% --------------------------------------------------------------------------
% the TASKS package
% 
%   Horizontal columned lists.
% 
% --------------------------------------------------------------------------
% Clemens Niederberger
% Web:    https://github.com/cgnieder/tasks/
% E-Mail: contact@mychemistry.eu
% --------------------------------------------------------------------------
% Copyright 2013-2014 Clemens Niederberger
% 
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or (at your option) any later version.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
% 
% This work has the LPPL maintenance status `maintained'.
% 
% The Current Maintainer of this work is Clemens Niederberger.
% --------------------------------------------------------------------------
% If you have any ideas, questions, suggestions or bugs to report, please
% feel free to contact me.
% --------------------------------------------------------------------------
\def\@tasks@date{2014/07/29}
\def\@tasks@version{0.10a}

\RequirePackage { expl3 , xparse , l3keys2e }
\ProvidesExplPackage
  {tasks}
  {\@tasks@date}
  {\@tasks@version}
  {Horizontal columned lists.}

% --------------------------------------------------------------------------
% check expl3 version:
\@ifpackagelater { expl3 } { 2014/01/01 }
  { }
  {
    \PackageError { tasks } { Support~package~expl3~too~old }
      {
        You~need~to~update~your~installation~of~the~bundles~'l3kernel'~and~
        'l3packages'.\MessageBreak
        Loading~tasks~will~abort!
      }
    \tex_endinput:D
  }

% --------------------------------------------------------------------------
% requirements:
\RequirePackage { epic , cntformats , xtemplate , environ }

\msg_new:nnn {tasks} {deprecated-option}
  {
    The~ option~ `#1'~ has~ been~ removed~ from~ the~ `tasks'~ package.~
    Please~ see~ the~ documentation~ for~details.
  }


% --------------------------------------------------------------------------
% variants of kernel functions:
\cs_generate_variant:Nn \tl_if_eq:nnTF { V }
\cs_generate_variant:Nn \tl_if_eq:nnT  { V }

% --------------------------------------------------------------------------
% variables:
\seq_new:N    \l__tasks_seq

\int_new:N    \l__tasks_depth_int
\int_new:N    \g__tasks_int
\int_new:N    \g__tasks_total_items_int
\int_new:N    \l__tasks_columns_int
\int_new:N    \l__tasks_rows_int
\int_new:N    \g__tasks_current_col_num_int
\int_new:N    \g__tasks_current_row_num_int
\int_new:N    \l__tasks_item_columns_int

\bool_new:N   \l__tasks_enumerate_bool
\bool_new:N   \l__tasks_resume_bool
\bool_new:N   \l__tasks_load_tasks_bool
\bool_new:N   \l__tasks_label_width_bool
\bool_new:N   \l__tasks_item_indent_bool
\bool_new:N   \l__tasks_label_offset_bool
\bool_new:N   \l__tasks_custom_label_bool
\bool_new:N   \l__tasks_custom_after_item_skip_bool
\bool_new:N   \l__tasks_debug_bool
\bool_new:N   \l__tasks_item_full_line_bool
\bool_new:N   \l__tasks_item_rest_of_line_bool

\tl_new:N     \l__tasks_instance_tl
\tl_new:N     \l__tasks_label_tl
\tl_new:N     \l__tasks_custom_label_tl
\tl_new:N     \l__tasks_label_pattern_tl
\tl_new:N     \l__tasks_custom_label_pattern_tl
\tl_new:N     \l__tasks_label_format_tl
\tl_new:N     \l__tasks_custom_label_format_tl
\tl_new:N     \l__tasks_item_fill_left_tl
\tl_new:N     \l__tasks_item_fill_right_tl
\tl_new:N     \l__tasks_label_align_tl
% \tl_new:N     \task
\tl_new:N     \l__tasks_item_tl
\tl_new:N     \l__tasks_tmp_label_tl

\dim_new:N    \l__tasks_item_indent_dim
\dim_new:N    \l__tasks_item_default_indent_dim
\dim_new:N    \l__tasks_item_width_dim
\dim_new:N    \l__tasks_label_width_dim
\dim_new:N    \l__tasks_label_default_width_dim
\dim_new:N    \l__tasks_label_offset_dim
\dim_new:N    \l__tasks_label_default_offset_dim
\dim_new:N    \l__tasks_column_sep_dim

