envconf/main.go
2021-03-23 12:57:09 +01:00

119 lines
2.5 KiB
Go

package envconf
import ("strings"
"unicode"
"strconv"
"time"
"errors"
"fmt"
"os")
type cEntry struct {
value string
parsed cValue
dtype DataType
unset bool
empty bool
}
type cValue struct {
intval int64
durval time.Duration
strval string
err error
}
type Config struct {
parsed bool
env map[string]cEntry
}
func NewConfig()(*Config) {
config := new(Config)
config.parsed = false
config.env = make(map[string]cEntry)
for _,v := range os.Environ() {
splitted := strings.SplitN(v, "=", 2)
if len(splitted) == 2 {
key := strings.TrimSpace(strings.ToLower(splitted[0]))
if unicode.IsLetter(getFirstRune(key)) {
var entry cEntry
entry.value = splitted[1]
entry.dtype = TypeNone
entry.unset = false
entry.empty = false
config.env[key] = entry
}
}
}
return config
}
func (c *Config) Define(key string, dtype DataType) {
entry, ok := c.env[key]
if ok {
entry.dtype = dtype
} else {
var entry cEntry
entry.dtype = dtype
entry.unset = true
entry.empty = true
c.env[key] = entry
}
}
func (c *Config) DefineDefault(key string, val string, dtype DataType) {
entry, ok := c.env[key]
if ok {
if entry.unset {
entry.empty = false
entry.value = val
entry.dtype = dtype
}
} else {
var entry cEntry
entry.dtype = dtype
entry.unset = true
entry.empty = false
c.env[key] = entry
}
}
func (c *Config) Parse() {
parsers := make(map[DataType](func(string)(cValue)))
parsers[TypeInt] = parseInt
parsers[TypeDuration] = parseDuration
for k,v := range c.env {
parser, ok := parsers[v.dtype]
if ok {
if v.empty {
if v.unset {
v.parsed.err = errors.New(fmt.Sprintf("Environment variable %s not found. It should have been of type %s", k, v.dtype))
}
} else {
v.parsed = parser(v.value)
}
}
}
}
func parseInt(str string)(ret cValue) {
ret.intval, ret.err = strconv.ParseInt(str, 10, 64)
return
}
func parseDuration(str string)(ret cValue) {
ret.durval, ret.err = time.ParseDuration(str)
return
}
func getFirstRune(str string)(rune) {
for _,v := range str {
return v
}
return rune(0)
}