Content inside fengaldar<br />
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<pre><code>// Fengaldar provides a logger, or, &#39;one who cuts trees&#39;.
//
// The result of NewLogger().Println(&#34;Some message&#34;) looks like:
//	INFO 2020-09-03T18:53:04-06:00 Some message
//
// The result of NewJSONLogger().Println(&#34;Some message&#34;) looks like:
//	{&#34;timestamp&#34;:&#34;2020-09-03T18:53:04-06:00&#34;, &#34;severity&#34;:&#34;INFO&#34;, &#34;message&#34;:&#34;Some message&#34;}
//
// The result of NewJSONLogger().Notice(&#34;Some message&#34;, LogContext{&#34;extra&#34;:&#34;info&#34;}) looks like:
//	{&#34;timestamp&#34;: &#34;2020-09-03T18:53:04-06:00&#34;, &#34;severity&#34;: &#34;INFO&#34;, &#34;message&#34;: &#34;Some message&#34;, &#34;additionalContext&#34;: &#34;{\&#34;extra\&#34;:\&#34;info\&#34;}&#34;}
//
// Of course you&#39;ll likely store the result of NewLogger() in a var so your code might look more like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	l := fen.NewLogger()
//	...
//	l.Log(&#34;Something happened&#34;)
//	...
//	l.Notice(&#34;Something interesting happened&#34;)
//
// You might also want to tweak the defaults with your own. That might look something like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	minSeverityToLog := fen.Warning
//	defaultLogSeverity := fen.Notice
//	customOptions := fen.Options{minSeverityToLog, defaultLogSeverity, time.RFC822, false, &#34;more&#34;}
//	l := fen.NewLoggerWithOptions(customOptions)
//	...
//	l.Log(&#34;Something happened&#34;) // This will be ignored due to having set &#39;minSeverityToLog&#39; to a higher Severity than the default (which was provided in defaultLogSeverity)
//	...
//	l.Notice(&#34;Something interesting happened&#34;) // This will also be ignored due to having set &#39;minSeverityToLog&#39; to a higher Severity than the default (which was provided in defaultLogSeverity)
//	...
//	l.Critical(&#34;Something caused a brief outage&#34;) // This will NOT be ignored
//
// You might also want to add some context to the log entry, and that might look something like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	l := fen.NewLogger()
//	...
//	l.Log(&#34;Something happened&#34;, fen.LogContext{&#34;somethingWasSetTo&#34;: &#34;someValue&#34;})
package fengaldar

import (
	&#34;fmt&#34;
	&#34;os&#34;
	&#34;sort&#34;
	&#34;strconv&#34;
	&#34;strings&#34;
	&#34;time&#34;
)

// Severity represents the severity of the related log entry.
// Naming, ordering, and guidlines are based on severity consts found at https://pkg.go.dev/cloud.google.com/go/logging#pkg-constants
type Severity int

const (
	Debug     Severity = iota // Debug - debug or trace information.
	Info                      // Info - routine information, such as ongoing status or performance.
	Notice                    // Notice - normal but significant events, such as start up, shut down, or configuration.
	Warning                   // Warning - events that might cause problems.
	Error                     // Error - events that are likely to cause problems.
	Critical                  // Critical - events that cause more severe problems or brief outages.
	Alert                     // Alert - a person must take an action immediately.
	Emergency                 // Emergency - one or more systems are unusable.
	Panic                     // Panic - one or more systems are unusable and this package will throw a panic.
	Fatal                     // Fatal - one or more systems are unusable and this package will call os.Exit(1).
)

var sevStrings = []string{
	&#34;DEBUG&#34;,
	&#34;INFO&#34;,
	&#34;NOTICE&#34;,
	&#34;WARNING&#34;,
	&#34;ERROR&#34;,
	&#34;CRITICAL&#34;,
	&#34;ALERT&#34;,
	&#34;EMERGENCY&#34;,
	&#34;PANIC&#34;,
	&#34;FATAL&#34;,
}

func (s Severity) String() string {
	return sevStrings[s]
}

// LogContext provides a way to express additional context on a log entry.
type LogContext map[string]string

func (a LogContext) Merge(b LogContext) {
	for k, v := range b {
		a[k] = v
	}
}

// LogContext.String will produce a unicode box-drawing prefix-wrapped output where each key in the LogContext is on it&#39;s own line
func (lc LogContext) String() string {
	var s strings.Builder
	s.WriteString(&#34; \u250f\n&#34;)
	slc := []string{}
	for k, _ := range lc {
		slc = append(slc, k)
	}
	sort.Strings(slc)
	for _, k := range slc {
		s.WriteString(fmt.Sprintf(&#34; \u2503 %q: %q\n&#34;, k, lc[k]))
	}
	s.WriteString(&#34; \u2517&#34;)
	return s.String()
}

