taldir

print.go (23802B)

---

 // Copyright 2017 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package message
 
 import (
 	"bytes"
 	"fmt" // TODO: consider copying interfaces from package fmt to avoid dependency.
 	"math"
 	"reflect"
 	"sync"
 	"unicode/utf8"
 
 	"golang.org/x/text/internal/format"
 	"golang.org/x/text/internal/number"
 	"golang.org/x/text/language"
 	"golang.org/x/text/message/catalog"
 )
 
 // Strings for use with buffer.WriteString.
 // This is less overhead than using buffer.Write with byte arrays.
 const (
 	commaSpaceString  = ", "
 	nilAngleString    = "<nil>"
 	nilParenString    = "(nil)"
 	nilString         = "nil"
 	mapString         = "map["
 	percentBangString = "%!"
 	missingString     = "(MISSING)"
 	badIndexString    = "(BADINDEX)"
 	panicString       = "(PANIC="
 	extraString       = "%!(EXTRA "
 	badWidthString    = "%!(BADWIDTH)"
 	badPrecString     = "%!(BADPREC)"
 	noVerbString      = "%!(NOVERB)"
 
 	invReflectString = "<invalid reflect.Value>"
 )
 
 var printerPool = sync.Pool{
 	New: func() interface{} { return new(printer) },
 }
 
 // newPrinter allocates a new printer struct or grabs a cached one.
 func newPrinter(pp *Printer) *printer {
 	p := printerPool.Get().(*printer)
 	p.Printer = *pp
 	// TODO: cache most of the following call.
 	p.catContext = pp.cat.Context(pp.tag, p)
 
 	p.panicking = false
 	p.erroring = false
 	p.fmt.init(&p.Buffer)
 	return p
 }
 
 // free saves used printer structs in printerFree; avoids an allocation per invocation.
 func (p *printer) free() {
 	p.Buffer.Reset()
 	p.arg = nil
 	p.value = reflect.Value{}
 	printerPool.Put(p)
 }
 
 // printer is used to store a printer's state.
 // It implements "golang.org/x/text/internal/format".State.
 type printer struct {
 	Printer
 
 	// the context for looking up message translations
 	catContext *catalog.Context
 
 	// buffer for accumulating output.
 	bytes.Buffer
 
 	// arg holds the current item, as an interface{}.
 	arg interface{}
 	// value is used instead of arg for reflect values.
 	value reflect.Value
 
 	// fmt is used to format basic items such as integers or strings.
 	fmt formatInfo
 
 	// panicking is set by catchPanic to avoid infinite panic, recover, panic, ... recursion.
 	panicking bool
 	// erroring is set when printing an error string to guard against calling handleMethods.
 	erroring bool
 }
 
 // Language implements "golang.org/x/text/internal/format".State.
 func (p *printer) Language() language.Tag { return p.tag }
 
 func (p *printer) Width() (wid int, ok bool) { return p.fmt.Width, p.fmt.WidthPresent }
 
 func (p *printer) Precision() (prec int, ok bool) { return p.fmt.Prec, p.fmt.PrecPresent }
 
 func (p *printer) Flag(b int) bool {
 	switch b {
 	case '-':
 		return p.fmt.Minus
 	case '+':
 		return p.fmt.Plus || p.fmt.PlusV
 	case '#':
 		return p.fmt.Sharp || p.fmt.SharpV
 	case ' ':
 		return p.fmt.Space
 	case '0':
 		return p.fmt.Zero
 	}
 	return false
 }
 
