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.\" ========================================================================
.\"
.IX Title "PPI::Node 3pm"
.TH PPI::Node 3pm "2017-06-25" "perl v5.24.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
PPI::Node \- Abstract PPI Node class, an Element that can contain other Elements
.SH "INHERITANCE"
.IX Header "INHERITANCE"
.Vb 2
\&  PPI::Node
\&  isa PPI::Element
.Ve
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\&  # Create a typical node (a Document in this case)
\&  my $Node = PPI::Document\->new;
\&  
\&  # Add an element to the node( in this case, a token )
\&  my $Token = PPI::Token::Word\->new(\*(Aqmy\*(Aq);
\&  $Node\->add_element( $Token );
\&  
\&  # Get the elements for the Node
\&  my @elements = $Node\->children;
\&  
\&  # Find all the barewords within a Node
\&  my $barewords = $Node\->find( \*(AqPPI::Token::Word\*(Aq );
\&  
\&  # Find by more complex criteria
\&  my $my_tokens = $Node\->find( sub { $_[1]\->content eq \*(Aqmy\*(Aq } );
\&  
\&  # Remove all the whitespace
\&  $Node\->prune( \*(AqPPI::Token::Whitespace\*(Aq );
\&  
\&  # Remove by more complex criteria
\&  $Node\->prune( sub { $_[1]\->content eq \*(Aqmy\*(Aq } );
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \f(CW\*(C`PPI::Node\*(C'\fR class provides an abstract base class for the Element
classes that are able to contain other elements PPI::Document,
PPI::Statement, and PPI::Structure.
.PP
As well as those listed below, all of the methods that apply to
PPI::Element objects also apply to \f(CW\*(C`PPI::Node\*(C'\fR objects.
.SH "METHODS"
.IX Header "METHODS"
.SS "scope"
.IX Subsection "scope"
The \f(CW\*(C`scope\*(C'\fR method returns true if the node represents a lexical scope
boundary, or false if it does not.
.ie n .SS "add_element $Element"
.el .SS "add_element \f(CW$Element\fP"
.IX Subsection "add_element $Element"
The \f(CW\*(C`add_element\*(C'\fR method adds a PPI::Element object to the end of a
\&\f(CW\*(C`PPI::Node\*(C'\fR. Because Elements maintain links to their parent, an
Element can only be added to a single Node.
.PP
Returns true if the PPI::Element was added. Returns \f(CW\*(C`undef\*(C'\fR if the
Element was already within another Node, or the method is not passed 
a PPI::Element object.
.SS "elements"
.IX Subsection "elements"
The \f(CW\*(C`elements\*(C'\fR method accesses all child elements \fBstructurally\fR within
the \f(CW\*(C`PPI::Node\*(C'\fR object. Note that in the base of the PPI::Structure
classes, this \f(CW\*(C`DOES\*(C'\fR include the brace tokens at either end of the
structure.
.PP
Returns a list of zero or more PPI::Element objects.
.PP
Alternatively, if called in the scalar context, the \f(CW\*(C`elements\*(C'\fR method
returns a count of the number of elements.
.SS "first_element"
.IX Subsection "first_element"
The \f(CW\*(C`first_element\*(C'\fR method accesses the first element structurally within
the \f(CW\*(C`PPI::Node\*(C'\fR object. As for the \f(CW\*(C`elements\*(C'\fR method, this does include
the brace tokens for PPI::Structure objects.
.PP
Returns a PPI::Element object, or \f(CW\*(C`undef\*(C'\fR if for some reason the
\&\f(CW\*(C`PPI::Node\*(C'\fR object does not contain any elements.
.SS "last_element"
.IX Subsection "last_element"
The \f(CW\*(C`last_element\*(C'\fR method accesses the last element structurally within
the \f(CW\*(C`PPI::Node\*(C'\fR object. As for the \f(CW\*(C`elements\*(C'\fR method, this does include
the brace tokens for PPI::Structure objects.
.PP
Returns a PPI::Element object, or \f(CW\*(C`undef\*(C'\fR if for some reason the
\&\f(CW\*(C`PPI::Node\*(C'\fR object does not contain any elements.
