Merge pull request #2836 from triska/format_floats

Correct handling of floats in format/2 and portray_clause/1

src/lib/format.pl

@@ -285,36 +285,12 @@ cells([~|Fs0], Args0, Tab, Es, VNs) -->
         cells(Fs, Args, 0, [], VNs).
 cells([~,s|Fs], [Arg|Args], Tab, Es, VNs) --> !,
         cells(Fs, Args, Tab, [chars(Arg)|Es], VNs).
-cells([~,f|Fs], [Arg|Args], Tab, Es, VNs) --> !,
+cells([~,f|Fs], Args, Tab, Es, VNs) --> !,
-        { G = format_number_chars(Arg, Chars) },
+        cells([~,'6',f|Fs], Args, Tab, Es, VNs).
-        cells(Fs, Args, Tab, [chars(Chars),goal(G)|Es], VNs).
 cells([~|Fs0], Args0, Tab, Es, VNs) -->
         { numeric_argument(Fs0, Num, [f|Fs], Args0, [Arg|Args]) },
         !,
-        { G = (format_number_chars(Arg, Cs0),
+        { G = phrase(float_with_n_decimal_digits(Arg, Num), Chars) },
-               phrase(upto_what(Bs, .), Cs0, Cs),
-               (   Num =:= 0 -> Chars = Bs
-               ;   (   Cs = ['.'|Rest] ->
-                       length(Rest, L),
-                       (   Num < L ->
-                           length(Ds, Num),
-                           append(Ds, _, Rest)
-                       ;   Num =:= L ->
-                           Ds = Rest
-                       ;   Num > L,
-                           Delta is Num - L,
-                           % we should look into the float with
-                           % greater accuracy here, and use the
-                           % actual digits instead of 0.
-                           length(Zs, Delta),
-                           maplist(=('0'), Zs),
-                           append(Rest, Zs, Ds)
-                       )
-                   ;   length(Ds, Num),
-                       maplist(=('0'), Ds)
-                   ),
-                   append(Bs, ['.'|Ds], Chars)
-               )) },
         cells(Fs, Args, Tab, [chars(Chars),goal(G)|Es], VNs).
 cells([~,r|Fs], Args, Tab, Es, VNs) --> !,
         cells([~,'8',r|Fs], Args, Tab, Es, VNs).
@@ -369,9 +345,18 @@ cells(Fs0, Args, Tab, Es, VNs) -->
           Fs1 = [_|_] },
         cells(Fs, Args, Tab, [chars(Fs1)|Es], VNs).
 
-format_number_chars(N0, Chars) :-
+float_with_n_decimal_digits(F, N) -->
-        N is N0, % evaluate compound expression
+   {  Fr is abs(float_fractional_part(F)),
-        number_chars(N, Chars).
+      FrR0 is round(Fr*10^N),
+      I0 is truncate(F),
+      (  FrR0 >= 10^N
+      -> I is I0+truncate(sign(F)), FrR = FrR0
+      ;  I = I0, FrR is FrR0+10^N
+      )
+   },
+   ( { I=0, F<0, FrR>10^N } -> "-0" ; { number_chars(I, Is) }, seq(Is) ),
+   ".",
+   ( { FrR = 1 } -> "0" ; { number_chars(FrR, ['1'|FrRs]) }, seq(FrRs) ).
 
 n_newlines(N0) --> { N0 > 0, N is N0 - 1 }, [newline], n_newlines(N).
 n_newlines(0)  --> [].
@@ -595,6 +580,7 @@ portray_clause_(Term) -->
 literal(Lit, VNs) -->
         { write_term_to_chars(Lit, [quoted(true),variable_names(VNs),double_quotes(true)], Ls) },
         (   { nonvar(Lit),
+              \+ number(Lit),
               functor(Lit, F, A),
               current_op(Pri, _, F),
               (   A =:= 0