NAME Data::CSel::WrapStruct - Wrap data structure into a tree of objects suitable for use with Data::CSel VERSION This document describes version 0.008 of Data::CSel::WrapStruct (from Perl distribution Data-CSel-WrapStruct), released on 2020-04-15. SYNOPSIS use Data::CSel qw(csel); use Data::CSel::WrapStruct qw(wrap_struct unwrap_tree); my $data = [ 0, 1, [2, ["two","dua"], {url=>"http://example.com/two.jpg"}, ["even","prime"]], 3, [4, ["four","empat"], {}, ["even"]], ]; my $tree = wrap_struct($data); my @nodes = csel(":root > * > *:nth-child(4) > *", $tree); my @tags = map { $_->value } @nodes; # -> ("even", "prime", "even") Scalars are wrapped using "Data::CSel::WrapStruct::Scalar" class, scalarrefs are wrapped using "Data::CSel::WrapStruct::ScalarRef" class, arrays are wrapped using "Data::CSel::WrapStruct::Array" class, and hashes are wrapped using "Data::CSel::WrapStruct::Hash" class. For convenience, when you load "Data::CSel::WrapStruct", it adds "Data::CSel::WrapStruct" to @Data::CSel::CLASS_PREFIXES so you don't have to specify "{class_prefixes=>["Data::CSel::WrapStruct"]}" "csel()" option everytime. my @hashes = map {$_->value} csel("Hash", $tree); # -> ({url=>"http://example.com/two.jpg"}, {}) The wrapper objects provide some methods, e.g.: my @empty_hashes = map {$_->value} csel("Hash[length=0]", $tree); # -> ({}) my @hashes_that_have_url_key = map {$_->value} csel("Hash[has_key('url')]", $tree); # -> ({url=>"http://example.com/two.jpg"}) my @larger_scalars = [map {$_->value} csel("Scalar[value >= 3]", $tree)] # -> (3, 4) See "NODE METHODS", "SCALAR NODE METHODS", "SCALARREF NODE METHODS", "ARRAY NODE METHODS", "HASH NODE METHODS" for more details on the provided methods. You can replace the value of nodes using "value": my @posint_scalar_nodes = csel("Scalar[value > 0]", $tree); for (@posint_scalar_nodes) { $_->value( $_->value * 10 ) } use Data::Dump; dd unwrap_tree($data); # => [ # 0, # 10, # [20, ["two","dua"], {url=>"http://example.com/two.jpg"}, ["even","prime"]], # 30, # [40, ["four","empat"], {}, ["even"]], # ]; DESCRIPTION This module provides "wrap_struct()" which creates a tree of objects from a generic data structure. You can then perform node selection using Data::CSel's "csel()". You can retrieve the original value of data items by calling "value()" method on the tree nodes. NODE METHODS parent children value Usage: my $val = $node->value; # get node value $node->value(1); # set node value Get or set node value. Note that when setting node value, the new node value is not automatically wrapped for you. If you want to set new node value and expect to select it or part of it again with "csel()", you will have to wrap the new value first with "wrap_struct". remove Usage: $node->remove; Remove node from parent. SCALAR NODE METHODS In addition to methods listed in "NODE METHODS", Scalar nodes also have the following methods. SCALARREF NODE METHODS In addition to methods listed in "NODE METHODS", ScalarRef nodes also have the following methods. ARRAY NODE METHODS In addition to methods listed in "NODE METHODS", Array nodes also have the following methods. length Get array length. Can be used to select an array based on its length, e.g.: @nodes = csel('Array[length > 0]'); HASH NODE METHODS In addition to methods listed in "NODE METHODS", Hash nodes also have the following methods. length Get the number of keys. Can be used to select a hash based on its number of keys, e.g.: @nodes = csel('Hash[length > 0]'); has_key Usage: my $bool = $node->has_key("foo"); Check whether hash has a certain key. Can be used to select a hash, e.g.: @nodes = csel('Hash[has_key("foo")]'); key Usage: my $key_val = $node->key("foo"); Get a hash key's value. Can be used to select a hash based on the value of one of its keys, e.g.: @nodes = csel('Hash[key("name") = "lisa"]'); FUNCTIONS None exported by default, but exportable. wrap_struct Usage: my $tree = wrap_struct($data); Wrap a data structure into a tree of objects. Currently cannot handle recursive structure. unwrap_tree Usage: my $data = unwrap_tree($wrapped_data); Unwrap a tree produced by "wrap_tree" back into unwrapped data structure. FAQ Changing the node value doesn't work! my $data = [0, 1, 2]; my @nodes = csel("Scalar[value > 0]", wrap_struct($data)); for (@nodes) { $_->[0] = "x" } use Data::Dump; dd $data; still prints "[0,1,2]" instead of "[0,'x','x']". Why? To set node value, you have to use the "value()" node method with an argument: ... for (@nodes) { $->value("x") } ... will then print the expected "[0,'x','x']". This module is slow! If you intend to select a data structure with thousands of nodes or more, you're probably better off using other approach, for example Data::Walk::More. Data::Walk::More provides containers for the nodes you're traversing. For example, the CSel expression "Hash[has_keys("foo")] > Array > Scalar[value > 0]" can be written as: walk sub { my $ref = ref $_; return if ref $_; # ... Scalar return if $_ <= 0; # ... [value > 0] return unless ref $Data::Walk::More::containers[-1] eq 'ARRAY'; # ... Array return unless ref $Data::Walk::More::containers[-2] eq 'HASH'; # ... Hash return unless exists $Data::Walk::More::containers[-2]{foo}; # ... [has_keys("foo")] push @matches, $_; }, $data; HOMEPAGE Please visit the project's homepage at <https://metacpan.org/release/Data-CSel-WrapStruct>. SOURCE Source repository is at <https://github.com/perlancar/perl-Data-CSel-WrapStruct>. BUGS Please report any bugs or feature requests on the bugtracker website <https://rt.cpan.org/Public/Dist/Display.html?Name=Data-CSel-WrapStruct> When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature. SEE ALSO Data::CSel AUTHOR perlancar <perlancar@cpan.org> COPYRIGHT AND LICENSE This software is copyright (c) 2020, 2016 by perlancar@cpan.org. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.