field.go

/*
 * Copyright 2019 Metaleaf.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package log

import (
	"reflect"
	"strconv"
)

// Field stores a name/value pair to be formatted by the emitter.
type Field struct {
	Name        string
	Type        reflect.Kind
	BoolValue   bool
	IntValue    int64
	StringValue string
}

// Bool returns a Field that contains a boolean value.
func Bool(name string, value bool) Field {
	return Field{Name:name, Type:reflect.Bool, BoolValue:value}
}

// Int returns a Field that contains a default integer.
func Int(name string, value int) Field {
	return Field{Name:name, Type:reflect.Int, IntValue:int64(value)}
}

// Int8 returns a Field that contains an 8-bit integer
func Int8(name string, value int8) Field {
	return Field{Name:name, Type:reflect.Int8, IntValue:int64(value)}
}

// Int16 returns a Field that contains an 16-bit integer
func Int16(name string, value int16) Field {
	return Field{Name:name, Type:reflect.Int16, IntValue:int64(value)}
}

// Int32 returns a Field that contains an 32-bit integer
func Int32(name string, value int32) Field {
	return Field{Name:name, Type:reflect.Int32, IntValue:int64(value)}
}

// Int64 returns a Field that contains an 64-bit integer
func Int64(name string, value int64) Field {
	return Field{Name:name, Type:reflect.Int64, IntValue:value}
}

// String returns a Field that contains a string.
func String(name string, value string) Field {
	return Field{Name:name, Type:reflect.String, StringValue:value}
}

// Err returns a Field that contains the message from an error.
func Err(value error) Field {
	return Field{Name:"error", Type:reflect.String, StringValue:value.Error()}
}

// Json returns the contents of the Field as `"key":value`.
func (field Field) Json() string {
	return "\"" + field.Name + "\":" + stringValue(field, true)
}

// String returns the contents of the Field as `key=value`.
func (field Field) String() string {
	return field.Name + "=" + stringValue(field, false)
}

// stringValue converts the field's value into a string.
func stringValue(field Field, quoted bool) string {
	switch field.Type {
	case reflect.Bool:
		if field.BoolValue {
			return "true"
		}
		return "false"
	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return strconv.FormatInt(field.IntValue, 10)
	case reflect.String:
		if quoted {
			return "\"" + field.StringValue + "\""
		}
		return field.StringValue
	default:
		panic("Invalid type")
	}
}