| // Copyright 2009 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 fmt |
| |
| import ( |
| "internal/fmtsort" |
| "io" |
| "os" |
| "reflect" |
| "strconv" |
| "sync" |
| "unicode/utf8" |
| ) |
| |
| // 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>" |
| ) |
| |
| // State represents the printer state passed to custom formatters. |
| // It provides access to the io.Writer interface plus information about |
| // the flags and options for the operand's format specifier. |
| type State interface { |
| // Write is the function to call to emit formatted output to be printed. |
| Write(b []byte) (n int, err error) |
| // Width returns the value of the width option and whether it has been set. |
| Width() (wid int, ok bool) |
| // Precision returns the value of the precision option and whether it has been set. |
| Precision() (prec int, ok bool) |
| |
| // Flag reports whether the flag c, a character, has been set. |
| Flag(c int) bool |
| } |
| |
| // Formatter is implemented by any value that has a Format method. |
| // The implementation controls how State and rune are interpreted, |
| // and may call Sprint() or Fprint(f) etc. to generate its output. |
| type Formatter interface { |
| Format(f State, verb rune) |
| } |
| |
| // Stringer is implemented by any value that has a String method, |
| // which defines the “native” format for that value. |
| // The String method is used to print values passed as an operand |
| // to any format that accepts a string or to an unformatted printer |
| // such as Print. |
| type Stringer interface { |
| String() string |
| } |
| |
| // GoStringer is implemented by any value that has a GoString method, |
| // which defines the Go syntax for that value. |
| // The GoString method is used to print values passed as an operand |
| // to a %#v format. |
| type GoStringer interface { |
| GoString() string |
| } |
| |
| // FormatString returns a string representing the fully qualified formatting |
| // directive captured by the State, followed by the argument verb. (State does not |
| // itself contain the verb.) The result has a leading percent sign followed by any |
| // flags, the width, and the precision. Missing flags, width, and precision are |
| // omitted. This function allows a Formatter to reconstruct the original |
| // directive triggering the call to Format. |
| func FormatString(state State, verb rune) string { |
| var tmp [16]byte // Use a local buffer. |
| b := append(tmp[:0], '%') |
| for _, c := range " +-#0" { // All known flags |
| if state.Flag(int(c)) { // The argument is an int for historical reasons. |
| b = append(b, byte(c)) |
| } |
| } |
| if w, ok := state.Width(); ok { |
| b = strconv.AppendInt(b, int64(w), 10) |
| } |
| if p, ok := state.Precision(); ok { |
| b = append(b, '.') |
| b = strconv.AppendInt(b, int64(p), 10) |
| } |
| b = utf8.AppendRune(b, verb) |
| return string(b) |
| } |
| |
| // Use simple []byte instead of bytes.Buffer to avoid large dependency. |
| type buffer []byte |
| |
| func (b *buffer) write(p []byte) { |
| *b = append(*b, p...) |
| } |
| |
| func (b *buffer) writeString(s string) { |
| *b = append(*b, s...) |
| } |
| |
| func (b *buffer) writeByte(c byte) { |
| *b = append(*b, c) |
| } |
| |
| func (b *buffer) writeRune(r rune) { |
| *b = utf8.AppendRune(*b, r) |
| } |
| |
| // pp is used to store a printer's state and is reused with sync.Pool to avoid allocations. |
| type pp struct { |
| buf buffer |
| |
