flagger/flagger.go
Stanislav Nikitin 6091893d30 Initial commit.
2017-08-20 14:59:51 +05:00

122 lines
3.8 KiB
Go

// Flagger - arbitrary CLI flags parser.
//
// Copyright (c) 2017, Stanislav N. aka pztrn.
// All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package flagger
import (
// stdlib
"errors"
"flag"
"sync"
)
// Flagger implements (kinda) extended CLI parameters parser. As it
// available from CommonContext, these flags will be available to
// whole application.
//
// It uses reflection to determine what kind of variable we should
// parse or get.
type Flagger struct {
// Flags that was added by user.
flags map[string]*Flag
flagsMutex sync.Mutex
// Flags that will be passed to flag module.
flagsBool map[string]*bool
flagsInt map[string]*int
flagsString map[string]*string
}
// Adds flag to list of flags we will pass to ``flag`` package.
func (f *Flagger) AddFlag(flag *Flag) error {
_, present := f.flags[flag.Name]
if present {
logger.Fatalln("Cannot add flag '" + flag.Name + "' - already added!")
return errors.New("Cannot add flag '" + flag.Name + "' - already added!")
}
f.flags[flag.Name] = flag
return nil
}
// This function returns boolean value for flag with given name.
// Returns bool value for flag and nil as error on success
// and false bool plus error with text on error.
func (f *Flagger) GetBoolValue(name string) (bool, error) {
fl, present := f.flagsBool[name]
if !present {
return false, errors.New("No such flag: " + name)
}
return (*fl), nil
}
// This function returns integer value for flag with given name.
// Returns integer on success and 0 on error.
func (f *Flagger) GetIntValue(name string) (int, error) {
fl, present := f.flagsInt[name]
if !present {
return 0, errors.New("No such flag: " + name)
}
return (*fl), nil
}
// This function returns string value for flag with given name.
// Returns string on success or empty string on error.
func (f *Flagger) GetStringValue(name string) (string, error) {
fl, present := f.flagsString[name]
if !present {
return "", errors.New("No such flag: " + name)
}
return (*fl), nil
}
// Flagger initialization.
func (f *Flagger) Initialize() {
logger.Println("Initializing CLI parameters parser...")
f.flags = make(map[string]*Flag)
f.flagsBool = make(map[string]*bool)
f.flagsInt = make(map[string]*int)
f.flagsString = make(map[string]*string)
}
// This function adds flags from flags map to flag package and parse
// them. They can be obtained later by calling GetTYPEValue(name),
// where TYPE is one of Bool, Int, String.
func (f *Flagger) Parse() {
for name, fl := range f.flags {
if fl.Type == "bool" {
fdef := fl.DefaultValue.(bool)
f.flagsBool[name] = &fdef
flag.BoolVar(&fdef, name, fdef, fl.Description)
} else if fl.Type == "int" {
fdef := fl.DefaultValue.(int)
f.flagsInt[name] = &fdef
flag.IntVar(&fdef, name, fdef, fl.Description)
} else if fl.Type == "string" {
fdef := fl.DefaultValue.(string)
f.flagsString[name] = &fdef
flag.StringVar(&fdef, name, fdef, fl.Description)
}
}
logger.Println("Parsing CLI parameters...")
flag.Parse()
}