correct way is a lot of work, because
there is so much freedom in the RFCs, but at the same time so many
restrictions.  Most fields are implemented, but if you have your own
field (and do no want to contribute it to Mail::Box), then simply call
new on your own package.

You have the choice to instantiate the object as string or in prepared
parts:

=over 4

=item * B<new> LINE

Pass a LINE as it could be found in a file: a (possibly folded) line
which is terminated by a new-line.

=item * B<new> NAME, BODY, [ATTRIBUTES], OPTIONS

A set of values which shape the line.

=back

The NAME is a wellformed header name (you may use wellformedName()) to
be sure about the casing.  The BODY is a string, one object, or an
ref-array of objects.  In case of objects, they must fit to the
constructor of the field: the types which are accepted may differ.
The optional ATTRIBUTE list contains L<Mail::Message::Field::Attribute|Mail::Message::Field::Attribute>
objects.  Finally, there are some OPTIONS.

 Option         Defined in       Default      
 attributes                      C<[]>        
 charset                         undef        
 encoding                        C<'q'>       
 extra                           undef        
 force                           false        
 is_structured                   C<depends>   
 language                        undef        
 log            L<Mail::Reporter>  C<'WARNINGS'>
 trace          L<Mail::Reporter>  C<'WARNINGS'>

. attributes ATTRS

=over 4

There are various ways to specify these attributes: pass a reference
to an array which list of key-value pairs representing attributes,
or reference to a hash containing these pairs, or an array with
L<Mail::Message::Field::Attribute|Mail::Message::Field::Attribute> objects.

=back

. charset STRING

=over 4

The body is specified in utf8, and must become 7-bits ascii to be
transmited.  Specify a charset to which the multi-byte utf8 is converted
before it gets encoded.  See L<encode()|"Internals">, which does the job.

=back

. encoding 'q'|'Q'|'b'|'B'

=over 4

Non-ascii characters are encoded using Quoted-Printable ('q' or 'Q') or
Base64 ('b' or 'B') encoding.

=back

. extra STRING

=over 4

Text which is appended after the line (preceded by a semicolon).

=back

. force BOOLEAN

=over 4

Enforce encoding in the specified charset, even when it is not needed
because the body does not contain any non-ascii characters.

=back

. is_structured BOOLEAN

=over 4

If the name of the field is known, than the internals know whether the
field is structured or not.  If you call the constructor on your own
class which is derived from L<Mail::Message::Field::Full|Mail::Message::Field::Full>, the default
is C<true>.  If you have no own implementation for an unknown field,
the boolean is considered C<false>.

For fields which are not known, C<true> means that a
Mail::Message::Field::Structured will be created.  The C<false> value will
create a L<Mail::Message::Field::Unstructured|Mail::Message::Field::Unstructured>.

=back

. language STRING

=over 4

The language used can be specified, however is rarely used my mail clients.

=back

. log LEVEL

. trace LEVEL

I<Example:> 

 my $s = Mail::Message::Field::Full->new('Subject: Hello World');
 my $s = Mail::Message::Field::Full->new('Subject', 'Hello World');

 my @attrs   = (Mail::Message::Field::Attribute->new(...), ...);
 my @options = (extra => 'the color blue');
 my $t = Mail::Message::Field::Full->new(To => \@addrs, @attrs, @options);

=back

=head2 The field


$obj-E<gt>B<isStructured>

Mail::Message::Field::Full-E<gt>B<isStructured>

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<length>

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<nrLines>

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<print>([FILEHANDLE])

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<size>

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<string>([WRAP])

=over 4

See L<Mail::Message::Field/"The field">

=back

$obj-E<gt>B<toDisclose>

=over 4

See L<Mail::Message::Field/"The field">

=back

=head2 Access to the name


$obj-E<gt>B<Name>

=over 4

See L<Mail::Message::Field/"Access to the name">

=back

$obj-E<gt>B<name>

=over 4

See L<Mail::Message::Field/"Access to the name">

=back

$obj-E<gt>B<wellformedName>([STRING])

=over 4

See L<Mail::Message::Field/"Access to the name">

=back

=head2 Access to the body


$obj-E<gt>B<body>

=over 4

See L<Mail::Message::Field/"Access to the body">

=back

$obj-E<gt>B<decodedBody>(OPTIONS)

=over 4

Returns the unfolded body of the field, where encodings are resolved.  The
returned line will still contain comments and such.  The OPTIONS are passed
to the decoder, see L<decode()|"Internals">.

