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Commit e1a6d1fc authored by Russ Cox's avatar Russ Cox
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fmt: format hex floats and complexes 

This CL modifies fmt's printer to implement %x and %X
for formatting floating-point data (floats and complexes)
in standard hexadecimal notation.

See golang.org/design/19308-number-literals for background.

For #29008.
Vet update is #29986.

Change-Id: If2842a11631bc393a1ebcf6914ed07658652af5a
Reviewed-on: https://go-review.googlesource.com/c/160245Reviewed-by: default avatarRobert Griesemer <gri@golang.org>
Reviewed-by: default avatarRob Pike <r@golang.org>
parent 50bb2b6b
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Inline Side-by-side
Showing with 39 additions and 6 deletions
src/fmt/doc.go
View file @ e1a6d1fc
......@@ -40,6 +40,8 @@
%F synonym for %f
%g %e for large exponents, %f otherwise. Precision is discussed below.
%G %E for large exponents, %F otherwise
%x hexadecimal notation (with decimal power of two exponent), e.g. -0x1.23abcp+20
%X upper-case hexadecimal notation, e.g. -0X1.23ABCP+20
String and slice of bytes (treated equivalently with these verbs):
%s the uninterpreted bytes of the string or slice
%q a double-quoted string safely escaped with Go syntax
......
src/fmt/fmt_test.go
View file @ e1a6d1fc
......@@ -413,6 +413,8 @@ var fmtTests = []struct {
// floats
{"%+.3e", 0.0, "+0.000e+00"},
{"%+.3e", 1.0, "+1.000e+00"},
{"%+.3x", 0.0, "+0x0.000p+00"},
{"%+.3x", 1.0, "+0x1.000p+00"},
{"%+.3f", -1.0, "-1.000"},
{"%+.3F", -1.0, "-1.000"},
{"%+.3F", float32(-1.0), "-1.000"},
......@@ -428,6 +430,8 @@ var fmtTests = []struct {
{"%+10.2f", -1.0, " -1.00"},
{"% .3E", -1.0, "-1.000E+00"},
{"% .3e", 1.0, " 1.000e+00"},
{"% .3X", -1.0, "-0X1.000P+00"},
{"% .3x", 1.0, " 0x1.000p+00"},
{"%+.3g", 0.0, "+0"},
{"%+.3g", 1.0, "+1"},
{"%+.3g", -1.0, "-1"},
......@@ -445,17 +449,21 @@ var fmtTests = []struct {
{"%#g", 1000000.0, "1.00000e+06"},
{"%#.0f", 1.0, "1."},
{"%#.0e", 1.0, "1.e+00"},
{"%#.0x", 1.0, "0x1.p+00"},
{"%#.0g", 1.0, "1."},
{"%#.0g", 1100000.0, "1.e+06"},
{"%#.4f", 1.0, "1.0000"},
{"%#.4e", 1.0, "1.0000e+00"},
{"%#.4x", 1.0, "0x1.0000p+00"},
{"%#.4g", 1.0, "1.000"},
{"%#.4g", 100000.0, "1.000e+05"},
{"%#.0f", 123.0, "123."},
{"%#.0e", 123.0, "1.e+02"},
{"%#.0x", 123.0, "0x1.p+07"},
{"%#.0g", 123.0, "1.e+02"},
{"%#.4f", 123.0, "123.0000"},
{"%#.4e", 123.0, "1.2300e+02"},
{"%#.4x", 123.0, "0x1.ec00p+06"},
{"%#.4g", 123.0, "123.0"},
{"%#.4g", 123000.0, "1.230e+05"},
{"%#9.4g", 1.0, " 1.000"},
......@@ -474,17 +482,23 @@ var fmtTests = []struct {
{"%20f", posInf, " +Inf"},
{"% 20F", posInf, " Inf"},
{"% 20e", negInf, " -Inf"},
{"% 20x", negInf, " -Inf"},
{"%+20E", negInf, " -Inf"},
{"%+20X", negInf, " -Inf"},
{"% +20g", negInf, " -Inf"},
{"%+-20G", posInf, "+Inf "},
{"%20e", NaN, " NaN"},
{"%20x", NaN, " NaN"},
{"% +20E", NaN, " +NaN"},
{"% +20X", NaN, " +NaN"},
{"% -20g", NaN, " NaN "},
{"%+-20G", NaN, "+NaN "},
// Zero padding does not apply to infinities and NaN.
{"%+020e", posInf, " +Inf"},
{"%+020x", posInf, " +Inf"},
{"%-020f", negInf, "-Inf "},
{"%-020E", NaN, "NaN "},
{"%-020X", NaN, "NaN "},
// complex values
{"%.f", 0i, "(0+0i)"},
......@@ -492,23 +506,29 @@ var fmtTests = []struct {
{"%+.f", 0i, "(+0+0i)"},
{"% +.f", 0i, "(+0+0i)"},
{"%+.3e", 0i, "(+0.000e+00+0.000e+00i)"},
{"%+.3x", 0i, "(+0x0.000p+00+0x0.000p+00i)"},
{"%+.3f", 0i, "(+0.000+0.000i)"},
{"%+.3g", 0i, "(+0+0i)"},
{"%+.3e", 1 + 2i, "(+1.000e+00+2.000e+00i)"},
{"%+.3x", 1 + 2i, "(+0x1.000p+00+0x1.000p+01i)"},
{"%+.3f", 1 + 2i, "(+1.000+2.000i)"},
{"%+.3g", 1 + 2i, "(+1+2i)"},
{"%.3e", 0i, "(0.000e+00+0.000e+00i)"},
