aboutsummaryrefslogblamecommitdiffstats
path: root/lib/syntax_tools/src/erl_syntax_lib.erl
blob: 1c0367c3d9babc3ec956e73371fc6f37b7f55e9d (plain) (tree)
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900















































                                                                        


                                                                        











                                                                        


                                                                    






















                                                                        


                                                                             























                                                                        


                                                            































                                                                        


                                                                     













                                                                        


                                                     


























                                                                        


                                                                                          





































                                                                        




                                                                 




















                                                                        


                                                                    

























                                                                        

                                                  




















































                                                                        

                                         























                                                                        

                                                                     
























                                                                
                                                                   


















                                                                        

                                                       













                                                                        


                                                                         






































                                                                        


                                                                   















                                                                        

                                                                            














































































































































































































































































































































































































                                                                                   
                                                      











                                                                    

                                                         








































































































































































                                                                        





                                                                            





































































































































































                                                                        

                                                                         







































































                                                                        


                                                                 

















































                                                                        

                                                                      


                           


                                                          





































                                                                        

                                                                      


                           




                                                                            







































                                                                        

                                                                       





















































                                                                        

                                                                      


                           


                                                          





















                                                                        
                                                                   




                                                        

                                                                      


                           

                                                                          















































                                                                        



                                                                              





































































                                                                        




                                                                                






































































                                                                        


                                                      





























                                                                        

                                                                               


































                                                                        

                                                                     




























                                                                        

                                                                 































                                                                        

                                                                      


                                 
                                                                      



















                                                                        

                                                                      


                               



                                                                             







































                                                                        




                                                                    
























                                                                        

                                                                         



















                                                                        

                                                                     













                                                                        

                                                                               




























                                                                        



                                                               












                                                                        

                                                                           



























                                                                        


                                                                           











































































































































                                                                           
%% =====================================================================
%% This library is free software; you can redistribute it and/or modify
%% it under the terms of the GNU Lesser General Public License as
%% published by the Free Software Foundation; either version 2 of the
%% License, or (at your option) any later version.
%%
%% This library is distributed in the hope that it will be useful, but
%% WITHOUT ANY WARRANTY; without even the implied warranty of
%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%% Lesser General Public License for more details.
%%
%% You should have received a copy of the GNU Lesser General Public
%% License along with this library; if not, write to the Free Software
%% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
%% USA
%%
%% $Id$
%%
%% @copyright 1997-2006 Richard Carlsson
%% @author Richard Carlsson <[email protected]>
%% @end
%% =====================================================================

%% @doc Support library for abstract Erlang syntax trees.
%%
%% This module contains utility functions for working with the
%% abstract data type defined in the module {@link erl_syntax}.
%%
%% @type syntaxTree() = erl_syntax:syntaxTree(). An abstract syntax
%% tree. See the {@link erl_syntax} module for details.

-module(erl_syntax_lib).

-export([analyze_application/1, analyze_attribute/1,
         analyze_export_attribute/1, analyze_file_attribute/1,
         analyze_form/1, analyze_forms/1, analyze_function/1,
         analyze_function_name/1, analyze_implicit_fun/1,
         analyze_import_attribute/1, analyze_module_attribute/1,
         analyze_record_attribute/1, analyze_record_expr/1,
         analyze_record_field/1, analyze_rule/1,
         analyze_wild_attribute/1, annotate_bindings/1,
         annotate_bindings/2, fold/3, fold_subtrees/3, foldl_listlist/3,
         function_name_expansions/1, is_fail_expr/1, limit/2, limit/3,
         map/2, map_subtrees/2, mapfold/3, mapfold_subtrees/3,
         mapfoldl_listlist/3, new_variable_name/1, new_variable_name/2,
         new_variable_names/2, new_variable_names/3, strip_comments/1,
         to_comment/1, to_comment/2, to_comment/3, variables/1]).

%% =====================================================================

-type ordset(X) :: [X].  % XXX: TAKE ME OUT

%% =====================================================================
%% @spec map(Function, Tree::syntaxTree()) -> syntaxTree()
%%
%%          Function = (syntaxTree()) -> syntaxTree()
%% 
%% @doc Applies a function to each node of a syntax tree. The result of
%% each application replaces the corresponding original node. The order
%% of traversal is bottom-up.
%%
%% @see map_subtrees/2

-spec map(fun((erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree()),
	  erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree().

map(F, Tree) ->
    case erl_syntax:subtrees(Tree) of
        [] ->
            F(Tree);
        Gs ->
            Tree1 = erl_syntax:make_tree(erl_syntax:type(Tree),
                                         [[map(F, T) || T <- G]
                                          || G <- Gs]),
            F(erl_syntax:copy_attrs(Tree, Tree1))
    end.


%% =====================================================================
%% @spec map_subtrees(Function, syntaxTree()) -> syntaxTree()
%%
%%          Function = (Tree) -> Tree1
%%         
%% @doc Applies a function to each immediate subtree of a syntax tree.
%% The result of each application replaces the corresponding original
%% node.
%%
%% @see map/2

-spec map_subtrees(fun((erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree()),
		   erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree().

map_subtrees(F, Tree) ->
    case erl_syntax:subtrees(Tree) of
        [] ->
            Tree;
        Gs ->
            Tree1 = erl_syntax:make_tree(erl_syntax:type(Tree),
                                         [[F(T) || T <- G] || G <- Gs]),
            erl_syntax:copy_attrs(Tree, Tree1)
    end.


%% =====================================================================
%% @spec fold(Function, Start::term(), Tree::syntaxTree()) -> term()
%%
%%          Function = (syntaxTree(), term()) -> term()
%%
%% @doc Folds a function over all nodes of a syntax tree. The result is
%% the value of `Function(X1, Function(X2, ... Function(Xn, Start)
%% ... ))', where `[X1, X2, ..., Xn]' are the nodes of
%% `Tree' in a post-order traversal.
%%
%% @see fold_subtrees/3
%% @see foldl_listlist/3

-spec fold(fun((erl_syntax:syntaxTree(), term()) -> term()),
	   term(), erl_syntax:syntaxTree()) -> term().

fold(F, S, Tree) ->
    case erl_syntax:subtrees(Tree) of
        [] ->
            F(Tree, S);
        Gs ->
            F(Tree, fold_1(F, S, Gs))
    end.

fold_1(F, S, [L | Ls]) ->
    fold_1(F, fold_2(F, S, L), Ls);
fold_1(_, S, []) ->
    S.

fold_2(F, S, [T | Ts]) ->
    fold_2(F, fold(F, S, T), Ts);
fold_2(_, S, []) ->
    S.


%% =====================================================================
%% @spec fold_subtrees(Function, Start::term(), Tree::syntaxTree()) ->
%%           term()
%%
%%          Function = (syntaxTree(), term()) -> term()
%%
%% @doc Folds a function over the immediate subtrees of a syntax tree.
%% This is similar to `fold/3', but only on the immediate
%% subtrees of `Tree', in left-to-right order; it does not
%% include the root node of `Tree'.
%%
%% @see fold/3

-spec fold_subtrees(fun((erl_syntax:syntaxTree(), term()) -> term()),
		    term(), erl_syntax:syntaxTree()) -> term().

fold_subtrees(F, S, Tree) ->
    foldl_listlist(F, S, erl_syntax:subtrees(Tree)).


%% =====================================================================
%% @spec foldl_listlist(Function, Start::term(), [[term()]]) -> term()
%%
%%          Function = (term(), term()) -> term()
%%
%% @doc Like `lists:foldl/3', but over a list of lists.
%%
%% @see fold/3
%% @see //stdlib/lists:foldl/3

-spec foldl_listlist(fun((term(), term()) -> term()),
		     term(), [[term()]]) -> term().

foldl_listlist(F, S, [L | Ls]) ->
    foldl_listlist(F, foldl(F, S, L), Ls);
foldl_listlist(_, S, []) ->
    S.

foldl(F, S, [T | Ts]) ->
    foldl(F, F(T, S), Ts);
foldl(_, S, []) ->
    S.


%% =====================================================================
%% @spec mapfold(Function, Start::term(), Tree::syntaxTree()) ->
%%           {syntaxTree(), term()}
%%
%%          Function = (syntaxTree(), term()) -> {syntaxTree(), term()}
%%
%% @doc Combines map and fold in a single operation. This is similar to
%% `map/2', but also propagates an extra value from each
%% application of the `Function' to the next, while doing a
%% post-order traversal of the tree like `fold/3'. The value
%% `Start' is passed to the first function application, and
%% the final result is the result of the last application.
%%
%% @see map/2
%% @see fold/3

-spec mapfold(fun((erl_syntax:syntaxTree(), term()) -> {erl_syntax:syntaxTree(), term()}),
	      term(), erl_syntax:syntaxTree()) -> {erl_syntax:syntaxTree(), term()}.

mapfold(F, S, Tree) ->
    case erl_syntax:subtrees(Tree) of
        [] ->
            F(Tree, S);
        Gs ->
            {Gs1, S1} = mapfold_1(F, S, Gs),
            Tree1 = erl_syntax:make_tree(erl_syntax:type(Tree), Gs1),
            F(erl_syntax:copy_attrs(Tree, Tree1), S1)
    end.

mapfold_1(F, S, [L | Ls]) ->
    {L1, S1} = mapfold_2(F, S, L),
    {Ls1, S2} = mapfold_1(F, S1, Ls),
    {[L1 | Ls1], S2};
mapfold_1(_, S, []) ->
    {[], S}.

mapfold_2(F, S, [T | Ts]) ->
    {T1, S1} = mapfold(F, S, T),
    {Ts1, S2} = mapfold_2(F, S1, Ts),
    {[T1 | Ts1], S2};
mapfold_2(_, S, []) ->
    {[], S}.


