Rewrite the project

The new code is much more readable and easier to extend. I took
inspiration from Haskell's Parsec project which seems to only
write the happy-path and applied the idea to Erlang's exceptions.
When the parser tries to parse, say, a list, and crashes, it
tries with a table next, and so on until something matches.
Normal paragraphs always match so there can be no parsing
failures.

The parser now has a number of passes: first the block parser,
then lists and tables passes to build a proper tree out of
them and finally an inline pass to apply inline formatting.
The resulting AST can then be modified at will and passed on
to translator modules which output a different format.

The man page translator was also rewritten and has been tested
against both Cowboy and Gun. Numerous issues were fixed as a
result of this rewrite.

1 files changed, 112 insertions, 0 deletions

diff --git a/src/asciideck_attributes_pass.erl b/src/asciideck_attributes_pass.erl
new file mode 100644
index 0000000..393b57d
--- /dev/null
+++ b/src/asciideck_attributes_pass.erl
@@ -0,0 +1,112 @@
+%% Copyright (c) 2017-2018, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+%% The purpose of this pass is to apply attributes to
+%% their corresponding blocks. For macros the attributes
+%% are already applied. For inline elements the inline
+%% pass is taking care of it.
+-module(asciideck_attributes_pass).
+
+-export([run/1]).
+
+run([]) ->
+	[];
+%% A block identifier is an alternative way of specifying
+%% the id attribute for a block.
+run([{block_id, #{id := ID}, <<>>, _}|Tail0]) ->
+	Tail = apply_attributes(Tail0, #{<<"id">> => ID}),
+	run(Tail);
+%% A block title is ultimately treated as an attribute
+%% for the following block.
+run([{block_title, _, Title, _}|Tail0]) ->
+	Tail = apply_attributes(Tail0, #{<<"title">> => Title}),
+	run(Tail);
+run([{attribute_list, Attrs, <<>>, _}|Tail0]) ->
+	Tail = apply_attributes(Tail0, Attrs),
+	run(Tail);
+run([Block|Tail]) ->
+	[Block|run(Tail)].
+
+%% Find the next block to apply the attributes.
+apply_attributes([], _) ->
+	[];
+apply_attributes(AST=[Element0={Type, Attrs0, Content, Ann}|Tail], Attrs) ->
+	case can_apply(Type) of
+		drop ->
+			AST;
+		skip ->
+			[Element0|apply_attributes(Tail, Attrs)];
+		apply ->
+			Element = {Type, maps:merge(Attrs0, Attrs), Content, Ann},
+			[Element|Tail]
+	end.
+
+%% Block macros already come with a mandatory attribute list.
+%% Just to play it safe we drop the attributes for now.
+can_apply(block_macro) -> drop;
+%% If we hit a list item continuation, drop the attributes for now.
+can_apply(list_item_continuation) -> drop;
+%% We skip attribute lists and alike and let it sort itself out.
+can_apply(block_id) -> skip;
+can_apply(attribute_list) -> skip;
+can_apply(block_title) -> skip;
+%% Everything else is a block.
+can_apply(_) -> apply.
+
+-ifdef(TEST).
+attribute_list_test() ->
+	AST0 = [
+		{attribute_list, #{
+			0 => <<"width=400">>,
+			<<"width">> => <<"400">>
+		}, <<>>, #{line => 1}},
+		{listing_block, #{}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = [
+		{listing_block, #{
+			0 => <<"width=400">>,
+			<<"width">> => <<"400">>
+		}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = run(AST0),
+	ok.
+
+block_id_test() ->
+	AST0 = [
+		{block_id, #{
+			id => <<"cowboy_req">>
+		}, <<>>, #{line => 1}},
+		{listing_block, #{}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = [
+		{listing_block, #{
+			<<"id">> => <<"cowboy_req">>
+		}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = run(AST0),
+	ok.
+
+block_title_test() ->
+	AST0 = [
+		{block_title, #{}, <<"Title">>, #{line => 1}},
+		{listing_block, #{}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = [
+		{listing_block, #{
+			<<"title">> => <<"Title">>
+		}, <<"Hello!">>, #{line => 2}}
+	],
+	AST = run(AST0),
+	ok.
+-endif.