| // arg holds the current item, as an interface{}. |
| arg any |
| |
| // 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 fmt |
| |
| // reordered records whether the format string used argument reordering. |
| reordered bool |
| // goodArgNum records whether the most recent reordering directive was valid. |
| goodArgNum bool |
| // 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 |
| // wrapErrs is set when the format string may contain a %w verb. |
| wrapErrs bool |
| // wrappedErrs records the targets of the %w verb. |
| wrappedErrs []int |
| } |
| |
| var ppFree = sync.Pool{ |
| New: func() any { return new(pp) }, |
| } |
| |
| // newPrinter allocates a new pp struct or grabs a cached one. |
| func newPrinter() *pp { |
| p := ppFree.Get().(*pp) |
| p.panicking = false |
| p.erroring = false |
| p.wrapErrs = false |
| p.fmt.init(&p.buf) |
| return p |
| } |
| |
| // free saves used pp structs in ppFree; avoids an allocation per invocation. |
| func (p *pp) free() { |
| // Proper usage of a sync.Pool requires each entry to have approximately |
| // the same memory cost. To obtain this property when the stored type |
| // contains a variably-sized buffer, we add a hard limit on the maximum |
| // buffer to place back in the pool. If the buffer is larger than the |
| // limit, we drop the buffer and recycle just the printer. |
| // |
| // See https://golang.org/issue/23199. |
| if cap(p.buf) > 64*1024 { |
| p.buf = nil |
| } else { |
| p.buf = p.buf[:0] |
| } |
| if cap(p.wrappedErrs) > 8 { |
| p.wrappedErrs = nil |
| } |
| |
| p.arg = nil |
| p.value = reflect.Value{} |
| p.wrappedErrs = p.wrappedErrs[:0] |
| ppFree.Put(p) |
| } |
| |
| func (p *pp) Width() (wid int, ok bool) { return p.fmt.wid, p.fmt.widPresent } |
| |
| func (p *pp) Precision() (prec int, ok bool) { return p.fmt.prec, p.fmt.precPresent } |
| |
| func (p *pp) 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 |
| } |
| |
| // Implement Write so we can call Fprintf on a pp (through State), for |
| // recursive use in custom verbs. |
| func (p *pp) Write(b []byte) (ret int, err error) { |
| p.buf.write(b) |
| return len(b), nil |
| } |
| |
| // Implement WriteString so that we can call io.WriteString |
| // on a pp (through state), for efficiency. |
| func (p *pp) WriteString(s string) (ret int, err error) { |
| p.buf.writeString(s) |
| return len(s), nil |
| } |
| |
| // These routines end in 'f' and take a format string. |
| |
| // Fprintf formats according to a format specifier and writes to w. |
| // It returns the number of bytes written and any write error encountered. |
| func Fprintf(w io.Writer, format string, a ...any) (n int, err error) { |
| p := newPrinter() |
| p.doPrintf(format, a) |
| n, err = w.Write(p.buf) |
| p.free() |
| return |
| } |
| |
| // Printf formats according to a format specifier and writes to standard output. |
| // It returns the number of bytes written and any write error encountered. |
| func Printf(format string, a ...any) (n int, err error) { |
| return Fprintf(os.Stdout, format, a...) |
| } |
| |
| // Sprintf formats according to a format specifier and returns the resulting string. |
| func Sprintf(format string, a ...any) string { |
| p := newPrinter() |
| p.doPrintf(format, a) |
| s := string(p.buf) |
| p.free() |
| return s |
| } |
| |
| // Appendf formats according to a format specifier, appends the result to the byte |
| // slice, and returns the updated slice. |
| func Appendf(b []byte, format string, a ...any) []byte { |
