From ff4c06dd0a9e95f6ee2b4114e29f278d0eec1bcf Mon Sep 17 00:00:00 2001
From: kingecg <kingecg@hotmail.com>
Date: Tue, 22 Oct 2024 01:21:09 +0800
Subject: [PATCH] add code

---
 flag.go | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 flag.go

diff --git a/flag.go b/flag.go
new file mode 100644
index 0000000..1f2259f
--- /dev/null
+++ b/flag.go
@@ -0,0 +1,110 @@
+package command
+
+import (
+	"errors"
+	"flag"
+	"reflect"
+	"strconv"
+)
+
+type FVSet struct {
+	Name  string
+	Value *any
+	flags flag.FlagSet
+}
+
+func (f *FVSet) Parse(args []string) error {
+	return f.flags.Parse(args)
+}
+func isPtr(v interface{}) bool {
+	return reflect.TypeOf(v).Kind() == reflect.Ptr
+}
+
+// NewFVSet 创建一个新的FVSet实例，用于处理命令行标志。
+// 参数v是一个指向结构体的指针，该结构体的字段将被用作命令行标志。
+// 返回值是一个指向FVSet的指针和一个错误对象，如果操作成功，错误对象为nil。
+// 如果v不是指向结构体的指针，函数将返回错误。
+func NewFVSet(v interface{}) (*FVSet, error) {
+	// 判断v是不是指针
+	vv := reflect.ValueOf(v)
+	if !isPtr(v) {
+		return nil, errors.New("v must be a pointer")
+	}
+	// 判断指针指向的值是不是结构体
+	vvv := vv.Elem()
+	if vvv.Kind() != reflect.Struct {
+		return nil, errors.New("v must be a pointer to a struct")
+	}
+	flags := flag.NewFlagSet(vvv.Type().Name(), flag.ContinueOnError)
+	name := vvv.Type().Name()
+	// 遍历结构体字段
+	for i := 0; i < vvv.NumField(); i++ {
+		//skip private field
+		stField := vvv.Type().Field(i)
+		if stField.PkgPath != "" {
+			continue
+		}
+		// 获取字段名
+		field := vvv.Field(i)
+		nameTag := stField.Tag.Get("flag_name")
+		flaName := nameTag
+		if flaName == "" {
+			flaName = stField.Name
+		}
+		defVal := stField.Tag.Get("flag_default")
+		usageStr := stField.Tag.Get("flag_usage")
+		if usageStr == "" {
+			usageStr = "Set " + flaName + "(default " + defVal + ")"
+		}
+
+		if field.CanSet() {
+			switch expression := field.Interface().(type) {
+			case string:
+				flags.StringVar(&expression, flaName, defVal, usageStr)
+				break
+			case int:
+				v, _ := strconv.Atoi(defVal)
+				flags.IntVar(&expression, flaName, v, usageStr)
+				break
+			case bool:
+				flags.BoolVar(&expression, flaName, false, usageStr)
+				break
+
+			default:
+				return nil, errors.New("unsupported type")
+			}
+		}
+	}
+	return &FVSet{
+		Name:  name,
+		Value: &v,
+		flags: *flags,
+	}, nil
+}
+
+// Parse is used to parse command line arguments based on one or more flag sets.
+// args represents the list of command line arguments.
+// flagSet is a variable-length parameter that contains the flag sets to be parsed.
+// If no flag set is provided, it throws a panic exception.
+// If only one flag set is provided, it directly parses the arguments with that flag set.
+// If multiple flag sets are provided, it attempts to match and parse based on the first argument in args.
+// If no matching flag set is found, it returns an error.
+func Parse(args []string, flagSet ...*FVSet) error {
+	// Check if the flag set is missing, if so, throw a panic exception.
+	if len(flagSet) == 0 {
+		panic("flag set missing")
+	}
+	// If only one flag set is provided, directly parse the arguments with that flag set.
+	if len(flagSet) == 1 {
+		return flagSet[0].Parse(args)
+	}
+	// Iterate through the flag sets to find a match for parsing.
+	for _, f := range flagSet {
+		// If a matching flag set is found, parse the remaining arguments with that flag set.
+		if f.Name == args[0] {
+			return f.Parse(args[1:])
+		}
+	}
+	// If no matching flag set is found, return an error.
+	return errors.New("flag set not found")
+}