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Polymorphic printing.

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R=rsc
DELTA=100  (70 added, 10 deleted, 20 changed)
OCL=18663
CL=18669
This commit is contained in:
Rob Pike 2008-11-06 10:40:57 -08:00
parent 79fbbe37a7
commit f15dfa7802
1 changed files with 89 additions and 29 deletions
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114
src/lib/fmt/print.go
View File

@ -15,6 +15,23 @@ import (
"os";
)
export type Writer interface {
Write(b *[]byte) (ret int, err *os.Error);
}
// Representation of printer state passed to custom formatters.
// Provides access to the Writer interface plus information about
// the active formatting verb.
export type FormatHelper interface {
Write(b *[]byte) (ret int, err *os.Error);
Width() (wid int, ok bool);
Precision() (prec int, ok bool);
}
export type Formatter interface {
Format(f FormatHelper, c int);
}
const Runeself = 0x80
const AllocSize = 32
@ -22,6 +39,10 @@ type P struct {
n int;
buf *[]byte;
fmt *Fmt;
wid int;
wid_ok bool;
prec int;
prec_ok bool;
}
func Printer() *P {
@ -30,6 +51,14 @@ func Printer() *P {
return p;
}
func (p *P) Width() (wid int, ok bool) {
return p.wid, p.wid_ok
}
func (p *P) Precision() (prec int, ok bool) {
return p.prec, p.prec_ok
}
func (p *P) ensure(n int) {
if p.buf == nil || len(p.buf) < n {
newn := AllocSize;
@ -81,10 +110,6 @@ func (p *P) Write(b *[]byte) (ret int, err *os.Error) {
return len(b), nil;
}
export type Writer interface {
Write(b *[]byte) (ret int, err *os.Error);
}
func (p *P) doprintf(format string, v reflect.StructValue);
func (p *P) doprint(v reflect.StructValue, addspace, addnewline bool);
@ -159,6 +184,14 @@ export func sprintln(v ...) string {
// Getters for the fields of the argument structure.
func getBool(v reflect.Value) (val bool, ok bool) {
switch v.Kind() {
case reflect.BoolKind:
return v.(reflect.BoolValue).Get(), true;
}
return false, false
}
func getInt(v reflect.Value) (val int64, signed, ok bool) {
switch v.Kind() {
case reflect.IntKind:
@ -215,7 +248,7 @@ func getPtr(v reflect.Value) (val uint64, ok bool) {
return 0, false;
}
// Convert ASCII to integer.
// Convert ASCII to integer. n is 0 (and got is false) if no number present.
func parsenum(s string, start, end int) (n int, got bool, newi int) {
if start >= end {
@ -248,18 +281,12 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
i += w;
continue;
}
var got bool;
// saw % - do we have %20 (width)?
w, got, i = parsenum(format, i+1, end);
if got {
p.fmt.w(w);
}
p.wid, p.wid_ok, i = parsenum(format, i+1, end);
p.prec_ok = false;
// do we have %.20 (precision)?
if i < end && format[i] == '.' {
w, got, i = parsenum(format, i+1, end);
if got {
p.fmt.p(w);
}
p.prec, p.prec_ok, i = parsenum(format, i+1, end);
}
c, w = sys.stringtorune(format, i);
i += w;
@ -269,27 +296,49 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
continue;
}
if fieldnum >= v.Len() { // out of operands
p.addstr("???");
p.add('%');
p.add(c);
p.addstr("(missing)");
continue;
}
field := v.Field(fieldnum);
fieldnum++;
if formatter, ok := field.Interface().(Formatter); ok {
formatter.Format(p, c);
continue;
}
s := "";
if p.wid_ok {
p.fmt.w(p.wid);
}
if p.prec_ok {
p.fmt.p(p.prec);
}
switch c {
// bool
case 't':
if field.(reflect.BoolValue).Get() {
if v, ok := getBool(field); ok {
if v {
s = "true";
} else {
s = "false";
}
} else {
goto badtype;
}
// int
case 'b':
if v, signed, ok := getInt(field); ok {
s = p.fmt.b64(uint64(v)).str() // always unsigned
} else {
s = "%b%"
goto badtype
}
case 'c':
if v, signed, ok := getInt(field); ok {
s = p.fmt.c(int(v)).str()
} else {
goto badtype
}
case 'd':
if v, signed, ok := getInt(field); ok {
@ -299,7 +348,7 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
s = p.fmt.ud64(uint64(v)).str()
}
} else {
s = "%d%"
goto badtype
}
case 'o':
if v, signed, ok := getInt(field); ok {
@ -309,7 +358,7 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
s = p.fmt.uo64(uint64(v)).str()
}
} else {
s= "%o%"
goto badtype
}
case 'x':
if v, signed, ok := getInt(field); ok {
@ -319,7 +368,7 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
s = p.fmt.ux64(uint64(v)).str()
}
} else {
s = "%x%"
goto badtype
}
// float
@ -327,19 +376,19 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
if v, ok := getFloat(field); ok {
s = p.fmt.e64(v).str()
} else {
s = "%e%"
goto badtype
}
case 'f':
if v, ok := getFloat(field); ok {
s = p.fmt.f64(v).str()
} else {
s = "%f%";
goto badtype
}
case 'g':
if v, ok := getFloat(field); ok {
s = p.fmt.g64(v).str()
} else {
s = "%g%"
goto badtype
}
// string
@ -347,7 +396,7 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
if v, ok := getString(field); ok {
s = p.fmt.s(v).str()
} else {
s = "%s%"
goto badtype
}
// pointer
@ -355,14 +404,25 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
if v, ok := getPtr(field); ok {
s = "0x" + p.fmt.uX64(v).str()
} else {
s = "%p%"
goto badtype
}
default:
s = "?" + string(c) + "?";
badtype:
s = "%" + string(c) + "(" + field.Type().String() + ")%";
}
p.addstr(s);
}
if fieldnum < v.Len() {
p.addstr("?(extra ");
for ; fieldnum < v.Len(); fieldnum++ {
p.addstr(v.Field(fieldnum).Type().String());
if fieldnum + 1 < v.Len() {
p.addstr(", ");
}
}
p.addstr(")");
}
}
func (p *P) doprint(v reflect.StructValue, addspace, addnewline bool) {
@ -404,7 +464,7 @@ func (p *P) doprint(v reflect.StructValue, addspace, addnewline bool) {
p.doprint(field, true, false);
p.add('}');
default:
s = "???";
s = "?" + field.Type().String() + "?";
}
p.addstr(s);
prev_string = field.Kind() == reflect.StringKind;