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fmt: normalize processing of format string

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The old loop was a bit odd; change it to be more regular.
This also enables a diagnostic for Printf("%", 3): %!(NOVERB)

R=rsc, Kyle C
CC=golang-dev
https://golang.org/cl/3749044
This commit is contained in:
Rob Pike 2011-01-05 10:11:34 -08:00
parent d71d08af5a
commit c0332fc93f
2 changed files with 16 additions and 12 deletions
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8
src/pkg/fmt/fmt_test.go
View File

@ -381,11 +381,13 @@ var fmttests = []fmtTest{
{"%p", 27, "%!p(int=27)"}, // not a pointer at all
// erroneous things
{"%s %", "hello", "hello %!(NOVERB)"},
{"%s %.2", "hello", "hello %!(NOVERB)"},
{"%d", "hello", "%!d(string=hello)"},
{"no args", "hello", "no args%!(EXTRA string=hello)"},
{"%s", nil, "%!s(<nil>)"},
{"%T", nil, "<nil>"},
{"%-1", 100, "%!1(int=100)"},
{"%-1", 100, "%!(NOVERB)%!(EXTRA int=100)"},
}
func TestSprintf(t *testing.T) {
@ -638,7 +640,7 @@ var startests = []starTest{
{"%.*d", args(nil, 42), "%!(BADPREC)42"},
{"%*d", args(5, "foo"), "%!d(string= foo)"},
{"%*% %d", args(20, 5), "% 5"},
{"%*", args(4), "%!(BADWIDTH)%!*(int=4)"},
{"%*", args(4), "%!(NOVERB)"},
{"%*d", args(int32(4), 42), "%!(BADWIDTH)42"},
}
@ -655,7 +657,7 @@ func TestWidthAndPrecision(t *testing.T) {
for _, tt := range startests {
s := sprintf[len(tt.in)](tt.fmt, tt.in)
if s != tt.out {
t.Errorf("got %q expected %q", s, tt.out)
t.Errorf("%q: got %q expected %q", tt.fmt, s, tt.out)
}
}
}

20
src/pkg/fmt/print.go
View File

@ -26,6 +26,7 @@ var (
bytesBytes = []byte("[]byte{")
widthBytes = []byte("%!(BADWIDTH)")
precBytes = []byte("%!(BADPREC)")
noVerbBytes = []byte("%!(NOVERB)")
)
// State represents the printer state passed to custom formatters.
@ -821,19 +822,16 @@ func intFromArg(a []interface{}, end, i, fieldnum int) (num int, isInt bool, new
}
func (p *pp) doPrintf(format string, a []interface{}) {
end := len(format) - 1
end := len(format)
fieldnum := 0 // we process one field per non-trivial format
for i := 0; i <= end; {
for i := 0; i < end; {
c, w := utf8.DecodeRuneInString(format[i:])
if c != '%' || i == end {
if w == 1 {
p.buf.WriteByte(byte(c))
} else {
p.buf.WriteString(format[i : i+w])
}
if c != '%' {
p.buf.WriteRune(c)
i += w
continue
}
// Process one verb
i++
// flags and widths
p.fmt.clearflags()
@ -855,7 +853,7 @@ func (p *pp) doPrintf(format string, a []interface{}) {
}
}
// do we have width?
if format[i] == '*' {
if i < end && format[i] == '*' {
p.fmt.wid, p.fmt.widPresent, i, fieldnum = intFromArg(a, end, i, fieldnum)
if !p.fmt.widPresent {
p.buf.Write(widthBytes)
@ -874,6 +872,10 @@ func (p *pp) doPrintf(format string, a []interface{}) {
p.fmt.prec, p.fmt.precPresent, i = parsenum(format, i+1, end)
}
}
if i >= end {
p.buf.Write(noVerbBytes)
continue
}
c, w = utf8.DecodeRuneInString(format[i:])
i += w
// percent is special - absorbs no operand