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+package Tree::Template::Declare;
+use strict;
+use warnings;
+use Sub::Exporter;
+use Devel::Caller 'caller_args';
+use Carp;
+use Data::Dumper;
+use 5.006;
+
+our $VERSION='0.6';
+
+{
+my $exporter=Sub::Exporter::build_exporter({
+    groups => {
+        default => \&_build_group,
+    },
+});
+
+sub import {
+    my ($pack,@rest)=@_;
+
+    if (@rest) {
+        @_=($pack,-default => {@rest});
+    }
+    goto $exporter;
+}
+}
+
+our @nodes_stack;
+
+sub _build_group {
+    my ($class,$name,$args,$coll)=@_;
+
+    my $builder=$args->{builder};
+
+    if (! ref $builder) {
+        my $builder_pkg=$builder;
+        if ($builder_pkg=~m{\A [+](\w+) \z}smx) {
+            $builder_pkg="Tree::Template::Declare::$1";
+        }
+        eval "require $builder_pkg" ## no critic (ProhibitStringyEval)
+            or croak "Can't load $builder_pkg: $@"; ## no critic (ProhibitPunctuationVars)
+
+        if ($builder_pkg->can('new')) {
+            $builder=$builder_pkg->new();
+        }
+        else {
+            $builder=$builder_pkg;
+        }
+    }
+
+    my $normal_exports= {
+        tree => sub(&) {
+            my $tree=$builder->new_tree();
+
+            unshift @nodes_stack,$tree;
+            $_[0]->(caller_args(1));
+            shift @nodes_stack;
+
+            return $builder->finalize_tree($tree);
+        },
+        node => sub (&) {
+            my $node=$builder->new_node();
+
+            unshift @nodes_stack, $node;
+            $_[0]->(caller_args(1));
+            shift @nodes_stack;
+
+            my $scalar_context=defined wantarray && !wantarray;
+            if (@nodes_stack && !$scalar_context) {
+                $builder->add_child_node($nodes_stack[0],$node);
+            }
+            return $node;
+        },
+        attach_nodes => sub {
+            if (@nodes_stack) {
+                for my $newnode (@_) {
+                    $builder->add_child_node($nodes_stack[0],
+                                             $newnode);
+                }
+            }
+        },
+        name => sub ($) {
+            $builder->set_node_name($nodes_stack[0],$_[0]);
+            return;
+        },
+        attribs => sub {
+            my %attrs=@_;
+            $builder->set_node_attributes($nodes_stack[0],\%attrs);
+            return;
+        },
+        detached => sub($) { return scalar $_[0] },
+    };
+    if ($builder->can('_munge_exports')) {
+        return $builder->_munge_exports($normal_exports,\@nodes_stack);
+    }
+    else {
+        return $normal_exports;
+    }
+}
+
+1;
+__END__
+
+=head1 NAME
+
+Tree::Template::Declare - easily build tree structures
+
+=head1 SYNOPSIS
+
+ use Tree::Template::Declare builder => '+DAG_Node';
+
+ my $tree=tree {
+     node {
+         name 'root';
+         attribs name => 'none';
+         node {
+             name 'first';
+             attribs name => 'number_1';
+             attribs other => 'some';
+         };
+         node {
+             name 'second';
+         };
+     };
+ };
+
+=head1 FUNCTIONS
+
+For details on the implementation of these functions, see the
+L</BUILDER> section, and the documentation of your chosen builder.
+
+=head2 C<tree>
+
+This function takes a code ref or a block, inside which calls to
+C<node> should be made, and returns a properly constructed tree
+containing those nodes.
+
+Uses the builder's C<new_tree> and C<finalize_tree>.
+
+=head2 C<node>
+
+This function takes a code ref or a block, inside which calls to
+C<name>, C<attribs>, and C<node> should be made, and returns the node.
+
+If I<not> called in scalar context, it also adds the node to the
+"calling" node or tree.
+
+Uses the builder's C<new_node> and C<add_child_node>.
