getting ancestors of element

jccunning has asked for the wisdom of the Perl Monks concerning the following question:

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Re: getting ancestors of element by philiprbrenan (Monk) on Aug 30, 2012 at 19:23 UTC
The following calls a user supplied routine with a list of ancestors of a node when it encounters a node with the right name in the XML tree. use feature ":5.14"; use warnings FATAL => qw(all); use strict; use Data::Dump qw(dump pp); use XML::Simple; my $x = XMLin(<<'END'); <files name="Common.h"> <enums> <members kind="enum" name="PermissionLevel" protection="public" +static="no" virtualness="non_virtual"> <values initializer=" 99" name="PERMISSION_PUBLIC"></values> <values initializer=" 98" name="PERMISSION_NDA"></values> </members> <members kind="enum" name="RegisterType" protection="public" sta +tic="no" virtualness="non_virtual"> <values initializer=" 4" name="REGISTER_PCI"></values> </members> </enums> <functions> <members const="no" kind="function" name="Compare" protection="p +ublic" static="no" type="bool" virtualness="non_virtual" volatile="no +"> <parameters declaration_name="first" type="T"/> <parameters declaration_name="second" type="T"/> </members> </functions> </files> END pp($x); sub r($$$;$); sub r($$$;$) {my ($r, $l, $e, $a) = @_; $a = [] unless $a; return unless $l and ref($l); if (ref($l) =~ /HASH/) {for(sort keys %$l) {unless (/$e/) {push @$a, $_; r($r, $l->{$_}, $e, $a); pop @$a; } else {&$r(@$a); } } } elsif (ref($l) =~ /ARRAY/) {for(1..@$l) {unless ($l->[$_-1] =~ /$e/) {push @$a, $_; r($r, $l->[$_-1], $e, $a); pop @$a; } else {&$r(@$a); } } } } r sub {say "@_"}, $x, "values"; [download] Produces enums members PermissionLevel enums members RegisterType	[reply] [d/l]
Re^2: getting ancestors of element by jccunning (Acolyte) on Aug 31, 2012 at 15:09 UTC
Thanks for reply. Maybe you can tell me what arguments are implied in sub r($$$;$) Not familiar with that string of special variables. Thanks	[reply]
Re^3: getting ancestors of element by Athanasius (Archbishop) on Aug 31, 2012 at 15:25 UTC
See perlsub. `$` means a scalar value, and A semicolon (`;`) separates mandatory arguments from optional arguments. So, `sub r($$$;$)` means: `r` is a subroutine prototyped to take at least 3, and at most 4, scalar arguments. Hope that helps, Athanasius <°(((>< contra mundum	[reply]
Re^2: getting ancestors of element by jccunning (Acolyte) on Aug 31, 2012 at 17:51 UTC
Does not appear to work on different string, for example if $x is equal to following and search for "parameters": <classes name="Panoply::AttributeDesc"> <all_members name="AttributeDesc" protection="public" scope="Panop +ly::AttributeDesc" virtualness="non_virtual"/> <all_members name="AttributeDesc" protection="public" scope="Panop +ly::AttributeDesc" virtualness="non_virtual"/> <all_members name="description" protection="public" scope="Panoply +::AttributeDesc" virtualness="non_virtual"/> <all_members name="name" protection="public" scope="Panoply::Attri +buteDesc" virtualness="non_virtual"/> <all_members name="value" protection="private" scope="Panoply::Att +ributeDesc" virtualness="non_virtual"/> <public_members> <members kind="variable" name="name" protection="public" static= +"no" type="std::string" virtualness="non_virtual"></members> <members kind="variable" name="value" protection="public" static +="no" type="std::string" virtualness="non_virtual"></members> <members kind="variable" name="description" protection="public" +static="no" type="std::string" virtualness="non_virtual"></members> </public_members> <public_methods> <members const="no" kind="function" name="AttributeDesc" protect +ion="public" static="no" virtualness="non_virtual" volatile="no"> <parameters declaration_name="name" type="const std::string &a +mp;"/> <parameters declaration_name="value" type="const std::string & +amp;"/> <parameters declaration_name="desc" default_value=""&quot +;" type="const std::string &"/> </members> <members const="no" kind="function" name="AttributeDesc" protect +ion="public" static="no" virtualness="non_virtual" volatile="no"></me +mbers> </public_methods> </classes> [download]	[reply] [d/l]