 // getField gets the i'th field of the struct value.
 // If the field is itself is an interface, return a value for
 // the thing inside the interface, not the interface itself.
 func getField(v reflect.Value, i int) reflect.Value {
 	val := v.Field(i)
 	if val.Kind() == reflect.Interface && !val.IsNil() {
 		val = val.Elem()
 	}
 	return val
 }
 
 func (p *printer) unknownType(v reflect.Value) {
 	if !v.IsValid() {
 		p.WriteString(nilAngleString)
 		return
 	}
 	p.WriteByte('?')
 	p.WriteString(v.Type().String())
 	p.WriteByte('?')
 }
 
 func (p *printer) badVerb(verb rune) {
 	p.erroring = true
 	p.WriteString(percentBangString)
 	p.WriteRune(verb)
 	p.WriteByte('(')
 	switch {
 	case p.arg != nil:
 		p.WriteString(reflect.TypeOf(p.arg).String())
 		p.WriteByte('=')
 		p.printArg(p.arg, 'v')
 	case p.value.IsValid():
 		p.WriteString(p.value.Type().String())
 		p.WriteByte('=')
 		p.printValue(p.value, 'v', 0)
 	default:
 		p.WriteString(nilAngleString)
 	}
 	p.WriteByte(')')
 	p.erroring = false
 }
 
 func (p *printer) fmtBool(v bool, verb rune) {
 	switch verb {
 	case 't', 'v':
 		p.fmt.fmt_boolean(v)
 	default:
 		p.badVerb(verb)
 	}
 }
 
 // fmt0x64 formats a uint64 in hexadecimal and prefixes it with 0x or
 // not, as requested, by temporarily setting the sharp flag.
 func (p *printer) fmt0x64(v uint64, leading0x bool) {
 	sharp := p.fmt.Sharp
 	p.fmt.Sharp = leading0x
 	p.fmt.fmt_integer(v, 16, unsigned, ldigits)
 	p.fmt.Sharp = sharp
 }
 
 // fmtInteger formats a signed or unsigned integer.
 func (p *printer) fmtInteger(v uint64, isSigned bool, verb rune) {
 	switch verb {
 	case 'v':
 		if p.fmt.SharpV && !isSigned {
 			p.fmt0x64(v, true)
 			return
 		}
 		fallthrough
 	case 'd':
 		if p.fmt.Sharp || p.fmt.SharpV {
 			p.fmt.fmt_integer(v, 10, isSigned, ldigits)
 		} else {
 			p.fmtDecimalInt(v, isSigned)
 		}
 	case 'b':
 		p.fmt.fmt_integer(v, 2, isSigned, ldigits)
 	case 'o':
 		p.fmt.fmt_integer(v, 8, isSigned, ldigits)
 	case 'x':
 		p.fmt.fmt_integer(v, 16, isSigned, ldigits)
 	case 'X':
 		p.fmt.fmt_integer(v, 16, isSigned, udigits)
 	case 'c':
 		p.fmt.fmt_c(v)
 	case 'q':
 		if v <= utf8.MaxRune {
 			p.fmt.fmt_qc(v)
 		} else {
 			p.badVerb(verb)
 		}
 	case 'U':
 		p.fmt.fmt_unicode(v)
 	default:
 		p.badVerb(verb)
 	}
 }
 
 // fmtFloat formats a float. The default precision for each verb
 // is specified as last argument in the call to fmt_float.
 func (p *printer) fmtFloat(v float64, size int, verb rune) {
 	switch verb {
 	case 'b':
 		p.fmt.fmt_float(v, size, verb, -1)
 	case 'v':
 		verb = 'g'
 		fallthrough
 	case 'g', 'G':
 		if p.fmt.Sharp || p.fmt.SharpV {
 			p.fmt.fmt_float(v, size, verb, -1)
 		} else {
 			p.fmtVariableFloat(v, size)
 		}
 	case 'e', 'E':
 		if p.fmt.Sharp || p.fmt.SharpV {
 			p.fmt.fmt_float(v, size, verb, 6)
 		} else {
 			p.fmtScientific(v, size, 6)
 		}
 	case 'f', 'F':
 		if p.fmt.Sharp || p.fmt.SharpV {
 			p.fmt.fmt_float(v, size, verb, 6)
 		} else {
 			p.fmtDecimalFloat(v, size, 6)
 		}
 	default:
 		p.badVerb(verb)
 	}
 }
 