BE WARNED: if the field is a structured field, the content may change syntax,
because of encapsulated special characters.  By default, the body is decoded
as text, which results in a small difference within comments as well
(read the RFC).

=back

$obj-E<gt>B<folded>

=over 4

See L<Mail::Message::Field/"Access to the body">

=back

$obj-E<gt>B<foldedBody>([BODY])

=over 4

See L<Mail::Message::Field/"Access to the body">

=back

$obj-E<gt>B<stripCFWS>([STRING])

Mail::Message::Field::Full-E<gt>B<stripCFWS>([STRING])

=over 4

See L<Mail::Message::Field/"Access to the body">

=back

$obj-E<gt>B<unfoldedBody>([BODY, [WRAP]])

=over 4

See L<Mail::Message::Field/"Access to the body">

=back

=head2 Access to the content


$obj-E<gt>B<addAttribute>(OBJECT|(STRING, OPTIONS)|(NAME,VALUE,OPTIONS))

=over 4

Add an attribute to the field.  The attributes are added left-to-right into
the string representation of the field, although the order of the attributes
is un-important, according to the RFCs.

You may pass a fully prepared L<Mail::Message::Field::Attribute|Mail::Message::Field::Attribute> OBJECT,
if you like to do all preparations for correct representation of the
data yourself.  You may also pass one STRING, which is a fully prepared
attribute.  This STRING will not be changed, so be careful about quoting
and encodings.

As third possibility, you can specify an attribute NAME and its VALUE.
An attribute object will be created for you implicitly in both
cases where such object is not supplied, passing the OPTIONS.  See
L<Mail::Message::Field::Attribute::new()|"Constructors"> about the available OPTIONS.

The attribute object is returned, however, when continuations are used this
may be an object you already know about.  C<undef> is returned when
construction fails (when the attribute is incorrect).

I<Example:> 

 $f->addAttribute('filename=passwd');
 $f->addAttribute(filename => 'passwd', use_continuations => 0);
 my $attr = Mail::Message::Field::Attribute->new(...);
 $f->addAttribute($attr);

=back

$obj-E<gt>B<addComment>(COMMENT, OPTIONS)

=over 4

Creates a comment (see L<createComment()|"Access to the content">) and adds it immediately to
this field.  Empty or undefined COMMENTs are ignored.  The created comment
is returned.

=back

$obj-E<gt>B<addExtra>(STRING)

=over 4

Adds a string to the line, which is not an attribute however does start with
a semi-colon.  Empty or undefined STRINGs are ignored.

=back

$obj-E<gt>B<addPhrase>(STRING, OPTIONS)

=over 4

Create a phrase (see L<createPhrase()|"Access to the content">) and immediately add it to this field.
Empty or undefined values of STRING are ignored.  The created phrase is
returned.

=back

$obj-E<gt>B<addresses>

=over 4

See L<Mail::Message::Field/"Access to the content">

=back

$obj-E<gt>B<attribute>(NAME [, VALUE])

=over 4

See L<Mail::Message::Field/"Access to the content">

=back

$obj-E<gt>B<attributes>

=over 4

Returns a list with all attributes, which are all
L<Mail::Message::Field::Attribute|Mail::Message::Field::Attribute> objects.  The attributes are not
ordered in any way.  The list may be empty.  Double attributes or
continuations are folded into one.

=back

$obj-E<gt>B<comment>([STRING])

=over 4

See L<Mail::Message::Field/"Access to the content">

=back

$obj-E<gt>B<createComment>(STRING, OPTIONS)

Mail::Message::Field::Full-E<gt>B<createComment>(STRING, OPTIONS)

=over 4

Create a comment to become part in a field.  Comments are automatically
included within parenthesis.  Matching pairs of parenthesis are
permitted within the STRING.  When a non-matching parenthesis are used,
it is only permitted with an escape (a backslash) in front of them.
These backslashes will be added automatically if needed (don't worry!).
Backslashes will stay, except at the end, where it will be doubled.

The OPTIONS are C<charset>, C<language>, and C<encoding> as always.
See L<addComment()|"Access to the content">.  The created comment is returned.

