————package
PPI::Statement;
=pod
=head1 NAME
PPI::Statement - The base class for Perl statements
=head1 INHERITANCE
PPI::Statement
isa PPI::Node
isa PPI::Element
=head1 DESCRIPTION
PPI::Statement is the root class for all Perl statements. This includes (from
L<perlsyn>) "Declarations", "Simple Statements" and "Compound Statements".
The class PPI::Statement itself represents a "Simple Statement" as defined
in the L<perlsyn> manpage.
=head1 STATEMENT CLASSES
Please note that unless documented themselves, these classes are yet to be
frozen/finalised. Names may change slightly or be added or removed.
=head2 L<PPI::Statement::Scheduled>
This covers all "scheduled" blocks, chunks of code that are executed
separately from the main body of the code, at a particular time. This
includes all C<BEGIN>, C<CHECK>, C<INIT> and C<END> blocks.
=head2 L<PPI::Statement::Package>
A package declaration, as defined in L<perlfunc|perlfunc/package>.
=head2 L<PPI::Statement::Include>
A statement that loads or unloads another module.
This includes 'use', 'no', and 'require' statements.
=head2 L<PPI::Statement::Sub>
A named subroutine declaration, or forward declaration
=head2 L<PPI::Statement::Variable>
A variable declaration statement. This could be either a straight
declaration or also be an expression.
This includes all 'my', 'local' and 'out' statements.
=head2 L<PPI::Statement::Compound>
This covers the whole family of 'compound' statements, as described in
L<perlsyn|perlsyn>.
This includes all statements starting with 'if', 'unless', 'for', 'foreach'
and 'while'. Note that this does NOT include 'do', as it is treated
differently.
All compound statements have implicit ends. That is, they do not end with
a ';' statement terminator.
=head2 L<PPI::Statement::Break>
A statement that breaks out of a structure.
This includes all of 'redo', 'next', 'last' and 'return' statements.
=head2 L<PPI::Statement::Data>
A special statement which encompasses an entire C<__DATA__> block, including
the initial C<'__DATA__'> token itself and the entire contents.
=head2 L<PPI::Statement::End>
A special statement which encompasses an entire __END__ block, including
the initial '__END__' token itself and the entire contents, including any
parsed PPI::Token::POD that may occur in it.
=head2 L<PPI::Statement::Expression>
L<PPI::Statement::Expression> is a little more speculative, and is intended
to help represent the special rules relating to "expressions" such as in:
# Several examples of expression statements
# Boolean conditions
if ( expression ) { ... }
# Lists, such as for arguments
Foo->bar( expression )
=head2 L<PPI::Statement::Null>
A null statement is a special case for where we encounter two consecutive
statement terminators. ( ;; )
The second terminator is given an entire statement of its own, but one
that serves no purpose. Hence a 'null' statement.
Theoretically, assuming a correct parsing of a perl file, all null statements
are superfluous and should be able to be removed without damage to the file.
But don't do that, in case PPI has parsed something wrong.
=head2 L<PPI::Statement::UnmatchedBrace>
Because L<PPI> is intended for use when parsing incorrect or incomplete code,
the problem arises of what to do with a stray closing brace.
Rather than die, it is allocated its own "unmatched brace" statement,
which really means "unmatched closing brace". An unmatched open brace at the
end of a file would become a structure with no contents and no closing brace.
If the document loaded is intended to be correct and valid, finding a
L<PPI::Statement::UnmatchedBrace> in the PDOM is generally indicative of a
misparse.
=head2 L<PPI::Statement::Unknown>
This is used temporarily mid-parsing to hold statements for which the lexer
cannot yet determine what class it should be, usually because there are
insufficient clues, or it might be more than one thing.
You should never encounter these in a fully parsed PDOM tree.
=head1 METHODS
C<PPI::Statement> itself has very few methods. Most of the time, you will be
working with the more generic L<PPI::Element> or L<PPI::Node> methods, or one
of the methods that are subclass-specific.
