%% start of file `collection.sty'.
%% Copyright 2013-2013 Xavier Danaux (xdanaux@gmail.com).
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License version 1.3c,
% available at http://www.latex-project.org/lppl/.


%-------------------------------------------------------------------------------
%                identification
%-------------------------------------------------------------------------------
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{collection}[2013/03/28 v1.0.0 collections]


%-------------------------------------------------------------------------------
%                requirements
%-------------------------------------------------------------------------------


\RequirePackage{ifthen}


%-------------------------------------------------------------------------------
%                code
%-------------------------------------------------------------------------------

% creates a new collection
% usage: \collectionnew{<collection name>}
\newcommand*{\collectionnew}[1]{%
  \newcounter{collection@#1@count}}

% adds an item to a collection
% usage: \collectionadd[<optional key>]{<collection name>}{<item to add>}
\newcommand*{\collectionadd}[3][]{%
  \expandafter\def\csname collection@#2@item\roman{collection@#2@count}\endcsname{#3}%
  \if\relax\noexpand#1\relax% if #1 is empty
    \else\expandafter\def\csname collection@#2@key\roman{collection@#2@count}\endcsname{#1}\fi%
  \stepcounter{collection@#2@count}}

% returns the number of items in a collection
% usage: \collectioncount{<collection name>}
\newcommand*{\collectioncount}[1]{%
  \value{collection@#1@count}}

% gets an item from a collection
% usage: \collectiongetitem{<collection name>}{<element id>}
% where <element id> is an integer between 0 and (collectioncount-1)
\newcommand*{\collectiongetitem}[2]{%
  \csname collection@#1@item\romannumeral #2\endcsname}

% gets a key from a collection
% usage: \collectiongetkey{<collection name>}{<element id>}
% where <element id> is an integer between 0 and (collectioncount-1)
\newcommand*{\collectiongetkey}[2]{%
  \csname collection@#1@key\romannumeral #2\endcsname}

% loops through a collection and perform the given operation on every element
% usage: \collectionloop{<collection name>}{<operation sequence>}
% where <operation sequence> is the code sequence to be evaluated for each collection item,
%   code which can refer to \collectionloopid, \collectionloopkey, \collectionloopitem and
%   \collectionloopbreak
\newcounter{collection@iterator}
\newcommand*{\collectionloopbreak}{\let\iterate\relax}
\newcommand*{\collectionloop}[2]{%
  \setcounter{collection@iterator}{0}%
  \loop\ifnum\value{collection@iterator}<\value{collection@#1@count}%
    \def\collectionloopid{\arabic{collection@iterator}}%
    \def\collectionloopitem{\collectiongetitem{#1}{\collectionloopid}}%
    \def\collectionloopkey{\collectiongetkey{#1}{\collectionloopid}}%
    #2%
    \stepcounter{collection@iterator}%
    \repeat}

% loops through a collection and finds the (first) element matching the given key
% usage: \collectionfindbykey{<collection name>}{key>}
\newcommand*{\collectionfindbykey}[2]{%
  \collectionloop{#1}{%
    \ifthenelse{\equal{\collectionloopkey}{#2}}{\collectionloopitem\collectionloopbreak}{}}}


\endinput


%% end of file `collection.cls'.