[release-branch.go1.3] fmt: fix signs when zero padding.
««« CL 103480043 / 777dd5a434db
fmt: fix signs when zero padding.
Bug was introduced recently. Add more tests, fix the bugs.
Suppress + sign when not required in zero padding.
Do not zero pad infinities.
All old tests still pass.
This time for sure!
Fixes #8217.
LGTM=rsc
R=golang-codereviews, dan.kortschak, rsc
CC=golang-codereviews
https://golang.org/cl/103480043
»»»
LGTM=r, rsc
R=r, rsc
CC=golang-codereviews
https://golang.org/cl/110040043
diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index a55a665..7e3d06b 100644
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -513,9 +513,76 @@
{"%0.100f", 1.0, zeroFill("1.", 100, "")},
{"%0.100f", -1.0, zeroFill("-1.", 100, "")},
- // Zero padding floats used to put the minus sign in the middle.
- {"%020f", -1.0, "-000000000001.000000"},
+ // Comparison of padding rules with C printf.
+ /*
+ C program:
+ #include <stdio.h>
+
+ char *format[] = {
+ "[%.2f]",
+ "[% .2f]",
+ "[%+.2f]",
+ "[%7.2f]",
+ "[% 7.2f]",
+ "[%+7.2f]",
+ "[%07.2f]",
+ "[% 07.2f]",
+ "[%+07.2f]",
+ };
+
+ int main(void) {
+ int i;
+ for(i = 0; i < 9; i++) {
+ printf("%s: ", format[i]);
+ printf(format[i], 1.0);
+ printf(" ");
+ printf(format[i], -1.0);
+ printf("\n");
+ }
+ }
+
+ Output:
+ [%.2f]: [1.00] [-1.00]
+ [% .2f]: [ 1.00] [-1.00]
+ [%+.2f]: [+1.00] [-1.00]
+ [%7.2f]: [ 1.00] [ -1.00]
+ [% 7.2f]: [ 1.00] [ -1.00]
+ [%+7.2f]: [ +1.00] [ -1.00]
+ [%07.2f]: [0001.00] [-001.00]
+ [% 07.2f]: [ 001.00] [-001.00]
+ [%+07.2f]: [+001.00] [-001.00]
+ */
+ {"%.2f", 1.0, "1.00"},
+ {"%.2f", -1.0, "-1.00"},
+ {"% .2f", 1.0, " 1.00"},
+ {"% .2f", -1.0, "-1.00"},
+ {"%+.2f", 1.0, "+1.00"},
+ {"%+.2f", -1.0, "-1.00"},
+ {"%7.2f", 1.0, " 1.00"},
+ {"%7.2f", -1.0, " -1.00"},
+ {"% 7.2f", 1.0, " 1.00"},
+ {"% 7.2f", -1.0, " -1.00"},
+ {"%+7.2f", 1.0, " +1.00"},
+ {"%+7.2f", -1.0, " -1.00"},
+ {"%07.2f", 1.0, "0001.00"},
+ {"%07.2f", -1.0, "-001.00"},
+ {"% 07.2f", 1.0, " 001.00"},
+ {"% 07.2f", -1.0, "-001.00"},
+ {"%+07.2f", 1.0, "+001.00"},
+ {"%+07.2f", -1.0, "-001.00"},
+
+ // Complex numbers: exhaustively tested in TestComplexFormatting.
+ {"%7.2f", 1 + 2i, "( 1.00 +2.00i)"},
+ {"%+07.2f", -1 - 2i, "(-001.00-002.00i)"},
+ // Zero padding does not apply to infinities.
+ {"%020f", math.Inf(-1), " -Inf"},
+ {"%020f", math.Inf(+1), " +Inf"},
+ {"% 020f", math.Inf(-1), " -Inf"},
+ {"% 020f", math.Inf(+1), " Inf"},
+ {"%+020f", math.Inf(-1), " -Inf"},
+ {"%+020f", math.Inf(+1), " +Inf"},
{"%20f", -1.0, " -1.000000"},
+ // Make sure we can handle very large widths.
{"%0100f", -1.0, zeroFill("-", 99, "1.000000")},
// Complex fmt used to leave the plus flag set for future entries in the array
@@ -601,6 +668,50 @@
}
}
+// TestComplexFormatting checks that a complex always formats to the same
+// thing as if done by hand with two singleton prints.