\skip_new:N   \l__tasks_after_item_skip
\skip_new:N   \l__tasks_custom_after_item_skip
\skip_new:N   \l__tasks_before_list_skip
\skip_new:N   \l__tasks_after_list_skip

\coffin_new:N \l__tasks_item_coffin
\coffin_new:N \l__tasks_label_coffin

\NewCounterPattern* [ tasks ] { task } { tsk }
\ReadCounterFrom [ tasks ] { task } \g__tasks_int

% temporary variables:
\int_new:N    \l__tasks_tmpa_int
\int_new:N    \l__tasks_tmpb_int
\tl_new:N     \l__tasks_tmpa_tl
\coffin_new:N \l__tasks_tmpa_coffin

\cs_new:Npn \__tasks_debug:n #1
  {
    \bool_if:NTF \l__tasks_debug_bool
      { \fbox {#1} }
      { \use:n {#1} }
  }

% --------------------------------------------------------------------------
% collect the tasks:
\cs_new_protected:Npn \__tasks_collect_tasks:nww #1#2 \end #3
  {
    \tl_put_right:Nn \l__tasks_body_tl { #1 }
    \end { #3 }
    \tl_if_eq:nnF { #1 } { #3 }
      { \__tasks_collect_tasks:nww { #1 } }
  }

%  #1: instance
%  #2: number of columns
%  #3: item separator
%  #4: environment body
\cs_new_protected:Npn \__tasks:nnnn #1#2#3#4
  {
    \bool_if:NT \l__tasks_debug_bool { \dim_set:Nn \fboxsep {0pt} }
    \seq_set_split:Nnn \l__tasks_seq { #3 } { #4 }
    % remove the first (empty) item:
    \seq_pop_left:NN \l__tasks_seq \l__tasks_tmpa_tl
    \tl_if_blank:VF \l__tasks_tmpa_tl { \@noitemerr }
    \int_gset:Nn \g__tasks_total_items_int
      { \seq_count:N \l__tasks_seq }
    \UseInstance { tasks } { #1 }
      { \g__tasks_total_items_int }
      { #2 }
      { \l__tasks_custom_label_pattern_tl }
    % just to be sure:
    \seq_clear:N \l__tasks_seq
  }
\cs_generate_variant:Nn \__tasks:nnnn { VnnV }

