B::XPath 0.01

B::XPath class can search Perl optrees with XPath syntax.

SYNOPSIS

Perl represents programs internally as a tree of opcodes. To execute a program, it walks this tree, performing each operation as it encounters it. The B family of modules allows you to examine (and in some cases, manipulate) this optree on programs even as they run.

B::XPath allows you to use XPath syntax to select ops in the optree.

use B::XPath;

my $node = B::XPath->fetch_root( &some_function );
my $root = B::XPath->fetch_main_root();

# find all global scalar accesses
my @globals = $root->match( //gvsv );

# find all global scalar accesses within some_function() named $bob
my @bobs = $node->match( //gvsv[@NAME="bob"] );

Class Methods

There are two methods to use to start your match; both set the root of the tree to search. Theres also a nice helper method youll probably never use unless you find a bug.

fetch_root( $subref )

This method returns the B::XPath::Node object at the root of the optree for the subroutine reference. All matches performed on this node will search this branch of the optree for matching nodes.

fetch_main_root()

This method returns the B::XPath::Node object at the root of the program. Use this to search your entire program (at least, the part of it outside of any given subroutine).

find_op_class( $op )

Given a B::OP or descendent object, returns the name of the appropriate B::XPath::Node subclass to use to wrap that op so that B::XPath can manipulate it appropriately.