evm/cmd/utils/flags.go

// Copyright 2015 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum 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.
//
// go-ethereum 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 go-ethereum. If not, see <http://www.gnu.org/licenses/>.

// Package utils contains internal helper functions for go-ethereum commands.
package utils

import (
	"fmt"
	"strings"

	"github.com/urfave/cli/v2"
)

// CheckExclusive verifies that only a single instance of the provided flags was
// set by the user. Each flag might optionally be followed by a string type to
// specialize it further.
func CheckExclusive(ctx *cli.Context, args ...interface{}) {
	set := make([]string, 0, 1)
	for i := 0; i < len(args); i++ {
		// Make sure the next argument is a flag and skip if not set
		flag, ok := args[i].(cli.Flag)
		if !ok {
			panic(fmt.Sprintf("invalid argument, not cli.Flag type: %T", args[i]))
		}
		// Check if next arg extends current and expand its name if so
		name := flag.Names()[0]

		if i+1 < len(args) {
			switch option := args[i+1].(type) {
			case string:
				// Extended flag check, make sure value set doesn't conflict with passed in option
				if ctx.String(flag.Names()[0]) == option {
					name += "=" + option
					set = append(set, "--"+name)
				}
				// shift arguments and continue
				i++
				continue

			case cli.Flag:
			default:
				panic(fmt.Sprintf("invalid argument, not cli.Flag or string extension: %T", args[i+1]))
			}
		}
		// Mark the flag if it's set
		if ctx.IsSet(flag.Names()[0]) {
			set = append(set, "--"+name)
		}
	}
	if len(set) > 1 {
		Fatalf("Flags %v can't be used at the same time", strings.Join(set, ", "))
	}
}