143 lines
2.7 KiB
Go
143 lines
2.7 KiB
Go
/*
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Copyright (c) 2014-2015 VMware, Inc. All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cli
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import (
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"flag"
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"fmt"
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"io/ioutil"
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"os"
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"sort"
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"text/tabwriter"
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"golang.org/x/net/context"
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)
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type HasFlags interface {
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// Register may be called more than once and should be idempotent.
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Register(ctx context.Context, f *flag.FlagSet)
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// Process may be called more than once and should be idempotent.
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Process(ctx context.Context) error
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}
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type Command interface {
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HasFlags
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Run(ctx context.Context, f *flag.FlagSet) error
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}
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func generalHelp() {
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fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
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cmds := []string{}
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for name := range commands {
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cmds = append(cmds, name)
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}
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sort.Strings(cmds)
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for _, name := range cmds {
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fmt.Fprintf(os.Stderr, " %s\n", name)
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}
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}
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func commandHelp(name string, cmd Command, f *flag.FlagSet) {
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type HasUsage interface {
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Usage() string
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}
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fmt.Fprintf(os.Stderr, "Usage: %s %s [OPTIONS]", os.Args[0], name)
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if u, ok := cmd.(HasUsage); ok {
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fmt.Fprintf(os.Stderr, " %s", u.Usage())
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}
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fmt.Fprintf(os.Stderr, "\n")
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type HasDescription interface {
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Description() string
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}
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if u, ok := cmd.(HasDescription); ok {
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fmt.Fprintf(os.Stderr, "%s\n", u.Description())
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}
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n := 0
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f.VisitAll(func(_ *flag.Flag) {
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n += 1
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})
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if n > 0 {
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fmt.Fprintf(os.Stderr, "\nOptions:\n")
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tw := tabwriter.NewWriter(os.Stderr, 2, 0, 2, ' ', 0)
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f.VisitAll(func(f *flag.Flag) {
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fmt.Fprintf(tw, "\t-%s=%s\t%s\n", f.Name, f.DefValue, f.Usage)
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})
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tw.Flush()
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}
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}
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func Run(args []string) int {
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var err error
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if len(args) == 0 {
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generalHelp()
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return 1
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}
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// Look up real command name in aliases table.
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name, ok := aliases[args[0]]
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if !ok {
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name = args[0]
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}
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cmd, ok := commands[name]
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if !ok {
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generalHelp()
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return 1
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}
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fs := flag.NewFlagSet("", flag.ContinueOnError)
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fs.SetOutput(ioutil.Discard)
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ctx := context.Background()
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cmd.Register(ctx, fs)
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if err = fs.Parse(args[1:]); err != nil {
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goto error
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}
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if err = cmd.Process(ctx); err != nil {
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goto error
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}
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if err = cmd.Run(ctx, fs); err != nil {
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goto error
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}
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return 0
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error:
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if err == flag.ErrHelp {
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commandHelp(args[0], cmd, fs)
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} else {
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fmt.Fprintf(os.Stderr, "%s: %s\n", os.Args[0], err)
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}
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return 1
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}
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