// LogContext.JSON will produce a JSON object, where each key and value remain
// keys and values and are converted with fmt.Sprintf(&#34;%q&#34;)
func (lc LogContext) JSON() string     { return &#34;{&#34; &#43; lc.keyedJSON(&#34;&#34;) &#43; &#34;}&#34; }
func (lc LogContext) flatJSON() string { return lc.keyedJSON(&#34;&#34;) }
func (lc LogContext) keyedJSON(prefix string) string {
	var s strings.Builder
	first := true
	slc := []string{}
	for k, _ := range lc {
		slc = append(slc, k)
	}
	sort.Strings(slc)
	for _, k := range slc {
		if !first {
			s.WriteString(&#34;, &#34;)
		}
		prefixedK := k
		if len(prefix) &gt; 0 {
			prefixedK = fmt.Sprintf(&#34;%s:%s&#34;, prefix, k)
		}
		s.WriteString(fmt.Sprintf(&#34;%q:%q&#34;, prefixedK, lc[k]))
		first = false
	}
	return s.String()
}

// FOR ALL DECLARATIONS OF `...LogContext` ONLY THE FIRST LogContext WILL BE USED.
// This allows the LogContext to be optional.
//
// You might notice that Printf is not provided.
//
// In cases where you would use Printf you should explore constructing a LogContext to
// convey the additional data, or use fmt.Sprintf.
type Logger interface {
	Clone() Logger
	Trace(string) Logger             // Trace sets the given TraceKey to the given value and returns a func that resets the value on a defer
	Time() string                    // Time is the result of applying the time.Layout specified in Options.TF in a call to time.Now().Format
	Sev() Severity                   // Sev is the default severity used in Println and Log
	Println(...interface{})          // For NewLogger, each parameter will be on it&#39;s own line. For NewJSONLogger, they&#39;re combined with a strings.Join(&#34;\n&#34;).
	Log(string, ...LogContext)       // FOR ALL DECLARATIONS OF `...LogContext` ONLY THE FIRST LogContext WILL BE USED
	Debug(string, ...LogContext)     // Debug - debug or trace information.
	Info(string, ...LogContext)      // Info - routine information, such as ongoing status or performance.
	Notice(string, ...LogContext)    // Notice - normal but significant events, such as start up, shut down, or configuration.
	Warning(string, ...LogContext)   // Warning - events that might cause problems.
	Error(string, ...LogContext)     // Error - events that are likely to cause problems.
	Critical(string, ...LogContext)  // Critical - events that cause more severe problems or brief outages.
	Alert(string, ...LogContext)     // Alert - a person must take an action immediately.
	Emergency(string, ...LogContext) // Emergency - one or more systems are unusable.
	Panic(string, ...LogContext)     // Panic - one or more systems are unusable and this package will throw a panic.
	Fatal(string, ...LogContext)     // Fatal - one or more systems are unusable and this package will call os.Exit(1).
}

type ContextStyleOption int

const (
	Flat ContextStyleOption = iota
	Nest
	Prefix
)

// Options allow you to specify different defaults for loggers
type Options struct {
	Min Severity // The minimum severity to actually produce output. Any log entry with an associated severity *below* this will be ignored.
	Sev Severity
	// TF is the TimeFormat that will be used when producing log entries.
	// This follows the time.Layout format seen here: https://pkg.go.dev/time#pkg-constants
	TF string
	// ContextStyle sets the use of the ContextKey as either a prefix to each LogContext key or
	// as the key to a nested object of LogContext keys and values or, finally, as a flattened set of keys
	// that are added to the root of the JSON log entry without prefix. This only matters for the JSON logger
	ContextStyle ContextStyleOption
	ContextKey   string // ContextKey is used to namespace the LogContext
	TraceKey     string // TraceKey is the key that the traceid, if any, will be placed under for the JSON logger
}

const DefaultContextKey = &#34;additionalContext&#34;
const DefaultTraceKey = &#34;traceid&#34;

var DefaultOptions = Options{
	Min:          Debug,
	Sev:          Info,
	TF:           time.RFC3339,
	ContextStyle: Flat,
	ContextKey:   DefaultContextKey,
	TraceKey:     DefaultTraceKey,
}