=back

$obj-E<gt>B<createPhrase>(STRING, OPTIONS)

Mail::Message::Field::Full-E<gt>B<createPhrase>(STRING, OPTIONS)

=over 4

A phrase is a text which plays a well defined role.  This is the main
difference with comments, which have do specified meaning.  Some special
characters in the phrase will cause it to be surrounded with double
quotes: do not specify them yourself.

The OPTIONS are C<charset>, C<language>, and C<encoding> as always.
See addPhrase().

=back

$obj-E<gt>B<toDate>([TIME])

Mail::Message::Field::Full-E<gt>B<toDate>([TIME])

=over 4

See L<Mail::Message::Field/"Access to the content">

=back

$obj-E<gt>B<toInt>

=over 4

See L<Mail::Message::Field/"Access to the content">

=back

=head2 Other methods


$obj-E<gt>B<dateToTimestamp>(STRING)

Mail::Message::Field::Full-E<gt>B<dateToTimestamp>(STRING)

=over 4

See L<Mail::Message::Field/"Other methods">

=back

=head2 Internals


$obj-E<gt>B<consume>(LINE | (NAME,BODY|OBJECTS))

=over 4

See L<Mail::Message::Field/"Internals">

=back

$obj-E<gt>B<consumeComment>(STRING)

Mail::Message::Field::Full-E<gt>B<consumeComment>(STRING)

=over 4

Try to read a comment from the STRING.  When successful, the comment
without encapsulation parenthesis is returned, together with the rest
of the string.

=back

$obj-E<gt>B<consumeDotAtom>(STRING)

=over 4

Returns three elemens: the atom-text, the rest string, and the
concatenated comments.  Both atom and comments can be undef.

=back

$obj-E<gt>B<consumePhrase>(STRING)

Mail::Message::Field::Full-E<gt>B<consumePhrase>(STRING)

=over 4

Take the STRING, and try to strip-off a valid phrase.  In the obsolete
phrase syntax, any sequence of words is accepted as phrase (as long as
certain special characters are not used).  RFC2882 is stricter: only
one word or a quoted string is allowed.  As always, the obsolete
syntax is accepted, and the new syntax is produced.

This method returns two elements: the phrase (or undef) followed
by the resulting string.  The phrase will be removed from the optional
quotes.  Be warned that C<""> will return an empty, valid phrase.

I<Example:> 

 my ($phrase, $rest) = $field->consumePhrase( q["hi!" <sales@example.com>] );

=back

$obj-E<gt>B<decode>(STRING, OPTIONS)

Mail::Message::Field::Full-E<gt>B<decode>(STRING, OPTIONS)

=over 4

Decode field encoded STRING to an utf8 string.  The input STRING is part of
a header field, and as such, may contain encoded words in C<=?...?.?...?=>
format defined by RFC2047.  The STRING may contain multiple encoded parts,
maybe using different character sets.

Be warned:  you MUST first interpret the field into parts, like phrases and
comments, and then decode each part separately, otherwise the decoded text
may interfere with your markup characters.

Be warned: language information, which is defined in RFC2231, is ignored.

 Option   Defined in  Default
 is_text              C<1>   

. is_text BOOLEAN

=over 4

Encoding on text is slightly more complicated than encoding structured data,
because it contains blanks.  Visible blanks have to be ignored between two
encoded words in the text, but not when an encoded word follows or preceeds
an unencoded word.  Phrases and comments are texts.

=back

I<Example:> 

 print Mail::Message::Field::Full->decode('=?iso-8859-1?Q?J=F8rgen?=');
    # prints   JE<0slash>rgen

=back

$obj-E<gt>B<defaultWrapLength>([LENGTH])

=over 4

See L<Mail::Message::Field/"Internals">

=back

$obj-E<gt>B<encode>(STRING, OPTIONS)

=over 4

Encode the (possibly utf8 encoded) STRING to a string which is acceptable
to the RFC2047 definition of a header: only containing us-ascii characters.

 Option    Defined in       Default      
 charset                    C<'us-ascii'>
 encoding                   C<'q'>       
 force                      <flase>      
 language                   undef        

. charset STRING

=over 4

STRING is an utf8 string which has to be translated into any byte-wise
character set for transport, because MIME-headers can only contain ascii
characters.