Re^3: getting ancestors of element by philiprbrenan (Monk) on Aug 31, 2012 at 21:24 UTC
XML::Simple folds (by default) on the name= attribute. At lines -3, -8 from the end you have two <members> lines with the same name="AttributeDesc". This fooled XML::Simple into treating the two blocks as the same, allowing the second instance to overwrite the first. By adding KeyAttr=>[] as an option to XMLin, this default behaviour is suppressed and the expected result is obtained. use feature ":5.14"; use warnings FATAL => qw(all); use strict; use Data::Dump qw(dump pp); use XML::Simple; my $x = XMLin(<<'END', KeyAttr=>[]); <classes name="Panoply::AttributeDesc"> <all_members name="AttributeDesc" protection="public" scope="Panop +ly::AttributeDesc" virtualness="non_virtual"/> <all_members name="AttributeDesc" protection="public" scope="Panop +ly::AttributeDesc" virtualness="non_virtual"/> <all_members name="description" protection="public" scope="Panoply +::AttributeDesc" virtualness="non_virtual"/> <all_members name="name" protection="public" scope="Panoply::Attri +buteDesc" virtualness="non_virtual"/> <all_members name="value" protection="private" scope="Panoply::Att +ributeDesc" virtualness="non_virtual"/> <public_members> <members kind="variable" name="name" protection="public" static= +"no" type="std::string" virtualness="non_virtual"></members> <members kind="variable" name="value" protection="public" static +="no" type="std::string" virtualness="non_virtual"></members> <members kind="variable" name="description" protection="public" +static="no" type="std::string" virtualness="non_virtual"></members> </public_members> <public_methods> <members const="no" kind="function" name="AttributeDesc" protect +ion="public" static="no" virtualness="non_virtual" volatile="no"> <parameters declaration_name="name" type="const std::string &a +mp;"/> <parameters declaration_name="value" type="const std::string & +amp;"/> <parameters declaration_name="desc" default_value=""&quot +;" type="const std::string &"/> </members> <members const="no" kind="function" name="AttributeDesc" protect +ion="public" static="no" virtualness="non_virtual" volatile="no"></me +mbers> </public_methods> </classes> END #pp($x); sub r($$$;$); sub r($$$;$) {my ($r, $l, $e, $a) = @_; $a = [] unless $a; return unless $l and ref($l); if (ref($l) =~ /HASH/) {for(sort keys %$l) {unless (/$e/) {push @$a, $_; r($r, $l->{$_}, $e, $a); pop @$a; } else {&$r(@$a); } } } elsif (ref($l) =~ /ARRAY/) {for(1..@$l) {unless ($l->[$_-1] =~ /$e/) {push @$a, $_; r($r, $l->[$_-1], $e, $a); pop @$a; } else {&$r(@$a); } } } } r sub {say "@_"}, $x, "parameters"; [download] Produces public_methods members 1	[reply] [d/l]
Re^4: getting ancestors of element by jccunning (Acolyte) on Sep 08, 2012 at 16:40 UTC
Re^5: getting ancestors of element by philiprbrenan (Monk) on Sep 08, 2012 at 17:12 UTC
Some notes below your chosen depth have not been shown here
Re^4: getting ancestors of element by jccunning (Acolyte) on Sep 12, 2012 at 15:58 UTC
Re: getting ancestors of element by Anonymous Monk on Aug 30, 2012 at 19:46 UTC
I get error cannot locate object method ancestors. When you read XML::Twig where is ancestors documented, which package does it belong to? Try $twig->root->ancestors	[reply]
Re: getting ancestors of element by mertserger (Curate) on Aug 31, 2012 at 09:12 UTC
I would recommend mirod's site http://xmltwig.org/xmltwig/ as he is the author of XML::Twig. I find this section http://xmltwig.org/xmltwig/twig_stable.html particularly useful. I think your code `my @names = $twig->ancestors('values');` has two problems. Firstly it is actually looking for ancestors of the string itself (and there are none). You need to find every tag within the string and find theirancestors. Secondly you have an optional condition on the ancestors: the ('values') bit. This means you would only get ancestors called 'values'. If you want every ancestor, no condition is needed.	[reply] [d/l]