/
flags.go
220 lines (202 loc) · 4.93 KB
/
flags.go
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package qcli
import (
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"log"
"os"
)
// Flag retrieves a value from a given flag name. If it is unable to dereference a
// value the function will return nil
func Flag(name string) interface{} {
val := flagvars.m["_"][name]
switch val.(type) {
case *bool:
return *(val.(*bool))
break
case *float64:
return *(val.(*float64))
break
case *string:
return *(val.(*string))
break
}
return nil
}
//FlagSet is just an empty accessor
type FlagSet struct {
m map[string]interface{}
}
// Flagset retrieves a FlagSet given the name as provided in the required JSON file
// Why the weird difference in case? Because Godocs complains at public members of private structures!
// Thus bloating up your IDEs and godocs with useless stuff. Yes this is a complaint
func Flagset(name string) FlagSet {
return FlagSet{flagvars.m[name]}
}
// Flag retrieves a flag value that is associated with a flag name on a parent FlagSet
func (f FlagSet) Flag(name string) interface{} {
val := f.m[name]
switch val.(type) {
case *bool:
return *(val.(*bool))
break
case *float64:
return *(val.(*float64))
break
case *string:
return *(val.(*string))
break
}
return nil
}
var flagvars struct {
m map[string]map[string]interface{}
}
func getArgIndex(name string) int {
for i, a := range os.Args {
if a == name {
return i
}
}
return -1
}
func initFlagSets(_flagsets interface{}) {
flagsets := _flagsets.([]interface{})
for i, _flagset := range flagsets {
flagset := _flagset.(map[string]interface{})
errorHandling := flagset["errorHandling"].(float64)
name := flagset["name"].(string)
if errorHandling < 0 || errorHandling > 2 {
log.Fatalf("Unable to parse flagset at index \"%d\"\n", i)
}
if len(name) == 0 {
log.Fatalf("Unable to parse flagset at index %d\n", i)
}
newFlagSet := flag.NewFlagSet(name, flag.ErrorHandling(errorHandling))
flagvars.m[name] = make(map[string]interface{})
err := initFlags(flagset["flags"], name, newFlagSet)
if err != nil {
log.Fatalf("Unable to parse flagset at index %d: %s\n", i, err)
}
if index := getArgIndex(name); index > -1 {
newFlagSet.Parse(os.Args[index:])
}
}
}
func initFlags(_flags interface{}, flagsetName string, flagset ...*flag.FlagSet) error {
var err error
var isFlagset bool
if len(flagset) > 0 {
isFlagset = true
}
flags := _flags.([]interface{})
for i, _flag := range flags {
flg := _flag.(map[string]interface{})
name := flg["name"].(string)
_type, _ := flg["type"].(string)
usage, _ := flg["usage"].(string)
def := flg["default"]
if len(name) == 0 {
return fmt.Errorf("Unable to parse flag at index %d: No name specified!", i)
}
if len(_type) == 0 {
//do type switch
switch def.(type) {
case bool:
var b bool
if isFlagset {
flagvars.m[flagsetName][name] = &b
flagset[0].BoolVar(&b, name, def.(bool), usage)
} else {
flag.BoolVar(&b, name, def.(bool), usage)
}
break
case float64:
var f float64
if isFlagset {
flagvars.m[flagsetName][name] = &f
flagset[0].Float64Var(&f, name, def.(float64), usage)
} else {
flag.Float64Var(&f, name, def.(float64), usage)
}
break
case string:
var s string
if isFlagset {
flagvars.m[flagsetName][name] = &s
flagset[0].StringVar(&s, name, def.(string), usage)
} else {
flag.StringVar(&s, name, def.(string), usage)
}
break
default:
return fmt.Errorf("Unable to parse flag at index %d: Unable to determine flag type!", i)
}
} else {
//do value switch
switch _type {
case "bool":
if def == nil {
def = false
}
var b bool
if isFlagset {
flagvars.m[flagsetName][name] = &b
flagset[0].BoolVar(&b, name, def.(bool), usage)
} else {
flag.BoolVar(&b, name, def.(bool), usage)
}
break
case "float64":
if def == nil {
def = 0
}
var f float64
if isFlagset {
flagvars.m[flagsetName][name] = &f
flagset[0].Float64Var(&f, name, def.(float64), usage)
} else {
flag.Float64Var(&f, name, def.(float64), usage)
}
break
case "string":
if def == nil {
def = ""
}
var s string
if isFlagset {
flagvars.m[flagsetName][name] = &s
flagset[0].StringVar(&s, name, def.(string), usage)
} else {
flag.StringVar(&s, name, def.(string), usage)
}
break
default:
return fmt.Errorf("Unable to parse flag at index %d: Unable to determine flag type!", i)
}
}
}
return err
}
func init() {
flagvars.m = make(map[string]map[string]interface{})
jsonFile, err := os.Open("./flags.json")
if err != nil {
return
}
jsonData, _ := ioutil.ReadAll(jsonFile)
var flagMap map[string]interface{}
err = json.Unmarshal(jsonData, &flagMap)
if err != nil {
log.Fatalln(err)
}
//handle top-level flags
flags := flagMap["flags"]
if flags != nil {
initFlags(flagMap["flags"], "")
}
//handle flagsets
initFlagSets(flagMap["flagsets"])
flag.Parse()
}