From: Jon Harper <jon.harper87@gmail.com>
Date: Sun, 26 Feb 2017 15:55:49 +0000 (+0100)
Subject: formatting: don't force the presence of ".0" for %f and %e when precision is 0
X-Git-Tag: 0.98~834
X-Git-Url: https://gitweb.factorcode.org/gitweb.cgi?p=factor.git;a=commitdiff_plain;h=552791d1cf959e7f6035f43f58c6caf176ba2bc9

formatting: don't force the presence of ".0" for %f and %e when precision is 0

It's misleading because you can think you have more precision than you really
do when looking at the output. So instead of "1.0", we can format it as "1" or
"1.".  And instead of "1.0e+00" we can format "1e+00" or "1.e+00".  In C,
printf does not print the radix character, it's prettier. But since the factor
parser accepts both styles, and keeping the radix character gives a stronger sense
that the number is approximate, I prefer to keep the radix character..
---

diff --git a/basis/formatting/formatting-tests.factor b/basis/formatting/formatting-tests.factor
index b3e503fd3a..d01b4f6336 100755
--- a/basis/formatting/formatting-tests.factor
+++ b/basis/formatting/formatting-tests.factor
@@ -35,8 +35,10 @@ IN: formatting.tests
 { "100000000000000000000000.000000" } [ 23 10^ "%f" sprintf ] unit-test
 { "1.2" } [ 125/100 "%.1f" sprintf ] unit-test
 { "1.4" } [ 135/100 "%.1f" sprintf ] unit-test
-{ "2.0" } [ 5/2 "%.0f" sprintf ] unit-test
-{ "4.0" } [ 7/2 "%.0f" sprintf ] unit-test
+{ "2." } [ 5/2 "%.0f" sprintf ] unit-test
+{ "4." } [ 7/2 "%.0f" sprintf ] unit-test
+{ "2.e+00" } [ 5/2 "%.0e" sprintf ] unit-test
+{ "4.e+00" } [ 7/2 "%.0e" sprintf ] unit-test
 { "  1.23" } [ 1.23456789 "%6.2f" sprintf ] unit-test
 { "001100" } [ 12 "%06b" sprintf ] unit-test
 { "==14" } [ 12 "%'=4o" sprintf ] unit-test
@@ -85,6 +87,30 @@ IN: formatting.tests
 { "-9007199254740992.0" } [ 53 2^ neg "%.1f" sprintf ] unit-test
 { "-9007199254740993.0" } [ 53 2^ 1 + neg "%.1f" sprintf ] unit-test
 
+{ "987654321098765432" } [ 987654321098765432 "%d" sprintf ] unit-test
+{ "987654321098765432.0" } [ 987654321098765432 "%.1f" sprintf ] unit-test
+{ "987654321098765432." } [ 987654321098765432 "%.0f" sprintf ] unit-test
+{ "9.8765432109876543200e+17" } [ 987654321098765432 "%.19e" sprintf ] unit-test
+{ "9.876543210987654320e+17" } [ 987654321098765432 "%.18e" sprintf ] unit-test
+{ "9.87654321098765432e+17" } [ 987654321098765432 "%.17e" sprintf ] unit-test
+{ "9.8765432109876543e+17" } [ 987654321098765432 "%.16e" sprintf ] unit-test
+{ "9.876543210987654e+17" } [ 987654321098765432 "%.15e" sprintf ] unit-test
+{ "9.87654321098765e+17" } [ 987654321098765432 "%.14e" sprintf ] unit-test
+{ "9.8765432109877e+17" } [ 987654321098765432 "%.13e" sprintf ] unit-test
+{ "9.876543210988e+17" } [ 987654321098765432 "%.12e" sprintf ] unit-test
+{ "9.87654321099e+17" } [ 987654321098765432 "%.11e" sprintf ] unit-test
+{ "9.8765432110e+17" } [ 987654321098765432 "%.10e" sprintf ] unit-test
+{ "9.876543211e+17" } [ 987654321098765432 "%.9e" sprintf ] unit-test
+{ "9.87654321e+17" } [ 987654321098765432 "%.8e" sprintf ] unit-test
+{ "9.8765432e+17" } [ 987654321098765432 "%.7e" sprintf ] unit-test
+{ "9.876543e+17" } [ 987654321098765432 "%.6e" sprintf ] unit-test
+{ "9.87654e+17" } [ 987654321098765432 "%.5e" sprintf ] unit-test
+{ "9.8765e+17" } [ 987654321098765432 "%.4e" sprintf ] unit-test
+{ "9.877e+17" } [ 987654321098765432 "%.3e" sprintf ] unit-test
+{ "9.88e+17" } [ 987654321098765432 "%.2e" sprintf ] unit-test
+{ "9.9e+17" } [ 987654321098765432 "%.1e" sprintf ] unit-test
+{ "1.e+18" } [ 987654321098765432 "%.0e" sprintf ] unit-test
+
 { "1.5625" } [ 1.5625 "%d" sprintf ] unit-test
 { "1.9p0" } [ 1.5625 "%x" sprintf ] unit-test
 { "1.9P0" } [ 1.5625 "%X" sprintf ] unit-test
diff --git a/basis/formatting/formatting.factor b/basis/formatting/formatting.factor
index 19bff37899..344a29c450 100644
--- a/basis/formatting/formatting.factor
+++ b/basis/formatting/formatting.factor
@@ -5,7 +5,7 @@ combinators.smart fry generalizations io io.streams.string
 kernel macros math math.functions math.parser namespaces
 peg.ebnf present prettyprint quotations sequences
 sequences.generalizations strings unicode vectors
-math.functions.integer-logs math.order ;
+math.functions.integer-logs splitting ;
 FROM: math.parser.private => format-float ;
 IN: formatting
 
@@ -33,8 +33,8 @@ IN: formatting
     [
         [ abs ] dip
         [ 10^ * round-to-even >integer number>string ]
-        [ 1 + CHAR: 0 pad-head 2 CHAR: 0 pad-tail ]
-        [ 1 max cut* ] tri "." glue
+        [ 1 + CHAR: 0 pad-head ]
+        [ cut* ] tri "." glue
     ] curry keep neg? [ CHAR: - prefix ] when ;
 
 : format-scientific-mantissa ( x log10x digits -- string )
@@ -63,10 +63,14 @@ IN: formatting
         [ [ [ >float ] dip ] when ] keep
     ] if ;
 
+: ?fix-nonsignificant-zero ( string digits -- string )
+    [ ".0" "." replace ] [ drop ] if-zero ;
+
 : format-scientific ( x digits -- string )
-    format-fast-scientific?
-    [ "e" format-float-fast ]
-    [ format-scientific-simple ] if ;
+    format-fast-scientific?  [
+        [ "e" format-float-fast ]
+        [ ?fix-nonsignificant-zero ] bi
+    ] [ format-scientific-simple ] if ;
 
 : format-fast-decimal? ( x digits -- x' digits ? )
     over float? [ t ]
@@ -82,9 +86,10 @@ IN: formatting
     ] if ; inline
 
 : format-decimal ( x digits -- string )
-    format-fast-decimal?
-    [ "f" format-float-fast ]
-    [ format-decimal-simple ] if ;
+    format-fast-decimal? [
+        [ "f" format-float-fast ]
+        [ ?fix-nonsignificant-zero ] bi
+    ] [ format-decimal-simple ] if ;
 
 ERROR: unknown-printf-directive ;