blob: 249f089ef002ee3fcde4c2f328131a0e7947d6df [file] [log] [blame]
package pretty
import (
"fmt"
"io"
"reflect"
"strconv"
"text/tabwriter"
"github.com/kr/text"
"github.com/rogpeppe/go-internal/fmtsort"
)
type formatter struct {
v reflect.Value
force bool
quote bool
}
// Formatter makes a wrapper, f, that will format x as go source with line
// breaks and tabs. Object f responds to the "%v" formatting verb when both the
// "#" and " " (space) flags are set, for example:
//
// fmt.Sprintf("%# v", Formatter(x))
//
// If one of these two flags is not set, or any other verb is used, f will
// format x according to the usual rules of package fmt.
// In particular, if x satisfies fmt.Formatter, then x.Format will be called.
func Formatter(x interface{}) (f fmt.Formatter) {
return formatter{v: reflect.ValueOf(x), quote: true}
}
func (fo formatter) String() string {
return fmt.Sprint(fo.v.Interface()) // unwrap it
}
func (fo formatter) passThrough(f fmt.State, c rune) {
s := "%"
for i := 0; i < 128; i++ {
if f.Flag(i) {
s += string(rune(i))
}
}
if w, ok := f.Width(); ok {
s += fmt.Sprintf("%d", w)
}
if p, ok := f.Precision(); ok {
s += fmt.Sprintf(".%d", p)
}
s += string(c)
fmt.Fprintf(f, s, fo.v.Interface())
}
func (fo formatter) Format(f fmt.State, c rune) {
if fo.force || c == 'v' && f.Flag('#') && f.Flag(' ') {
w := tabwriter.NewWriter(f, 4, 4, 1, ' ', 0)
p := &printer{tw: w, Writer: w, visited: make(map[visit]int)}
p.printValue(fo.v, true, fo.quote)
w.Flush()
return
}
fo.passThrough(f, c)
}
type printer struct {
io.Writer
tw *tabwriter.Writer
visited map[visit]int
depth int
}
func (p *printer) indent() *printer {
q := *p
q.tw = tabwriter.NewWriter(p.Writer, 4, 4, 1, ' ', 0)
q.Writer = text.NewIndentWriter(q.tw, []byte{'\t'})
return &q
}
func (p *printer) printInline(v reflect.Value, x interface{}, showType bool) {
if showType {
io.WriteString(p, v.Type().String())
fmt.Fprintf(p, "(%#v)", x)
} else {
fmt.Fprintf(p, "%#v", x)
}
}
// printValue must keep track of already-printed pointer values to avoid
// infinite recursion.
type visit struct {
v uintptr
typ reflect.Type
}
func (p *printer) printValue(v reflect.Value, showType, quote bool) {
if p.depth > 10 {
io.WriteString(p, "!%v(DEPTH EXCEEDED)")
return
}
if v.IsValid() && v.CanInterface() {
i := v.Interface()
if goStringer, ok := i.(fmt.GoStringer); ok {
io.WriteString(p, goStringer.GoString())
return
}
}
switch v.Kind() {
case reflect.Bool:
p.printInline(v, v.Bool(), showType)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
p.printInline(v, v.Int(), showType)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
p.printInline(v, v.Uint(), showType)
case reflect.Float32, reflect.Float64:
p.printInline(v, v.Float(), showType)
case reflect.Complex64, reflect.Complex128:
fmt.Fprintf(p, "%#v", v.Complex())
case reflect.String:
p.fmtString(v.String(), quote)
case reflect.Map:
t := v.Type()
if showType {
io.WriteString(p, t.String())
}
writeByte(p, '{')
if nonzero(v) {
expand := !canInline(v.Type())
pp := p
if expand {
writeByte(p, '\n')
pp = p.indent()
}
sm := fmtsort.Sort(v)
for i := 0; i < v.Len(); i++ {
k := sm.Key[i]
mv := sm.Value[i]
pp.printValue(k, false, true)
writeByte(pp, ':')
if expand {
writeByte(pp, '\t')
}
showTypeInStruct := t.Elem().Kind() == reflect.Interface
pp.printValue(mv, showTypeInStruct, true)
if expand {
io.WriteString(pp, ",\n")
} else if i < v.Len()-1 {
