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      1 // Copyright 2009 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 // Formatting of reflection types and values for debugging.
      6 // Not defined as methods so they do not need to be linked into most binaries;
      7 // the functions are not used by the library itself, only in tests.
      8 
      9 package reflect_test
     10 
     11 import (
     12 	. "reflect"
     13 	"strconv"
     14 )
     15 
     16 // valueToString returns a textual representation of the reflection value val.
     17 // For debugging only.
     18 func valueToString(val Value) string {
     19 	var str string
     20 	if !val.IsValid() {
     21 		return "<zero Value>"
     22 	}
     23 	typ := val.Type()
     24 	switch val.Kind() {
     25 	case Int, Int8, Int16, Int32, Int64:
     26 		return strconv.FormatInt(val.Int(), 10)
     27 	case Uint, Uint8, Uint16, Uint32, Uint64, Uintptr:
     28 		return strconv.FormatUint(val.Uint(), 10)
     29 	case Float32, Float64:
     30 		return strconv.FormatFloat(val.Float(), 'g', -1, 64)
     31 	case Complex64, Complex128:
     32 		c := val.Complex()
     33 		return strconv.FormatFloat(real(c), 'g', -1, 64) + "+" + strconv.FormatFloat(imag(c), 'g', -1, 64) + "i"
     34 	case String:
     35 		return val.String()
     36 	case Bool:
     37 		if val.Bool() {
     38 			return "true"
     39 		} else {
     40 			return "false"
     41 		}
     42 	case Ptr:
     43 		v := val
     44 		str = typ.String() + "("
     45 		if v.IsNil() {
     46 			str += "0"
     47 		} else {
     48 			str += "&" + valueToString(v.Elem())
     49 		}
     50 		str += ")"
     51 		return str
     52 	case Array, Slice:
     53 		v := val
     54 		str += typ.String()
     55 		str += "{"
     56 		for i := 0; i < v.Len(); i++ {
     57 			if i > 0 {
     58 				str += ", "
     59 			}
     60 			str += valueToString(v.Index(i))
     61 		}
     62 		str += "}"
     63 		return str
     64 	case Map:
     65 		t := typ
     66 		str = t.String()
     67 		str += "{"
     68 		str += "<can't iterate on maps>"
     69 		str += "}"
     70 		return str
     71 	case Chan:
     72 		str = typ.String()
     73 		return str
     74 	case Struct:
     75 		t := typ
     76 		v := val
     77 		str += t.String()
     78 		str += "{"
     79 		for i, n := 0, v.NumField(); i < n; i++ {
     80 			if i > 0 {
     81 				str += ", "
     82 			}
     83 			str += valueToString(v.Field(i))
     84 		}
     85 		str += "}"
     86 		return str
     87 	case Interface:
     88 		return typ.String() + "(" + valueToString(val.Elem()) + ")"
     89 	case Func:
     90 		v := val
     91 		return typ.String() + "(" + strconv.FormatUint(uint64(v.Pointer()), 10) + ")"
     92 	default:
     93 		panic("valueToString: can't print type " + typ.String())
     94 	}
     95 }
     96