blob: 2fc225e691a5f2ba7409cd3c490971861ea053f9 [file] [log] [blame]
// Copyright 2016 The LUCI Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package stringmapflag provides a flag.Value that, when parsed, augments a
// map[string]string with the supplied parameter. The parameter is expressed as
// a key[=value] option.
//
// Example
//
// Assuming the flag option, "opt", is bound to a stringmapflag.Value, and the
// following arguments are parsed:
// -opt foo=bar
// -opt baz
//
// The resulting map would be equivalent to:
// map[string]string {"foo": "bar", "baz": ""}
package stringmapflag
import (
"errors"
"flag"
"fmt"
"sort"
"strings"
)
// Value is a flag.Value implementation that stores arbitrary "key[=value]"
// command-line flags as a string map.
type Value map[string]string
// Assert that Value conforms to the "flag.Value" interface.
var _ = flag.Value(new(Value))
func (v *Value) String() string {
if len(*v) == 0 {
return ""
}
keys := make([]string, 0, len(*v))
for k := range *v {
keys = append(keys, k)
}
sort.Strings(keys)
for idx, k := range keys {
if value := (*v)[k]; value != "" {
keys[idx] = fmt.Sprintf("%s=%s", k, value)
}
}
return strings.Join(keys, ",")
}
// Set implements flag.Value.
func (v *Value) Set(key string) error {
key = strings.TrimSpace(key)
if len(key) == 0 {
return errors.New("cannot specify an empty tag")
}
value := ""
idx := strings.Index(key, "=")
switch {
case idx == -1:
break
case idx == 0:
return errors.New("cannot have tag with empty key")
case idx > 0:
key, value = key[:idx], key[idx+1:]
}
// Add the entry to our tag map.
if len(*v) > 0 {
if _, ok := (*v)[key]; ok {
return fmt.Errorf("tag '%s' has already been defined", key)
}
}
// Record this tag; create a new Value, if necessary.
if *v == nil {
*v = make(Value)
}
(*v)[key] = value
return nil
}