| p := newPrinter() |
| p.doPrintf(format, a) |
| b = append(b, p.buf...) |
| p.free() |
| return b |
| } |
| |
| // These routines do not take a format string |
| |
| // Fprint formats using the default formats for its operands and writes to w. |
| // Spaces are added between operands when neither is a string. |
| // It returns the number of bytes written and any write error encountered. |
| func Fprint(w io.Writer, a ...any) (n int, err error) { |
| p := newPrinter() |
| p.doPrint(a) |
| n, err = w.Write(p.buf) |
| p.free() |
| return |
| } |
| |
| // Print formats using the default formats for its operands and writes to standard output. |
| // Spaces are added between operands when neither is a string. |
| // It returns the number of bytes written and any write error encountered. |
| func Print(a ...any) (n int, err error) { |
| return Fprint(os.Stdout, a...) |
| } |
| |
| // Sprint formats using the default formats for its operands and returns the resulting string. |
| // Spaces are added between operands when neither is a string. |
| func Sprint(a ...any) string { |
| p := newPrinter() |
| p.doPrint(a) |
| s := string(p.buf) |
| p.free() |
| return s |
| } |
| |
| // Append formats using the default formats for its operands, appends the result to |
| // the byte slice, and returns the updated slice. |
| func Append(b []byte, a ...any) []byte { |
| p := newPrinter() |
| p.doPrint(a) |
| b = append(b, p.buf...) |
| p.free() |
| return b |
| } |
| |
| // These routines end in 'ln', do not take a format string, |
| // always add spaces between operands, and add a newline |
| // after the last operand. |
| |
| // Fprintln formats using the default formats for its operands and writes to w. |
| // Spaces are always added between operands and a newline is appended. |
| // It returns the number of bytes written and any write error encountered. |
| func Fprintln(w io.Writer, a ...any) (n int, err error) { |
| p := newPrinter() |
| p.doPrintln(a) |
| n, err = w.Write(p.buf) |
| p.free() |
| return |
| } |
| |
| // Println formats using the default formats for its operands and writes to standard output. |
| // Spaces are always added between operands and a newline is appended. |
| // It returns the number of bytes written and any write error encountered. |
| func Println(a ...any) (n int, err error) { |
| return Fprintln(os.Stdout, a...) |
| } |
| |
| // Sprintln formats using the default formats for its operands and returns the resulting string. |
| // Spaces are always added between operands and a newline is appended. |
| func Sprintln(a ...any) string { |
| p := newPrinter() |
| p.doPrintln(a) |
| s := string(p.buf) |
| p.free() |
| return s |
| } |
| |
| // Appendln formats using the default formats for its operands, appends the result |
| // to the byte slice, and returns the updated slice. Spaces are always added |
| // between operands and a newline is appended. |
| func Appendln(b []byte, a ...any) []byte { |
| p := newPrinter() |
| p.doPrintln(a) |
| b = append(b, p.buf...) |
| p.free() |
| return b |
| } |
| |
| // getField gets the i'th field of the struct value. |
| // If the field itself is a non-nil 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 |
| } |
| |
| // tooLarge reports whether the magnitude of the integer is |
| // too large to be used as a formatting width or precision. |
| func tooLarge(x int) bool { |
| const max int = 1e6 |
| return x > max || x < -max |
| } |