// simple

func NewLogger() Logger { return NewLoggerWithOptions(DefaultOptions) }

const defaultTraceID = &#34;no-trace-id&#34;

func NewLoggerWithOptions(o Options) Logger {
	return &amp;simpleLogger{
		o.Min,
		o.Sev,
		o.TF,
		strconv.Itoa(len(time.Now().Format(o.TF))),
		defaultTraceID,
	}
}

type simpleLogger struct {
	MS    Severity
	DS    Severity
	TF    string
	TS    string
	trace string
}

func (sl *simpleLogger) Clone() Logger {
	return &amp;simpleLogger{sl.MS, sl.DS, sl.TF, sl.TS, sl.trace}
}
func (sl *simpleLogger) Trace(id string) Logger {
	new := sl.Clone().(*simpleLogger)
	new.trace = id
	return new
}
func (sl simpleLogger) Time() string  { return time.Now().Format(sl.TF) }
func (sl simpleLogger) Sev() Severity { return sl.DS }
func (sl simpleLogger) line(sev Severity, s interface{}) string {
	if sl.trace != defaultTraceID {
		return fmt.Sprintf(&#34;%s %10.10s %&#34;&#43;sl.TS&#43;&#34;.&#34;&#43;sl.TS&#43;&#34;s %s\n&#34;, sl.trace, sev, sl.Time(), s)
	}
	return fmt.Sprintf(&#34;%10.10s %&#34;&#43;sl.TS&#43;&#34;.&#34;&#43;sl.TS&#43;&#34;s %s\n&#34;, sev, sl.Time(), s)
}
func (sl simpleLogger) Println(ss ...interface{}) {
	if sl.Sev() &lt; sl.MS {
		return
	}
	for _, s := range ss {
		fmt.Printf(sl.line(sl.Sev(), s))
	}
}
func (sl simpleLogger) internal(sev Severity, s string, lc ...LogContext) {
	if sev &lt; sl.MS {
		return
	}
	fmt.Printf(sl.line(sev, s))
	if len(lc) &gt; 0 {
		fmt.Println(lc[0])
	}
}
func (sl simpleLogger) Log(s string, lc ...LogContext)       { sl.internal(sl.Sev(), s, lc...) }
func (sl simpleLogger) Debug(s string, lc ...LogContext)     { sl.internal(Debug, s, lc...) }
func (sl simpleLogger) Info(s string, lc ...LogContext)      { sl.internal(Info, s, lc...) }
func (sl simpleLogger) Notice(s string, lc ...LogContext)    { sl.internal(Notice, s, lc...) }
func (sl simpleLogger) Warning(s string, lc ...LogContext)   { sl.internal(Warning, s, lc...) }
func (sl simpleLogger) Error(s string, lc ...LogContext)     { sl.internal(Error, s, lc...) }
func (sl simpleLogger) Critical(s string, lc ...LogContext)  { sl.internal(Critical, s, lc...) }
func (sl simpleLogger) Alert(s string, lc ...LogContext)     { sl.internal(Alert, s, lc...) }
func (sl simpleLogger) Emergency(s string, lc ...LogContext) { sl.internal(Emergency, s, lc...) }
func (sl simpleLogger) Panic(s string, lc ...LogContext)     { sl.internal(Panic, s, lc...); panic(s) }
func (sl simpleLogger) Fatal(s string, lc ...LogContext)     { sl.internal(Fatal, s, lc...); os.Exit(1) }

