map_string_string.go

/*
Copyright 2017 The Kubernetes 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 flag

import (
	"fmt"
	"sort"
	"strings"
)

// MapStringString can be set from the command line with the format `--flag "string=string"`.
// Multiple flag invocations are supported. For example: `--flag "a=foo" --flag "b=bar"`. If this is desired
// to be the only type invocation `NoSplit` should be set to true.
// Multiple comma-separated key-value pairs in a single invocation are supported if `NoSplit`
// is set to false. For example: `--flag "a=foo,b=bar"`.
type MapStringString struct {
	Map         *map[string]string
	initialized bool
	NoSplit     bool
}

// NewMapStringString takes a pointer to a map[string]string and returns the
// MapStringString flag parsing shim for that map
func NewMapStringString(m *map[string]string) *MapStringString {
	return &MapStringString{Map: m}
}

// NewMapStringString takes a pointer to a map[string]string and sets `NoSplit`
// value to `true` and returns the MapStringString flag parsing shim for that map
func NewMapStringStringNoSplit(m *map[string]string) *MapStringString {
	return &MapStringString{
		Map:     m,
		NoSplit: true,
	}
}

// String implements github.com/spf13/pflag.Value
func (m *MapStringString) String() string {
	if m == nil || m.Map == nil {
		return ""
	}
	pairs := []string{}
	for k, v := range *m.Map {
		pairs = append(pairs, fmt.Sprintf("%s=%s", k, v))
	}
	sort.Strings(pairs)
	return strings.Join(pairs, ",")
}

// Set implements github.com/spf13/pflag.Value
func (m *MapStringString) Set(value string) error {
	if m.Map == nil {
		return fmt.Errorf("no target (nil pointer to map[string]string)")
	}
	if !m.initialized || *m.Map == nil {
		// clear default values, or allocate if no existing map
		*m.Map = make(map[string]string)
		m.initialized = true
	}

	// account for comma-separated key-value pairs in a single invocation
	if !m.NoSplit {
		for _, s := range strings.Split(value, ",") {
			if len(s) == 0 {
				continue
			}
			arr := strings.SplitN(s, "=", 2)
			if len(arr) != 2 {
				return fmt.Errorf("malformed pair, expect string=string")
			}
			k := strings.TrimSpace(arr[0])
			v := strings.TrimSpace(arr[1])
			(*m.Map)[k] = v
		}
		return nil
	}

	// account for only one key-value pair in a single invocation
	arr := strings.SplitN(value, "=", 2)
	if len(arr) != 2 {
		return fmt.Errorf("malformed pair, expect string=string")
	}
	k := strings.TrimSpace(arr[0])
	v := strings.TrimSpace(arr[1])
	(*m.Map)[k] = v
	return nil

}

// Type implements github.com/spf13/pflag.Value
func (*MapStringString) Type() string {
	return "mapStringString"
}

// Empty implements OmitEmpty
func (m *MapStringString) Empty() bool {
	return len(*m.Map) == 0
}