 func (p *printer) setFlags(f *number.Formatter) {
 	f.Flags &^= number.ElideSign
 	if p.fmt.Plus || p.fmt.Space {
 		f.Flags |= number.AlwaysSign
 		if !p.fmt.Plus {
 			f.Flags |= number.ElideSign
 		}
 	} else {
 		f.Flags &^= number.AlwaysSign
 	}
 }
 
 func (p *printer) updatePadding(f *number.Formatter) {
 	f.Flags &^= number.PadMask
 	if p.fmt.Minus {
 		f.Flags |= number.PadAfterSuffix
 	} else {
 		f.Flags |= number.PadBeforePrefix
 	}
 	f.PadRune = ' '
 	f.FormatWidth = uint16(p.fmt.Width)
 }
 
 func (p *printer) initDecimal(minFrac, maxFrac int) {
 	f := &p.toDecimal
 	f.MinIntegerDigits = 1
 	f.MaxIntegerDigits = 0
 	f.MinFractionDigits = uint8(minFrac)
 	f.MaxFractionDigits = int16(maxFrac)
 	p.setFlags(f)
 	f.PadRune = 0
 	if p.fmt.WidthPresent {
 		if p.fmt.Zero {
 			wid := p.fmt.Width
 			// Use significant integers for this.
 			// TODO: this is not the same as width, but so be it.
 			if f.MinFractionDigits > 0 {
 				wid -= 1 + int(f.MinFractionDigits)
 			}
 			if p.fmt.Plus || p.fmt.Space {
 				wid--
 			}
 			if wid > 0 && wid > int(f.MinIntegerDigits) {
 				f.MinIntegerDigits = uint8(wid)
 			}
 		}
 		p.updatePadding(f)
 	}
 }
 
 func (p *printer) initScientific(minFrac, maxFrac int) {
 	f := &p.toScientific
 	if maxFrac < 0 {
 		f.SetPrecision(maxFrac)
 	} else {
 		f.SetPrecision(maxFrac + 1)
 		f.MinFractionDigits = uint8(minFrac)
 		f.MaxFractionDigits = int16(maxFrac)
 	}
 	f.MinExponentDigits = 2
 	p.setFlags(f)
 	f.PadRune = 0
 	if p.fmt.WidthPresent {
 		f.Flags &^= number.PadMask
 		if p.fmt.Zero {
 			f.PadRune = f.Digit(0)
 			f.Flags |= number.PadAfterPrefix
 		} else {
 			f.PadRune = ' '
 			f.Flags |= number.PadBeforePrefix
 		}
 		p.updatePadding(f)
 	}
 }
 
 func (p *printer) fmtDecimalInt(v uint64, isSigned bool) {
 	var d number.Decimal
 
 	f := &p.toDecimal
 	if p.fmt.PrecPresent {
 		p.setFlags(f)
 		f.MinIntegerDigits = uint8(p.fmt.Prec)
 		f.MaxIntegerDigits = 0
 		f.MinFractionDigits = 0
 		f.MaxFractionDigits = 0
 		if p.fmt.WidthPresent {
 			p.updatePadding(f)
 		}
 	} else {
 		p.initDecimal(0, 0)
 	}
 	d.ConvertInt(p.toDecimal.RoundingContext, isSigned, v)
 
 	out := p.toDecimal.Format([]byte(nil), &d)
 	p.Buffer.Write(out)
 }
 
 func (p *printer) fmtDecimalFloat(v float64, size, prec int) {
 	var d number.Decimal
 	if p.fmt.PrecPresent {
 		prec = p.fmt.Prec
 	}
 	p.initDecimal(prec, prec)
 	d.ConvertFloat(p.toDecimal.RoundingContext, v, size)
 
 	out := p.toDecimal.Format([]byte(nil), &d)
 	p.Buffer.Write(out)
 }
 
 func (p *printer) fmtVariableFloat(v float64, size int) {
 	prec := -1
 	if p.fmt.PrecPresent {
 		prec = p.fmt.Prec
 	}
 	var d number.Decimal
 	p.initScientific(0, prec)
 	d.ConvertFloat(p.toScientific.RoundingContext, v, size)
 