// JSON

func NewJSONLogger() Logger { return NewJSONLoggerWithOptions(DefaultOptions) }
func NewJSONLoggerWithOptions(o Options) Logger {
	return &amp;jsonLogger{o.Min, o.Sev, o.TF, o.ContextStyle, o.ContextKey, o.TraceKey, defaultTraceID}
}

type jsonLogger struct {
	MS           Severity
	DS           Severity
	TF           string
	ContextStyle ContextStyleOption
	ContextKey   string
	TraceKey     string
	trace        string
}

func (jl *jsonLogger) Clone() Logger {
	return &amp;jsonLogger{jl.MS, jl.DS, jl.TF, jl.ContextStyle, jl.ContextKey, jl.TraceKey, jl.trace}
}
func (jl *jsonLogger) Trace(id string) Logger {
	new := jl.Clone().(*jsonLogger)
	new.trace = id
	return new
}
func (jl *jsonLogger) Time() string { return time.Now().Format(jl.TF) }
func (jl jsonLogger) Sev() Severity { return jl.DS }
func (jl jsonLogger) line(sev Severity, s interface{}) string {
	if jl.trace != defaultTraceID {
		return fmt.Sprintf(
			`%q:%q, &#34;timestamp&#34;:%q, &#34;severity&#34;:%q, &#34;message&#34;:%q`,
			jl.TraceKey, jl.trace, jl.Time(), sev, s)
	}
	return fmt.Sprintf(`&#34;timestamp&#34;:%q, &#34;severity&#34;:%q, &#34;message&#34;:%q`, jl.Time(), sev, s)
}
func (jl jsonLogger) lineWithContext(s interface{}, lc LogContext) string {
	if jl.ContextStyle == Prefix {
		return fmt.Sprintf(`%s, %s`, jl.line(jl.Sev(), s), lc.keyedJSON(jl.ContextKey))
	}
	if jl.ContextStyle == Flat {
		return fmt.Sprintf(`%s, %s`, jl.line(jl.Sev(), s), lc.flatJSON())
	}
	return fmt.Sprintf(`%s, %q:%q`, jl.line(jl.Sev(), s), jl.ContextKey, lc.JSON())
}
func (jl jsonLogger) Println(ss ...interface{}) {
	if jl.Sev() &lt; jl.MS {
		return
	}
	var jss strings.Builder
	for i, s := range ss {
		if i &gt; 0 {
			jss.WriteString(&#34;\n&#34;)
		}
		jss.WriteString(s.(string))
	}
	fmt.Printf(&#34;{%s}\n&#34;, jl.line(jl.Sev(), jss.String()))
}
func (jl jsonLogger) internal(sev Severity, s string, lc ...LogContext) {
	if sev &lt; jl.MS {
		return
	}
	if len(lc) == 0 {
		fmt.Printf(&#34;{%s}\n&#34;, jl.line(sev, s))
	} else {
		fmt.Printf(&#34;{%s}\n&#34;, jl.lineWithContext(s, lc[0]))
	}
}
func (jl jsonLogger) Log(s string, lc ...LogContext)       { jl.internal(jl.Sev(), s, lc...) }
func (jl jsonLogger) Debug(s string, lc ...LogContext)     { jl.internal(Debug, s, lc...) }
func (jl jsonLogger) Info(s string, lc ...LogContext)      { jl.internal(Info, s, lc...) }
func (jl jsonLogger) Notice(s string, lc ...LogContext)    { jl.internal(Notice, s, lc...) }
func (jl jsonLogger) Warning(s string, lc ...LogContext)   { jl.internal(Warning, s, lc...) }
func (jl jsonLogger) Error(s string, lc ...LogContext)     { jl.internal(Error, s, lc...) }
func (jl jsonLogger) Critical(s string, lc ...LogContext)  { jl.internal(Critical, s, lc...) }
func (jl jsonLogger) Alert(s string, lc ...LogContext)     { jl.internal(Alert, s, lc...) }
func (jl jsonLogger) Emergency(s string, lc ...LogContext) { jl.internal(Emergency, s, lc...) }
func (jl jsonLogger) Panic(s string, lc ...LogContext)     { jl.internal(Panic, s, lc...); panic(s) }
func (jl jsonLogger) Fatal(s string, lc ...LogContext)     { jl.internal(Fatal, s, lc...); os.Exit(1) }
</code></pre>
<br /><br />
<div id='raw'>The raw file follows...</div>
<br /><br />
<div style="border:solid 1px black; padding:1em; overflow:scroll" contentEditable><pre>// Fengaldar provides a logger, or, &#39;one who cuts trees&#39;.
//
// The result of NewLogger().Println(&#34;Some message&#34;) looks like:
//	INFO 2020-09-03T18:53:04-06:00 Some message
//
// The result of NewJSONLogger().Println(&#34;Some message&#34;) looks like:
//	{&#34;timestamp&#34;:&#34;2020-09-03T18:53:04-06:00&#34;, &#34;severity&#34;:&#34;INFO&#34;, &#34;message&#34;:&#34;Some message&#34;}
//
// The result of NewJSONLogger().Notice(&#34;Some message&#34;, LogContext{&#34;extra&#34;:&#34;info&#34;}) looks like:
//	{&#34;timestamp&#34;: &#34;2020-09-03T18:53:04-06:00&#34;, &#34;severity&#34;: &#34;INFO&#34;, &#34;message&#34;: &#34;Some message&#34;, &#34;additionalContext&#34;: &#34;{\&#34;extra\&#34;:\&#34;info\&#34;}&#34;}
//
// Of course you&#39;ll likely store the result of NewLogger() in a var so your code might look more like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	l := fen.NewLogger()
//	...
//	l.Log(&#34;Something happened&#34;)
//	...
//	l.Notice(&#34;Something interesting happened&#34;)
//
// You might also want to tweak the defaults with your own. That might look something like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	minSeverityToLog := fen.Warning
//	defaultLogSeverity := fen.Notice
//	customOptions := fen.Options{minSeverityToLog, defaultLogSeverity, time.RFC822, false, &#34;more&#34;}
//	l := fen.NewLoggerWithOptions(customOptions)
//	...
//	l.Log(&#34;Something happened&#34;) // This will be ignored due to having set &#39;minSeverityToLog&#39; to a higher Severity than the default (which was provided in defaultLogSeverity)
//	...
//	l.Notice(&#34;Something interesting happened&#34;) // This will also be ignored due to having set &#39;minSeverityToLog&#39; to a higher Severity than the default (which was provided in defaultLogSeverity)
//	...
//	l.Critical(&#34;Something caused a brief outage&#34;) // This will NOT be ignored
//
// You might also want to add some context to the log entry, and that might look something like this:
//	import ( fen &#34;git.ondollo.com/fengaldar&#34; )
//	...
//	l := fen.NewLogger()
//	...
//	l.Log(&#34;Something happened&#34;, fen.LogContext{&#34;somethingWasSetTo&#34;: &#34;someValue&#34;})
package fengaldar