%% =====================================================================
%% @spec mapfold_subtrees(Function, Start::term(),
%%                        Tree::syntaxTree()) -> {syntaxTree(), term()}
%%
%%          Function = (syntaxTree(), term()) -> {syntaxTree(), term()}
%%
%% @doc Does a mapfold operation over the immediate subtrees of a syntax
%% tree. This is similar to `mapfold/3', but only on the
%% immediate subtrees of `Tree', in left-to-right order; it
%% does not include the root node of `Tree'.
%%
%% @see mapfold/3

-spec mapfold_subtrees(fun((erl_syntax:syntaxTree(), term()) ->
			      {erl_syntax:syntaxTree(), term()}),
		       term(), erl_syntax:syntaxTree()) ->
        {erl_syntax:syntaxTree(), term()}.

mapfold_subtrees(F, S, Tree) ->
    case erl_syntax:subtrees(Tree) of
        [] ->
            {Tree, S};
        Gs ->
            {Gs1, S1} = mapfoldl_listlist(F, S, Gs),
            Tree1 = erl_syntax:make_tree(erl_syntax:type(Tree), Gs1),
            {erl_syntax:copy_attrs(Tree, Tree1), S1}
    end.


%% =====================================================================
%% @spec mapfoldl_listlist(Function, State, [[term()]]) ->
%%           {[[term()]], term()}
%%
%%          Function = (term(), term()) -> {term(), term()}
%%
%% @doc Like `lists:mapfoldl/3', but over a list of lists.
%% The list of lists in the result has the same structure as the given
%% list of lists.

-spec mapfoldl_listlist(fun((term(), term()) -> {term(), term()}),
			term(), [[term()]]) -> {[[term()]], term()}.

mapfoldl_listlist(F, S, [L | Ls]) ->
    {L1, S1} = mapfoldl(F, S, L),
    {Ls1, S2} = mapfoldl_listlist(F, S1, Ls),
    {[L1 | Ls1], S2};
mapfoldl_listlist(_, S, []) ->
    {[], S}.

mapfoldl(F, S, [L | Ls]) ->
    {L1, S1} = F(L, S),
    {Ls1, S2} = mapfoldl(F, S1, Ls),
    {[L1 | Ls1], S2};
mapfoldl(_, S, []) ->
    {[], S}.


%% =====================================================================
%% @spec variables(syntaxTree()) -> set(atom())
%%
%%        set(T) = //stdlib/sets:set(T)
%%
%% @doc Returns the names of variables occurring in a syntax tree, The
%% result is a set of variable names represented by atoms. Macro names
%% are not included.
%%
%% @see //stdlib/sets

-spec variables(erl_syntax:syntaxTree()) -> set().

variables(Tree) ->
    variables(Tree, sets:new()).

variables(T, S) ->
    case erl_syntax:type(T) of
	variable ->
	    sets:add_element(erl_syntax:variable_name(T), S);
	macro ->
	    %% macro names are ignored, even if represented by variables
	    case erl_syntax:macro_arguments(T) of
		none -> S;
		As ->
		    variables_2(As, S)
	    end;
	_ ->
	    case erl_syntax:subtrees(T) of
		[] ->
		    S;
		Gs ->
		    variables_1(Gs, S)
	    end
    end.

variables_1([L | Ls], S) ->
    variables_1(Ls, variables_2(L, S));
variables_1([], S) ->
    S.

variables_2([T | Ts], S) ->
    variables_2(Ts, variables(T, S));
variables_2([], S) ->
    S.


-define(MINIMUM_RANGE, 100).
-define(START_RANGE_FACTOR, 100).
-define(MAX_RETRIES, 3).    % retries before enlarging range
-define(ENLARGE_ENUM, 8).   % range enlargment enumerator
-define(ENLARGE_DENOM, 1).  % range enlargment denominator

default_variable_name(N) ->
    list_to_atom("V" ++ integer_to_list(N)).

%% =====================================================================
%% @spec new_variable_name(Used::set(atom())) -> atom()
%%
%% @doc Returns an atom which is not already in the set `Used'. This is
%% equivalent to `new_variable_name(Function, Used)', where `Function'
%% maps a given integer `N' to the atom whose name consists of "`V'"
%% followed by the numeral for `N'.
%%
%% @see new_variable_name/2

-spec new_variable_name(set()) -> atom().

new_variable_name(S) ->
    new_variable_name(fun default_variable_name/1, S).

%% =====================================================================
%% @spec new_variable_name(Function, Used::set(atom())) -> atom()
%%
%%          Function = (integer()) -> atom()
%%
%% @doc Returns a user-named atom which is not already in the set
%% `Used'. The atom is generated by applying the given
%% `Function' to a generated integer. Integers are generated
%% using an algorithm which tries to keep the names randomly distributed
%% within a reasonably small range relative to the number of elements in
%% the set.
%%
%% This function uses the module `random' to generate new
%% keys. The seed it uses may be initialized by calling
%% `random:seed/0' or `random:seed/3' before this
%% function is first called.
%%
%% @see new_variable_name/1
%% @see //stdlib/sets
%% @see //stdlib/random

-spec new_variable_name(fun((integer()) -> atom()), set()) -> atom().

new_variable_name(F, S) ->
    R = start_range(S),
    new_variable_name(R, F, S).

new_variable_name(R, F, S) ->
    new_variable_name(generate(R, R), R, 0, F, S).

new_variable_name(N, R, T, F, S) when T < ?MAX_RETRIES ->
    A = F(N),
    case sets:is_element(A, S) of
        true ->
            new_variable_name(generate(N, R), R, T + 1, F, S);
        false ->
            A
    end;
new_variable_name(N, R, _T, F, S) ->
    %% Too many retries - enlarge the range and start over.
    R1 = (R * ?ENLARGE_ENUM) div ?ENLARGE_DENOM,
    new_variable_name(generate(N, R1), R1, 0, F, S).

%% Note that we assume that it is very cheap to take the size of
%% the given set. This should be valid for the stdlib
%% implementation of `sets'.

start_range(S) ->
    erlang:max(sets:size(S) * ?START_RANGE_FACTOR, ?MINIMUM_RANGE).

%% The previous number might or might not be used to compute the
%% next number to be tried. It is currently not used.
%%
%% It is important that this function does not generate values in
%% order, but (pseudo-)randomly distributed over the range.

generate(_Key, Range) ->
    random:uniform(Range).    % works well


%% =====================================================================
%% @spec new_variable_names(N::integer(), Used::set(atom())) -> [atom()]
%%
%% @doc Like `new_variable_name/1', but generates a list of
%% `N' new names.
%% 
%% @see new_variable_name/1

-spec new_variable_names(integer(), set()) -> [atom()].

new_variable_names(N, S) ->
    new_variable_names(N, fun default_variable_name/1, S).

%% =====================================================================
%% @spec new_variable_names(N::integer(), Function,
%%                          Used::set(atom())) -> [atom()]
%%
%%          Function = (integer()) -> atom()
%%
%% @doc Like `new_variable_name/2', but generates a list of
%% `N' new names.
%% 
%% @see new_variable_name/2

-spec new_variable_names(integer(), fun((integer()) -> atom()), set()) ->
	[atom()].

new_variable_names(N, F, S) when is_integer(N) ->
    R = start_range(S),
    new_variable_names(N, [], R, F, S).

new_variable_names(N, Names, R, F, S) when N > 0 ->
    Name = new_variable_name(R, F, S),
    S1 = sets:add_element(Name, S),
    new_variable_names(N - 1, [Name | Names], R, F, S1);
new_variable_names(0, Names, _, _, _) ->
    Names.


%% =====================================================================
%% @spec annotate_bindings(Tree::syntaxTree(),
%%                         Bindings::ordset(atom())) -> syntaxTree()
%%
%% @type ordset(T) = //stdlib/ordsets:ordset(T)
%%
%% @doc Adds or updates annotations on nodes in a syntax tree.
%% `Bindings' specifies the set of bound variables in the
%% environment of the top level node. The following annotations are
%% affected:
%% <ul>
%%     <li>`{env, Vars}', representing the input environment
%%     of the subtree.</li>
%%
%%     <li>`{bound, Vars}', representing the variables that
%%     are bound in the subtree.</li>
%%
%%     <li>`{free, Vars}', representing the free variables in
%%     the subtree.</li>
%% </ul>
%% `Bindings' and `Vars' are ordered-set lists
%% (cf. module `ordsets') of atoms representing variable
%% names.
%%
%% @see annotate_bindings/1
%% @see //stdlib/ordsets

-spec annotate_bindings(erl_syntax:syntaxTree(), ordset(atom())) ->
        erl_syntax:syntaxTree().

annotate_bindings(Tree, Env) ->
    {Tree1, _, _} = vann(Tree, Env),
    Tree1.