 	// Copy logic of 'g' formatting from strconv. It is simplified a bit as
 	// we don't have to mind having prec > len(d.Digits).
 	shortest := prec < 0
 	ePrec := prec
 	if shortest {
 		prec = len(d.Digits)
 		ePrec = 6
 	} else if prec == 0 {
 		prec = 1
 		ePrec = 1
 	}
 	exp := int(d.Exp) - 1
 	if exp < -4 || exp >= ePrec {
 		p.initScientific(0, prec)
 
 		out := p.toScientific.Format([]byte(nil), &d)
 		p.Buffer.Write(out)
 	} else {
 		if prec > int(d.Exp) {
 			prec = len(d.Digits)
 		}
 		if prec -= int(d.Exp); prec < 0 {
 			prec = 0
 		}
 		p.initDecimal(0, prec)
 
 		out := p.toDecimal.Format([]byte(nil), &d)
 		p.Buffer.Write(out)
 	}
 }
 
 func (p *printer) fmtScientific(v float64, size, prec int) {
 	var d number.Decimal
 	if p.fmt.PrecPresent {
 		prec = p.fmt.Prec
 	}
 	p.initScientific(prec, prec)
 	rc := p.toScientific.RoundingContext
 	d.ConvertFloat(rc, v, size)
 
 	out := p.toScientific.Format([]byte(nil), &d)
 	p.Buffer.Write(out)
 
 }
 
 // fmtComplex formats a complex number v with
 // r = real(v) and j = imag(v) as (r+ji) using
 // fmtFloat for r and j formatting.
 func (p *printer) 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':
 		p.WriteByte('(')
 		p.fmtFloat(real(v), size/2, verb)
 		// Imaginary part always has a sign.
 		if math.IsNaN(imag(v)) {
 			// By CLDR's rules, NaNs do not use patterns or signs. As this code
 			// relies on AlwaysSign working for imaginary parts, we need to
 			// manually handle NaNs.
 			f := &p.toScientific
 			p.setFlags(f)
 			p.updatePadding(f)
 			p.setFlags(f)
 			nan := f.Symbol(number.SymNan)
 			extra := 0
 			if w, ok := p.Width(); ok {
 				extra = w - utf8.RuneCountInString(nan) - 1
 			}
 			if f.Flags&number.PadAfterNumber == 0 {
 				for ; extra > 0; extra-- {
 					p.WriteRune(f.PadRune)
 				}
 			}
 			p.WriteString(f.Symbol(number.SymPlusSign))
 			p.WriteString(nan)
 			for ; extra > 0; extra-- {
 				p.WriteRune(f.PadRune)
 			}
 			p.WriteString("i)")
 			return
 		}
 		oldPlus := p.fmt.Plus
 		p.fmt.Plus = true
 		p.fmtFloat(imag(v), size/2, verb)
 		p.WriteString("i)") // TODO: use symbol?
 		p.fmt.Plus = oldPlus
 	default:
 		p.badVerb(verb)
 	}
 }
 
 func (p *printer) fmtString(v string, verb rune) {
 	switch verb {
 	case 'v':
 		if p.fmt.SharpV {
 			p.fmt.fmt_q(v)
 		} else {
 			p.fmt.fmt_s(v)
 		}
 	case 's':
 		p.fmt.fmt_s(v)
 	case 'x':
 		p.fmt.fmt_sx(v, ldigits)
 	case 'X':
 		p.fmt.fmt_sx(v, udigits)
 	case 'q':
 		p.fmt.fmt_q(v)
 	case 'm':
 		ctx := p.cat.Context(p.tag, rawPrinter{p})
 		if ctx.Execute(v) == catalog.ErrNotFound {
 			p.WriteString(v)
 		}
 	default:
 		p.badVerb(verb)
 	}
 }
 