import (
	&#34;fmt&#34;
	&#34;os&#34;
	&#34;sort&#34;
	&#34;strconv&#34;
	&#34;strings&#34;
	&#34;time&#34;
)

// Severity represents the severity of the related log entry.
// Naming, ordering, and guidlines are based on severity consts found at https://pkg.go.dev/cloud.google.com/go/logging#pkg-constants
type Severity int

const (
	Debug     Severity = iota // Debug - debug or trace information.
	Info                      // Info - routine information, such as ongoing status or performance.
	Notice                    // Notice - normal but significant events, such as start up, shut down, or configuration.
	Warning                   // Warning - events that might cause problems.
	Error                     // Error - events that are likely to cause problems.
	Critical                  // Critical - events that cause more severe problems or brief outages.
	Alert                     // Alert - a person must take an action immediately.
	Emergency                 // Emergency - one or more systems are unusable.
	Panic                     // Panic - one or more systems are unusable and this package will throw a panic.
	Fatal                     // Fatal - one or more systems are unusable and this package will call os.Exit(1).
)

var sevStrings = []string{
	&#34;DEBUG&#34;,
	&#34;INFO&#34;,
	&#34;NOTICE&#34;,
	&#34;WARNING&#34;,
	&#34;ERROR&#34;,
	&#34;CRITICAL&#34;,
	&#34;ALERT&#34;,
	&#34;EMERGENCY&#34;,
	&#34;PANIC&#34;,
	&#34;FATAL&#34;,
}

func (s Severity) String() string {
	return sevStrings[s]
}

// LogContext provides a way to express additional context on a log entry.
type LogContext map[string]string

