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defaults.go
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defaults.go
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package envflags
import (
"os"
"path"
"strings"
"github.com/spf13/pflag"
)
var (
DefaultConfig Config
DefaultFlags *pflag.FlagSet
DefaultEnv []string
)
func init() {
DefaultConfig = NewConfig()
DefaultFlags = pflag.CommandLine
DefaultEnv = os.Environ()
}
func NewConfig() Config {
cfg := Config{
TransformFn: defaultTransformFn,
NameFn: defaultNameFn,
Override: false,
}
if len(os.Args) > 0 {
cfg.Prefix = defaultTransformFn(path.Base(os.Args[0]))
}
return cfg
}
func Apply() error {
return ApplyTo(DefaultFlags)
}
func ApplyTo(flags *pflag.FlagSet) error {
return ApplyWith(DefaultEnv, flags)
}
func ApplyWith(env []string, flags *pflag.FlagSet) error {
return New(DefaultConfig).ApplyWith(env, flags)
}
func defaultNameFn(prefix string, flagName string) string {
switch {
case flagName == "":
return ""
case prefix == "":
return flagName
default:
return prefix + "_" + flagName
}
}
func defaultTransformFn(name string) string {
return strings.Map(func(c rune) rune {
switch {
// [A-Z_] -> passthrough
case c >= 'A' && c <= 'Z':
return c
case c == '_':
return '_'
// toupper
case c >= 'a' && c <= 'z':
return c + ('A' - 'a')
// {'-','.'} -> '_'
case c == '-' || c == '.':
return '_'
}
return -1
}, name)
}