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