%% =====================================================================
%% @spec annotate_bindings(Tree::syntaxTree()) -> syntaxTree()
%%
%% @doc Adds or updates annotations on nodes in a syntax tree.
%% Equivalent to `annotate_bindings(Tree, Bindings)' where
%% the top-level environment `Bindings' is taken from the
%% annotation `{env, Bindings}' on the root node of
%% `Tree'. An exception is thrown if no such annotation
%% should exist.
%%
%% @see annotate_bindings/2

-spec annotate_bindings(erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree().

annotate_bindings(Tree) ->
    As = erl_syntax:get_ann(Tree),
    case lists:keyfind(env, 1, As) of
        {env, InVars} ->
            annotate_bindings(Tree, InVars);
        _ ->
            erlang:error(badarg)
    end.

vann(Tree, Env) ->
    case erl_syntax:type(Tree) of
        variable ->
            %% Variable use
            Bound = [],
            Free = [erl_syntax:variable_name(Tree)],
            {ann_bindings(Tree, Env, Bound, Free), Bound, Free};
        match_expr ->
            vann_match_expr(Tree, Env);
        case_expr ->
            vann_case_expr(Tree, Env);
        if_expr ->
            vann_if_expr(Tree, Env);
        cond_expr ->
            vann_cond_expr(Tree, Env);
        receive_expr ->
            vann_receive_expr(Tree, Env);
        catch_expr ->
            vann_catch_expr(Tree, Env);
        try_expr ->
            vann_try_expr(Tree, Env);
        function ->
            vann_function(Tree, Env);
        rule ->
            vann_rule(Tree, Env);
        fun_expr ->
            vann_fun_expr(Tree, Env);
        list_comp ->
            vann_list_comp(Tree, Env);
        binary_comp ->
            vann_binary_comp(Tree, Env);
        generator ->
            vann_generator(Tree, Env);
        binary_generator ->
            vann_binary_generator(Tree, Env);
        block_expr ->
            vann_block_expr(Tree, Env);
        macro ->
            vann_macro(Tree, Env);
        _Type ->
            F = vann_list_join(Env),
            {Tree1, {Bound, Free}} = mapfold_subtrees(F, {[], []},
                                                      Tree),
            {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}
    end.

vann_list_join(Env) ->
    fun (T, {Bound, Free}) ->
            {T1, Bound1, Free1} = vann(T, Env),
            {T1, {ordsets:union(Bound, Bound1),
                  ordsets:union(Free, Free1)}}
    end.

vann_list(Ts, Env) ->
    lists:mapfoldl(vann_list_join(Env), {[], []}, Ts).

vann_function(Tree, Env) ->
    Cs = erl_syntax:function_clauses(Tree),
    {Cs1, {_, Free}} = vann_clauses(Cs, Env),
    N = erl_syntax:function_name(Tree),
    {N1, _, _} = vann(N, Env),
    Tree1 = rewrite(Tree, erl_syntax:function(N1, Cs1)),
    Bound = [],
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_rule(Tree, Env) ->
    Cs = erl_syntax:rule_clauses(Tree),
    {Cs1, {_, Free}} = vann_clauses(Cs, Env),
    N = erl_syntax:rule_name(Tree),
    {N1, _, _} = vann(N, Env),
    Tree1 = rewrite(Tree, erl_syntax:rule(N1, Cs1)),
    Bound = [],
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_fun_expr(Tree, Env) ->
    Cs = erl_syntax:fun_expr_clauses(Tree),
    {Cs1, {_, Free}} = vann_clauses(Cs, Env),
    Tree1 = rewrite(Tree, erl_syntax:fun_expr(Cs1)),
    Bound = [],
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_match_expr(Tree, Env) ->
    E = erl_syntax:match_expr_body(Tree),
    {E1, Bound1, Free1} = vann(E, Env),
    Env1 = ordsets:union(Env, Bound1),
    P = erl_syntax:match_expr_pattern(Tree),
    {P1, Bound2, Free2} = vann_pattern(P, Env1),
    Bound = ordsets:union(Bound1, Bound2),
    Free = ordsets:union(Free1, Free2),
    Tree1 = rewrite(Tree, erl_syntax:match_expr(P1, E1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_case_expr(Tree, Env) ->
    E = erl_syntax:case_expr_argument(Tree),
    {E1, Bound1, Free1} = vann(E, Env),
    Env1 = ordsets:union(Env, Bound1),
    Cs = erl_syntax:case_expr_clauses(Tree),
    {Cs1, {Bound2, Free2}} = vann_clauses(Cs, Env1),
    Bound = ordsets:union(Bound1, Bound2),
    Free = ordsets:union(Free1, Free2),
    Tree1 = rewrite(Tree, erl_syntax:case_expr(E1, Cs1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_if_expr(Tree, Env) ->
    Cs = erl_syntax:if_expr_clauses(Tree),
    {Cs1, {Bound, Free}} = vann_clauses(Cs, Env),
    Tree1 = rewrite(Tree, erl_syntax:if_expr(Cs1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_cond_expr(_Tree, _Env) ->
    erlang:error({not_implemented,cond_expr}).

vann_catch_expr(Tree, Env) ->
    E = erl_syntax:catch_expr_body(Tree),
    {E1, _, Free} = vann(E, Env),
    Tree1 = rewrite(Tree, erl_syntax:catch_expr(E1)),
    Bound = [],
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_try_expr(Tree, Env) ->
    Es = erl_syntax:try_expr_body(Tree),
    {Es1, {Bound1, Free1}} = vann_body(Es, Env),
    Cs = erl_syntax:try_expr_clauses(Tree),
    %% bindings in the body should be available in the success case,
    {Cs1, {_, Free2}} = vann_clauses(Cs, ordsets:union(Env, Bound1)),
    Hs = erl_syntax:try_expr_handlers(Tree),
    {Hs1, {_, Free3}} = vann_clauses(Hs, Env),
    %% the after part does not export anything, yet; this might change
    As = erl_syntax:try_expr_after(Tree),
    {As1, {_, Free4}} = vann_body(As, Env),
    Tree1 = rewrite(Tree, erl_syntax:try_expr(Es1, Cs1, Hs1, As1)),
    Bound = [],
    Free = ordsets:union(Free1, ordsets:union(Free2, ordsets:union(Free3, Free4))),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_receive_expr(Tree, Env) ->
    %% The timeout action is treated as an extra clause.
    %% Bindings in the expiry expression are local only.
    Cs = erl_syntax:receive_expr_clauses(Tree),
    Es = erl_syntax:receive_expr_action(Tree),
    C = erl_syntax:clause([], Es),
    {[C1 | Cs1], {Bound, Free1}} = vann_clauses([C | Cs], Env),
    Es1 = erl_syntax:clause_body(C1),
    {T1, _, Free2} = case erl_syntax:receive_expr_timeout(Tree) of
                         none ->
                             {none, [], []};
                         T ->
                             vann(T, Env)
                     end,
    Free = ordsets:union(Free1, Free2),
    Tree1 = rewrite(Tree, erl_syntax:receive_expr(Cs1, T1, Es1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_list_comp(Tree, Env) ->
    Es = erl_syntax:list_comp_body(Tree),
    {Es1, {Bound1, Free1}} = vann_list_comp_body(Es, Env),
    Env1 = ordsets:union(Env, Bound1),
    T = erl_syntax:list_comp_template(Tree),
    {T1, _, Free2} = vann(T, Env1),
    Free = ordsets:union(Free1, ordsets:subtract(Free2, Bound1)),
    Bound = [],
    Tree1 = rewrite(Tree, erl_syntax:list_comp(T1, Es1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_list_comp_body_join() ->
    fun (T, {Env, Bound, Free}) ->
            {T1, Bound1, Free1} = case erl_syntax:type(T) of
                                      binary_generator ->
				          vann_binary_generator(T,Env);
				      generator ->
                                          vann_generator(T, Env);
                                      _ ->
                                          %% Bindings in filters are not
                                          %% exported to the rest of the
                                          %% body.
                                          {T2, _, Free2} = vann(T, Env),
                                          {T2, [], Free2}
                                  end,
            Env1 = ordsets:union(Env, Bound1),
            {T1, {Env1, ordsets:union(Bound, Bound1),
                  ordsets:union(Free, 
                                ordsets:subtract(Free1, Bound))}}
    end.

vann_list_comp_body(Ts, Env) ->
    F = vann_list_comp_body_join(),
    {Ts1, {_, Bound, Free}} = lists:mapfoldl(F, {Env, [], []}, Ts),
    {Ts1, {Bound, Free}}.

vann_binary_comp(Tree, Env) ->
    Es = erl_syntax:binary_comp_body(Tree),
    {Es1, {Bound1, Free1}} = vann_binary_comp_body(Es, Env),
    Env1 = ordsets:union(Env, Bound1),
    T = erl_syntax:binary_comp_template(Tree),
    {T1, _, Free2} = vann(T, Env1),
    Free = ordsets:union(Free1, ordsets:subtract(Free2, Bound1)),
    Bound = [],
    Tree1 = rewrite(Tree, erl_syntax:binary_comp(T1, Es1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_binary_comp_body_join() ->
    fun (T, {Env, Bound, Free}) ->
            {T1, Bound1, Free1} = case erl_syntax:type(T) of
                                    binary_generator ->
				          vann_binary_generator(T, Env);
				    generator ->
                                          vann_generator(T, Env);
                                      _ ->
                                          %% Bindings in filters are not
                                          %% exported to the rest of the
                                          %% body.
                                          {T2, _, Free2} = vann(T, Env),
                                          {T2, [], Free2}
                                  end,
            Env1 = ordsets:union(Env, Bound1),
            {T1, {Env1, ordsets:union(Bound, Bound1),
                  ordsets:union(Free, 
                                ordsets:subtract(Free1, Bound))}}
    end.

vann_binary_comp_body(Ts, Env) ->
    F = vann_binary_comp_body_join(),
    {Ts1, {_, Bound, Free}} = lists:mapfoldl(F, {Env, [], []}, Ts),
    {Ts1, {Bound, Free}}.

%% In list comprehension generators, the pattern variables are always
%% viewed as new occurrences, shadowing whatever is in the input
%% environment (thus, the pattern contains no variable uses, only
%% bindings). Bindings in the generator body are not exported.

vann_generator(Tree, Env) ->
    P = erl_syntax:generator_pattern(Tree),
    {P1, Bound, _} = vann_pattern(P, []),
    E = erl_syntax:generator_body(Tree),
    {E1, _, Free} = vann(E, Env),
    Tree1 = rewrite(Tree, erl_syntax:generator(P1, E1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_binary_generator(Tree, Env) ->
    P = erl_syntax:binary_generator_pattern(Tree),
    {P1, Bound, _} = vann_pattern(P, Env),
    E = erl_syntax:binary_generator_body(Tree),
    {E1, _, Free} = vann(E, Env),
    Tree1 = rewrite(Tree, erl_syntax:binary_generator(P1, E1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_block_expr(Tree, Env) ->
    Es = erl_syntax:block_expr_body(Tree),
    {Es1, {Bound, Free}} = vann_body(Es, Env),
    Tree1 = rewrite(Tree, erl_syntax:block_expr(Es1)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_body_join() ->
    fun (T, {Env, Bound, Free}) ->
            {T1, Bound1, Free1} = vann(T, Env),
            Env1 = ordsets:union(Env, Bound1),
            {T1, {Env1, ordsets:union(Bound, Bound1),
                  ordsets:union(Free,
                                ordsets:subtract(Free1, Bound))}}
    end.

vann_body(Ts, Env) ->
    {Ts1, {_, Bound, Free}} = lists:mapfoldl(vann_body_join(),
                                             {Env, [], []}, Ts),
    {Ts1, {Bound, Free}}.