| |
| // parsenum converts ASCII to integer. num is 0 (and isnum is false) if no number present. |
| func parsenum(s string, start, end int) (num int, isnum bool, newi int) { |
| if start >= end { |
| return 0, false, end |
| } |
| for newi = start; newi < end && '0' <= s[newi] && s[newi] <= '9'; newi++ { |
| if tooLarge(num) { |
| return 0, false, end // Overflow; crazy long number most likely. |
| } |
| num = num*10 + int(s[newi]-'0') |
| isnum = true |
| } |
| return |
| } |
| |
| func (p *pp) unknownType(v reflect.Value) { |
| if !v.IsValid() { |
| p.buf.writeString(nilAngleString) |
| return |
| } |
| p.buf.writeByte('?') |
| p.buf.writeString(v.Type().String()) |
| p.buf.writeByte('?') |
| } |
| |
| func (p *pp) badVerb(verb rune) { |
| p.erroring = true |
| p.buf.writeString(percentBangString) |
| p.buf.writeRune(verb) |
| p.buf.writeByte('(') |
| switch { |
| case p.arg != nil: |
| p.buf.writeString(reflect.TypeOf(p.arg).String()) |
| p.buf.writeByte('=') |
| p.printArg(p.arg, 'v') |
| case p.value.IsValid(): |
| p.buf.writeString(p.value.Type().String()) |
| p.buf.writeByte('=') |
| p.printValue(p.value, 'v', 0) |
| default: |
| p.buf.writeString(nilAngleString) |
| } |
| p.buf.writeByte(')') |
| p.erroring = false |
| } |
| |
| func (p *pp) fmtBool(v bool, verb rune) { |
| switch verb { |
| case 't', 'v': |
| p.fmt.fmtBoolean(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 *pp) fmt0x64(v uint64, leading0x bool) { |
| sharp := p.fmt.sharp |
| p.fmt.sharp = leading0x |
| p.fmt.fmtInteger(v, 16, unsigned, 'v', ldigits) |
| p.fmt.sharp = sharp |
| } |
| |
| // fmtInteger formats a signed or unsigned integer. |
| func (p *pp) fmtInteger(v uint64, isSigned bool, verb rune) { |
| switch verb { |
| case 'v': |
| if p.fmt.sharpV && !isSigned { |
| p.fmt0x64(v, true) |
| } else { |
| p.fmt.fmtInteger(v, 10, isSigned, verb, ldigits) |
| } |
| case 'd': |
| p.fmt.fmtInteger(v, 10, isSigned, verb, ldigits) |
| case 'b': |
| p.fmt.fmtInteger(v, 2, isSigned, verb, ldigits) |
| case 'o', 'O': |
| p.fmt.fmtInteger(v, 8, isSigned, verb, ldigits) |
| case 'x': |
| p.fmt.fmtInteger(v, 16, isSigned, verb, ldigits) |
| case 'X': |
| p.fmt.fmtInteger(v, 16, isSigned, verb, udigits) |
| case 'c': |
| p.fmt.fmtC(v) |
| case 'q': |
| p.fmt.fmtQc(v) |
| case 'U': |
| p.fmt.fmtUnicode(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 *pp) fmtFloat(v float64, size int, verb rune) { |
| switch verb { |
| case 'v': |
| p.fmt.fmtFloat(v, size, 'g', -1) |
| case 'b', 'g', 'G', 'x', 'X': |
| p.fmt.fmtFloat(v, size, verb, -1) |
| case 'f', 'e', 'E': |
| p.fmt.fmtFloat(v, size, verb, 6) |
| case 'F': |
| p.fmt.fmtFloat(v, size, 'f', 6) |
| default: |
| p.badVerb(verb) |
| } |
| } |
| |
| // 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 *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', 'x', 'X', 'f', 'F', 'e', 'E': |
| oldPlus := p.fmt.plus |
| p.buf.writeByte('(') |
| p.fmtFloat(real(v), size/2, verb) |
| // Imaginary part always has a sign. |
| p.fmt.plus = true |
| p.fmtFloat(imag(v), size/2, verb) |
| p.buf.writeString("i)") |
| p.fmt.plus = oldPlus |
| default: |
| p.badVerb(verb) |
| } |
| } |
| |
| func (p *pp) fmtString(v string, verb rune) { |
| switch verb { |
| case 'v': |
| if p.fmt.sharpV { |
| p.fmt.fmtQ(v) |
| } else { |
| p.fmt.fmtS(v) |
| } |
| case 's': |
| p.fmt.fmtS(v) |
| case 'x': |
| p.fmt.fmtSx(v, ldigits) |
| case 'X': |
| p.fmt.fmtSx(v, udigits) |
| case 'q': |
| p.fmt.fmtQ(v) |
| default: |
