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diff --git a/src/asciideck_lists_pass.erl b/src/asciideck_lists_pass.erl
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+++ b/src/asciideck_lists_pass.erl
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+%% 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 aggregate list_item
+%% blocks into proper lists. This involves building a
+%% tree based on the rules for list items.
+%%
+%% The general rules are:
+%%
+%% - Any list item of different type/level than the
+%%   current list item is a child of the latter.
+%%
+%% - The level ultimately does not matter when building
+%%   the tree, * then **** then ** is accepted just fine.
+%%
+%% - Lists of the same type as a parent are not allowed.
+%%   On the other hand reusing a type in different parts
+%%   of the tree is not a problem.
+%%
+%% - Any literal paragraph following a list item is a
+%%   child of that list item. @todo
+%%
+%% - Any other block can be included as a child by using
+%%   list continuations.
+-module(asciideck_lists_pass).
+
+-export([run/1]).
+
+run(AST) ->
+	list(AST, []).
+
+list([], Acc) ->
+	lists:reverse(Acc);
+%% Any trailing block continuation is ignored.
+list([{list_item_continuation, _, _, _}], Acc) ->
+	lists:reverse(Acc);
+%% The first list item contains the attributes for the list.
+list([LI={list_item, Attrs, _, Ann}|Tail0], Acc) ->
+	{Items, Tail} = item(Tail0, LI, [type(Attrs)], []),
+	list(Tail, [{list, Attrs, Items, Ann}|Acc]);
+list([Block|Tail], Acc) ->
+	list(Tail, [Block|Acc]).
+
+%% Bulleted/numbered list item of the same type.
+item([NextLI={list_item, #{type := T, level := L}, _, _}|Tail],
+		CurrentLI={list_item, #{type := T, level := L}, _, _}, Parents, Acc) ->
+	item(Tail, NextLI, Parents, [reverse_children(CurrentLI)|Acc]);
+%% Labeled list item of the same type.
+item([NextLI={list_item, #{type := T, separator := S}, _, _}|Tail],
+		CurrentLI={list_item, #{type := T, separator := S}, _, _}, Parents, Acc) ->
+	item(Tail, NextLI, Parents, [reverse_children(CurrentLI)|Acc]);
+%% Other list items are either parent or children lists.
+item(FullTail=[NextLI={list_item, Attrs, _, Ann}|Tail0], CurrentLI, Parents, Acc) ->
+	case lists:member(type(Attrs), Parents) of
+		%% We have a parent list item. This is the end of this child list.
+		true ->
+			{lists:reverse([reverse_children(CurrentLI)|Acc]), FullTail};
+		%% We have a child list item. This is the beginning of a new list.
+		false ->
+			{Items, Tail} = item(Tail0, NextLI, [type(Attrs)|Parents], []),
+			item(Tail, add_child(CurrentLI, {list, Attrs, Items, Ann}), Parents, Acc)
+	end;
+%% Ignore multiple contiguous list continuations.
+item([LIC={list_item_continuation, _, _, _},
+		{list_item_continuation, _, _, _}|Tail], CurrentLI, Parents, Acc) ->
+	item([LIC|Tail], CurrentLI, Parents, Acc);
+%% Blocks that immediately follow list_item_continuation are children,
+%% unless they are list_item themselves in which case it depends on the
+%% type and level of the list item.
+item([{list_item_continuation, _, _, _}, LI={list_item, _, _, _}|Tail], CurrentLI, Parents, Acc) ->
+	item([LI|Tail], CurrentLI, Parents, Acc);
+item([{list_item_continuation, _, _, _}, Block|Tail], CurrentLI, Parents, Acc) ->
+	item(Tail, add_child(CurrentLI, Block), Parents, Acc);
+%% Anything else is the end of the list.
+item(Tail, CurrentLI, _, Acc) ->
+	{lists:reverse([reverse_children(CurrentLI)|Acc]), Tail}.
+
+type(Attrs) ->
+	maps:with([type, level, separator], Attrs).
+
+add_child({list_item, Attrs, Children, Ann}, Child) ->
+	{list_item, Attrs, [Child|Children], Ann}.
+
+reverse_children({list_item, Attrs, Children, Ann}) ->
+	{list_item, Attrs, lists:reverse(Children), Ann}.
+
+-ifdef(TEST).
+list_test() ->
+	[{list, #{type := bulleted, level := 1}, [
+		{list_item, #{type := bulleted, level := 1},
+			[{paragraph, #{}, <<"Hello!">>, _}], #{line := 1}},
+		{list_item, #{type := bulleted, level := 1},
+			[{paragraph, #{}, <<"World!">>, _}], #{line := 2}}
+	], #{line := 1}}] = run([
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"Hello!">>, #{line => 1}}], #{line => 1}},
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"World!">>, #{line => 2}}], #{line => 2}}
+	]),
+	ok.
+
+list_of_list_test() ->
+	[{list, #{type := bulleted, level := 1}, [
+		{list_item, #{type := bulleted, level := 1}, [
+			{paragraph, #{}, <<"Hello!">>, _},
+			{list, #{type := bulleted, level := 2}, [
+				{list_item, #{type := bulleted, level := 2},
+					[{paragraph, #{}, <<"Cat!">>, _}], #{line := 2}},
+				{list_item, #{type := bulleted, level := 2},
+					[{paragraph, #{}, <<"Dog!">>, _}], #{line := 3}}
+			], #{line := 2}}
+		], #{line := 1}},
+		{list_item, #{type := bulleted, level := 1},
+			[{paragraph, #{}, <<"World!">>, _}], #{line := 4}}
+	], #{line := 1}}] = run([
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"Hello!">>, #{line => 1}}], #{line => 1}},
+		{list_item, #{type => bulleted, level => 2},
+			[{paragraph, #{}, <<"Cat!">>, #{line => 2}}], #{line => 2}},
+		{list_item, #{type => bulleted, level => 2},
+			[{paragraph, #{}, <<"Dog!">>, #{line => 3}}], #{line => 3}},
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"World!">>, #{line => 4}}], #{line => 4}}
+	]),
+	ok.
+
+list_continuation_test() ->
+	[{list, #{type := bulleted, level := 1}, [
+		{list_item, #{type := bulleted, level := 1}, [
+			{paragraph, #{}, <<"Hello!">>, _},
+			{listing_block, #{}, <<"hello() -> world.">>, #{line := 3}}
+		], #{line := 1}},
+		{list_item, #{type := bulleted, level := 1},
+			[{paragraph, #{}, <<"World!">>, _}], #{line := 6}}
+	], #{line := 1}}] = run([
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"Hello!">>, #{line => 1}}], #{line => 1}},
+		{list_item_continuation, #{}, <<>>, #{line => 2}},
+		{listing_block, #{}, <<"hello() -> world.">>, #{line => 3}},
+		{list_item, #{type => bulleted, level => 1},
+			[{paragraph, #{}, <<"World!">>, #{line => 6}}], #{line => 6}}
+	]),
+	ok.
+-endif.