%% Macro names must be ignored even if they happen to be variables,
%% lexically speaking.

vann_macro(Tree, Env) ->
    {As, {Bound, Free}} = case erl_syntax:macro_arguments(Tree) of
                              none ->
                                  {none, {[], []}};
                              As1 ->
                                  vann_list(As1, Env)
                          end,
    N = erl_syntax:macro_name(Tree),
    Tree1 = rewrite(Tree, erl_syntax:macro(N, As)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_pattern(Tree, Env) ->
    case erl_syntax:type(Tree) of
        variable ->
            V = erl_syntax:variable_name(Tree),
            case ordsets:is_element(V, Env) of
                true ->
                    %% Variable use
                    Bound = [],
                    Free = [V],
                    {ann_bindings(Tree, Env, Bound, Free), Bound, Free};
                false ->
                    %% Variable binding
                    Bound = [V],
                    Free = [],
                    {ann_bindings(Tree, Env, Bound, Free), Bound, Free}
            end;
        match_expr ->
            %% Alias pattern
            P = erl_syntax:match_expr_pattern(Tree),
            {P1, Bound1, Free1} = vann_pattern(P, Env),
            E = erl_syntax:match_expr_body(Tree),
            {E1, Bound2, Free2} = vann_pattern(E, Env),
            Bound = ordsets:union(Bound1, Bound2),
            Free = ordsets:union(Free1, Free2),
            Tree1 = rewrite(Tree, erl_syntax:match_expr(P1, E1)),
            {ann_bindings(Tree1, Env, Bound, Free), Bound, Free};
        macro ->
            %% The macro name must be ignored. The arguments are treated
            %% as patterns.
            {As, {Bound, Free}} =
                case erl_syntax:macro_arguments(Tree) of
                    none ->
                        {none, {[], []}};
                    As1 ->
                        vann_patterns(As1, Env)
                end,
            N = erl_syntax:macro_name(Tree),
            Tree1 = rewrite(Tree, erl_syntax:macro(N, As)),
            {ann_bindings(Tree1, Env, Bound, Free), Bound, Free};
        _Type ->
            F = vann_patterns_join(Env),
            {Tree1, {Bound, Free}} = mapfold_subtrees(F, {[], []},
                                                      Tree),
            {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}
    end.

vann_patterns_join(Env) ->
    fun (T, {Bound, Free}) ->
            {T1, Bound1, Free1} = vann_pattern(T, Env),
            {T1, {ordsets:union(Bound, Bound1),
                  ordsets:union(Free, Free1)}}
    end.

vann_patterns(Ps, Env) ->
    lists:mapfoldl(vann_patterns_join(Env), {[], []}, Ps).

vann_clause(C, Env) ->
    {Ps, {Bound1, Free1}} = vann_patterns(erl_syntax:clause_patterns(C),
                                          Env),
    Env1 = ordsets:union(Env, Bound1),
    %% Guards cannot add bindings
    {G1, _, Free2} = case erl_syntax:clause_guard(C) of
                         none ->
                             {none, [], []};
                         G ->
                             vann(G, Env1)
                     end,
    {Es, {Bound2, Free3}} = vann_body(erl_syntax:clause_body(C), Env1),
    Bound = ordsets:union(Bound1, Bound2),
    Free = ordsets:union(Free1,
                         ordsets:subtract(ordsets:union(Free2, Free3),
                                          Bound1)),
    Tree1 = rewrite(C, erl_syntax:clause(Ps, G1, Es)),
    {ann_bindings(Tree1, Env, Bound, Free), Bound, Free}.

vann_clauses_join(Env) ->
    fun (C, {Bound, Free}) ->
            {C1, Bound1, Free1} = vann_clause(C, Env),
            {C1, {ordsets:intersection(Bound, Bound1),
                  ordsets:union(Free, Free1)}}
    end.

vann_clauses([C | Cs], Env) ->
    {C1, Bound, Free} = vann_clause(C, Env),
    {Cs1, BF} = lists:mapfoldl(vann_clauses_join(Env), {Bound, Free}, Cs),
    {[C1 | Cs1], BF};
vann_clauses([], _Env) ->
    {[], {[], []}}.

ann_bindings(Tree, Env, Bound, Free) ->
    As0 = erl_syntax:get_ann(Tree),
    As1 = [{env, Env},
           {bound, Bound},
           {free, Free}
           | delete_binding_anns(As0)],
    erl_syntax:set_ann(Tree, As1).

delete_binding_anns([{env, _} | As]) ->
    delete_binding_anns(As);
delete_binding_anns([{bound, _} | As]) ->
    delete_binding_anns(As);
delete_binding_anns([{free, _} | As]) ->
    delete_binding_anns(As);
delete_binding_anns([A | As]) ->
    [A | delete_binding_anns(As)];
delete_binding_anns([]) ->
    [].


%% =====================================================================
%% @spec is_fail_expr(Tree::syntaxTree()) -> boolean()
%%
%% @doc Returns `true' if `Tree' represents an
%% expression which never terminates normally. Note that the reverse
%% does not apply. Currently, the detected cases are calls to
%% `exit/1', `throw/1',
%% `erlang:error/1' and `erlang:error/2'.
%%
%% @see //erts/erlang:exit/1
%% @see //erts/erlang:throw/1
%% @see //erts/erlang:error/1
%% @see //erts/erlang:error/2

-spec is_fail_expr(erl_syntax:syntaxTree()) -> boolean().

is_fail_expr(E) ->          
    case erl_syntax:type(E) of
        application ->
            N = length(erl_syntax:application_arguments(E)),
            F = erl_syntax:application_operator(E),
            case catch {ok, analyze_function_name(F)} of
                syntax_error ->
                    false;
                {ok, exit} when N =:= 1 ->
                    true;
                {ok, throw} when N =:= 1 ->
                    true;
                {ok, {erlang, exit}} when N =:= 1 ->
                    true;
                {ok, {erlang, throw}} when N =:= 1 ->
                    true;
                {ok, {erlang, error}} when N =:= 1 ->
                    true;
                {ok, {erlang, error}} when N =:= 2 ->
                    true;
                {ok, {erlang, fault}} when N =:= 1 ->
                    true;
                {ok, {erlang, fault}} when N =:= 2 ->
                    true;
                _ ->
                    false
            end;
        _ ->
            false
    end.