| p.badVerb(verb) |
| } |
| } |
| |
| func (p *pp) fmtBytes(v []byte, verb rune, typeString string) { |
| switch verb { |
| case 'v', 'd': |
| if p.fmt.sharpV { |
| p.buf.writeString(typeString) |
| if v == nil { |
| p.buf.writeString(nilParenString) |
| return |
| } |
| p.buf.writeByte('{') |
| for i, c := range v { |
| if i > 0 { |
| p.buf.writeString(commaSpaceString) |
| } |
| p.fmt0x64(uint64(c), true) |
| } |
| p.buf.writeByte('}') |
| } else { |
| p.buf.writeByte('[') |
| for i, c := range v { |
| if i > 0 { |
| p.buf.writeByte(' ') |
| } |
| p.fmt.fmtInteger(uint64(c), 10, unsigned, verb, ldigits) |
| } |
| p.buf.writeByte(']') |
| } |
| case 's': |
| p.fmt.fmtBs(v) |
| case 'x': |
| p.fmt.fmtBx(v, ldigits) |
| case 'X': |
| p.fmt.fmtBx(v, udigits) |
| case 'q': |
| p.fmt.fmtQ(string(v)) |
| default: |
| p.printValue(reflect.ValueOf(v), verb, 0) |
| } |
| } |
| |
| func (p *pp) fmtPointer(value reflect.Value, verb rune) { |
| var u uintptr |
| switch value.Kind() { |
| case reflect.Chan, reflect.Func, reflect.Map, reflect.Pointer, reflect.Slice, reflect.UnsafePointer: |
| u = uintptr(value.UnsafePointer()) |
| default: |
| p.badVerb(verb) |
| return |
| } |
| |
| switch verb { |
| case 'v': |
| if p.fmt.sharpV { |
| p.buf.writeByte('(') |
| p.buf.writeString(value.Type().String()) |
| p.buf.writeString(")(") |
| if u == 0 { |
| p.buf.writeString(nilString) |
| } else { |
| p.fmt0x64(uint64(u), true) |
| } |
| p.buf.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': |
| p.fmtInteger(uint64(u), unsigned, verb) |
| default: |
| p.badVerb(verb) |
| } |
| } |
| |
| func (p *pp) catchPanic(arg any, verb rune, method string) { |
| 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.Pointer && v.IsNil() { |
| p.buf.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.fmtFlags |
| // For this output we want default behavior. |
| p.fmt.clearflags() |
| |
| p.buf.writeString(percentBangString) |
| p.buf.writeRune(verb) |
| p.buf.writeString(panicString) |
| p.buf.writeString(method) |
| p.buf.writeString(" method: ") |
| p.panicking = true |
| p.printArg(err, 'v') |
| p.panicking = false |
| p.buf.writeByte(')') |
| |
| p.fmt.fmtFlags = oldFlags |
| } |
| } |
| |
| func (p *pp) handleMethods(verb rune) (handled bool) { |
| if p.erroring { |
| return |
| } |
| if verb == 'w' { |
| // It is invalid to use %w other than with Errorf or with a non-error arg. |
| _, ok := p.arg.(error) |
| if !ok || !p.wrapErrs { |
| p.badVerb(verb) |
| return true |
| } |
| // If the arg is a Formatter, pass 'v' as the verb to it. |
| verb = 'v' |
| } |
| |
| // Is it a Formatter? |
| if formatter, ok := p.arg.(Formatter); ok { |
| handled = true |
| defer p.catchPanic(p.arg, verb, "Format") |
| 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.(GoStringer); ok { |
| handled = true |
| defer p.catchPanic(p.arg, verb, "GoString") |
| // Print the result of GoString unadorned. |
| p.fmt.fmtS(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, "Error") |
| p.fmtString(v.Error(), verb) |
| return |
| |
| case Stringer: |
| handled = true |
| defer p.catchPanic(p.arg, verb, "String") |
| p.fmtString(v.String(), verb) |
| return |
| } |
| } |
| } |
| return false |
| } |
| |
| func (p *pp) printArg(arg any, 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.fmtS(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 *pp) 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.buf.writeString(invReflectString) |
| } else { |
