Week 2 - Assignment - Erlang Course

index.erl

-module(index).
-export([get_dickens/0,get_gettysburg/0]).

% Used to read a file into a list of lines.
% Example files available in:
%   gettysburg-address.txt (short)
%   dickens-christmas.txt  (long)
  

% Get the contents of a text file into a list of lines.
% Each line has its trailing newline removed.

get_file_contents(Name) ->
    {ok,File} = file:open(Name,[read]),
    Rev = get_all_lines(File,[]),
lists:reverse(Rev).

% Auxiliary function for get_file_contents.
% Not exported.

get_all_lines(File,Partial) ->
    case io:get_line(File,"") of
        eof -> file:close(File),
               Partial;
        Line -> {Strip,_} = lists:split(length(Line)-1,Line),
                get_all_lines(File,[Strip|Partial])
    end.

% Show the contents of a list of strings.
% Can be used to check the results of calling get_file_contents.

show_file_contents([L|Ls]) ->
    io:format("~s~n",[L]),
    show_file_contents(Ls);
 show_file_contents([]) ->
    ok.    
     
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Rearrange the list of elements into the way asked: { "foo" , [{3,5},{7,7},{11,13}] }
rearrange( [X | Xs] ) -> rearrange( Xs, X, X, [] ).

rearrange( [], First, Last, Acc) ->
    [{ element(1, First), element(2, First), element(2, Last)}, Acc];

rearrange([X | Xs ], First, Last, Acc) ->
    case element(1,X) == element(1, First) of
        true ->
            case element(2,X) == element(2,Last) + 1 of
                true -> rearrange( Xs, First, X, Acc);
                false -> rearrange( Xs, X, X, Acc ++ [{element(2, First), element(2, Last)}])
            end;

        false ->
            [{ element(1, First), Acc ++ [{element(2, First), element(2, Last)}] }] ++ rearrange( Xs, X, X, [])
    end.

% Create a list with all words and the line that it belongs.
indexator(Lines) -> indexator(Lines, 1).

indexator([], _Pos) -> [];
indexator([X | Xs ], Pos) ->
  word_per_line(split_words(X), Pos) ++ indexator(Xs, Pos+1).

% Transform the line in a list of words.
word_per_line( [], _Pos) -> [];
word_per_line( [ X | Xs ], Pos) ->
    [ {X, Pos} | word_per_line( Xs, Pos)].


% Split the words of a string.
split_words(Str) ->
    remove_short_words(string:tokens(trans(Str), " "), 3).


% Remove the caps and punctuations
trans([]) -> [];
trans([X|Xs]) ->
    case lists:member(X, "()!@#$%*_-+='`[{]}^\~?<>.,;:\t\n\'\"") of
        true -> trans(Xs);
        false -> [ nocap(X) | trans(Xs) ]
    end.

% The same as string:to_lower(str)
nocap(X) ->
    case $A =< X andalso X =< $Z of
        true ->
            X + 32;
        false ->
            X
    end.

% Remove the words that is less than "Length"
remove_short_words([], _Length) -> [];
remove_short_words([X|Xs], Length) ->
    case string:len(X) < Length of
        true -> remove_short_words(Xs, Length);
        false -> [X | remove_short_words(Xs, Length)]
    end.

% Run all the fuctions in the order (I miss |> from Elixir :( )
get_list(File) -> 
    rearrange(lists:sort(indexator(get_file_contents(File)))).


get_dickens() -> get_list("dickens-christmas.txt").
get_gettysburg() -> get_list("gettysburg-address.txt").