 func (p *printer) fmtBytes(v []byte, verb rune, typeString string) {
 	switch verb {
 	case 'v', 'd':
 		if p.fmt.SharpV {
 			p.WriteString(typeString)
 			if v == nil {
 				p.WriteString(nilParenString)
 				return
 			}
 			p.WriteByte('{')
 			for i, c := range v {
 				if i > 0 {
 					p.WriteString(commaSpaceString)
 				}
 				p.fmt0x64(uint64(c), true)
 			}
 			p.WriteByte('}')
 		} else {
 			p.WriteByte('[')
 			for i, c := range v {
 				if i > 0 {
 					p.WriteByte(' ')
 				}
 				p.fmt.fmt_integer(uint64(c), 10, unsigned, ldigits)
 			}
 			p.WriteByte(']')
 		}
 	case 's':
 		p.fmt.fmt_s(string(v))
 	case 'x':
 		p.fmt.fmt_bx(v, ldigits)
 	case 'X':
 		p.fmt.fmt_bx(v, udigits)
 	case 'q':
 		p.fmt.fmt_q(string(v))
 	default:
 		p.printValue(reflect.ValueOf(v), verb, 0)
 	}
 }
 
 func (p *printer) fmtPointer(value reflect.Value, verb rune) {
 	var u uintptr
 	switch value.Kind() {
 	case reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer:
 		u = value.Pointer()
 	default:
 		p.badVerb(verb)
 		return
 	}
 
 	switch verb {
 	case 'v':
 		if p.fmt.SharpV {
 			p.WriteByte('(')
 			p.WriteString(value.Type().String())
 			p.WriteString(")(")
 			if u == 0 {
 				p.WriteString(nilString)
 			} else {
 				p.fmt0x64(uint64(u), true)
 			}
 			p.WriteByte(')')
 		} else {
 			if u == 0 {
 				p.fmt.padString(nilAngleString)
 			} else {
 				p.fmt0x64(uint64(u), !p.fmt.Sharp)
 			}
 		}
 	case 'p':
 		p.fmt0x64(uint64(u), !p.fmt.Sharp)
 	case 'b', 'o', 'd', 'x', 'X':
 		if verb == 'd' {
 			p.fmt.Sharp = true // Print as standard go. TODO: does this make sense?
 		}
 		p.fmtInteger(uint64(u), unsigned, verb)
 	default:
 		p.badVerb(verb)
 	}
 }
 
 func (p *printer) catchPanic(arg interface{}, verb rune) {
 	if err := recover(); err != nil {
 		// If it's a nil pointer, just say "<nil>". The likeliest causes are a
 		// Stringer that fails to guard against nil or a nil pointer for a
 		// value receiver, and in either case, "<nil>" is a nice result.
 		if v := reflect.ValueOf(arg); v.Kind() == reflect.Ptr && v.IsNil() {
 			p.WriteString(nilAngleString)
 			return
 		}
 		// Otherwise print a concise panic message. Most of the time the panic
 		// value will print itself nicely.
 		if p.panicking {
 			// Nested panics; the recursion in printArg cannot succeed.
 			panic(err)
 		}
 
 		oldFlags := p.fmt.Parser
 		// For this output we want default behavior.
 		p.fmt.ClearFlags()
 
 		p.WriteString(percentBangString)
 		p.WriteRune(verb)
 		p.WriteString(panicString)
 		p.panicking = true
 		p.printArg(err, 'v')
 		p.panicking = false
 		p.WriteByte(')')
 
 		p.fmt.Parser = oldFlags
 	}
 }
 
 func (p *printer) handleMethods(verb rune) (handled bool) {
 	if p.erroring {
 		return
 	}
 	// Is it a Formatter?
 	if formatter, ok := p.arg.(format.Formatter); ok {
 		handled = true
 		defer p.catchPanic(p.arg, verb)
 		formatter.Format(p, verb)
 		return
 	}
 	if formatter, ok := p.arg.(fmt.Formatter); ok {
 		handled = true
 		defer p.catchPanic(p.arg, verb)
 		formatter.Format(p, verb)
 		return
 	}
 