+
+=head2 C<detached>
+
+Alias for C<scalar>, so that you can say C<return detached node ...>
+without having to worry about the calling context.
+
+=head2 C<attach_nodes>
+
+This function takes a list of nodes, and adds them (in order) to the
+"calling" node or tree. You should only use this with nodes you
+obtained by calling C<node> in scalar context.
+
+Uses the builder's C<add_child_node>.
+
+=head2 C<name>
+
+This function takes a scalar, and sets the name of the current node to
+the value of that scalar.
+
+Uses the builder's C<set_node_name>.
+
+=head2 C<attribs>
+
+This function takes a hash (not a hash ref), and sets the attributes
+of the current node.
+
+Uses the builder's C<set_node_attributes>.
+
+=head1 BUILDER
+
+To actually create nodes and trees, this module uses helper classes
+called "builders". You must always specify a builder package, class or
+object with the C<builder> option in the C<use> line.
+
+If the builder is an object, the methods discussed below will be
+called on it; if it's a class (i.e. a package that has a C<new>
+function), they will be called on an instance created by calling
+C<new> without parameters; otherwise they will be called as class
+methods.
+
+The builder must implement these methods:
+
+=over
+
+=item C<new_tree>
+
+ $tree = $current_node = $builder->new_tree();
+
+returns a tree object; that object will be set as the current node
+within the code passed to the C<tree> function
+
+=item C<finalize_tree>
+
+  return $builder->finalize_tree($tree);
+
+this function will be passed the object returned by C<new_tree>, after
+the code passed to C<tree> has been executed; the result of
+C<finalize_tree> will be the result of C<tree>
+
+=item C<new_node>
+
+  $current_node=$builder->new_node();
+
+returns a new, unattached node
+
+=item C<set_node_name>
+
+  $builder->set_node_name($current_node, $name);
+
+sets the name of the node (e.g. for SGML-like trees, this is the "tag
+name")
+
+=item C<set_node_attributes>
+
+  $builder->set_node_attributes($current_node, \%attribs);
+
+sets attributes of the node; it should not remove previously-set attributes
+
+=item C<add_child_node>
+
+  $builder->add_child_node($parent_node, $child_node);
+
+adds the second node at the end of the children list of the first node
+
+=back
+
+The builder can also implement an C<_munge_exports> method. If it
+does, C<_munge_exports> will be called with:
+
+=over 4
+
+=item *
+
+a hash ref consisting of the functions that C<Tree::Template::Declare>
+wants to export,
+
+=item *
+
+an array ref, whose first element will be the current node whenever
+the user calls an exported function
+
+=back
+
+C<_munge_exports> should return a hash ref with the functions that
+will actually be exported.
+
+See L<Sub::Exporter>, in particular the section on group builders, for
+details. See L<Tree::Template::Declare::HTML_Element> and
+L<Tree::Template::Declare::LibXML> for examples.
+
+=head1 IMPORTING
+
+This module uses L<Sub::Exporter>, although it munges the C<use> list
+before passing it to L<Sub::Exporter>. A line like:
+
+ use Tree::Template::Declare @something;
+
+becomes a call to L<Sub::Exporter>'s export sub like:
+
+ $export->('Tree::Template::Declare',-default => {@something});
+
+See L<Sub::Exporter>'s documentation for things like renaming the
+imports.
+
+You can C<use> this module more than once, with different builders and
+different names for the imports:
+
+ use Tree::Template::Declare -prefix=> 'x', builder => '+LibXML';
+ use Tree::Template::Declare -prefix=> 'd', builder => '+DAG_Node';
+
+=head1 KNOWN ISSUES & BUGS
+
+=over 4
+
+=item *
+
+C<_munge_exports> is ugly
+
+=item *
+
+the context-sensitivity of C<node> might not be the best way to DWIM
+for the creation of detached nodes
+
+=back
+
+=head1 AUTHOR
+
+Gianni Ceccarelli <dakkar@thenautilus.net>
+
+=cut