%% =====================================================================
%% @spec analyze_forms(Forms) -> [{Key, term()}]
%%
%%          Forms = syntaxTree() | [syntaxTree()]
%%          Key = attributes | errors | exports | functions | imports
%%                | module | records | rules | warnings
%%
%% @doc Analyzes a sequence of "program forms". The given
%% `Forms' may be a single syntax tree of type
%% `form_list', or a list of "program form" syntax trees. The
%% returned value is a list of pairs `{Key, Info}', where
%% each value of `Key' occurs at most once in the list; the
%% absence of a particular key indicates that there is no well-defined
%% value for that key.
%%
%% Each entry in the resulting list contains the following
%% corresponding information about the program forms:
%% <dl>
%%     <dt>`{attributes, Attributes}'</dt>
%%       <dd><ul>
%% 	   <li>`Attributes = [{atom(), term()}]'</li>
%%       </ul>
%% 	 `Attributes' is a list of pairs representing the
%% 	 names and corresponding values of all so-called "wild"
%% 	 attributes (as e.g. "`-compile(...)'") occurring in
%% 	 `Forms' (cf. `analyze_wild_attribute/1').
%% 	 We do not guarantee that each name occurs at most once in the
%% 	 list. The order of listing is not defined.</dd>
%%
%%     <dt>`{errors, Errors}'</dt>
%%       <dd><ul>
%% 	   <li>`Errors = [term()]'</li>
%%       </ul>
%% 	 `Errors' is the list of error descriptors of all
%% 	 `error_marker' nodes that occur in
%% 	 `Forms'. The order of listing is not defined.</dd>
%%
%%     <dt>`{exports, Exports}'</dt>
%%       <dd><ul>
%% 	    <li>`Exports = [FunctionName]'</li>
%% 	    <li>`FunctionName = atom()
%%                    | {atom(), integer()}
%% 		      | {ModuleName, FunctionName}'</li>
%% 	    <li>`ModuleName = atom()'</li>
%%       </ul>
%% 	 `Exports' is a list of representations of those
%% 	 function names that are listed by export declaration attributes
%% 	 in `Forms' (cf.
%% 	 `analyze_export_attribute/1'). We do not guarantee
%% 	 that each name occurs at most once in the list. The order of
%% 	 listing is not defined.</dd>
%%
%%     <dt>`{functions, Functions}'</dt>
%%       <dd><ul>
%% 	    <li>`Functions = [{atom(), integer()}]'</li>
%%       </ul>
%% 	 `Functions' is a list of the names of the functions
%% 	 that are defined in `Forms' (cf.
%% 	 `analyze_function/1'). We do not guarantee that each
%% 	 name occurs at most once in the list. The order of listing is
%% 	 not defined.</dd>
%%
%%     <dt>`{imports, Imports}'</dt>
%%       <dd><ul>
%% 	    <li>`Imports = [{Module, Names}]'</li>
%% 	    <li>`Module = atom()'</li>
%% 	    <li>`Names = [FunctionName]'</li>
%% 	    <li>`FunctionName = atom()
%%                    | {atom(), integer()}
%% 		      | {ModuleName, FunctionName}'</li>
%% 	    <li>`ModuleName = atom()'</li>
%%       </ul>
%% 	 `Imports' is a list of pairs representing those
%% 	 module names and corresponding function names that are listed
%% 	 by import declaration attributes in `Forms' (cf.
%% 	 `analyze_import_attribute/1'), where each
%% 	 `Module' occurs at most once in
%% 	 `Imports'. We do not guarantee that each name occurs
%% 	 at most once in the lists of function names. The order of
%% 	 listing is not defined.</dd>
%%
%%     <dt>`{module, ModuleName}'</dt>
%%       <dd><ul>
%% 	    <li>`ModuleName = atom()'</li>
%%       </ul>
%% 	 `ModuleName' is the name declared by a module
%% 	 attribute in `Forms'. If no module name is defined
%% 	 in `Forms', the result will contain no entry for the
%% 	 `module' key. If multiple module name declarations
%% 	 should occur, all but the first will be ignored.</dd>
%%
%%     <dt>`{records, Records}'</dt>
%%       <dd><ul>
%% 	    <li>`Records = [{atom(), Fields}]'</li>
%% 	    <li>`Fields = [{atom(), Default}]'</li>
%% 	    <li>`Default = none | syntaxTree()'</li>
%%       </ul>
%% 	 `Records' is a list of pairs representing the names
%% 	 and corresponding field declarations of all record declaration
%% 	 attributes occurring in `Forms'. For fields declared
%% 	 without a default value, the corresponding value for
%% 	 `Default' is the atom `none' (cf.
%% 	 `analyze_record_attribute/1'). We do not guarantee
%% 	 that each record name occurs at most once in the list. The
%% 	 order of listing is not defined.</dd>
%%
%%     <dt>`{rules, Rules}'</dt>
%%       <dd><ul>
%% 	    <li>`Rules = [{atom(), integer()}]'</li>
%%       </ul>
%% 	 `Rules' is a list of the names of the rules that are
%% 	 defined in `Forms' (cf.
%% 	 `analyze_rule/1'). We do not guarantee that each
%% 	 name occurs at most once in the list. The order of listing is
%% 	 not defined.</dd>
%%
%%     <dt>`{warnings, Warnings}'</dt>
%%       <dd><ul>
%% 	    <li>`Warnings = [term()]'</li>
%%       </ul>
%% 	 `Warnings' is the list of error descriptors of all
%% 	 `warning_marker' nodes that occur in
%% 	 `Forms'. The order of listing is not defined.</dd>
%% </dl>
%%
%% The evaluation throws `syntax_error' if an ill-formed
%% Erlang construct is encountered.
%%
%% @see analyze_wild_attribute/1
%% @see analyze_export_attribute/1
%% @see analyze_import_attribute/1
%% @see analyze_record_attribute/1
%% @see analyze_function/1
%% @see analyze_rule/1
%% @see erl_syntax:error_marker_info/1
%% @see erl_syntax:warning_marker_info/1

-type key() :: 'attributes' | 'errors' | 'exports' | 'functions' | 'imports'
             | 'module' | 'records' | 'rules' | 'warnings'.
-type info_pair() :: {key(), term()}.

-spec analyze_forms(erl_syntax:forms()) -> [info_pair()].

analyze_forms(Forms) when is_list(Forms) ->
    finfo_to_list(lists:foldl(fun collect_form/2, new_finfo(), Forms));
analyze_forms(Forms) ->
    analyze_forms(
      erl_syntax:form_list_elements(
        erl_syntax:flatten_form_list(Forms))).

collect_form(Node, Info) ->
    case analyze_form(Node) of
        {attribute, {Name, Data}} ->
            collect_attribute(Name, Data, Info);
        {attribute, preprocessor} ->
            Info;
        {function, Name} ->
            finfo_add_function(Name, Info);
        {rule, Name} ->
            finfo_add_rule(Name, Info);
        {error_marker, Data} ->
            finfo_add_error(Data, Info);
        {warning_marker, Data} ->
            finfo_add_warning(Data, Info);
        _ ->
            Info
    end.

collect_attribute(module, M, Info) ->
    finfo_set_module(M, Info);
collect_attribute(export, L, Info) ->
    finfo_add_exports(L, Info);
collect_attribute(import, {M, L}, Info) ->
    finfo_add_imports(M, L, Info);
collect_attribute(import, M, Info) ->
    finfo_add_module_import(M, Info);
collect_attribute(file, _, Info) ->
    Info;
collect_attribute(record, {R, L}, Info) ->
    finfo_add_record(R, L, Info);
collect_attribute(spec, _, Info) ->
    Info;
collect_attribute(_, {N, V}, Info) ->
    finfo_add_attribute(N, V, Info).

%% Abstract datatype for collecting module information.

-record(forms, {module, exports, module_imports, imports, attributes,
		records, errors, warnings, functions, rules}).

new_finfo() ->
    #forms{module = none,
           exports = [],
           module_imports = [],
           imports = [],
           attributes = [],
           records = [],
           errors = [],
           warnings = [],
           functions = [],
           rules = []
          }.

finfo_set_module(Name, Info) ->
    case Info#forms.module of
        none ->
            Info#forms{module = {value, Name}};
        {value, _} ->
            Info
    end.

finfo_add_exports(L, Info) ->
    Info#forms{exports = L ++ Info#forms.exports}.

finfo_add_module_import(M, Info) ->
    Info#forms{module_imports = [M | Info#forms.module_imports]}.

finfo_add_imports(M, L, Info) ->
    Es = Info#forms.imports,
    case lists:keyfind(M, 1, Es) of
        {_, L1} ->
            Es1 = lists:keyreplace(M, 1, Es, {M, L ++ L1}),
            Info#forms{imports = Es1};
        false ->
            Info#forms{imports = [{M, L} | Es]}
    end.

finfo_add_attribute(Name, Val, Info) ->
    Info#forms{attributes = [{Name, Val} | Info#forms.attributes]}.

finfo_add_record(R, L, Info) ->
    Info#forms{records = [{R, L} | Info#forms.records]}.

finfo_add_error(R, Info) ->
    Info#forms{errors = [R | Info#forms.errors]}.

finfo_add_warning(R, Info) ->
    Info#forms{warnings = [R | Info#forms.warnings]}.

finfo_add_function(F, Info) ->
    Info#forms{functions = [F | Info#forms.functions]}.

finfo_add_rule(F, Info) ->
    Info#forms{rules = [F | Info#forms.rules]}.

finfo_to_list(Info) ->
    [{Key, Value}
     || {Key, {value, Value}} <-
            [{module, Info#forms.module},
             {exports, list_value(Info#forms.exports)},
             {imports, list_value(Info#forms.imports)},
             {module_imports, list_value(Info#forms.module_imports)},
             {attributes, list_value(Info#forms.attributes)},
             {records, list_value(Info#forms.records)},
             {errors, list_value(Info#forms.errors)},
             {warnings, list_value(Info#forms.warnings)},
             {functions, list_value(Info#forms.functions)},
             {rules, list_value(Info#forms.rules)}
            ]].

list_value([]) ->
    none;
list_value(List) ->
    {value, List}.


%% =====================================================================
%% @spec analyze_form(Node::syntaxTree()) -> {atom(), term()} | atom()
%%
%% @doc Analyzes a "source code form" node. If `Node' is a
%% "form" type (cf. `erl_syntax:is_form/1'), the returned
%% value is a tuple `{Type, Info}' where `Type' is
%% the node type and `Info' depends on `Type', as
%% follows:
%% <dl>
%%   <dt>`{attribute, Info}'</dt>
%%
%%      <dd>where `Info = analyze_attribute(Node)'.</dd>
%%
%%   <dt>`{error_marker, Info}'</dt>
%%
%% 	<dd>where `Info =
%% 	erl_syntax:error_marker_info(Node)'.</dd>
%%
%%   <dt>`{function, Info}'</dt>
%%
%% 	    <dd>where `Info = analyze_function(Node)'.</dd>
%%
%%   <dt>`{rule, Info}'</dt>
%%
%% 	    <dd>where `Info = analyze_rule(Node)'.</dd>
%%
%%   <dt>`{warning_marker, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    erl_syntax:warning_marker_info(Node)'.</dd>
%% </dl>
%% For other types of forms, only the node type is returned.
%%
%% The evaluation throws `syntax_error' if
%% `Node' is not well-formed.
%%
%% @see analyze_attribute/1
%% @see analyze_function/1
%% @see analyze_rule/1
%% @see erl_syntax:is_form/1
%% @see erl_syntax:error_marker_info/1
%% @see erl_syntax:warning_marker_info/1

-spec analyze_form(erl_syntax:syntaxTree()) -> {atom(), term()} | atom().

analyze_form(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            {attribute, analyze_attribute(Node)};
        function ->
            {function, analyze_function(Node)};
        rule ->
            {rule, analyze_rule(Node)};
        error_marker ->
            {error_marker, erl_syntax:error_marker_info(Node)};
        warning_marker ->
            {warning_marker, erl_syntax:warning_marker_info(Node)};
        _ ->
            case erl_syntax:is_form(Node) of
                true ->
                    erl_syntax:type(Node);
                false ->
                    throw(syntax_error)
            end
    end.

