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ENHANCED: more readable indentation of nested ( If -> Then ; Else ) constructs

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Example:

    ?- portray_clause((h :- ( a -> b ; c -> d ; e, f))).
    h :-
       (  a ->
          b
       ;  c ->
          d
       ;  e,
          f
       ).
       true.
This commit is contained in:
Markus Triska
2021-03-03 22:04:28 +01:00
parent d3612e956e
commit 6477d21e24
1 changed files with 19 additions and 7 deletions
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24
src/lib/format.pl
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@@ -494,8 +494,8 @@ body_(Var, C, I, VNs) --> { var(Var) }, !,
body_((A,B), C, I, VNs) --> !,
body_(A, C, I, VNs), ",\n",
body_(B, 0, I, VNs).
body_((A ; Else), C, I, VNs) --> % ( If -> Then ; Else )
{ nonvar(A), A = (If -> Then) },
body_(Body, C, I, VNs) -->
{ body_if_then_else(Body, If, Then, Else) },
!,
indent_to(C, I),
"( ",
@@ -513,16 +513,28 @@ body_(Goal, C, I, VNs) -->
indent_to(C, I), literal(Goal, VNs).
% True iff Body has the shape ( If -> Then ; Else ).
body_if_then_else(Body, If, Then, Else) :-
nonvar(Body),
Body = (A ; Else),
nonvar(A),
A = (If -> Then).
else_branch(Else, C, I, VNs) -->
indent_to(0, I),
"; ",
body_(Else, C, C, VNs), "\n",
( { body_if_then_else(Else, If, Then, NextElse) } ->
{ C1 is I + 3 },
body_(If, C1, C1, VNs), " ->\n",
body_(Then, 0, C1, VNs), "\n",
else_branch(NextElse, C1, I, VNs)
; body_(Else, C, C, VNs), "\n",
indent_to(0, I),
")".
")"
).
indent_to(CurrentColumn, Indent) -->
{ Delta is Indent - CurrentColumn },
format_("~t~*|", [Delta]).
format_("~t~*|", [Indent-CurrentColumn]).
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
?- portray_clause(a).