% #1: label
% #2: item
\cs_new_protected:Npn \__tasks_task:nn #1#2
  {
    % start a new item line if \l__tasks_item_full_line_bool
    \bool_if:NT \l__tasks_item_full_line_bool
      {
        % add skip if we were in the middle of a line, i.e., in horizontal
        % mode:
        \mode_if_horizontal:T
          { \skip_vertical:N \l__tasks_after_item_skip }
        \tasks_new_row:
      }
    \int_gincr:N \g__tasks_current_col_num_int
    \dim_set:Nn \l__tasks_item_width_dim
      {
        \bool_if:NTF \l__tasks_item_full_line_bool
          { \linewidth }
          {
            (
              \linewidth
              - \l__tasks_columns_int \l__tasks_column_sep_dim
              + \l__tasks_column_sep_dim
            ) / \l__tasks_columns_int
          }
        - \l__tasks_depth_int \l__tasks_item_indent_dim
        \bool_if:NT \l__tasks_debug_bool { -2\fboxrule }
      }
    \__tasks_gset_rows_num:NN
      \g__tasks_total_items_int
      \l__tasks_columns_int
    % set \g__tasks_current_col_num_int to 1 if at the start of a row,
    % the also step \g__tasks_current_row_num_int :
    \int_compare:nNnT { \g__tasks_current_col_num_int } > { \l__tasks_columns_int }
      {
        \int_gset:Nn \g__tasks_current_col_num_int { 1 }
        \int_incr:N \g__tasks_current_row_num_int
      }
    \bool_if:NT \l__tasks_item_rest_of_line_bool
      {
        \int_compare:nNnTF { \l__tasks_item_columns_int } = { 0 }
          {
            \int_set:Nn \l__tasks_tmpa_int
              { \l__tasks_columns_int - \g__tasks_current_col_num_int + 1 }
            \int_set:Nn \l__tasks_tmpb_int { \l__tasks_tmpa_int -1 }
          }
          {
            \int_set:Nn \l__tasks_tmpa_int
              { \l__tasks_columns_int - \g__tasks_current_col_num_int + 1 }
            \int_compare:nNnTF
              { \l__tasks_tmpa_int } > { \l__tasks_item_columns_int }
              { \int_set_eq:NN \l__tasks_tmpa_int \l__tasks_item_columns_int }
              { \int_zero:N \l__tasks_item_columns_int }
            \bool_if:nT
              {
                \l__tasks_item_rest_of_line_bool &&
                !\int_compare_p:nNn { \l__tasks_item_columns_int} = { 0 }
              }
              {
                \int_gadd:Nn \g__tasks_current_col_num_int
                  { \l__tasks_item_columns_int -1 }
                \int_gadd:Nn \g__tasks_total_items_int
                  { \l__tasks_item_columns_int -1 }
              }
            \int_set:Nn \l__tasks_tmpb_int { \l__tasks_tmpa_int -1 }
          }
        \dim_set:Nn \l__tasks_item_width_dim
          {
            \l__tasks_tmpa_int \l__tasks_item_width_dim
            + \l__tasks_tmpb_int \l__tasks_column_sep_dim
            + \l__tasks_tmpb_int \l__tasks_item_indent_dim
            \bool_if:NT \l__tasks_debug_bool
              { + \int_eval:n { \l__tasks_tmpb_int * 2 } \fboxrule }
          }
      }
    % set the item box:
    \hcoffin_set:Nn \l__tasks_item_coffin
      {
        \vcoffin_set:Nnn \l__tasks_tmpa_coffin
          { \l__tasks_item_width_dim }
          { \__tasks_setup: #2 \strut }
        \__tasks_debug:n
          {
            \coffin_typeset:Nnnnn \l__tasks_tmpa_coffin
              { l } { T } { 0pt } { 0pt }
          }
      }
    % set the label box:
    \hcoffin_set:Nn \l__tasks_label_coffin
      {
        \vcoffin_set:Nnn \l__tasks_tmpa_coffin
          {
            \l__tasks_label_width_dim
            \bool_if:NT \l__tasks_debug_bool {-2\fboxrule }
          }
          {
            \noindent
            \tl_use:N \l__tasks_item_fill_left_tl
            \strut #1
            \tl_use:N \l__tasks_item_fill_right_tl
          }
        \__tasks_debug:n
          {
            \coffin_typeset:Nnnnn \l__tasks_tmpa_coffin
              { l } { T } { 0pt } { 0pt }
          }
      }
    % attach the label box at the left of the item box, shifted by
    % \l__tasks_label_offset_dim :
    \coffin_attach:NnnNnnnn
      \l__tasks_item_coffin { l } { T }
      \l__tasks_label_coffin { r } { T }
      { - \l__tasks_label_offset_dim
        % - \l__tasks_label_width_dim - \l__tasks_label_offset_dim
      } { 0pt }
    % when a new row starts enter vertical mode:
    \int_compare:nNnT { \g__tasks_current_col_num_int } = { 1 }
      { \skip_vertical:N \c_zero_skip }
    % skip horizontally by \l__tasks_item_indent_dim
    \noindent
    \skip_horizontal:N \l__tasks_item_indent_dim
    % typeset the item (with the attached label protruding to the left):
    \coffin_typeset:Nnnnn \l__tasks_item_coffin
      { l } { T } { 0pt } { 0pt }
    \bool_if:nT
      {
        \l__tasks_item_full_line_bool ||
        (
          \l__tasks_item_rest_of_line_bool &&
          \int_compare_p:nNn { \l__tasks_item_columns_int } = { 0 }
        )
      }
      { \tasks_new_row: }
    % are we between items in a row? The skip by \l__tasks_column_sep_dim :
    \int_compare:nNnT
      { \g__tasks_current_col_num_int } < { \l__tasks_columns_int }
      { \skip_horizontal:N \l__tasks_column_sep_dim }
    % if we ended a row and a new row is still to come skip vertically by
    % \l__tasks_after_item_skip :
    \bool_if:nT
      {
        ( \int_compare_p:nNn { \g__tasks_current_col_num_int } = { \l__tasks_columns_int } )
        &&
        ( \int_compare_p:n { \g__tasks_current_row_num_int != \l__tasks_rows_int } )
      }
      { \skip_vertical:N \l__tasks_after_item_skip }
    % clean up:
    \coffin_clear:N \l__tasks_item_coffin
    \coffin_clear:N \l__tasks_label_coffin
    \coffin_clear:N \l__tasks_tmpa_coffin
    \bool_set_false:N \l__tasks_item_full_line_bool
    \bool_set_false:N \l__tasks_item_rest_of_line_bool
  }
\cs_generate_variant:Nn \__tasks_task:nn { VV }

