Merge pull request #69 from sile/support-maybe

Support maybe syntax

src/ktn_code.erl

@@ -333,6 +333,12 @@ to_map({match, Attrs, Left, Right}) ->
                  text => get_text(Attrs)},
       content => to_map([Left, Right])};
 
+to_map({maybe_match, Attrs, Left, Right}) ->
+    #{type => maybe_match,
+      attrs => #{location => get_location(Attrs),
+                 text => get_text(Attrs)},
+      content => to_map([Left, Right])};
+
 to_map({tuple, Attrs, Elements}) ->
     #{type => tuple,
       attrs => #{location => get_location(Attrs),
@@ -497,6 +503,22 @@ to_map({try_after, Attrs, AfterBody}) ->
                  text => get_text(Attrs)},
       content => to_map(AfterBody)};
 
+%% maybe..else..end
+
+to_map({'maybe', Attrs, Body, Else}) ->
+    MaybeBody = to_map(Body),
+    MaybeElse = to_map(Else),
+    #{type => 'maybe',
+      attrs => #{location => get_location(Attrs),
+                 text => get_text(Attrs)},
+      content => MaybeBody ++ [MaybeElse]};
+
+to_map({'else', Attrs, Clauses}) ->
+    #{type => 'else',
+      attrs => #{location => get_location(Attrs),
+                 text => get_text(Attrs)},
+      content => to_map(Clauses)};
+
 %% if
 
 to_map({'if', Attrs, IfClauses}) ->

test/ktn_code_SUITE.erl

@@ -15,6 +15,12 @@
          to_string/1
         ]).
 
+-if(?OTP_RELEASE >= 25).
+-export([
+         parse_maybe/1
+        ]).
+-endif.
+
 -define(EXCLUDED_FUNS,
         [
          module_info,
@@ -126,6 +132,23 @@ to_string(_Config) ->
 
     ok.
 
+-if(?OTP_RELEASE >= 25).
+-spec parse_maybe(config()) -> ok.
+parse_maybe(_Config) ->
+    %% Note that to pass this test case, the 'maybe_expr' feature must be enabled.
+
+    #{ type := root
+     , content :=
+           [#{ type := function
+             , content :=
+                   [#{ type := clause
+                     , content := [#{type := 'maybe'}]}]
+             }]
+     } = ktn_code:parse_tree(<<"foo() -> maybe ok ?= ok else _ -> ng end.">>),
+
+    ok.
+-endif.
+
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 %% Helper
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%