io.WriteString(pp, ", ")
}
}
if expand {
pp.tw.Flush()
}
}
writeByte(p, '}')
case reflect.Struct:
t := v.Type()
if v.CanAddr() {
addr := v.UnsafeAddr()
vis := visit{addr, t}
if vd, ok := p.visited[vis]; ok && vd < p.depth {
p.fmtString(t.String()+"{(CYCLIC REFERENCE)}", false)
break // don't print v again
}
p.visited[vis] = p.depth
}
if showType {
io.WriteString(p, t.String())
}
writeByte(p, '{')
if nonzero(v) {
expand := !canInline(v.Type())
pp := p
if expand {
writeByte(p, '\n')
pp = p.indent()
}
for i := 0; i < v.NumField(); i++ {
showTypeInStruct := true
if f := t.Field(i); f.Name != "" {
io.WriteString(pp, f.Name)
writeByte(pp, ':')
if expand {
writeByte(pp, '\t')
}
showTypeInStruct = labelType(f.Type)
}
pp.printValue(getField(v, i), showTypeInStruct, true)
if expand {
io.WriteString(pp, ",\n")
} else if i < v.NumField()-1 {
io.WriteString(pp, ", ")
}
}
if expand {
pp.tw.Flush()
}
}
writeByte(p, '}')
case reflect.Interface:
switch e := v.Elem(); {
case e.Kind() == reflect.Invalid:
io.WriteString(p, "nil")
case e.IsValid():
pp := *p
pp.depth++
pp.printValue(e, showType, true)
default:
io.WriteString(p, v.Type().String())
io.WriteString(p, "(nil)")
}
case reflect.Array, reflect.Slice:
t := v.Type()
if showType {
io.WriteString(p, t.String())
}
if v.Kind() == reflect.Slice && v.IsNil() && showType {
io.WriteString(p, "(nil)")
break
}
if v.Kind() == reflect.Slice && v.IsNil() {
io.WriteString(p, "nil")
break
}
writeByte(p, '{')
expand := !canInline(v.Type())
pp := p
if expand {
writeByte(p, '\n')
pp = p.indent()
}
for i := 0; i < v.Len(); i++ {
showTypeInSlice := t.Elem().Kind() == reflect.Interface
pp.printValue(v.Index(i), showTypeInSlice, true)
if expand {
io.WriteString(pp, ",\n")
} else if i < v.Len()-1 {
io.WriteString(pp, ", ")
}
}
if expand {
pp.tw.Flush()
}
writeByte(p, '}')
case reflect.Ptr:
e := v.Elem()
if !e.IsValid() {
writeByte(p, '(')
io.WriteString(p, v.Type().String())
io.WriteString(p, ")(nil)")
} else {
pp := *p
pp.depth++
writeByte(pp, '&')
pp.printValue(e, true, true)
}
case reflect.Chan:
x := v.Pointer()
if showType {
writeByte(p, '(')
io.WriteString(p, v.Type().String())
fmt.Fprintf(p, ")(%#v)", x)
} else {
fmt.Fprintf(p, "%#v", x)
}
case reflect.Func:
io.WriteString(p, v.Type().String())
io.WriteString(p, " {...}")
case reflect.UnsafePointer:
p.printInline(v, v.Pointer(), showType)
case reflect.Invalid:
io.WriteString(p, "nil")
}
}
func canInline(t reflect.Type) bool {
switch t.Kind() {
case reflect.Map:
return !canExpand(t.Elem())
case reflect.Struct:
for i := 0; i < t.NumField(); i++ {
if canExpand(t.Field(i).Type) {
return false
}
}
return true
case reflect.Interface:
return false
case reflect.Array, reflect.Slice:
return !canExpand(t.Elem())
case reflect.Ptr:
return false
case reflect.Chan, reflect.Func, reflect.UnsafePointer:
return false
}
return true
}
func canExpand(t reflect.Type) bool {
switch t.Kind() {
case reflect.Map, reflect.Struct,
reflect.Interface, reflect.Array, reflect.Slice,
reflect.Ptr:
return true
}
return false
}
func labelType(t reflect.Type) bool {
switch t.Kind() {
case reflect.Interface, reflect.Struct:
return true
}
return false
}
func (p *printer) fmtString(s string, quote bool) {
if quote {
s = strconv.Quote(s)
}
io.WriteString(p, s)
}
func writeByte(w io.Writer, b byte) {
w.Write([]byte{b})
}
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
}