\cs_new_protected:Npn \__tasks_setup:
  {
    \dim_set:Nn \parskip { 0pt }
    \skip_set:Nn \parfillskip { 0pt plus 1fil }
    \dim_set_eq:NN \parskip \parsep
    \dim_set_eq:NN \parindent \listparindent
    \noindent
    \strut
  }

\cs_new_protected:Npn \__tasks_gset_rows_num:NN #1#2
  {
    \int_gset:Nn \l__tasks_rows_int { \int_div_truncate:nn { #1 } { #2 } }
    \int_compare:nNnT { \int_mod:nn { #1 } { #2 } } > { 0 }
      { \int_gincr:N \l__tasks_rows_int }
  }

\cs_new_protected:Npn \__tasks_label_align:n #1
  {
    \clist_if_in:nnTF { left , center , right } { #1 }
      {
        \tl_if_eq:nnT { #1 } { left }
          {
            \tl_clear:N   \l__tasks_item_fill_left_tl
            \tl_set_eq:NN \l__tasks_item_fill_right_tl \hfill
          }
        \tl_if_eq:nnT { #1 } { right }
          {
            \tl_set_eq:NN \l__tasks_item_fill_left_tl \hfill
            \tl_clear:N   \l__tasks_item_fill_right_tl
          }
        \tl_if_eq:nnT { #1 } { center }
          {
            \tl_set_eq:NN \l__tasks_item_fill_left_tl  \hfill
            \tl_set_eq:NN \l__tasks_item_fill_right_tl \hfill
          }
      }
      {
        \tl_clear:N   \l__tasks_item_fill_left_tl
        \tl_set_eq:NN \l__tasks_item_fill_right_tl \hfill
      }
  }
\cs_generate_variant:Nn \__tasks_label_align:n { V }
\__tasks_label_align:n { left }

% --------------------------------------------------------------------------
% the `tasks' object:
%   #1: number of items
%   #2: number of columns
%   #3: label-format
\DeclareObjectType { tasks } { 3 }
% the `default' template interface:
\DeclareTemplateInterface { tasks } { default } { 3 }
  {
    enumerate       : boolean   = true    ,
    label           : tokenlist           ,
    indent          : length    = 2.5em   ,
    counter-format  : tokenlist = tsk[a]) ,
    label-format    : tokenlist ,
    label-width     : length    = 1em     ,
    label-offset    : length    = .3333em ,
    after-item-skip : skip      = 1ex plus 1ex minus 1ex
  }

% in the next three commands we want a really unlikely to occur marker; for
% this we use $ with unusual catcode in ``$tasks$default$label$'':
\cs_set:Nx \__tasks_restore_dollar:
  { \char_set_catcode:nn {36} { \char_value_catcode:n {36} } }
\char_set_catcode_alignment:N \$