{"%.3x", 0i, "(0x0.000p+00+0x0.000p+00i)"},
{"%.3f", 0i, "(0.000+0.000i)"},
{"%.3F", 0i, "(0.000+0.000i)"},
{"%.3F", complex64(0i), "(0.000+0.000i)"},
{"%.3g", 0i, "(0+0i)"},
{"%.3e", 1 + 2i, "(1.000e+00+2.000e+00i)"},
{"%.3x", 1 + 2i, "(0x1.000p+00+0x1.000p+01i)"},
{"%.3f", 1 + 2i, "(1.000+2.000i)"},
{"%.3g", 1 + 2i, "(1+2i)"},
{"%.3e", -1 - 2i, "(-1.000e+00-2.000e+00i)"},
{"%.3x", -1 - 2i, "(-0x1.000p+00-0x1.000p+01i)"},
{"%.3f", -1 - 2i, "(-1.000-2.000i)"},
{"%.3g", -1 - 2i, "(-1-2i)"},
{"% .3E", -1 - 2i, "(-1.000E+00-2.000E+00i)"},
{"% .3X", -1 - 2i, "(-0X1.000P+00-0X1.000P+01i)"},
{"%+.3g", 1 + 2i, "(+1+2i)"},
{"%+.3g", complex64(1 + 2i), "(+1+2i)"},
{"%#g", 1 + 2i, "(1.00000+2.00000i)"},
......@@ -517,11 +537,13 @@ var fmtTests = []struct {
{"%#g", -1e10 - 1.11e100i, "(-1.00000e+10-1.11000e+100i)"},
{"%#.0f", 1.23 + 1.0i, "(1.+1.i)"},
{"%#.0e", 1.23 + 1.0i, "(1.e+00+1.e+00i)"},
{"%#.0x", 1.23 + 1.0i, "(0x1.p+00+0x1.p+00i)"},
{"%#.0g", 1.23 + 1.0i, "(1.+1.i)"},
{"%#.0g", 0 + 100000i, "(0.+1.e+05i)"},
{"%#.0g", 1230000 + 0i, "(1.e+06+0.i)"},
{"%#.4f", 1 + 1.23i, "(1.0000+1.2300i)"},
{"%#.4e", 123 + 1i, "(1.2300e+02+1.0000e+00i)"},
{"%#.4x", 123 + 1i, "(0x1.ec00p+06+0x1.0000p+00i)"},
{"%#.4g", 123 + 1.23i, "(123.0+1.230i)"},
{"%#12.5g", 0 + 100000i, "( 0.0000 +1.0000e+05i)"},
{"%#12.5g", 1230000 - 0i, "( 1.2300e+06 +0.0000i)"},
......@@ -541,7 +563,9 @@ var fmtTests = []struct {
{"% f", complex(negInf, negInf), "(-Inf-Infi)"},
{"% f", complex(NaN, NaN), "( NaN+NaNi)"},
{"%8e", complex(posInf, posInf), "( +Inf +Infi)"},
{"%8x", complex(posInf, posInf), "( +Inf +Infi)"},
{"% 8E", complex(posInf, posInf), "( Inf +Infi)"},
{"% 8X", complex(posInf, posInf), "( Inf +Infi)"},
{"%+8f", complex(negInf, negInf), "( -Inf -Infi)"},
{"% +8g", complex(negInf, negInf), "( -Inf -Infi)"},
{"% -8G", complex(NaN, NaN), "( NaN +NaN i)"},
......
src/fmt/format.go
View file @ e1a6d1fc
......@@ -510,7 +510,7 @@ func (f *fmt) fmtFloat(v float64, size int, verb rune, prec int) {
if f.sharp && verb != 'b' {
digits := 0
switch verb {
case 'v', 'g', 'G':
case 'v', 'g', 'G', 'x':
digits = prec
// If no precision is set explicitly use a precision of 6.
if digits == -1 {
......@@ -519,8 +519,8 @@ func (f *fmt) fmtFloat(v float64, size int, verb rune, prec int) {
}
// Buffer pre-allocated with enough room for
// exponent notations of the form "e+123".
var tailBuf [5]byte
// exponent notations of the form "e+123" or "p-1023".
var tailBuf [6]byte
tail := tailBuf[:0]
hasDecimalPoint := false
......@@ -529,9 +529,16 @@ func (f *fmt) fmtFloat(v float64, size int, verb rune, prec int) {
switch num[i] {
case '.':
hasDecimalPoint = true
case 'e', 'E':
case 'p', 'P':
tail = append(tail, num[i:]...)
num = num[:i]
case 'e', 'E':
if verb != 'x' && verb != 'X' {
tail = append(tail, num[i:]...)
num = num[:i]
break
}
fallthrough
default:
digits--
}
......
src/fmt/print.go
View file @ e1a6d1fc
......@@ -407,7 +407,7 @@ func (p *pp) fmtFloat(v float64, size int, verb rune) {
switch verb {
case 'v':
p.fmt.fmtFloat(v, size, 'g', -1)
case 'b', 'g', 'G':
case 'b', 'g', 'G', 'x', 'X':
p.fmt.fmtFloat(v, size, verb, -1)
case 'f', 'e', 'E':
p.fmt.fmtFloat(v, size, verb, 6)
......@@ -425,7 +425,7 @@ func (p *pp) fmtComplex(v complex128, size int, verb rune) {
// Make sure any unsupported verbs are found before the
// calls to fmtFloat to not generate an incorrect error string.
switch verb {
case 'v', 'b', 'g', 'G', 'f', 'F', 'e', 'E':
case 'v', 'b', 'g', 'G', 'x', 'X', 'f', 'F', 'e', 'E':
oldPlus := p.fmt.plus
p.buf.WriteByte('(')
p.fmtFloat(real(v), size/2, verb)
......
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