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.\" ========================================================================
.\"
.IX Title "PPIx::Utils::Traversal 3pm"
.TH PPIx::Utils::Traversal 3pm "2021-09-29" "perl v5.32.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
PPIx::Utils::Traversal \- Utility functions for traversing PPI documents
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use PPIx::Utils::Traversal \*(Aq:all\*(Aq;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This package is a component of PPIx::Utils that contains functions for
traversal of \s-1PPI\s0 documents.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
All functions can be imported by name, or with the tag \f(CW\*(C`:all\*(C'\fR.
.SS "first_arg"
.IX Subsection "first_arg"
.Vb 1
\&    my $first_arg = first_arg($element);
.Ve
.PP
Given a PPI::Element that is presumed to be a function call (which
is usually a PPI::Token::Word), return the first argument.  This is
similar of \*(L"parse_arg_list\*(R" and follows the same logic.  Note that
for the code:
.PP
.Vb 1
\&    int($x + 0.5)
.Ve
.PP
this function will return just the \f(CW$x\fR, not the whole expression.
This is different from the behavior of \*(L"parse_arg_list\*(R".  Another
caveat is:
.PP
.Vb 1
\&    int(($x + $y) + 0.5)
.Ve
.PP
which returns \f(CW\*(C`($x + $y)\*(C'\fR as a PPI::Structure::List instance.
.SS "parse_arg_list"
.IX Subsection "parse_arg_list"
.Vb 1
\&    my @args = parse_arg_list($element);
.Ve
.PP
Given a PPI::Element that is presumed to be a function call (which
is usually a PPI::Token::Word), splits the argument expressions
into arrays of tokens.  Returns a list containing references to each
of those arrays.  This is useful because parentheses are optional when
calling a function, and \s-1PPI\s0 parses them very differently.  So this
method is a poor-man's parse tree of \s-1PPI\s0 nodes.  It's not bullet-proof
because it doesn't respect precedence. In general, I don't like the
way this function works, so don't count on it to be stable (or even
present).
.SS "split_nodes_on_comma"
.IX Subsection "split_nodes_on_comma"
.Vb 1
\&    my @args = split_nodes_on_comma(@nodes);
.Ve
.PP
This has the same return type as \*(L"parse_arg_list\*(R" but expects to be
passed the nodes that represent the interior of a list, like:
.PP
.Vb 1
\&    \*(Aqfoo\*(Aq, 1, 2, \*(Aqbar\*(Aq
.Ve
.SS "get_next_element_in_same_simple_statement"
.IX Subsection "get_next_element_in_same_simple_statement"
.Vb 1
\&    my $element = get_next_element_in_same_simple_statement($element);
.Ve
.PP
Given a PPI::Element, this subroutine returns the next element in
the same simple statement as defined by
\&\*(L"is_ppi_simple_statement\*(R" in PPIx::Utils::Classification. If no next
element can be found, this subroutine simply returns \f(CW\*(C`undef\*(C'\fR.
.PP
If the \f(CW$element\fR is undefined or unblessed, we simply return \f(CW\*(C`undef\*(C'\fR.
.PP
If the \f(CW$element\fR satisfies
\&\*(L"is_ppi_simple_statement\*(R" in PPIx::Utils::Classification, we return
\&\f(CW\*(C`undef\*(C'\fR, \fBunless\fR it has a parent which is a PPI::Structure::List.
.PP
If the \f(CW$element\fR is the last significant element in its PPI::Node,
we replace it with its parent and iterate again.
.PP
Otherwise, we return \f(CW\*(C`$element\->snext_sibling()\*(C'\fR.
.SS "get_previous_module_used_on_same_line"
.IX Subsection "get_previous_module_used_on_same_line"
.Vb 1
\&    my $element = get_previous_module_used_on_same_line($element);
.Ve
.PP
Given a PPI::Element, returns the PPI::Element representing the
name of the module included by the previous \f(CW\*(C`use\*(C'\fR or \f(CW\*(C`require\*(C'\fR on
the same line as the \f(CW$element\fR. If none is found, simply returns
\&\f(CW\*(C`undef\*(C'\fR.
.PP
For example, with the line
.PP
.Vb 1
\&    use version; our $VERSION = ...;
.Ve
.PP
given the PPI::Token::Symbol instance for \f(CW$VERSION\fR, this will
return \*(L"version\*(R".
.PP
If the given element is in a \f(CW\*(C`use\*(C'\fR or <require>, the return is from
the previous \f(CW\*(C`use\*(C'\fR or \f(CW\*(C`require\*(C'\fR on the line, if any.