% the `default' template code:
\DeclareTemplateCode { tasks } { default } { 3 }
  {
    enumerate       = \l__tasks_enumerate_bool           ,
    label           = \l__tasks_label_tl                 ,
    indent          = \l__tasks_item_default_indent_dim  ,
    counter-format  = \l__tasks_label_pattern_tl         ,
    label-format    = \l__tasks_label_format_tl          ,
    label-width     = \l__tasks_label_default_width_dim  ,
    label-offset    = \l__tasks_label_default_offset_dim ,
    after-item-skip = \l__tasks_after_item_skip
  }
  {
    \AssignTemplateKeys
    \bool_if:NF \l__tasks_label_width_bool
      {
        \dim_set_eq:NN
          \l__tasks_label_width_dim
          \l__tasks_label_default_width_dim
      }
    \bool_if:NF \l__tasks_item_indent_bool
      {
        \dim_set_eq:NN
          \l__tasks_item_indent_dim
          \l__tasks_item_default_indent_dim
      }
    \bool_if:NF \l__tasks_label_offset_bool
      {
        \dim_set_eq:NN
          \l__tasks_label_offset_dim
          \l__tasks_label_default_offset_dim
      }
    \dim_compare:nNnT
      { \l__tasks_item_indent_dim }
       <
      { \l__tasks_label_offset_dim + \l__tasks_label_width_dim }
      {
        \dim_set:Nn \l__tasks_item_indent_dim
          { \l__tasks_label_offset_dim + \l__tasks_label_width_dim }
      }
    \bool_if:NT \l__tasks_custom_after_item_skip_bool
      {
        \skip_set_eq:NN
          \l__tasks_after_item_skip
          \l__tasks_custom_after_item_skip
      }
    \bool_if:NT \l__tasks_custom_label_bool
      {
        \tl_set_eq:NN
          \l__tasks_label_tl
          \l__tasks_custom_label_tl
        \bool_set_false:N \l__tasks_enumerate_bool
      }
    \__tasks_label_align:V \l__tasks_label_align_tl
    % need this for enumerate list:
    \bool_if:nT { !\l__tasks_resume_bool && \l__tasks_enumerate_bool }
      { \int_gzero:N \g__tasks_int }
    \int_set:Nn \l__tasks_columns_int { #2 }
    % set all the items in their own coffins and join with the ground:
    \int_gzero:N \g__tasks_current_col_num_int
    \int_set:Nn \g__tasks_current_row_num_int { 1 }
    \tl_if_blank:VF \l__tasks_custom_label_pattern_tl
      {
        \tl_set_eq:NN
          \l__tasks_label_pattern_tl
          \l__tasks_custom_label_pattern_tl
      }
    \tl_if_blank:VF \l__tasks_custom_label_format_tl
      {
        \tl_set_eq:NN
          \l__tasks_label_format_tl
          \l__tasks_custom_label_format_tl
      }
    \seq_map_inline:Nn \l__tasks_seq
      {
        \__tasks_read_item:www ##1 \q_stop
        \bool_if:NTF \l__tasks_enumerate_bool
          {
            \tl_if_eq:VnT \l__tasks_tmp_label_tl { $tasks$default$label$ }
              {
                \int_gincr:N \g__tasks_int
                \SaveCounterPatternFrom [ tasks ]
                  \l__tasks_tmpa_tl
                  \l__tasks_label_tl
                  \l__tasks_label_pattern_tl
                \cs_gset:Npx \@currentlabel { \l__tasks_label_tl }
              }
          }
          {
            \tl_if_blank:VT \l__tasks_label_tl
              { \tl_set_eq:NN \l__tasks_label_tl \labelitemi }
          }
        \tl_put_left:NV \l__tasks_label_tl \l__tasks_label_format_tl
        \tl_if_eq:VnTF \l__tasks_tmp_label_tl { $tasks$default$label$ }
          {
            \__tasks_task:VV
              \l__tasks_label_tl
              \l__tasks_item_tl
          }
          {
            \__tasks_task:VV
              \l__tasks_tmp_label_tl
              \l__tasks_item_tl
            \tl_clear:N \l__tasks_tmp_label_tl
          }
      }
  }

\cs_new_protected:Npn \__tasks_read_item:www
  {
    \peek_meaning_remove:NTF !
      {
        \bool_set_true:N \l__tasks_item_full_line_bool
        \__tasks_read_item_aux:ww
      }
      {
        \peek_meaning_remove:NTF *
          {
            \bool_set_true:N \l__tasks_item_rest_of_line_bool
            \__tasks_read_item_rest_of_line:ww
          }
          { \__tasks_read_item_aux:ww }
      }
  }

\cs_new_protected:Npn \__tasks_read_item_rest_of_line:ww
  {
    \peek_meaning:NTF ( % )
      { \__tasks_read_item_rest_of_line_aux:ww }
      { \__tasks_read_item_rest_of_line_aux:ww (0) }
  }

\cs_new_protected:Npn \__tasks_read_item_rest_of_line_aux:ww (#1)
  {
    \int_set:Nn \l__tasks_item_columns_int {#1}
    \__tasks_read_item_aux:ww
  }

\cs_new_protected:Npn \__tasks_read_item_aux:ww
  {
    \peek_meaning:NTF [ % ]
      { \__tasks_read_item_aux_ii:ww }
      { \__tasks_read_item_aux_ii:ww [$tasks$default$label$] }
  }

\cs_new_protected:Npn \__tasks_read_item_aux_ii:ww [#1]#2 \q_stop
  {
    \tl_set:Nn \l__tasks_tmp_label_tl { #1 }
    \tl_if_eq:nnF { #1 } { $tasks$default$label$ }
      { \tl_put_left:NV \l__tasks_tmp_label_tl \l__tasks_label_format_tl }
    \tl_set:Nn \l__tasks_item_tl { \ignorespaces #2 }
  }