| switch verb { |
| case 'v': |
| p.buf.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.buf.writeString(f.Type().String()) |
| if f.IsNil() { |
| p.buf.writeString(nilParenString) |
| return |
| } |
| p.buf.writeByte('{') |
| } else { |
| p.buf.writeString(mapString) |
| } |
| sorted := fmtsort.Sort(f) |
| for i, key := range sorted.Key { |
| if i > 0 { |
| if p.fmt.sharpV { |
| p.buf.writeString(commaSpaceString) |
| } else { |
| p.buf.writeByte(' ') |
| } |
| } |
| p.printValue(key, verb, depth+1) |
| p.buf.writeByte(':') |
| p.printValue(sorted.Value[i], verb, depth+1) |
| } |
| if p.fmt.sharpV { |
| p.buf.writeByte('}') |
| } else { |
| p.buf.writeByte(']') |
| } |
| case reflect.Struct: |
| if p.fmt.sharpV { |
| p.buf.writeString(f.Type().String()) |
| } |
| p.buf.writeByte('{') |
| for i := 0; i < f.NumField(); i++ { |
| if i > 0 { |
| if p.fmt.sharpV { |
| p.buf.writeString(commaSpaceString) |
| } else { |
| p.buf.writeByte(' ') |
| } |
| } |
| if p.fmt.plusV || p.fmt.sharpV { |
| if name := f.Type().Field(i).Name; name != "" { |
| p.buf.writeString(name) |
| p.buf.writeByte(':') |
| } |
| } |
| p.printValue(getField(f, i), verb, depth+1) |
| } |
| p.buf.writeByte('}') |
| case reflect.Interface: |
| value := f.Elem() |
| if !value.IsValid() { |
| if p.fmt.sharpV { |
| p.buf.writeString(f.Type().String()) |
| p.buf.writeString(nilParenString) |
| } else { |
| p.buf.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 || f.CanAddr() { |
| bytes = f.Bytes() |
| } else { |
| // We have an array, but we cannot Bytes() 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.buf.writeString(f.Type().String()) |
| if f.Kind() == reflect.Slice && f.IsNil() { |
| p.buf.writeString(nilParenString) |
| return |
| } |
| p.buf.writeByte('{') |
| for i := 0; i < f.Len(); i++ { |
| if i > 0 { |
| p.buf.writeString(commaSpaceString) |
| } |
| p.printValue(f.Index(i), verb, depth+1) |
| } |
| p.buf.writeByte('}') |
| } else { |
| p.buf.writeByte('[') |
| for i := 0; i < f.Len(); i++ { |
| if i > 0 { |
| p.buf.writeByte(' ') |
| } |
| p.printValue(f.Index(i), verb, depth+1) |
| } |
| p.buf.writeByte(']') |
| } |
| case reflect.Pointer: |
| // pointer to array or slice or struct? ok at top level |
| // but not embedded (avoid loops) |
| if depth == 0 && f.UnsafePointer() != nil { |
| switch a := f.Elem(); a.Kind() { |
| case reflect.Array, reflect.Slice, reflect.Struct, reflect.Map: |
| p.buf.writeByte('&') |
| p.printValue(a, verb, depth+1) |
| return |
| } |
| } |
| fallthrough |
| case reflect.Chan, reflect.Func, reflect.UnsafePointer: |
| p.fmtPointer(f, verb) |
| default: |
| p.unknownType(f) |
| } |
| } |
| |
| // intFromArg gets the argNumth element of a. On return, isInt reports whether the argument has integer type. |
| func intFromArg(a []any, argNum int) (num int, isInt bool, newArgNum int) { |
| newArgNum = argNum |
| if argNum < len(a) { |
| num, isInt = a[argNum].(int) // Almost always OK. |
| if !isInt { |
| // Work harder. |
| switch v := reflect.ValueOf(a[argNum]); v.Kind() { |
| case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: |
| n := v.Int() |
| if int64(int(n)) == n { |
| num = int(n) |
| isInt = true |
| } |
| case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: |
| n := v.Uint() |
| if int64(n) >= 0 && uint64(int(n)) == n { |
| num = int(n) |
| isInt = true |
| } |
| default: |
| // Already 0, false. |
| } |
| } |
| newArgNum = argNum + 1 |
| if tooLarge(num) { |
| num = 0 |
| isInt = false |