func (a LogContext) Merge(b LogContext) {
	for k, v := range b {
		a[k] = v
	}
}

// LogContext.String will produce a unicode box-drawing prefix-wrapped output where each key in the LogContext is on it&#39;s own line
func (lc LogContext) String() string {
	var s strings.Builder
	s.WriteString(&#34; \u250f\n&#34;)
	slc := []string{}
	for k, _ := range lc {
		slc = append(slc, k)
	}
	sort.Strings(slc)
	for _, k := range slc {
		s.WriteString(fmt.Sprintf(&#34; \u2503 %q: %q\n&#34;, k, lc[k]))
	}
	s.WriteString(&#34; \u2517&#34;)
	return s.String()
}

// LogContext.JSON will produce a JSON object, where each key and value remain
// keys and values and are converted with fmt.Sprintf(&#34;%q&#34;)
func (lc LogContext) JSON() string     { return &#34;{&#34; &#43; lc.keyedJSON(&#34;&#34;) &#43; &#34;}&#34; }
func (lc LogContext) flatJSON() string { return lc.keyedJSON(&#34;&#34;) }
func (lc LogContext) keyedJSON(prefix string) string {
	var s strings.Builder
	first := true
	slc := []string{}
	for k, _ := range lc {
		slc = append(slc, k)
	}
	sort.Strings(slc)
	for _, k := range slc {
		if !first {
			s.WriteString(&#34;, &#34;)
		}
		prefixedK := k
		if len(prefix) &gt; 0 {
			prefixedK = fmt.Sprintf(&#34;%s:%s&#34;, prefix, k)
		}
		s.WriteString(fmt.Sprintf(&#34;%q:%q&#34;, prefixedK, lc[k]))
		first = false
	}
	return s.String()
}

// FOR ALL DECLARATIONS OF `...LogContext` ONLY THE FIRST LogContext WILL BE USED.
// This allows the LogContext to be optional.
//
// You might notice that Printf is not provided.
//
// In cases where you would use Printf you should explore constructing a LogContext to
// convey the additional data, or use fmt.Sprintf.
type Logger interface {
	Clone() Logger
	Trace(string) Logger             // Trace sets the given TraceKey to the given value and returns a func that resets the value on a defer
	Time() string                    // Time is the result of applying the time.Layout specified in Options.TF in a call to time.Now().Format
	Sev() Severity                   // Sev is the default severity used in Println and Log
	Println(...interface{})          // For NewLogger, each parameter will be on it&#39;s own line. For NewJSONLogger, they&#39;re combined with a strings.Join(&#34;\n&#34;).
	Log(string, ...LogContext)       // FOR ALL DECLARATIONS OF `...LogContext` ONLY THE FIRST LogContext WILL BE USED
	Debug(string, ...LogContext)     // Debug - debug or trace information.
	Info(string, ...LogContext)      // Info - routine information, such as ongoing status or performance.
	Notice(string, ...LogContext)    // Notice - normal but significant events, such as start up, shut down, or configuration.
	Warning(string, ...LogContext)   // Warning - events that might cause problems.
	Error(string, ...LogContext)     // Error - events that are likely to cause problems.
	Critical(string, ...LogContext)  // Critical - events that cause more severe problems or brief outages.
	Alert(string, ...LogContext)     // Alert - a person must take an action immediately.
	Emergency(string, ...LogContext) // Emergency - one or more systems are unusable.
	Panic(string, ...LogContext)     // Panic - one or more systems are unusable and this package will throw a panic.
	Fatal(string, ...LogContext)     // Fatal - one or more systems are unusable and this package will call os.Exit(1).
}

type ContextStyleOption int

const (
	Flat ContextStyleOption = iota
	Nest
	Prefix
)