\__tasks_restore_dollar:

% --------------------------------------------------------------------------
% choice box:
\bool_new:N \l__tasks_choice_checked_bool
\dim_new:N  \l__tasks_choice_width_dim
\dim_set:Nn \l__tasks_choice_width_dim { 1.25ex }
\dim_new:N  \l__tasks_choice_linewidth_dim
\dim_set:Nn \l__tasks_choice_linewidth_dim { .3pt }
\dim_new:N  \l__tasks_choice_checkwidth_dim
\dim_set:Nn \l__tasks_choice_checkwidth_dim { .5pt }
\dim_new:N  \l__tasks_choice_raise_dim
\dim_set:Nn \l__tasks_choice_raise_dim { .1ex }

\cs_new_protected:Npn \tasks_choice:
  {
    \leavevmode
    \group_begin:
      \bool_set_false:N \l__tasks_choice_checked_bool
      \box_move_up:nn
        { \l__tasks_choice_raise_dim }
        { \hbox:n { \__tasks_choice: } }
    \group_end:
  }

\cs_new_protected:Npn \tasks_choice_checked:
  {
    \leavevmode
    \group_begin:
      \bool_set_true:N \l__tasks_choice_checked_bool
      \box_move_up:nn
        { \l__tasks_choice_raise_dim }
        { \hbox:n { \__tasks_choice: } }
    \group_end:
  }

\cs_new_protected:Npn \__tasks_choice:
  {%
    \dim_set:Nn \unitlength { .1\l__tasks_choice_width_dim }
    \begin{picture}(10,0)
      \linethickness \l__tasks_choice_linewidth_dim
      \drawline(0,0)(0,10)(10,10)(10,0)(0,0)
      \linethickness \l__tasks_choice_checkwidth_dim
      \bool_if:NT \l__tasks_choice_checked_bool
        {
          \drawline(2,2)(8,8)
          \drawline(2,8)(8,2)
        }
    \end{picture}%
  }

\providecommand* \choicebox { \tasks_choice: }
\providecommand* \checkedchoicebox { \tasks_choice_checked: }

% --------------------------------------------------------------------------
% base instance:
% ALPHABETIZE: a) b) c)
\DeclareInstance { tasks } { alphabetize } { default } { }

\keys_define:nn { tasks / list }
  {
    debug           .bool_set:N = \l__tasks_debug_bool ,
    style           .tl_set:N   = \l__tasks_instance_tl ,
    counter-format  .tl_set:N   = \l__tasks_custom_label_pattern_tl ,
    label           .code:n     =
      \bool_set_true:N \l__tasks_custom_label_bool
      \tl_set:Nn \l__tasks_custom_label_tl { #1 } ,
    label-format    .tl_set:N   = \l__tasks_custom_label_format_tl ,
    label-width     .code:n     =
      \dim_set:Nn \l__tasks_label_width_dim { #1 }
      \bool_set_true:N \l__tasks_label_width_bool ,
    label-offset    .code:n     =
      \dim_set:Nn \l__tasks_label_offset_dim { #1 }
      \bool_set_true:N \l__tasks_label_offset_bool ,
    label-align     .tl_set:N   = \l__tasks_label_align_tl ,
    item-indent     .code:n     =
      \dim_set:Nn \l__tasks_item_indent_dim { #1 }
      \bool_set_true:N \l__tasks_item_indent_bool ,
    column-sep      .dim_set:N  = \l__tasks_column_sep_dim ,
    before-skip     .skip_set:N = \l__tasks_before_list_skip ,
    after-skip      .skip_set:N = \l__tasks_after_list_skip ,
    after-item-skip .code:n     =
      \bool_set_true:N \l__tasks_custom_after_item_skip_bool
      \skip_set:Nn \l__tasks_custom_after_item_skip { #1 } ,
    resume          .bool_set:N = \l__tasks_resume_bool
  }

% --------------------------------------------------------------------------
% the generic environment:
\NewEnviron { __tasks_env: } [ 3 ]
  {
    \keys_set:nn { tasks / list } { #2 }
    \tl_if_blank:VT \l__tasks_instance_tl
      { \keys_set:nn { tasks / list } { style = alphabetize } }
    \vspace {\l__tasks_before_list_skip}
    \list {}
      {
        \dim_set:Nn \leftmargin { 0pt }
        \dim_set:Nn \rightmargin { 0pt }
      }
    \item \scan_stop:
    \int_incr:N \l__tasks_depth_int
    \__tasks:VnnV \l__tasks_instance_tl { #3 } { #1 } \BODY
    \endlist
    \vspace {\l__tasks_after_list_skip}
  }