| } |
| } |
| return |
| } |
| |
| // parseArgNumber returns the value of the bracketed number, minus 1 |
| // (explicit argument numbers are one-indexed but we want zero-indexed). |
| // The opening bracket is known to be present at format[0]. |
| // The returned values are the index, the number of bytes to consume |
| // up to the closing paren, if present, and whether the number parsed |
| // ok. The bytes to consume will be 1 if no closing paren is present. |
| func parseArgNumber(format string) (index int, wid int, ok bool) { |
| // There must be at least 3 bytes: [n]. |
| if len(format) < 3 { |
| return 0, 1, false |
| } |
| |
| // Find closing bracket. |
| for i := 1; i < len(format); i++ { |
| if format[i] == ']' { |
| width, ok, newi := parsenum(format, 1, i) |
| if !ok || newi != i { |
| return 0, i + 1, false |
| } |
| return width - 1, i + 1, true // arg numbers are one-indexed and skip paren. |
| } |
| } |
| return 0, 1, false |
| } |
| |
| // argNumber returns the next argument to evaluate, which is either the value of the passed-in |
| // argNum or the value of the bracketed integer that begins format[i:]. It also returns |
| // the new value of i, that is, the index of the next byte of the format to process. |
| func (p *pp) argNumber(argNum int, format string, i int, numArgs int) (newArgNum, newi int, found bool) { |
| if len(format) <= i || format[i] != '[' { |
| return argNum, i, false |
| } |
| p.reordered = true |
| index, wid, ok := parseArgNumber(format[i:]) |
| if ok && 0 <= index && index < numArgs { |
| return index, i + wid, true |
| } |
| p.goodArgNum = false |
| return argNum, i + wid, ok |
| } |
| |
| func (p *pp) badArgNum(verb rune) { |
| p.buf.writeString(percentBangString) |
| p.buf.writeRune(verb) |
| p.buf.writeString(badIndexString) |
| } |
| |
| func (p *pp) missingArg(verb rune) { |
| p.buf.writeString(percentBangString) |
| p.buf.writeRune(verb) |
| p.buf.writeString(missingString) |
| } |
| |
| func (p *pp) doPrintf(format string, a []any) { |
| end := len(format) |
| argNum := 0 // we process one argument per non-trivial format |
| afterIndex := false // previous item in format was an index like [3]. |
| p.reordered = false |
| formatLoop: |
| for i := 0; i < end; { |
| p.goodArgNum = true |
| lasti := i |
| for i < end && format[i] != '%' { |
| i++ |
| } |
| if i > lasti { |
| p.buf.writeString(format[lasti:i]) |
| } |
| if i >= end { |
| // done processing format string |
| break |
| } |
| |
| // Process one verb |
| i++ |
| |
| // Do we have flags? |
| p.fmt.clearflags() |
| simpleFormat: |
| for ; i < end; i++ { |
| c := format[i] |
| switch c { |
| case '#': |
| p.fmt.sharp = true |
| case '0': |
| p.fmt.zero = !p.fmt.minus // Only allow zero padding to the left. |
| case '+': |
| p.fmt.plus = true |
| case '-': |
| p.fmt.minus = true |
| p.fmt.zero = false // Do not pad with zeros to the right. |
| case ' ': |
| p.fmt.space = true |
| default: |
| // Fast path for common case of ascii lower case simple verbs |
| // without precision or width or argument indices. |
| if 'a' <= c && c <= 'z' && argNum < len(a) { |
| switch c { |
| case 'w': |
| p.wrappedErrs = append(p.wrappedErrs, argNum) |
| fallthrough |
| case 'v': |
| // Go syntax |
| p.fmt.sharpV = p.fmt.sharp |
| p.fmt.sharp = false |
| // Struct-field syntax |
| p.fmt.plusV = p.fmt.plus |
| p.fmt.plus = false |
| } |
| p.printArg(a[argNum], rune(c)) |
| argNum++ |
| i++ |
| continue formatLoop |
| } |