// Options allow you to specify different defaults for loggers
type Options struct {
	Min Severity // The minimum severity to actually produce output. Any log entry with an associated severity *below* this will be ignored.
	Sev Severity
	// TF is the TimeFormat that will be used when producing log entries.
	// This follows the time.Layout format seen here: https://pkg.go.dev/time#pkg-constants
	TF string
	// ContextStyle sets the use of the ContextKey as either a prefix to each LogContext key or
	// as the key to a nested object of LogContext keys and values or, finally, as a flattened set of keys
	// that are added to the root of the JSON log entry without prefix. This only matters for the JSON logger
	ContextStyle ContextStyleOption
	ContextKey   string // ContextKey is used to namespace the LogContext
	TraceKey     string // TraceKey is the key that the traceid, if any, will be placed under for the JSON logger
}

const DefaultContextKey = &#34;additionalContext&#34;
const DefaultTraceKey = &#34;traceid&#34;

var DefaultOptions = Options{
	Min:          Debug,
	Sev:          Info,
	TF:           time.RFC3339,
	ContextStyle: Flat,
	ContextKey:   DefaultContextKey,
	TraceKey:     DefaultTraceKey,
}

// simple

func NewLogger() Logger { return NewLoggerWithOptions(DefaultOptions) }

const defaultTraceID = &#34;no-trace-id&#34;

func NewLoggerWithOptions(o Options) Logger {
	return &amp;simpleLogger{
		o.Min,
		o.Sev,
		o.TF,
		strconv.Itoa(len(time.Now().Format(o.TF))),
		defaultTraceID,
	}
}

type simpleLogger struct {
	MS    Severity
	DS    Severity
	TF    string
	TS    string
	trace string
}

func (sl *simpleLogger) Clone() Logger {
	return &amp;simpleLogger{sl.MS, sl.DS, sl.TF, sl.TS, sl.trace}
}
func (sl *simpleLogger) Trace(id string) Logger {
	new := sl.Clone().(*simpleLogger)
	new.trace = id
	return new
}
func (sl simpleLogger) Time() string  { return time.Now().Format(sl.TF) }
func (sl simpleLogger) Sev() Severity { return sl.DS }
func (sl simpleLogger) line(sev Severity, s interface{}) string {
	if sl.trace != defaultTraceID {
		return fmt.Sprintf(&#34;%s %10.10s %&#34;&#43;sl.TS&#43;&#34;.&#34;&#43;sl.TS&#43;&#34;s %s\n&#34;, sl.trace, sev, sl.Time(), s)
	}
	return fmt.Sprintf(&#34;%10.10s %&#34;&#43;sl.TS&#43;&#34;.&#34;&#43;sl.TS&#43;&#34;s %s\n&#34;, sev, sl.Time(), s)
}
func (sl simpleLogger) Println(ss ...interface{}) {
	if sl.Sev() &lt; sl.MS {
		return
	}
	for _, s := range ss {
		fmt.Printf(sl.line(sl.Sev(), s))
	}
}
func (sl simpleLogger) internal(sev Severity, s string, lc ...LogContext) {
	if sev &lt; sl.MS {
		return
	}
	fmt.Printf(sl.line(sev, s))
	if len(lc) &gt; 0 {
		fmt.Println(lc[0])
	}
}
func (sl simpleLogger) Log(s string, lc ...LogContext)       { sl.internal(sl.Sev(), s, lc...) }
func (sl simpleLogger) Debug(s string, lc ...LogContext)     { sl.internal(Debug, s, lc...) }
func (sl simpleLogger) Info(s string, lc ...LogContext)      { sl.internal(Info, s, lc...) }
func (sl simpleLogger) Notice(s string, lc ...LogContext)    { sl.internal(Notice, s, lc...) }
func (sl simpleLogger) Warning(s string, lc ...LogContext)   { sl.internal(Warning, s, lc...) }
func (sl simpleLogger) Error(s string, lc ...LogContext)     { sl.internal(Error, s, lc...) }
func (sl simpleLogger) Critical(s string, lc ...LogContext)  { sl.internal(Critical, s, lc...) }
func (sl simpleLogger) Alert(s string, lc ...LogContext)     { sl.internal(Alert, s, lc...) }
func (sl simpleLogger) Emergency(s string, lc ...LogContext) { sl.internal(Emergency, s, lc...) }
func (sl simpleLogger) Panic(s string, lc ...LogContext)     { sl.internal(Panic, s, lc...); panic(s) }
func (sl simpleLogger) Fatal(s string, lc ...LogContext)     { sl.internal(Fatal, s, lc...); os.Exit(1) }