.SS "children"
.IX Subsection "children"
The \f(CW\*(C`children\*(C'\fR method accesses all child elements lexically within the
\&\f(CW\*(C`PPI::Node\*(C'\fR object. Note that in the case of the PPI::Structure
classes, this does \fB\s-1NOT\s0\fR include the brace tokens at either end of the
structure.
.PP
Returns a list of zero of more PPI::Element objects.
.PP
Alternatively, if called in the scalar context, the \f(CW\*(C`children\*(C'\fR method
returns a count of the number of lexical children.
.SS "schildren"
.IX Subsection "schildren"
The \f(CW\*(C`schildren\*(C'\fR method is really just a convenience, the significant-only
variation of the normal \f(CW\*(C`children\*(C'\fR method.
.PP
In list context, returns a list of significant children. In scalar context,
returns the number of significant children.
.ie n .SS "child $index"
.el .SS "child \f(CW$index\fP"
.IX Subsection "child $index"
The \f(CW\*(C`child\*(C'\fR method accesses a child PPI::Element object by its
position within the Node.
.PP
Returns a PPI::Element object, or \f(CW\*(C`undef\*(C'\fR if there is no child
element at that node.
.ie n .SS "schild $index"
.el .SS "schild \f(CW$index\fP"
.IX Subsection "schild $index"
The lexical structure of the Perl language ignores 'insignificant' items,
such as whitespace and comments, while \s-1PPI\s0 treats these items as valid
tokens so that it can reassemble the file at any time. Because of this,
in many situations there is a need to find an Element within a Node by
index, only counting lexically significant Elements.
.PP
The \f(CW\*(C`schild\*(C'\fR method returns a child Element by index, ignoring
insignificant Elements. The index of a child Element is specified in the
same way as for a normal array, with the first Element at index 0, and
negative indexes used to identify a \*(L"from the end\*(R" position.
.ie n .SS "contains $Element"
.el .SS "contains \f(CW$Element\fP"
.IX Subsection "contains $Element"
The \f(CW\*(C`contains\*(C'\fR method is used to determine if another PPI::Element
object is logically \*(L"within\*(R" a \f(CW\*(C`PPI::Node\*(C'\fR. For the special case of the
brace tokens at either side of a PPI::Structure object, they are
generally considered \*(L"within\*(R" a PPI::Structure object, even if they are
not actually in the elements for the PPI::Structure.
.PP
Returns true if the PPI::Element is within us, false if not, or \f(CW\*(C`undef\*(C'\fR
on error.
.ie n .SS "find $class | \e&wanted"
.el .SS "find \f(CW$class\fP | \e&wanted"
.IX Subsection "find $class | &wanted"
The \f(CW\*(C`find\*(C'\fR method is used to search within a code tree for
PPI::Element objects that meet a particular condition.
.PP
To specify the condition, the method can be provided with either a simple
class name (full or shortened), or a \f(CW\*(C`CODE\*(C'\fR/function reference.
.PP
.Vb 2
\&  # Find all single quotes in a Document (which is a Node)
\&  $Document\->find(\*(AqPPI::Quote::Single\*(Aq);
\&  
\&  # The same thing with a shortened class name
\&  $Document\->find(\*(AqQuote::Single\*(Aq);
\&  
\&  # Anything more elaborate, we go with the sub
\&  $Document\->find( sub {
\&        # At the top level of the file...
\&        $_[1]\->parent == $_[0]
\&        and (
\&                # ...find all comments and POD
\&                $_[1]\->isa(\*(AqPPI::Token::Pod\*(Aq)
\&                or
\&                $_[1]\->isa(\*(AqPPI::Token::Comment\*(Aq)
\&        )
\&  } );
.Ve
.PP
The function will be passed two arguments, the top-level \f(CW\*(C`PPI::Node\*(C'\fR
you are searching in and the current PPI::Element that the condition
is testing.
.PP
The anonymous function should return one of three values. Returning true
indicates a condition match, defined-false (\f(CW0\fR or \f(CW\*(Aq\*(Aq\fR) indicates
no-match, and \f(CW\*(C`undef\*(C'\fR indicates no-match and no-descend.