| // Format is more complex than simple flags and a verb or is malformed. |
| break simpleFormat |
| } |
| } |
| |
| // Do we have an explicit argument index? |
| argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a)) |
| |
| // Do we have width? |
| if i < end && format[i] == '*' { |
| i++ |
| p.fmt.wid, p.fmt.widPresent, argNum = intFromArg(a, argNum) |
| |
| if !p.fmt.widPresent { |
| p.buf.writeString(badWidthString) |
| } |
| |
| // We have a negative width, so take its value and ensure |
| // that the minus flag is set |
| if p.fmt.wid < 0 { |
| p.fmt.wid = -p.fmt.wid |
| p.fmt.minus = true |
| p.fmt.zero = false // Do not pad with zeros to the right. |
| } |
| afterIndex = false |
| } else { |
| p.fmt.wid, p.fmt.widPresent, i = parsenum(format, i, end) |
| if afterIndex && p.fmt.widPresent { // "%[3]2d" |
| p.goodArgNum = false |
| } |
| } |
| |
| // Do we have precision? |
| if i+1 < end && format[i] == '.' { |
| i++ |
| if afterIndex { // "%[3].2d" |
| p.goodArgNum = false |
| } |
| argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a)) |
| if i < end && format[i] == '*' { |
| i++ |
| p.fmt.prec, p.fmt.precPresent, argNum = intFromArg(a, argNum) |
| // Negative precision arguments don't make sense |
| if p.fmt.prec < 0 { |
| p.fmt.prec = 0 |
| p.fmt.precPresent = false |
| } |
| if !p.fmt.precPresent { |
| p.buf.writeString(badPrecString) |
| } |
| afterIndex = false |
| } else { |
| p.fmt.prec, p.fmt.precPresent, i = parsenum(format, i, end) |
| if !p.fmt.precPresent { |
| p.fmt.prec = 0 |
| p.fmt.precPresent = true |
| } |
| } |
| } |
| |
| if !afterIndex { |
| argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a)) |
| } |
| |
| if i >= end { |
| p.buf.writeString(noVerbString) |
| break |
| } |
| |
| verb, size := rune(format[i]), 1 |
| if verb >= utf8.RuneSelf { |
| verb, size = utf8.DecodeRuneInString(format[i:]) |
| } |
| i += size |
| |
| switch { |
| case verb == '%': // Percent does not absorb operands and ignores f.wid and f.prec. |
| p.buf.writeByte('%') |
| case !p.goodArgNum: |
| p.badArgNum(verb) |
| case argNum >= len(a): // No argument left over to print for the current verb. |
| p.missingArg(verb) |
| case verb == 'w': |
| p.wrappedErrs = append(p.wrappedErrs, argNum) |
| fallthrough |
| case verb == 'v': |
| // Go syntax |
| p.fmt.sharpV = p.fmt.sharp |
| p.fmt.sharp = false |
| // Struct-field syntax |
| p.fmt.plusV = p.fmt.plus |
| p.fmt.plus = false |
| fallthrough |
| default: |
| p.printArg(a[argNum], verb) |
| argNum++ |
| } |
| } |
| |
| // Check for extra arguments unless the call accessed the arguments |
| // out of order, in which case it's too expensive to detect if they've all |
| // been used and arguably OK if they're not. |
| if !p.reordered && argNum < len(a) { |
| p.fmt.clearflags() |
| p.buf.writeString(extraString) |
| for i, arg := range a[argNum:] { |
| if i > 0 { |
| p.buf.writeString(commaSpaceString) |
| } |
| if arg == nil { |
| p.buf.writeString(nilAngleString) |
| } else { |
| p.buf.writeString(reflect.TypeOf(arg).String()) |
| p.buf.writeByte('=') |
| p.printArg(arg, 'v') |
| } |
| } |
| p.buf.writeByte(')') |
| } |
| } |
| |
| func (p *pp) doPrint(a []any) { |
| 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.buf.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 *pp) doPrintln(a []any) { |
| for argNum, arg := range a { |
| if argNum > 0 { |
| p.buf.writeByte(' ') |
| } |
| p.printArg(arg, 'v') |
| } |
| p.buf.writeByte('\n') |
| } |