%% =====================================================================
%% @spec analyze_attribute(Node::syntaxTree()) ->
%%           preprocessor | {atom(), atom()}
%%
%% @doc Analyzes an attribute node. If `Node' represents a
%% preprocessor directive, the atom `preprocessor' is
%% returned. Otherwise, if `Node' represents a module
%% attribute "`-<em>Name</em>...'", a tuple `{Name,
%% Info}' is returned, where `Info' depends on
%% `Name', as follows:
%% <dl>
%%     <dt>`{module, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    analyze_module_attribute(Node)'.</dd>
%%
%%     <dt>`{export, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    analyze_export_attribute(Node)'.</dd>
%%
%%     <dt>`{import, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    analyze_import_attribute(Node)'.</dd>
%%
%%     <dt>`{file, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    analyze_file_attribute(Node)'.</dd>
%%
%%     <dt>`{record, Info}'</dt>
%%
%% 	    <dd>where `Info =
%% 	    analyze_record_attribute(Node)'.</dd>
%%
%%     <dt>`{Name, Info}'</dt>
%%
%% 	    <dd>where `{Name, Info} =
%% 	    analyze_wild_attribute(Node)'.</dd>
%% </dl>
%% The evaluation throws `syntax_error' if `Node'
%% does not represent a well-formed module attribute.
%%
%% @see analyze_module_attribute/1
%% @see analyze_export_attribute/1
%% @see analyze_import_attribute/1
%% @see analyze_file_attribute/1
%% @see analyze_record_attribute/1
%% @see analyze_wild_attribute/1

-spec analyze_attribute(erl_syntax:syntaxTree()) ->
        'preprocessor' | {atom(), term()}.  % XXX: underspecified

analyze_attribute(Node) ->
    Name = erl_syntax:attribute_name(Node),
    case erl_syntax:type(Name) of
        atom ->
            case erl_syntax:atom_value(Name) of
                define -> preprocessor;
                undef -> preprocessor;
                include -> preprocessor;
                include_lib -> preprocessor;
                ifdef -> preprocessor;
                ifndef -> preprocessor;
                else -> preprocessor;
                endif -> preprocessor;
                A ->
                    {A, analyze_attribute(A, Node)}
            end;
        _ ->
            throw(syntax_error)
    end.

analyze_attribute(module, Node) ->
    analyze_module_attribute(Node);
analyze_attribute(export, Node) ->
    analyze_export_attribute(Node);
analyze_attribute(import, Node) ->
    analyze_import_attribute(Node);
analyze_attribute(file, Node) ->
    analyze_file_attribute(Node);
analyze_attribute(record, Node) ->
    analyze_record_attribute(Node);
analyze_attribute(define, _Node) ->
    define;
analyze_attribute(spec, _Node) ->
    spec;
analyze_attribute(_, Node) ->
    %% A "wild" attribute (such as e.g. a `compile' directive).
    analyze_wild_attribute(Node).


%% =====================================================================
%% @spec analyze_module_attribute(Node::syntaxTree()) ->
%%           Name::atom() | {Name::atom(), Variables::[atom()]}
%%
%% @doc Returns the module name and possible parameters declared by a
%% module attribute. If the attribute is a plain module declaration such
%% as `-module(name)', the result is the module name. If the attribute
%% is a parameterized module declaration, the result is a tuple
%% containing the module name and a list of the parameter variable
%% names.
%%
%% The evaluation throws `syntax_error' if `Node' does not represent a
%% well-formed module attribute.
%%
%% @see analyze_attribute/1

-spec analyze_module_attribute(erl_syntax:syntaxTree()) ->
        atom() | {atom(), [atom()]}.

analyze_module_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            case erl_syntax:attribute_arguments(Node) of
                [M] ->
                    module_name_to_atom(M);
                [M, L] ->
		    M1 = module_name_to_atom(M),
		    L1 = analyze_variable_list(L),
		    {M1, L1};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.

analyze_variable_list(Node) ->
    case erl_syntax:is_proper_list(Node) of
        true ->
            [erl_syntax:variable_name(V)
	     || V <- erl_syntax:list_elements(Node)];
        false ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_export_attribute(Node::syntaxTree()) -> [FunctionName]
%%
%%          FunctionName = atom() | {atom(), integer()}
%%                       | {ModuleName, FunctionName}
%%          ModuleName = atom()
%%
%% @doc Returns the list of function names declared by an export
%% attribute. We do not guarantee that each name occurs at most once in
%% the list. The order of listing is not defined.
%%
%% The evaluation throws `syntax_error' if `Node' does not represent a
%% well-formed export attribute.
%%
%% @see analyze_attribute/1

-type functionN()    :: atom() | {atom(), arity()}.
-type functionName() :: functionN() | {atom(), functionN()}.

-spec analyze_export_attribute(erl_syntax:syntaxTree()) -> [functionName()].

analyze_export_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            case erl_syntax:attribute_arguments(Node) of
                [L] ->
                    analyze_function_name_list(L);
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.

analyze_function_name_list(Node) ->
    case erl_syntax:is_proper_list(Node) of
        true ->
            [analyze_function_name(F)
             || F <- erl_syntax:list_elements(Node)];
        false ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_function_name(Node::syntaxTree()) -> FunctionName
%%
%%          FunctionName = atom() | {atom(), integer()}
%%                       | {ModuleName, FunctionName}
%%          ModuleName = atom()
%%
%% @doc Returns the function name represented by a syntax tree. If
%% `Node' represents a function name, such as
%% "`foo/1'" or "`bloggs:fred/2'", a uniform
%% representation of that name is returned. Different nestings of arity
%% and module name qualifiers in the syntax tree does not affect the
%% result.
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed function name.

-spec analyze_function_name(erl_syntax:syntaxTree()) -> functionName().

analyze_function_name(Node) ->
    case erl_syntax:type(Node) of
        atom ->
            erl_syntax:atom_value(Node);
        arity_qualifier ->
            A = erl_syntax:arity_qualifier_argument(Node),
            case erl_syntax:type(A) of
                integer ->
                    F = erl_syntax:arity_qualifier_body(Node),
                    F1 = analyze_function_name(F),
                    append_arity(erl_syntax:integer_value(A), F1);
                _ ->
                    throw(syntax_error)
            end;
        module_qualifier ->
            M = erl_syntax:module_qualifier_argument(Node),
            case erl_syntax:type(M) of
                atom ->
                    F = erl_syntax:module_qualifier_body(Node),
                    F1 = analyze_function_name(F),
                    {erl_syntax:atom_value(M), F1};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.

append_arity(A, {Module, Name}) ->
    {Module, append_arity(A, Name)};
append_arity(A, Name) when is_atom(Name) ->
    {Name, A};
append_arity(A, A) ->
    A;
append_arity(_A, Name) ->
    Name.    % quietly drop extra arity in case of conflict


%% =====================================================================
%% @spec analyze_import_attribute(Node::syntaxTree()) ->
%%           {atom(), [FunctionName]} | atom()
%%
%%          FunctionName = atom() | {atom(), integer()}
%%                       | {ModuleName, FunctionName}
%%          ModuleName = atom()
%%
%% @doc Returns the module name and (if present) list of function names
%% declared by an import attribute. The returned value is an atom
%% `Module' or a pair `{Module, Names}', where
%% `Names' is a list of function names declared as imported
%% from the module named by `Module'. We do not guarantee
%% that each name occurs at most once in `Names'. The order
%% of listing is not defined.
%%
%% The evaluation throws `syntax_error' if `Node' does not represent a
%% well-formed import attribute.
%%
%% @see analyze_attribute/1

-spec analyze_import_attribute(erl_syntax:syntaxTree()) ->
        {atom(), [functionName()]} | atom().

analyze_import_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            case erl_syntax:attribute_arguments(Node) of
		[M] ->
		    module_name_to_atom(M);
		[M, L] ->
		    M1 = module_name_to_atom(M),
		    L1 = analyze_function_name_list(L),
		    {M1, L1};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_wild_attribute(Node::syntaxTree()) -> {atom(), term()}
%%
%% @doc Returns the name and value of a "wild" attribute. The result is
%% the pair `{Name, Value}', if `Node' represents "`-Name(Value)'".
%%
%% Note that no checking is done whether `Name' is a
%% reserved attribute name such as `module' or
%% `export': it is assumed that the attribute is "wild".
%%
%% The evaluation throws `syntax_error' if `Node' does not represent a
%% well-formed wild attribute.
%%
%% @see analyze_attribute/1

-spec analyze_wild_attribute(erl_syntax:syntaxTree()) -> {atom(), term()}.

analyze_wild_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            N = erl_syntax:attribute_name(Node),
            case erl_syntax:type(N) of
                atom ->
                    case erl_syntax:attribute_arguments(Node) of
                        [V] ->
			    case catch {ok, erl_syntax:concrete(V)} of
				{ok, Val} ->
				    {erl_syntax:atom_value(N), Val};
				_ ->
				    throw(syntax_error)
			    end;
                        _ ->
                            throw(syntax_error)
                    end;
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_record_attribute(Node::syntaxTree()) ->
%%           {atom(), Fields}
%%
%%          Fields = [{atom(), none | syntaxTree()}]
%%
%% @doc Returns the name and the list of fields of a record declaration
%% attribute. The result is a pair `{Name, Fields}', if
%% `Node' represents "`-record(Name, {...}).'",
%% where `Fields' is a list of pairs `{Label,
%% Default}' for each field "`Label'" or "`Label =
%% <em>Default</em>'" in the declaration, listed in left-to-right
%% order. If the field has no default-value declaration, the value for
%% `Default' will be the atom `none'. We do not
%% guarantee that each label occurs at most one in the list.
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed record declaration
%% attribute.
%%
%% @see analyze_attribute/1
%% @see analyze_record_field/1

-type fields() :: [{atom(), 'none' | erl_syntax:syntaxTree()}].