+func TestComplexFormatting(t *testing.T) {
+ var yesNo = []bool{true, false}
+ var signs = []float64{1, 0, -1}
+ for _, plus := range yesNo {
+ for _, zero := range yesNo {
+ for _, space := range yesNo {
+ for _, char := range "fFeEgG" {
+ realFmt := "%"
+ if zero {
+ realFmt += "0"
+ }
+ if space {
+ realFmt += " "
+ }
+ if plus {
+ realFmt += "+"
+ }
+ realFmt += "10.2"
+ realFmt += string(char)
+ // Imaginary part always has a sign, so force + and ignore space.
+ imagFmt := "%"
+ if zero {
+ imagFmt += "0"
+ }
+ imagFmt += "+"
+ imagFmt += "10.2"
+ imagFmt += string(char)
+ for _, realSign := range signs {
+ for _, imagSign := range signs {
+ one := Sprintf(realFmt, complex(realSign, imagSign))
+ two := Sprintf("("+realFmt+imagFmt+"i)", realSign, imagSign)
+ if one != two {
+ t.Error(f, one, two)
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+}
+
type SE []interface{} // slice of empty; notational compactness.
var reorderTests = []struct {
diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index c1d948c..a89c542 100644
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -368,14 +368,25 @@
} else {
num[0] = '+'
}
+ // Special handling for infinity, which doesn't look like a number so shouldn't be padded with zeros.
+ if math.IsInf(v, 0) {
+ if f.zero {
+ defer func() { f.zero = true }()
+ f.zero = false
+ }
+ }
// num is now a signed version of the number.
// If we're zero padding, want the sign before the leading zeros.
// Achieve this by writing the sign out and then padding the unsigned number.
if f.zero && f.widPresent && f.wid > len(num) {
- f.buf.WriteByte(num[0])
- f.wid--
+ if f.space && v >= 0 {
+ f.buf.WriteByte(' ') // This is what C does: even with zero, f.space means space.
+ f.wid--
+ } else if f.plus || v < 0 {
+ f.buf.WriteByte(num[0])
+ f.wid--
+ }
f.pad(num[1:])
- f.wid++ // Restore width; complex numbers will reuse this value for imaginary part.
return
}
// f.space says to replace a leading + with a space.
@@ -436,60 +447,46 @@
// fmt_c64 formats a complex64 according to the verb.
func (f *fmt) fmt_c64(v complex64, verb rune) {
- f.buf.WriteByte('(')
- r := real(v)
- oldPlus := f.plus
- for i := 0; ; i++ {
- switch verb {
- case 'b':
- f.fmt_fb32(r)
- case 'e':
- f.fmt_e32(r)
- case 'E':
- f.fmt_E32(r)
- case 'f', 'F':
- f.fmt_f32(r)
- case 'g':
- f.fmt_g32(r)
- case 'G':
- f.fmt_G32(r)
- }
- if i != 0 {
- break
- }
- f.plus = true
- r = imag(v)
- }
- f.plus = oldPlus
- f.buf.Write(irparenBytes)
+ f.fmt_complex(float64(real(v)), float64(imag(v)), 32, verb)
}
// fmt_c128 formats a complex128 according to the verb.
func (f *fmt) fmt_c128(v complex128, verb rune) {
+ f.fmt_complex(real(v), imag(v), 64, verb)
+}
+
+// fmt_complex formats a complex number as (r+ji).
+func (f *fmt) fmt_complex(r, j float64, size int, verb rune) {
f.buf.WriteByte('(')
- r := real(v)
oldPlus := f.plus
+ oldSpace := f.space
+ oldWid := f.wid
for i := 0; ; i++ {
switch verb {
case 'b':
- f.fmt_fb64(r)
+ f.formatFloat(r, 'b', 0, size)
case 'e':
- f.fmt_e64(r)
+ f.formatFloat(r, 'e', doPrec(f, 6), size)
case 'E':
- f.fmt_E64(r)
+ f.formatFloat(r, 'E', doPrec(f, 6), size)
case 'f', 'F':
- f.fmt_f64(r)
+ f.formatFloat(r, 'f', doPrec(f, 6), size)
case 'g':
- f.fmt_g64(r)
+ f.formatFloat(r, 'g', doPrec(f, -1), size)
case 'G':
- f.fmt_G64(r)
+ f.formatFloat(r, 'G', doPrec(f, -1), size)
}
if i != 0 {
break
}
+ // Imaginary part always has a sign.
f.plus = true
- r = imag(v)
+ f.space = false
+ f.wid = oldWid
+ r = j
}
+ f.space = oldSpace
f.plus = oldPlus
+ f.wid = oldWid
f.buf.Write(irparenBytes)
}