 	// If we're doing Go syntax and the argument knows how to supply it, take care of it now.
 	if p.fmt.SharpV {
 		if stringer, ok := p.arg.(fmt.GoStringer); ok {
 			handled = true
 			defer p.catchPanic(p.arg, verb)
 			// Print the result of GoString unadorned.
 			p.fmt.fmt_s(stringer.GoString())
 			return
 		}
 	} else {
 		// If a string is acceptable according to the format, see if
 		// the value satisfies one of the string-valued interfaces.
 		// Println etc. set verb to %v, which is "stringable".
 		switch verb {
 		case 'v', 's', 'x', 'X', 'q':
 			// Is it an error or Stringer?
 			// The duplication in the bodies is necessary:
 			// setting handled and deferring catchPanic
 			// must happen before calling the method.
 			switch v := p.arg.(type) {
 			case error:
 				handled = true
 				defer p.catchPanic(p.arg, verb)
 				p.fmtString(v.Error(), verb)
 				return
 
 			case fmt.Stringer:
 				handled = true
 				defer p.catchPanic(p.arg, verb)
 				p.fmtString(v.String(), verb)
 				return
 			}
 		}
 	}
 	return false
 }
 
 func (p *printer) printArg(arg interface{}, verb rune) {
 	p.arg = arg
 	p.value = reflect.Value{}
 
 	if arg == nil {
 		switch verb {
 		case 'T', 'v':
 			p.fmt.padString(nilAngleString)
 		default:
 			p.badVerb(verb)
 		}
 		return
 	}
 
 	// Special processing considerations.
 	// %T (the value's type) and %p (its address) are special; we always do them first.
 	switch verb {
 	case 'T':
 		p.fmt.fmt_s(reflect.TypeOf(arg).String())
 		return
 	case 'p':
 		p.fmtPointer(reflect.ValueOf(arg), 'p')
 		return
 	}
 
 	// Some types can be done without reflection.
 	switch f := arg.(type) {
 	case bool:
 		p.fmtBool(f, verb)
 	case float32:
 		p.fmtFloat(float64(f), 32, verb)
 	case float64:
 		p.fmtFloat(f, 64, verb)
 	case complex64:
 		p.fmtComplex(complex128(f), 64, verb)
 	case complex128:
 		p.fmtComplex(f, 128, verb)
 	case int:
 		p.fmtInteger(uint64(f), signed, verb)
 	case int8:
 		p.fmtInteger(uint64(f), signed, verb)
 	case int16:
 		p.fmtInteger(uint64(f), signed, verb)
 	case int32:
 		p.fmtInteger(uint64(f), signed, verb)
 	case int64:
 		p.fmtInteger(uint64(f), signed, verb)
 	case uint:
 		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint8:
 		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint16:
 		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint32:
 		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint64:
 		p.fmtInteger(f, unsigned, verb)
 	case uintptr:
 		p.fmtInteger(uint64(f), unsigned, verb)
 	case string:
 		p.fmtString(f, verb)
 	case []byte:
 		p.fmtBytes(f, verb, "[]byte")
 	case reflect.Value:
 		// Handle extractable values with special methods
 		// since printValue does not handle them at depth 0.
 		if f.IsValid() && f.CanInterface() {
 			p.arg = f.Interface()
 			if p.handleMethods(verb) {
 				return
 			}
 		}
 		p.printValue(f, verb, 0)
 	default:
 		// If the type is not simple, it might have methods.
 		if !p.handleMethods(verb) {
 			// Need to use reflection, since the type had no
 			// interface methods that could be used for formatting.
 			p.printValue(reflect.ValueOf(f), verb, 0)
 		}
 	}
 }
 
 // printValue is similar to printArg but starts with a reflect value, not an interface{} value.
 // It does not handle 'p' and 'T' verbs because these should have been already handled by printArg.
 func (p *printer) printValue(value reflect.Value, verb rune, depth int) {
 	// Handle values with special methods if not already handled by printArg (depth == 0).
 	if depth > 0 && value.IsValid() && value.CanInterface() {
 		p.arg = value.Interface()
 		if p.handleMethods(verb) {
 			return
 		}
 	}
 	p.arg = nil
 	p.value = value
 
