PPI::Statement(3) The base class for Perl statements

INHERITANCE

  PPI::Statement
  isa PPI::Node
      isa PPI::Element

DESCRIPTION

PPI::Statement is the root class for all Perl statements. This includes (from perlsyn) ``Declarations'', ``Simple Statements'' and ``Compound Statements''.

The class PPI::Statement itself represents a ``Simple Statement'' as defined in the perlsyn manpage.

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.

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 "BEGIN", "CHECK", "UNITCHECK", "INIT" and "END" blocks.

PPI::Statement::Package

A package declaration, as defined in perlfunc.

PPI::Statement::Include

A statement that loads or unloads another module.

This includes 'use', 'no', and 'require' statements.

PPI::Statement::Sub

A named subroutine declaration, or forward declaration

PPI::Statement::Variable

A variable declaration statement. This could be either a straight declaration or also be an expression.

This includes all 'my', 'state', 'local' and 'our' statements.

PPI::Statement::Compound

This covers the whole family of 'compound' statements, as described in 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.

PPI::Statement::Break

A statement that breaks out of a structure.

This includes all of 'redo', 'goto', 'next', 'last' and 'return' statements.

PPI::Statement::Given

The kind of statement introduced in Perl 5.10 that starts with 'given'. This has an implicit end.

PPI::Statement::When

The kind of statement introduced in Perl 5.10 that starts with 'when' or 'default'. This also has an implicit end.

PPI::Statement::Data

A special statement which encompasses an entire "__DATA__" block, including the initial '__DATA__' token itself and the entire contents.

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.

PPI::Statement::Expression

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 )

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.

PPI::Statement::UnmatchedBrace

Because 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 PPI::Statement::UnmatchedBrace in the PDOM is generally indicative of a misparse.

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.

METHODS

"PPI::Statement" itself has very few methods. Most of the time, you will be working with the more generic PPI::Element or PPI::Node methods, or one of the methods that are subclass-specific.

label

One factor common to most statements is their ability to be labeled.

The "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 "label" method would return 'MYLABEL'.

Returns false if the statement does not have a label.

specialized

Answer whether this is a plain statement or one that has more significance.

Returns true if the statement is a subclass of this one, false otherwise.

stable

Much like the 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 "undef" on error.

TO DO

- Complete, freeze and document the remaining classes

SUPPORT

See the support section in the main module.

AUTHOR

Adam Kennedy <[email protected]>

COPYRIGHT

Copyright 2001 - 2011 Adam Kennedy.

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.

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