.SS "get_constant_name_elements_from_declaring_statement"
.IX Subsection "get_constant_name_elements_from_declaring_statement"
.Vb 1
\&    my @constants = get_constant_name_elements_from_declaring_statement($statement);
.Ve
.PP
Given a PPI::Statement, if the statement is a Readonly, ReadonlyX, or
Const::Fast declaration statement or a \f(CW\*(C`use constant\*(C'\fR, returns the names
of the things being defined.
.PP
Given
.PP
.Vb 1
\&    use constant 1.16 FOO => \*(Aqbar\*(Aq;
.Ve
.PP
this will return the PPI::Token::Word containing \f(CW\*(AqFOO\*(Aq\fR.
Given
.PP
.Vb 1
\&    use constant 1.16 { FOO => \*(Aqbar\*(Aq, \*(AqBAZ\*(Aq => \*(Aqburfle\*(Aq };
.Ve
.PP
this will return a list of the PPI::Tokens containing \f(CW\*(AqFOO\*(Aq\fR and \f(CW\*(AqBAZ\*(Aq\fR.
Similarly, given
.PP
.Vb 1
\&    Readonly::Hash my %FOO => ( bar => \*(Aqbaz\*(Aq );
.Ve
.PP
or
.PP
.Vb 1
\&    const my %FOO => ( bar => \*(Aqbaz\*(Aq );
.Ve
.PP
this will return the PPI::Token::Symbol containing \f(CW\*(Aq%FOO\*(Aq\fR.
.SS "split_ppi_node_by_namespace"
.IX Subsection "split_ppi_node_by_namespace"
.Vb 1
\&    my $subtrees = split_ppi_node_by_namespace($node);
.Ve
.PP
Returns the sub-trees for each namespace in the node as a reference to a hash
of references to arrays of PPI::Nodes.  Say we've got the following code:
.PP
.Vb 1
\&    #!perl
\&
\&    my $x = blah();
\&
\&    package Foo;
\&
\&    my $y = blah_blah();
\&
\&    {
\&        say \*(AqWhee!\*(Aq;
\&
\&        package Bar;
\&
\&        something();
\&    }
\&
\&    thingy();
\&
\&    package Baz;
\&
\&    da_da_da();
\&
\&    package Foo;
\&
\&    foreach ( blrfl() ) {
\&        ...
\&    }
.Ve
.PP
Calling this function on a PPI::Document for the above returns a
value that looks like this, using multi-line string literals for the
actual code parts instead of \s-1PPI\s0 trees to make this easier to read:
.PP
.Vb 4
\&    {
\&        main    => [
\&            q<
\&                #!perl
\&
\&                my $x = blah();
\&            >,
\&        ],
\&        Foo     => [
\&            q<
\&                package Foo;
\&
\&                my $y = blah_blah();
\&
\&                {
\&                    say \*(AqWhee!\*(Aq;
\&
\&                }
\&
\&                thingy();
\&            >,
\&            q<
\&                package Foo;
\&
\&                foreach ( blrfl() ) {
\&                    ...
\&                }
\&            >,
\&        ],
\&        Bar     => [
\&            q<
\&                package Bar;
\&
\&                something();
\&            >,
\&        ],
\&        Baz     => [
\&            q<
\&                package Baz;
\&
\&                da_da_da();
\&            >,
\&        ],
\&    }
.Ve
.PP
Note that the return value contains copies of the original nodes, and not the
original nodes themselves due to the need to handle namespaces that are not
file-scoped.  (Notice how the first element for \*(L"Foo\*(R" above differs from the
original code.)
.SH "BUGS"
.IX Header "BUGS"
Report any issues on the public bugtracker.
.SH "AUTHOR"
.IX Header "AUTHOR"
Dan Book <dbook@cpan.org>
.PP
Code originally from Perl::Critic::Utils by Jeffrey Ryan Thalhammer
<jeff@imaginative\-software.com>, Perl::Critic::Utils::PPI and
PPIx::Utilities::Node by Elliot Shank <perl@galumph.com>, and
PPIx::Utilities::Statement by Thomas R. Wyant, \s-1III\s0 <wyant@cpan.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2005\-2011 Imaginative Software Systems,
2007\-2011 Elliot Shank, 2009\-2010 Thomas R. Wyant, \s-1III, 2017\s0 Dan Book.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Perl::Critic::Utils, Perl::Critic::Utils::PPI, PPIx::Utilities