 	switch f := value; value.Kind() {
 	case reflect.Invalid:
 		if depth == 0 {
 			p.WriteString(invReflectString)
 		} else {
 			switch verb {
 			case 'v':
 				p.WriteString(nilAngleString)
 			default:
 				p.badVerb(verb)
 			}
 		}
 	case reflect.Bool:
 		p.fmtBool(f.Bool(), verb)
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		p.fmtInteger(uint64(f.Int()), signed, verb)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		p.fmtInteger(f.Uint(), unsigned, verb)
 	case reflect.Float32:
 		p.fmtFloat(f.Float(), 32, verb)
 	case reflect.Float64:
 		p.fmtFloat(f.Float(), 64, verb)
 	case reflect.Complex64:
 		p.fmtComplex(f.Complex(), 64, verb)
 	case reflect.Complex128:
 		p.fmtComplex(f.Complex(), 128, verb)
 	case reflect.String:
 		p.fmtString(f.String(), verb)
 	case reflect.Map:
 		if p.fmt.SharpV {
 			p.WriteString(f.Type().String())
 			if f.IsNil() {
 				p.WriteString(nilParenString)
 				return
 			}
 			p.WriteByte('{')
 		} else {
 			p.WriteString(mapString)
 		}
 		keys := f.MapKeys()
 		for i, key := range keys {
 			if i > 0 {
 				if p.fmt.SharpV {
 					p.WriteString(commaSpaceString)
 				} else {
 					p.WriteByte(' ')
 				}
 			}
 			p.printValue(key, verb, depth+1)
 			p.WriteByte(':')
 			p.printValue(f.MapIndex(key), verb, depth+1)
 		}
 		if p.fmt.SharpV {
 			p.WriteByte('}')
 		} else {
 			p.WriteByte(']')
 		}
 	case reflect.Struct:
 		if p.fmt.SharpV {
 			p.WriteString(f.Type().String())
 		}
 		p.WriteByte('{')
 		for i := 0; i < f.NumField(); i++ {
 			if i > 0 {
 				if p.fmt.SharpV {
 					p.WriteString(commaSpaceString)
 				} else {
 					p.WriteByte(' ')
 				}
 			}
 			if p.fmt.PlusV || p.fmt.SharpV {
 				if name := f.Type().Field(i).Name; name != "" {
 					p.WriteString(name)
 					p.WriteByte(':')
 				}
 			}
 			p.printValue(getField(f, i), verb, depth+1)
 		}
 		p.WriteByte('}')
 	case reflect.Interface:
 		value := f.Elem()
 		if !value.IsValid() {
 			if p.fmt.SharpV {
 				p.WriteString(f.Type().String())
 				p.WriteString(nilParenString)
 			} else {
 				p.WriteString(nilAngleString)
 			}
 		} else {
 			p.printValue(value, verb, depth+1)
 		}
 	case reflect.Array, reflect.Slice:
 		switch verb {
 		case 's', 'q', 'x', 'X':
 			// Handle byte and uint8 slices and arrays special for the above verbs.
 			t := f.Type()
 			if t.Elem().Kind() == reflect.Uint8 {
 				var bytes []byte
 				if f.Kind() == reflect.Slice {
 					bytes = f.Bytes()
 				} else if f.CanAddr() {
 					bytes = f.Slice(0, f.Len()).Bytes()
 				} else {
 					// We have an array, but we cannot Slice() a non-addressable array,
 					// so we build a slice by hand. This is a rare case but it would be nice
 					// if reflection could help a little more.
 					bytes = make([]byte, f.Len())
 					for i := range bytes {
 						bytes[i] = byte(f.Index(i).Uint())
 					}
 				}
 				p.fmtBytes(bytes, verb, t.String())
 				return
 			}
 		}
 		if p.fmt.SharpV {
 			p.WriteString(f.Type().String())
 			if f.Kind() == reflect.Slice && f.IsNil() {
 				p.WriteString(nilParenString)
 				return
 			}
 			p.WriteByte('{')
 			for i := 0; i < f.Len(); i++ {
 				if i > 0 {
 					p.WriteString(commaSpaceString)
 				}
 				p.printValue(f.Index(i), verb, depth+1)
 			}
 			p.WriteByte('}')
 		} else {
 			p.WriteByte('[')
 			for i := 0; i < f.Len(); i++ {
 				if i > 0 {
 					p.WriteByte(' ')
 				}
 				p.printValue(f.Index(i), verb, depth+1)
 			}
 			p.WriteByte(']')
 		}
 	case reflect.Ptr:
 		// pointer to array or slice or struct?  ok at top level
 		// but not embedded (avoid loops)
 		if depth == 0 && f.Pointer() != 0 {
 			switch a := f.Elem(); a.Kind() {
 			case reflect.Array, reflect.Slice, reflect.Struct, reflect.Map:
 				p.WriteByte('&')
 				p.printValue(a, verb, depth+1)
 				return
 			}
 		}
 		fallthrough
 	case reflect.Chan, reflect.Func, reflect.UnsafePointer:
 		p.fmtPointer(f, verb)
 	default:
 		p.unknownType(f)
 	}
 }
 