% --------------------------------------------------------------------------
% command to start a new row:
\cs_new_protected:Npn \tasks_new_row:
  {
    \int_gset:Nn \g__tasks_total_items_int
      { \g__tasks_total_items_int + \l__tasks_columns_int - \g__tasks_current_col_num_int }
    \__tasks_gset_rows_num:NN
      \g__tasks_total_items_int
      \l__tasks_columns_int
    \int_gset_eq:NN \g__tasks_current_col_num_int \l__tasks_columns_int
  }

\NewDocumentCommand \startnewitemline {}
  { \tasks_new_row: }

% --------------------------------------------------------------------------
% the user environment:
\NewDocumentCommand \NewTasks { O{}mO{\task}D(){1} }
  {
    \NewDocumentEnvironment { #2 } { O{}D(){#4} }
      { \__tasks_env: { #3 } { #1,##1 } { ##2 } }
      { \end__tasks_env: }
  }

\NewDocumentCommand \RenewTasks { O{}mO{\task}D(){1} }
  {
    \RenewDocumentEnvironment { #2 } { O{}D(){#4} }
      { \__tasks_env: { #3 } { #1,##1 } { ##2 } }
      { \end__tasks_env: }
  }

% --------------------------------------------------------------------------
% default list:
\NewTasks { tasks }

% --------------------------------------------------------------------------
% package options:
\keys_define:nn { tasks / options }
  {
    more .code:n = \msg_warning:nnn {tasks} {deprecated-option} {more}
  }

\ProcessKeysOptions { tasks / options }

\cs_if_exist:NF \tasks_config_file_loaded:
  { \file_input:n { tasks.cfg } }

% --------------------------------------------------------------------------
% setup:
\cs_new_protected:Npn \tasks_setup:n #1
  { \keys_set:nn { tasks / list } { #1 } }

\NewDocumentCommand \settasks { m }
  { \tasks_setup:n { #1 } }

% --------------------------------------------------------------------------
\tex_endinput:D

% HISTORY:
2013/01/19 v0.7   - extracted from `exsheets' package; this also lead to a
                    slightly new syntax and a few new options for it
2013/04/04 v0.8a  - corrected \seq_length:N => \seq_count:N
2013/04/07 v0.9   - protected internal commands where appropriate
                  - made enumerated item referenceable with \label{}
                    and \ref{}; this introduced new options:
                     * the former `label-format' is now `counter-format'
                     * new: `label-format'
                  - changed defaults for `label-width' and `label-offset'
                  - ensure that the `after-item-skip' is only
                          inserted in between rows
                  - new option `after-item-skip'
                  - improvements when label are set with optional argument:
                     * a provided but empty argument is now correctly recognized
                     * the counter is  _not_ stepped anymore for enumerated
                       lists when the optional argument is provided
                  - new command \startnewitemline that forces the next item to
                    be put at the beginning of a row
2013/04/22 v0.9a  - new option `item-indent'
                  - synchronized version number with `exsheets' until now but
                    won't any more
2013/12/03 v0.9b  - add missing \noindent for the case when \listparindent is
                    non-zero, fixes http://tex.stackexchange.com/q/148082/5049
2014/05/11 v0.9c  - remove definition of the \task macro: it is not necessary
                    for `tasks' to function but it conflicts e.g. with `ltxdoc'
                    class
2014/07/20 v0.10  - new option `debug'
                  - new option `column-sep
                  - renamed a few internal variables
                  - remove package from the `exsheets' bundle and distribute
                    it as package of its own
                  - new: optional bang to a \task forces an item to use a full
                    line (\task!)
                  - new: optional star to a \task forces an item to use the
                    complete remaining line (\task*); the star has itself has
                    an optional argument for specifying the number of columns
                    to span (\task*(<num>))
2014/07/29 v0.10a - bug-fix: correct typo in option definition of `column-sep'
                  - insert before/after skip with \vspace*
                  - remove unnecessary (and unused) arguments of
                    \__tasks_task:nn
                  - add \strut to the end of an item