=back

. encoding 'q'|'Q'|'b'|'B'

=over 4

The character encoding to be used.  With C<q> or C<Q>, quoted-printable
encoding will be used.  With C<b > or C<B >, base64 encoding will be taken.

=back

. force BOOLEAN

=over 4

Encode the string, even when it only contains us-ascii characters.  By
default, this is off because it decreases readibility of the produced
header fields.

=back

. language STRING

=over 4

RFC2231 defines how to specify language encodings in encoded words.  The
STRING is a strandard iso language name.

=back

=back

$obj-E<gt>B<fold>(NAME, BODY, [MAXCHARS])

=over 4

See L<Mail::Message::Field/"Internals">

=back

$obj-E<gt>B<setWrapLength>([LENGTH])

=over 4

See L<Mail::Message::Field/"Internals">

=back

$obj-E<gt>B<unfold>(STRING)

=over 4

See L<Mail::Message::Field/"Internals">

=back

=head2 Error handling


$obj-E<gt>B<AUTOLOAD>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<defaultTrace>([LEVEL, [LEVEL])

Mail::Message::Field::Full-E<gt>B<defaultTrace>([LEVEL, [LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<errors>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<log>([LEVEL [,STRINGS]])

Mail::Message::Field::Full-E<gt>B<log>([LEVEL [,STRINGS]])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logPriority>(LEVEL)

Mail::Message::Field::Full-E<gt>B<logPriority>(LEVEL)

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<logSettings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<notImplemented>

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<report>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<reportAll>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<trace>([LEVEL])

=over 4

See L<Mail::Reporter/"Error handling">

=back

$obj-E<gt>B<warnings>

=over 4

See L<Mail::Reporter/"Error handling">

=back

=head2 Cleanup


$obj-E<gt>B<DESTROY>

=over 4

See L<Mail::Reporter/"Cleanup">

=back

$obj-E<gt>B<inGlobalDestruction>

=over 4

See L<Mail::Reporter/"Cleanup">

=back



=head1 DIAGNOSTICS

I<Error:> Attributes cannot be added to unstructured fields

Unstructured fields are free format, attributes are not.  So: it is not
correct to try adding these well-defined strings to an unknown text.

I<Error:> Comments cannot be added to unstructured fields

Unstructured fields are free format, comments are not.  So: it is not
correct to try adding these well-defined strings to an unknown text.

I<Error:> Extras cannot be added to unstructured fields

Unstructured fields are free format, extras are not.  Although an extra is
a nearly free format piece of text preceded by a semi-colon, they do (by
definition) not interfere with other structured data in fields.
So: it is not correct to try adding these to an fully free formatted text
because you are never sure the data can be regained correctly.

I<Warning:> Field content is not numerical: $content

The numeric value of a field is requested (for instance the C<Lines> or
C<Content-Length> fields should be numerical), however the data contains
weird characters.

I<Warning:> Illegal character in charset '$charset'

The field is created with an utf8 string which only contains data from the
specified character set.  However, that character set can never be a valid
name because it contains characters which are not permitted.

I<Warning:> Illegal character in field name $name

A new field is being created which does contain characters not permitted
by the RFCs.  Using this field in messages may break other e-mail clients
or transfer agents, and therefore mutulate or extinguish your message.

I<Warning:> Illegal character in language '$lang'

The field is created with data which is specified to be in a certain language,
however, the name of the language cannot be valid: it contains characters
which are not permitted by the RFCs.

I<Warning:> Illegal encoding '$encoding', used 'q'

The RFCs only permit base64 (C<b > or C<B >) or quoted-printable
(C<q> or C<Q>) encoding.  Other than these four options are illegal.

I<Error:> Package $package does not implement $method.

Fatal error: the specific package (or one of its superclasses) does not
implement this method where it should. This message means that some other
related classes do implement this method however the class at hand does
not.  Probably you should investigate this and probably inform the author
of the package.






=head1 REFERENCES

See the Mail::Box website at L<http://perl.overmeer.net/mailbox/> for more details.

=head1 COPYRIGHTS

Module version 2.042.
Written by Mark Overmeer (mark@overmeer.net).  See the ChangeLog for
other contributors.

Copyright (c) 2001-2003 by the author(s). All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.


