attr.go

Documentation: log/slog

     1  // Copyright 2022 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  package slog
     6  
     7  import (
     8  	"fmt"
     9  	"time"
    10  )
    11  
    12  // An Attr is a key-value pair.
    13  type Attr struct {
    14  	Key   string
    15  	Value Value
    16  }
    17  
    18  // String returns an Attr for a string value.
    19  func String(key, value string) Attr {
    20  	return Attr{key, StringValue(value)}
    21  }
    22  
    23  // Int64 returns an Attr for an int64.
    24  func Int64(key string, value int64) Attr {
    25  	return Attr{key, Int64Value(value)}
    26  }
    27  
    28  // Int converts an int to an int64 and returns
    29  // an Attr with that value.
    30  func Int(key string, value int) Attr {
    31  	return Int64(key, int64(value))
    32  }
    33  
    34  // Uint64 returns an Attr for a uint64.
    35  func Uint64(key string, v uint64) Attr {
    36  	return Attr{key, Uint64Value(v)}
    37  }
    38  
    39  // Float64 returns an Attr for a floating-point number.
    40  func Float64(key string, v float64) Attr {
    41  	return Attr{key, Float64Value(v)}
    42  }
    43  
    44  // Bool returns an Attr for a bool.
    45  func Bool(key string, v bool) Attr {
    46  	return Attr{key, BoolValue(v)}
    47  }
    48  
    49  // Time returns an Attr for a [time.Time].
    50  // It discards the monotonic portion.
    51  func Time(key string, v time.Time) Attr {
    52  	return Attr{key, TimeValue(v)}
    53  }
    54  
    55  // Duration returns an Attr for a [time.Duration].
    56  func Duration(key string, v time.Duration) Attr {
    57  	return Attr{key, DurationValue(v)}
    58  }
    59  
    60  // Group returns an Attr for a Group [Value].
    61  // The first argument is the key; the remaining arguments
    62  // are converted to Attrs as in [Logger.Log].
    63  //
    64  // Use Group to collect several key-value pairs under a single
    65  // key on a log line, or as the result of LogValue
    66  // in order to log a single value as multiple Attrs.
    67  func Group(key string, args ...any) Attr {
    68  	return Attr{key, GroupValue(argsToAttrSlice(args)...)}
    69  }
    70  
    71  func argsToAttrSlice(args []any) []Attr {
    72  	var (
    73  		attr  Attr
    74  		attrs []Attr
    75  	)
    76  	for len(args) > 0 {
    77  		attr, args = argsToAttr(args)
    78  		attrs = append(attrs, attr)
    79  	}
    80  	return attrs
    81  }
    82  
    83  // Any returns an Attr for the supplied value.
    84  // See [AnyValue] for how values are treated.
    85  func Any(key string, value any) Attr {
    86  	return Attr{key, AnyValue(value)}
    87  }
    88  
    89  // Equal reports whether a and b have equal keys and values.
    90  func (a Attr) Equal(b Attr) bool {
    91  	return a.Key == b.Key && a.Value.Equal(b.Value)
    92  }
    93  
    94  func (a Attr) String() string {
    95  	return fmt.Sprintf("%s=%s", a.Key, a.Value)
    96  }
    97  
    98  // isEmpty reports whether a has an empty key and a nil value.
    99  // That can be written as Attr{} or Any("", nil).
   100  func (a Attr) isEmpty() bool {
   101  	return a.Key == "" && a.Value.num == 0 && a.Value.any == nil
   102  }
   103
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