=cut
use
strict;
use
PPI::Statement::Break ();
use
PPI::Statement::Compound ();
use
PPI::Statement::Data ();
use
PPI::Statement::End ();
use
PPI::Statement::Expression ();
use
PPI::Statement::Include ();
use
PPI::Statement::Null ();
use
PPI::Statement::Package ();
use
PPI::Statement::Scheduled ();
use
PPI::Statement::Sub ();
use
PPI::Statement::UnmatchedBrace ();
use
PPI::Statement::Unknown ();
use
PPI::Statement::Variable ();
BEGIN {
$VERSION
=
'1.113'
;
}
# "Normal" statements end at a statement terminator ;
# Some are not, and need the more rigorous _statement_continues to see
# if we are at an implicit statement boundary.
sub
__LEXER__normal { 1 }
#####################################################################
# Constructor
sub
new {
my
$class
=
ref
$_
[0] ?
ref
shift
:
shift
;
# Create the object
my
$self
=
bless
{
children
=> [],
},
$class
;
# If we have been passed what should be an initial token, add it
if
( _INSTANCE(
$_
[0],
'PPI::Token'
) ) {
$self
->__add_element(
shift
);
}
$self
;
}
=pod
=head2 label
One factor common to most statements is their ability to be labelled.
The C<label> method returns the label for a statement, if one has been
defined, but without the trailing colon. Take the following example
MYLABEL: while ( 1 .. 10 ) { last MYLABEL if $_ > 5 }
For the above statement, the C<label> method would return 'MYLABEL'.
Returns false if the statement does not have a label.
=cut
sub
label {
my
$first
=
shift
->schild(1) or
return
''
;
$first
->isa(
'PPI::Token::Label'
)
?
substr
(
$first
, 0,
length
(
$first
) - 1)
:
''
;
}
=pod
=head2 stable
Much like the L<PPI::Document> method of the same name, the ->stable
method converts a statement to source and back again, to determine if
a modified statement is still legal, and won't be interpreted in a
different way.
Returns true if the statement is stable, false if not, or C<undef> on
error.
=cut
sub
stable {
my
$self
=
shift
;
die
"The ->stable method has not yet been implemented"
;
}
#####################################################################
# PPI::Element Methods
# You can insert either a statement, or a non-significant token.
sub
insert_before {
my
$self
=
shift
;
my
$Element
= _INSTANCE(
shift
,
'PPI::Element'
) or
return
undef
;
if
(
$Element
->isa(
'PPI::Statement'
) ) {
return
$self
->__insert_before(
$Element
);
}
elsif
(
$Element
->isa(
'PPI::Token'
) and !
$Element
->significant ) {
return
$self
->__insert_before(
$Element
);
}
''
;
}
# As above, you can insert a statement, or a non-significant token
sub
insert_after {
my
$self
=
shift
;
my
$Element
= _INSTANCE(
shift
,
'PPI::Element'
) or
return
undef
;
if
(
$Element
->isa(
'PPI::Statement'
) ) {
return
$self
->__insert_after(
$Element
);
}
elsif
(
$Element
->isa(
'PPI::Token'
) and !
$Element
->significant ) {
return
$self
->__insert_after(
$Element
);
}
''
;
}
#####################################################################
# Support Methods
sub
_Fragment {
my
$self
=
shift
;
# Because we are potentially part of a larger structure,
# we need to clone ourselves first.
my
$clone
=
$self
->clone or
return
undef
;
# Create the empty Fragment
my
$Fragment
= PPI::Document::Fragment->new;
$Fragment
->add_element(
$self
) or
return
undef
;
}
1;
=pod
=head1 TO DO
- Complete, freeze and document the remaining classes
=head1 SUPPORT
See the L<support section|PPI/SUPPORT> in the main module
=head1 AUTHOR
Adam Kennedy, L<http://ali.as/>, cpan@ali.as
=head1 COPYRIGHT
Copyright (c) 2001 - 2005 Adam Kennedy. All rights reserved.
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
The full text of the license can be found in the
LICENSE file included with this module.
=cut