// JSON

func NewJSONLogger() Logger { return NewJSONLoggerWithOptions(DefaultOptions) }
func NewJSONLoggerWithOptions(o Options) Logger {
	return &amp;jsonLogger{o.Min, o.Sev, o.TF, o.ContextStyle, o.ContextKey, o.TraceKey, defaultTraceID}
}

type jsonLogger struct {
	MS           Severity
	DS           Severity
	TF           string
	ContextStyle ContextStyleOption
	ContextKey   string
	TraceKey     string
	trace        string
}

func (jl *jsonLogger) Clone() Logger {
	return &amp;jsonLogger{jl.MS, jl.DS, jl.TF, jl.ContextStyle, jl.ContextKey, jl.TraceKey, jl.trace}
}
func (jl *jsonLogger) Trace(id string) Logger {
	new := jl.Clone().(*jsonLogger)
	new.trace = id
	return new
}
func (jl *jsonLogger) Time() string { return time.Now().Format(jl.TF) }
func (jl jsonLogger) Sev() Severity { return jl.DS }
func (jl jsonLogger) line(sev Severity, s interface{}) string {
	if jl.trace != defaultTraceID {
		return fmt.Sprintf(
			`%q:%q, &#34;timestamp&#34;:%q, &#34;severity&#34;:%q, &#34;message&#34;:%q`,
			jl.TraceKey, jl.trace, jl.Time(), sev, s)
	}
	return fmt.Sprintf(`&#34;timestamp&#34;:%q, &#34;severity&#34;:%q, &#34;message&#34;:%q`, jl.Time(), sev, s)
}
func (jl jsonLogger) lineWithContext(s interface{}, lc LogContext) string {
	if jl.ContextStyle == Prefix {
		return fmt.Sprintf(`%s, %s`, jl.line(jl.Sev(), s), lc.keyedJSON(jl.ContextKey))
	}
	if jl.ContextStyle == Flat {
		return fmt.Sprintf(`%s, %s`, jl.line(jl.Sev(), s), lc.flatJSON())
	}
	return fmt.Sprintf(`%s, %q:%q`, jl.line(jl.Sev(), s), jl.ContextKey, lc.JSON())
}
func (jl jsonLogger) Println(ss ...interface{}) {
	if jl.Sev() &lt; jl.MS {
		return
	}
	var jss strings.Builder
	for i, s := range ss {
		if i &gt; 0 {
			jss.WriteString(&#34;\n&#34;)
		}
		jss.WriteString(s.(string))
	}
	fmt.Printf(&#34;{%s}\n&#34;, jl.line(jl.Sev(), jss.String()))
}
func (jl jsonLogger) internal(sev Severity, s string, lc ...LogContext) {
	if sev &lt; jl.MS {
		return
	}
	if len(lc) == 0 {
		fmt.Printf(&#34;{%s}\n&#34;, jl.line(sev, s))
	} else {
		fmt.Printf(&#34;{%s}\n&#34;, jl.lineWithContext(s, lc[0]))
	}
}
func (jl jsonLogger) Log(s string, lc ...LogContext)       { jl.internal(jl.Sev(), s, lc...) }
func (jl jsonLogger) Debug(s string, lc ...LogContext)     { jl.internal(Debug, s, lc...) }
func (jl jsonLogger) Info(s string, lc ...LogContext)      { jl.internal(Info, s, lc...) }
func (jl jsonLogger) Notice(s string, lc ...LogContext)    { jl.internal(Notice, s, lc...) }
func (jl jsonLogger) Warning(s string, lc ...LogContext)   { jl.internal(Warning, s, lc...) }
func (jl jsonLogger) Error(s string, lc ...LogContext)     { jl.internal(Error, s, lc...) }
func (jl jsonLogger) Critical(s string, lc ...LogContext)  { jl.internal(Critical, s, lc...) }
func (jl jsonLogger) Alert(s string, lc ...LogContext)     { jl.internal(Alert, s, lc...) }
func (jl jsonLogger) Emergency(s string, lc ...LogContext) { jl.internal(Emergency, s, lc...) }
func (jl jsonLogger) Panic(s string, lc ...LogContext)     { jl.internal(Panic, s, lc...); panic(s) }
func (jl jsonLogger) Fatal(s string, lc ...LogContext)     { jl.internal(Fatal, s, lc...); os.Exit(1) }
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