 func (p *printer) badArgNum(verb rune) {
 	p.WriteString(percentBangString)
 	p.WriteRune(verb)
 	p.WriteString(badIndexString)
 }
 
 func (p *printer) missingArg(verb rune) {
 	p.WriteString(percentBangString)
 	p.WriteRune(verb)
 	p.WriteString(missingString)
 }
 
 func (p *printer) doPrintf(fmt string) {
 	for p.fmt.Parser.SetFormat(fmt); p.fmt.Scan(); {
 		switch p.fmt.Status {
 		case format.StatusText:
 			p.WriteString(p.fmt.Text())
 		case format.StatusSubstitution:
 			p.printArg(p.Arg(p.fmt.ArgNum), p.fmt.Verb)
 		case format.StatusBadWidthSubstitution:
 			p.WriteString(badWidthString)
 			p.printArg(p.Arg(p.fmt.ArgNum), p.fmt.Verb)
 		case format.StatusBadPrecSubstitution:
 			p.WriteString(badPrecString)
 			p.printArg(p.Arg(p.fmt.ArgNum), p.fmt.Verb)
 		case format.StatusNoVerb:
 			p.WriteString(noVerbString)
 		case format.StatusBadArgNum:
 			p.badArgNum(p.fmt.Verb)
 		case format.StatusMissingArg:
 			p.missingArg(p.fmt.Verb)
 		default:
 			panic("unreachable")
 		}
 	}
 
 	// Check for extra arguments, but only if there was at least one ordered
 	// argument. Note that this behavior is necessarily different from fmt:
 	// different variants of messages may opt to drop some or all of the
 	// arguments.
 	if !p.fmt.Reordered && p.fmt.ArgNum < len(p.fmt.Args) && p.fmt.ArgNum != 0 {
 		p.fmt.ClearFlags()
 		p.WriteString(extraString)
 		for i, arg := range p.fmt.Args[p.fmt.ArgNum:] {
 			if i > 0 {
 				p.WriteString(commaSpaceString)
 			}
 			if arg == nil {
 				p.WriteString(nilAngleString)
 			} else {
 				p.WriteString(reflect.TypeOf(arg).String())
 				p.WriteString("=")
 				p.printArg(arg, 'v')
 			}
 		}
 		p.WriteByte(')')
 	}
 }
 
 func (p *printer) doPrint(a []interface{}) {
 	prevString := false
 	for argNum, arg := range a {
 		isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
 		// Add a space between two non-string arguments.
 		if argNum > 0 && !isString && !prevString {
 			p.WriteByte(' ')
 		}
 		p.printArg(arg, 'v')
 		prevString = isString
 	}
 }
 
 // doPrintln is like doPrint but always adds a space between arguments
 // and a newline after the last argument.
 func (p *printer) doPrintln(a []interface{}) {
 	for argNum, arg := range a {
 		if argNum > 0 {
 			p.WriteByte(' ')
 		}
 		p.printArg(arg, 'v')
 	}
 	p.WriteByte('\n')
 }