.PP
In the last case, the tree walker will skip over anything below the
\&\f(CW\*(C`undef\*(C'\fR\-returning element and move on to the next element at the same
level.
.PP
To halt the entire search and return \f(CW\*(C`undef\*(C'\fR immediately, a condition
function should throw an exception (i.e. \f(CW\*(C`die\*(C'\fR).
.PP
Note that this same wanted logic is used for all methods documented to
have a \f(CW\*(C`\e&wanted\*(C'\fR parameter, as this one does.
.PP
The \f(CW\*(C`find\*(C'\fR method returns a reference to an array of PPI::Element
objects that match the condition, false (but defined) if no Elements match
the condition, or \f(CW\*(C`undef\*(C'\fR if you provide a bad condition, or an error
occurs during the search process.
.PP
In the case of a bad condition, a warning will be emitted as well.
.ie n .SS "find_first $class | \e&wanted"
.el .SS "find_first \f(CW$class\fP | \e&wanted"
.IX Subsection "find_first $class | &wanted"
If the normal \f(CW\*(C`find\*(C'\fR method is like a grep, then \f(CW\*(C`find_first\*(C'\fR is
equivalent to the List::Util \f(CW\*(C`first\*(C'\fR function.
.PP
Given an element class or a wanted function, it will search depth-first
through a tree until it finds something that matches the condition,
returning the first Element that it encounters.
.PP
See the \f(CW\*(C`find\*(C'\fR method for details on the format of the search condition.
.PP
Returns the first PPI::Element object that matches the condition, false
if nothing matches the condition, or \f(CW\*(C`undef\*(C'\fR if given an invalid condition,
or an error occurs.
.ie n .SS "find_any $class | \e&wanted"
.el .SS "find_any \f(CW$class\fP | \e&wanted"
.IX Subsection "find_any $class | &wanted"
The \f(CW\*(C`find_any\*(C'\fR method is a short-circuiting true/false method that behaves
like the normal \f(CW\*(C`find\*(C'\fR method, but returns true as soon as it finds any
Elements that match the search condition.
.PP
See the \f(CW\*(C`find\*(C'\fR method for details on the format of the search condition.
.PP
Returns true if any Elements that match the condition can be found, false if
not, or \f(CW\*(C`undef\*(C'\fR if given an invalid condition, or an error occurs.
.ie n .SS "remove_child $Element"
.el .SS "remove_child \f(CW$Element\fP"
.IX Subsection "remove_child $Element"
If passed a PPI::Element object that is a direct child of the Node,
the \f(CW\*(C`remove_element\*(C'\fR method will remove the \f(CW\*(C`Element\*(C'\fR intact, along
with any of its children. As such, this method acts essentially as a
\&'cut' function.
.PP
If successful, returns the removed element.  Otherwise, returns \f(CW\*(C`undef\*(C'\fR.
.ie n .SS "prune $class | \e&wanted"
.el .SS "prune \f(CW$class\fP | \e&wanted"
.IX Subsection "prune $class | &wanted"
The \f(CW\*(C`prune\*(C'\fR method is used to strip PPI::Element objects out of a code
tree. The argument is the same as for the \f(CW\*(C`find\*(C'\fR method, either a class
name, or an anonymous subroutine which returns true/false. Any Element
that matches the class|wanted will be deleted from the code tree, along
with any of its children.
.PP
The \f(CW\*(C`prune\*(C'\fR method returns the number of \f(CW\*(C`Element\*(C'\fR objects that matched
and were removed, \fBnon-recursively\fR. This might also be zero, so avoid a
simple true/false test on the return false of the \f(CW\*(C`prune\*(C'\fR method. It
returns \f(CW\*(C`undef\*(C'\fR on error, which you probably \fBshould\fR test for.
.SH "TO DO"
.IX Header "TO DO"
\&\- Move as much as possible to \s-1PPI::XS\s0
.SH "SUPPORT"
.IX Header "SUPPORT"
See the support section in the main module.
.SH "AUTHOR"
.IX Header "AUTHOR"
Adam Kennedy <adamk@cpan.org>
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2001 \- 2011 Adam Kennedy.
.PP
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
.PP
The full text of the license can be found in the
\&\s-1LICENSE\s0 file included with this module.