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%% Handle code related to args, guard and -> matching for case,
%% fn, receive and friends. try is handled in elixir_erl_try.
-module(elixir_erl_clauses).
-export([match/4, clause/6, clauses/2, guards/4, get_clauses/3]).
-include("elixir.hrl").
%% Get clauses under the given key.
get_clauses(Key, Keyword, As) ->
case lists:keyfind(Key, 1, Keyword) of
{Key, Clauses} when is_list(Clauses) ->
[{As, Meta, Left, Right} || {'->', Meta, [Left, Right]} <- Clauses];
_ ->
[]
end.
%% Translate matches
match(Ann, Fun, Match, #elixir_erl{context=Context} = S) when Context =/= match ->
{Result, NewS} = Fun(Match, Ann, S#elixir_erl{context=match}),
{Result, NewS#elixir_erl{context=Context}};
match(Ann, Fun, Match, S) ->
Fun(Match, Ann, S).
%% Translate clauses with args, guards and expressions
clause(Ann, Fun, Match, Expr, Guards, S) ->
{TMatch, SA} = match(Ann, Fun, Match, S),
SG = SA#elixir_erl{extra_guards=[]},
TGuards = guards(Ann, Guards, SA#elixir_erl.extra_guards, SG),
{TExpr, SE} = elixir_erl_pass:translate(Expr, Ann, SG),
{{clause, Ann, TMatch, TGuards, unblock(TExpr)}, SE}.
% Translate/Extract guards from the given expression.
guards(Ann, Guards, Extra, S) ->
SG = S#elixir_erl{context=guard},
case Guards of
[] -> case Extra of [] -> []; _ -> [Extra] end;
_ -> [translate_guard(Guard, Ann, SG, Extra) || Guard <- Guards]
end.
translate_guard(Guard, Ann, S, Extra) ->
[element(1, elixir_erl_pass:translate(Guard, Ann, S)) | Extra].
% Function for translating macros with match style like case and receive.
clauses([], S) ->
{[], S};
clauses(Clauses, S) ->
lists:mapfoldl(fun each_clause/2, S, Clauses).
each_clause({match, Meta, [Condition], Expr}, S) ->
{Arg, Guards} = elixir_utils:extract_guards(Condition),
clause(?ann(Meta), fun elixir_erl_pass:translate_args/3, [Arg], Expr, Guards, S);
each_clause({expr, Meta, [Condition], Expr}, S) ->
Ann = ?ann(Meta),
{TCondition, SC} = elixir_erl_pass:translate(Condition, Ann, S),
{TExpr, SB} = elixir_erl_pass:translate(Expr, Ann, SC),
{{clause, Ann, [TCondition], [], unblock(TExpr)}, SB}.
unblock({'block', _, Exprs}) -> Exprs;
unblock(Exprs) -> [Exprs].
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