-spec analyze_record_attribute(erl_syntax:syntaxTree()) -> {atom(), fields()}.

analyze_record_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            case erl_syntax:attribute_arguments(Node) of
                [R, T] ->
                    case erl_syntax:type(R) of
                        atom ->
                            Es = analyze_record_attribute_tuple(T),
                            {erl_syntax:atom_value(R), Es};
                        _ ->
                            throw(syntax_error)
                    end;
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.

analyze_record_attribute_tuple(Node) ->
    case erl_syntax:type(Node) of
        tuple ->
            [analyze_record_field(F)
	     || F <- erl_syntax:tuple_elements(Node)];
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_record_expr(Node::syntaxTree()) ->
%%     {atom(), Info} | atom()
%%
%%    Info = {atom(), [{atom(), Value}]} | {atom(), atom()} | atom()
%%    Value = none | syntaxTree()
%%
%% @doc Returns the record name and field name/names of a record
%% expression. If `Node' has type `record_expr',
%% `record_index_expr' or `record_access', a pair
%% `{Type, Info}' is returned, otherwise an atom
%% `Type' is returned. `Type' is the node type of
%% `Node', and `Info' depends on
%% `Type', as follows:
%% <dl>
%%   <dt>`record_expr':</dt>
%%     <dd>`{atom(), [{atom(), Value}]}'</dd>
%%   <dt>`record_access':</dt>
%%     <dd>`{atom(), atom()} | atom()'</dd>
%%   <dt>`record_index_expr':</dt>
%%     <dd>`{atom(), atom()}'</dd>
%% </dl>
%%
%% For a `record_expr' node, `Info' represents
%% the record name and the list of descriptors for the involved fields,
%% listed in the order they appear. (See
%% `analyze_record_field/1' for details on the field
%% descriptors). For a `record_access' node,
%% `Info' represents the record name and the field name (or
%% if the record name is not included, only the field name; this is
%% allowed only in Mnemosyne-query syntax). For a
%% `record_index_expr' node, `Info' represents the
%% record name and the name field name.
%%
%% The evaluation throws `syntax_error' if
%% `Node' represents a record expression that is not
%% well-formed.
%%
%% @see analyze_record_attribute/1
%% @see analyze_record_field/1

-type info() :: {atom(), [{atom(), 'none' | erl_syntax:syntaxTree()}]}
              | {atom(), atom()} | atom().

-spec analyze_record_expr(erl_syntax:syntaxTree()) -> {atom(), info()} | atom().

analyze_record_expr(Node) ->
    case erl_syntax:type(Node) of
	record_expr ->
            A = erl_syntax:record_expr_type(Node),
            case erl_syntax:type(A) of
                atom ->
                    Fs = [analyze_record_field(F)
			  || F <- erl_syntax:record_expr_fields(Node)],
                    {record_expr, {erl_syntax:atom_value(A), Fs}};
                _ ->
                    throw(syntax_error)
            end;
	record_access ->
	    F = erl_syntax:record_access_field(Node),
	    case erl_syntax:type(F) of
		atom ->
		    case erl_syntax:record_access_type(Node) of
			none ->
			    {record_access, erl_syntax:atom_value(F)};
			A ->
			    case erl_syntax:type(A) of
				atom ->
				    {record_access,
				     {erl_syntax:atom_value(A),
				      erl_syntax:atom_value(F)}};
				_ ->
				    throw(syntax_error)
			    end
		    end;
		_ ->
		    throw(syntax_error)
	    end;
	record_index_expr ->
	    F = erl_syntax:record_index_expr_field(Node),
	    case erl_syntax:type(F) of
		atom ->
		    A = erl_syntax:record_index_expr_type(Node),
		    case erl_syntax:type(A) of
			atom ->
			    {record_index_expr,
			     {erl_syntax:atom_value(A),
			      erl_syntax:atom_value(F)}};
			_ ->
			    throw(syntax_error)
		    end;
		_ ->
		    throw(syntax_error)
	    end;
	Type ->
	    Type
    end.

%% =====================================================================
%% @spec analyze_record_field(Node::syntaxTree()) -> {atom(), Value}
%%
%%          Value = none | syntaxTree()
%%
%% @doc Returns the label and value-expression of a record field
%% specifier. The result is a pair `{Label, Value}', if
%% `Node' represents "`Label = <em>Value</em>'" or
%% "`Label'", where in the first case, `Value' is
%% a syntax tree, and in the second case `Value' is
%% `none'.
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed record field
%% specifier.
%%
%% @see analyze_record_attribute/1
%% @see analyze_record_expr/1

-spec analyze_record_field(erl_syntax:syntaxTree()) ->
        {atom(), 'none' | erl_syntax:syntaxTree()}.

analyze_record_field(Node) ->
    case erl_syntax:type(Node) of
        record_field ->
            A = erl_syntax:record_field_name(Node),
            case erl_syntax:type(A) of
                atom ->
                    T = erl_syntax:record_field_value(Node),
                    {erl_syntax:atom_value(A), T};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_file_attribute(Node::syntaxTree()) ->
%%           {string(), integer()}
%%
%% @doc Returns the file name and line number of a `file'
%% attribute. The result is the pair `{File, Line}' if
%% `Node' represents "`-file(File, Line).'".
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed `file'
%% attribute.
%%
%% @see analyze_attribute/1

-spec analyze_file_attribute(erl_syntax:syntaxTree()) -> {string(), integer()}.

analyze_file_attribute(Node) ->
    case erl_syntax:type(Node) of
        attribute ->
            case erl_syntax:attribute_arguments(Node) of
                [F, N] ->
                    case (erl_syntax:type(F) =:= string)
                        and (erl_syntax:type(N) =:= integer) of
                        true ->
                            {erl_syntax:string_value(F),
                             erl_syntax:integer_value(N)};
                        false ->
                            throw(syntax_error)
                    end;
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_function(Node::syntaxTree()) -> {atom(), integer()}
%%
%% @doc Returns the name and arity of a function definition. The result
%% is a pair `{Name, A}' if `Node' represents a
%% function definition "`Name(<em>P_1</em>, ..., <em>P_A</em>) ->
%% ...'".
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed function
%% definition.
%%
%% @see analyze_rule/1

-spec analyze_function(erl_syntax:syntaxTree()) -> {atom(), arity()}.

analyze_function(Node) ->
    case erl_syntax:type(Node) of
        function ->
            N = erl_syntax:function_name(Node),
            case erl_syntax:type(N) of
                atom ->
                    {erl_syntax:atom_value(N),
                     erl_syntax:function_arity(Node)};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_rule(Node::syntaxTree()) -> {atom(), integer()}
%%
%% @doc Returns the name and arity of a Mnemosyne rule. The result is a
%% pair `{Name, A}' if `Node' represents a rule
%% "`Name(<em>P_1</em>, ..., <em>P_A</em>) :- ...'".
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed Mnemosyne
%% rule.
%%
%% @see analyze_function/1

-spec analyze_rule(erl_syntax:syntaxTree()) -> {atom(), arity()}.

analyze_rule(Node) ->
    case erl_syntax:type(Node) of
        rule ->
            N = erl_syntax:rule_name(Node),
            case erl_syntax:type(N) of
                atom ->
                    {erl_syntax:atom_value(N),
                     erl_syntax:rule_arity(Node)};
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_implicit_fun(Node::syntaxTree()) -> FunctionName
%%
%%          FunctionName = atom() | {atom(), integer()}
%%                       | {ModuleName, FunctionName}
%%          ModuleName = atom()
%%      
%% @doc Returns the name of an implicit fun expression "`fun
%% <em>F</em>'". The result is a representation of the function
%% name `F'. (Cf. `analyze_function_name/1'.)
%%
%% The evaluation throws `syntax_error' if
%% `Node' does not represent a well-formed implicit fun.
%%
%% @see analyze_function_name/1

-spec analyze_implicit_fun(erl_syntax:syntaxTree()) -> functionName().

analyze_implicit_fun(Node) ->
    case erl_syntax:type(Node) of
        implicit_fun ->
            analyze_function_name(erl_syntax:implicit_fun_name(Node));
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec analyze_application(Node::syntaxTree()) -> FunctionName | Arity
%%
%%          FunctionName = {atom(), Arity}
%%                       | {ModuleName, FunctionName}
%%          Arity = integer()
%%          ModuleName = atom()
%%
%% @doc Returns the name of a called function. The result is a
%% representation of the name of the applied function `F/A',
%% if `Node' represents a function application
%% "`<em>F</em>(<em>X_1</em>, ..., <em>X_A</em>)'". If the
%% function is not explicitly named (i.e., `F' is given by
%% some expression), only the arity `A' is returned.
%%
%% The evaluation throws `syntax_error' if `Node' does not represent a
%% well-formed application expression.
%%
%% @see analyze_function_name/1

-type appFunName() :: {atom(), arity()} | {atom(), {atom(), arity()}}.

-spec analyze_application(erl_syntax:syntaxTree()) -> appFunName() | arity().

analyze_application(Node) ->
    case erl_syntax:type(Node) of
        application ->
            A = length(erl_syntax:application_arguments(Node)),
            F = erl_syntax:application_operator(Node),
            case catch {ok, analyze_function_name(F)} of
                syntax_error ->
                    A;
                {ok, N} ->
                    append_arity(A, N);
                _ ->
                    throw(syntax_error)
            end;
        _ ->
            throw(syntax_error)
    end.


%% =====================================================================
%% @spec function_name_expansions(Names::[Name]) -> [{ShortName, Name}]
%%
%%          Name = ShortName | {atom(), Name}
%%          ShortName = atom() | {atom(), integer()}
%%
%% @doc Creates a mapping from corresponding short names to full
%% function names. Names are represented by nested tuples of atoms and
%% integers (cf. `analyze_function_name/1'). The result is a
%% list containing a pair `{ShortName, Name}' for each
%% element `Name' in the given list, where the corresponding
%% `ShortName' is the rightmost-innermost part of
%% `Name'. The list thus represents a finite mapping from
%% unqualified names to the corresponding qualified names.
%%
%% Note: the resulting list can contain more than one tuple
%% `{ShortName, Name}' for the same `ShortName',
%% possibly with different values for `Name', depending on
%% the given list.
%%
%% @see analyze_function_name/1

-type shortname() :: atom() | {atom(), arity()}.
-type name()      :: shortname() | {atom(), shortname()}.

