prettify.go

Documentation: github.com/aws/aws-sdk-go-v2/internal/awsutil

     1  package awsutil
     2  
     3  import (
     4  	"bytes"
     5  	"fmt"
     6  	"io"
     7  	"reflect"
     8  	"strings"
     9  )
    10  
    11  // Prettify returns the string representation of a value.
    12  func Prettify(i interface{}) string {
    13  	var buf bytes.Buffer
    14  	prettify(reflect.ValueOf(i), 0, &buf)
    15  	return buf.String()
    16  }
    17  
    18  // prettify will recursively walk value v to build a textual
    19  // representation of the value.
    20  func prettify(v reflect.Value, indent int, buf *bytes.Buffer) {
    21  	isPtr := false
    22  	for v.Kind() == reflect.Ptr {
    23  		isPtr = true
    24  		v = v.Elem()
    25  	}
    26  
    27  	switch v.Kind() {
    28  	case reflect.Struct:
    29  		strtype := v.Type().String()
    30  		if strtype == "time.Time" {
    31  			fmt.Fprintf(buf, "%s", v.Interface())
    32  			break
    33  		} else if strings.HasPrefix(strtype, "io.") {
    34  			buf.WriteString("<buffer>")
    35  			break
    36  		}
    37  
    38  		if isPtr {
    39  			buf.WriteRune('&')
    40  		}
    41  		buf.WriteString("{\n")
    42  
    43  		names := []string{}
    44  		for i := 0; i < v.Type().NumField(); i++ {
    45  			name := v.Type().Field(i).Name
    46  			f := v.Field(i)
    47  			if name[0:1] == strings.ToLower(name[0:1]) {
    48  				continue // ignore unexported fields
    49  			}
    50  			if (f.Kind() == reflect.Ptr || f.Kind() == reflect.Slice || f.Kind() == reflect.Map) && f.IsNil() {
    51  				continue // ignore unset fields
    52  			}
    53  			names = append(names, name)
    54  		}
    55  
    56  		for i, n := range names {
    57  			val := v.FieldByName(n)
    58  			buf.WriteString(strings.Repeat(" ", indent+2))
    59  			buf.WriteString(n + ": ")
    60  			prettify(val, indent+2, buf)
    61  
    62  			if i < len(names)-1 {
    63  				buf.WriteString(",\n")
    64  			}
    65  		}
    66  
    67  		buf.WriteString("\n" + strings.Repeat(" ", indent) + "}")
    68  	case reflect.Slice:
    69  		strtype := v.Type().String()
    70  		if strtype == "[]uint8" {
    71  			fmt.Fprintf(buf, "<binary> len %d", v.Len())
    72  			break
    73  		}
    74  
    75  		nl, id, id2 := "\n", strings.Repeat(" ", indent), strings.Repeat(" ", indent+2)
    76  		if isPtr {
    77  			buf.WriteRune('&')
    78  		}
    79  		buf.WriteString("[" + nl)
    80  		for i := 0; i < v.Len(); i++ {
    81  			buf.WriteString(id2)
    82  			prettify(v.Index(i), indent+2, buf)
    83  
    84  			if i < v.Len()-1 {
    85  				buf.WriteString("," + nl)
    86  			}
    87  		}
    88  
    89  		buf.WriteString(nl + id + "]")
    90  	case reflect.Map:
    91  		if isPtr {
    92  			buf.WriteRune('&')
    93  		}
    94  		buf.WriteString("{\n")
    95  
    96  		for i, k := range v.MapKeys() {
    97  			buf.WriteString(strings.Repeat(" ", indent+2))
    98  			buf.WriteString(k.String() + ": ")
    99  			prettify(v.MapIndex(k), indent+2, buf)
   100  
   101  			if i < v.Len()-1 {
   102  				buf.WriteString(",\n")
   103  			}
   104  		}
   105  
   106  		buf.WriteString("\n" + strings.Repeat(" ", indent) + "}")
   107  	default:
   108  		if !v.IsValid() {
   109  			fmt.Fprint(buf, "<invalid value>")
   110  			return
   111  		}
   112  
   113  		for v.Kind() == reflect.Interface && !v.IsNil() {
   114  			v = v.Elem()
   115  		}
   116  
   117  		if v.Kind() == reflect.Ptr || v.Kind() == reflect.Struct || v.Kind() == reflect.Map || v.Kind() == reflect.Slice {
   118  			prettify(v, indent, buf)
   119  			return
   120  		}
   121  
   122  		format := "%v"
   123  		switch v.Interface().(type) {
   124  		case string:
   125  			format = "%q"
   126  		case io.ReadSeeker, io.Reader:
   127  			format = "buffer(%p)"
   128  		}
   129  		fmt.Fprintf(buf, format, v.Interface())
   130  	}
   131  }
   132
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