tostring_test.go

Documentation: reflect

		 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
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