-spec function_name_expansions([name()]) -> [{shortname(), name()}].

function_name_expansions(Fs) ->
    function_name_expansions(Fs, []).

function_name_expansions([F | Fs], Ack) ->
    function_name_expansions(Fs,
                             function_name_expansions(F, F, Ack));
function_name_expansions([], Ack) ->
    Ack.

function_name_expansions({A, N}, Name, Ack) when is_integer(N) ->
    [{{A, N}, Name} | Ack];
function_name_expansions({_, N}, Name, Ack) ->
    function_name_expansions(N, Name,  Ack);
function_name_expansions(A, Name, Ack) ->
    [{A, Name} | Ack].


%% =====================================================================
%% @spec strip_comments(Tree::syntaxTree()) -> syntaxTree()
%%
%% @doc Removes all comments from all nodes of a syntax tree. All other
%% attributes (such as position information) remain unchanged.
%% Standalone comments in form lists are removed; any other standalone
%% comments are changed into null-comments (no text, no indentation).

-spec strip_comments(erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree().

strip_comments(Tree) ->
    map(fun strip_comments_1/1, Tree).

strip_comments_1(T) ->
    case erl_syntax:type(T) of
	form_list ->
	    Es = erl_syntax:form_list_elements(T),
	    Es1 = [E || E <- Es, erl_syntax:type(E) /= comment],
	    T1 = erl_syntax:copy_attrs(T, erl_syntax:form_list(Es1)),
	    erl_syntax:remove_comments(T1);
	comment ->
	    erl_syntax:comment([]);
	_ ->
	    erl_syntax:remove_comments(T)
    end.

%% =====================================================================
%% @spec to_comment(Tree) -> syntaxTree()
%% @equiv to_comment(Tree, "% ")

-spec to_comment(erl_syntax:syntaxTree()) -> erl_syntax:syntaxTree().

to_comment(Tree) ->
    to_comment(Tree, "% ").

%% =====================================================================
%% @spec to_comment(Tree::syntaxTree(), Prefix::string()) ->
%%           syntaxTree()
%%
%% @doc Equivalent to `to_comment(Tree, Prefix, F)' for a
%% default formatting function `F'. The default
%% `F' simply calls `erl_prettypr:format/1'.
%%
%% @see to_comment/3
%% @see erl_prettypr:format/1

-spec to_comment(erl_syntax:syntaxTree(), string()) -> erl_syntax:syntaxTree().

to_comment(Tree, Prefix) ->
    F = fun (T) -> erl_prettypr:format(T) end,
    to_comment(Tree, Prefix, F).

%% =====================================================================
%% @spec to_comment(Tree::syntaxTree(), Prefix::string(), Printer) ->
%%           syntaxTree()
%%
%%          Printer = (syntaxTree()) -> string()
%%
%% @doc Transforms a syntax tree into an abstract comment. The lines of
%% the comment contain the text for `Node', as produced by
%% the given `Printer' function. Each line of the comment is
%% prefixed by the string `Prefix' (this does not include the
%% initial "`%'" character of the comment line).
%%
%% For example, the result of
%% `to_comment(erl_syntax:abstract([a,b,c]))' represents
%% <pre>
%%         %% [a,b,c]</pre>
%% (cf. `to_comment/1').
%%
%% Note: the text returned by the formatting function will be split
%% automatically into separate comment lines at each line break. No
%% extra work is needed.
%%
%% @see to_comment/1
%% @see to_comment/2

-spec to_comment(erl_syntax:syntaxTree(), string(),
		 fun((erl_syntax:syntaxTree()) -> string())) ->
        erl_syntax:syntaxTree().

to_comment(Tree, Prefix, F) ->
    erl_syntax:comment(split_lines(F(Tree), Prefix)).


%% =====================================================================
%% @spec limit(Tree, Depth) -> syntaxTree()
%%
%% @doc Equivalent to `limit(Tree, Depth, Text)' using the
%% text `"..."' as default replacement.
%%
%% @see limit/3
%% @see erl_syntax:text/1

-spec limit(erl_syntax:syntaxTree(), integer()) -> erl_syntax:syntaxTree().

limit(Tree, Depth) ->
    limit(Tree, Depth, erl_syntax:text("...")).

%% =====================================================================
%% @spec limit(Tree::syntaxTree(), Depth::integer(),
%%             Node::syntaxTree()) -> syntaxTree()
%%
%% @doc Limits a syntax tree to a specified depth. Replaces all non-leaf
%% subtrees in `Tree' at the given `Depth' by
%% `Node'. If `Depth' is negative, the result is
%% always `Node', even if `Tree' has no subtrees.
%%
%% When a group of subtrees (as e.g., the argument list of an
%% `application' node) is at the specified depth, and there
%% are two or more subtrees in the group, these will be collectively
%% replaced by `Node' even if they are leaf nodes. Groups of
%% subtrees that are above the specified depth will be limited in size,
%% as if each subsequent tree in the group were one level deeper than
%% the previous. E.g., if `Tree' represents a list of
%% integers "`[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]'", the result
%% of `limit(Tree, 5)' will represent `[1, 2, 3, 4,
%% ...]'.
%%
%% The resulting syntax tree is typically only useful for
%% pretty-printing or similar visual formatting.
%%
%% @see limit/2

-spec limit(erl_syntax:syntaxTree(), integer(), erl_syntax:syntaxTree()) ->
        erl_syntax:syntaxTree().

limit(_Tree, Depth, Node) when Depth < 0 ->
    Node;
limit(Tree, Depth, Node) ->
    limit_1(Tree, Depth, Node).

limit_1(Tree, Depth, Node) ->
    %% Depth is nonnegative here.
    case erl_syntax:subtrees(Tree) of
        [] ->
            if Depth > 0 ->
                    Tree;
               true ->
                    case is_simple_leaf(Tree) of
                        true ->
                            Tree;
                        false ->
                            Node
                    end
            end;
        Gs ->
            if Depth > 1 ->
                    Gs1 = [[limit_1(T, Depth - 1, Node)
                            || T <- limit_list(G, Depth, Node)]
                           || G <- Gs],
                    rewrite(Tree,
                            erl_syntax:make_tree(erl_syntax:type(Tree),
                                                 Gs1));
               Depth =:= 0 ->
                    %% Depth is zero, and this is not a leaf node
                    %% so we always replace it.
                    Node;
               true ->
                    %% Depth is 1, so all subtrees are to be cut.
                    %% This is done groupwise.
                    Gs1 = [cut_group(G, Node) || G <- Gs],
                    rewrite(Tree,
                            erl_syntax:make_tree(erl_syntax:type(Tree),
                                                 Gs1))
            end
    end.

cut_group([], _Node) ->
    [];
cut_group([T], Node) ->
    %% Only if the group contains a single subtree do we try to
    %% preserve it if suitable.
    [limit_1(T, 0, Node)];
cut_group(_Ts, Node) ->
    [Node].

is_simple_leaf(Tree) ->
    case erl_syntax:type(Tree) of
        atom -> true;
        char -> true;
        float -> true;
        integer -> true;
        nil -> true;
        operator -> true;
        tuple -> true;
        underscore -> true;
        variable -> true;
        _ -> false
    end.

%% If list has more than N elements, take the N - 1 first and
%% append Node; otherwise return list as is.

limit_list(Ts, N, Node) ->
    if length(Ts) > N ->
            limit_list_1(Ts, N - 1, Node);
       true ->
            Ts
    end.

limit_list_1([T | Ts], N, Node) ->
    if N > 0 ->
            [T | limit_list_1(Ts, N - 1, Node)];
       true ->
            [Node]
    end;
limit_list_1([], _N, _Node) ->
    [].


%% =====================================================================
%% Utility functions

rewrite(Tree, Tree1) ->
    erl_syntax:copy_attrs(Tree, Tree1).

module_name_to_atom(M) ->
    case erl_syntax:type(M) of
	atom ->
	    erl_syntax:atom_value(M);
	qualified_name ->
	    list_to_atom(packages:concat(
			   [erl_syntax:atom_value(A)
			    || A <- erl_syntax:qualified_name_segments(M)])
			);
	_ ->
	    throw(syntax_error)
    end.

%% This splits lines at line terminators and expands tab characters to
%% spaces. The width of a tab is assumed to be 8.

% split_lines(Cs) ->
%     split_lines(Cs, "").

split_lines(Cs, Prefix) ->
    split_lines(Cs, Prefix, 0).

split_lines(Cs, Prefix, N) ->
    lists:reverse(split_lines(Cs, N, [], [], Prefix)).

split_lines([$\r, $\n | Cs], _N, Cs1, Ls, Prefix) ->
    split_lines_1(Cs, Cs1, Ls, Prefix);
split_lines([$\r | Cs], _N, Cs1, Ls, Prefix) ->
    split_lines_1(Cs, Cs1, Ls, Prefix);
split_lines([$\n | Cs], _N, Cs1, Ls, Prefix) ->
    split_lines_1(Cs, Cs1, Ls, Prefix);
split_lines([$\t | Cs], N, Cs1, Ls, Prefix) ->
    split_lines(Cs, 0, push(8 - (N rem 8), $\040, Cs1), Ls,
                Prefix);
split_lines([C | Cs], N, Cs1, Ls, Prefix) ->
    split_lines(Cs, N + 1, [C | Cs1], Ls, Prefix);
split_lines([], _, [], Ls, _) ->
    Ls;
split_lines([], _N, Cs, Ls, Prefix) ->
    [Prefix ++ lists:reverse(Cs) | Ls].

split_lines_1(Cs, Cs1, Ls, Prefix) ->
    split_lines(Cs, 0, [], [Prefix ++ lists:reverse(Cs1) | Ls],
                Prefix).

push(N, C, Cs) when N > 0 ->
    push(N - 1, C, [C | Cs]);
push(0, _, Cs) ->
    Cs.