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|
package capability
import (
"bytes"
"errors"
"fmt"
"strings"
)
var (
// ErrUnknownCapability is returned if a unknown capability is given
ErrUnknownCapability = errors.New("unknown capability")
// ErrArgumentsRequired is returned if no arguments are giving with a
// capability that requires arguments
ErrArgumentsRequired = errors.New("arguments required")
// ErrArguments is returned if arguments are given with a capabilities that
// not supports arguments
ErrArguments = errors.New("arguments not allowed")
// ErrEmtpyArgument is returned when an empty value is given
ErrEmtpyArgument = errors.New("empty argument")
// ErrMultipleArguments multiple argument given to a capabilities that not
// support it
ErrMultipleArguments = errors.New("multiple arguments not allowed")
)
// List represents a list of capabilities
type List struct {
m map[Capability]*entry
sort []string
}
type entry struct {
Name Capability
Values []string
}
// NewList returns a new List of capabilities
func NewList() *List {
return &List{
m: make(map[Capability]*entry),
}
}
// IsEmpty returns true if the List is empty
func (l *List) IsEmpty() bool {
return len(l.sort) == 0
}
// Decode decodes list of capabilities from raw into the list
func (l *List) Decode(raw []byte) error {
if len(raw) == 0 {
return nil
}
for _, data := range bytes.Split(raw, []byte{' '}) {
pair := bytes.SplitN(data, []byte{'='}, 2)
c := Capability(pair[0])
if len(pair) == 1 {
if err := l.Add(c); err != nil {
return err
}
continue
}
if err := l.Add(c, string(pair[1])); err != nil {
return err
}
}
return nil
}
// Get returns the values for a capability
func (l *List) Get(capability Capability) []string {
if _, ok := l.m[capability]; !ok {
return nil
}
return l.m[capability].Values
}
// Set sets a capability removing the previous values
func (l *List) Set(capability Capability, values ...string) error {
if _, ok := l.m[capability]; ok {
delete(l.m, capability)
}
return l.Add(capability, values...)
}
// Add adds a capability, values are optional
func (l *List) Add(c Capability, values ...string) error {
if err := l.validate(c, values); err != nil {
return err
}
if !l.Supports(c) {
l.m[c] = &entry{Name: c}
l.sort = append(l.sort, c.String())
}
if len(values) == 0 {
return nil
}
if !multipleArgument[c] && len(l.m[c].Values) > 0 {
return ErrMultipleArguments
}
l.m[c].Values = append(l.m[c].Values, values...)
return nil
}
func (l *List) validate(c Capability, values []string) error {
if _, ok := valid[c]; !ok {
return ErrUnknownCapability
}
if requiresArgument[c] && len(values) == 0 {
return ErrArgumentsRequired
}
if !requiresArgument[c] && len(values) != 0 {
return ErrArguments
}
if !multipleArgument[c] && len(values) > 1 {
return ErrMultipleArguments
}
for _, v := range values {
if v == "" {
return ErrEmtpyArgument
}
}
return nil
}
// Supports returns true if capability is present
func (l *List) Supports(capability Capability) bool {
_, ok := l.m[capability]
return ok
}
// Delete deletes a capability from the List
func (l *List) Delete(capability Capability) {
if !l.Supports(capability) {
return
}
delete(l.m, capability)
for i, c := range l.sort {
if c != string(capability) {
continue
}
l.sort = append(l.sort[:i], l.sort[i+1:]...)
return
}
}
// String generates the capabilities strings, the capabilities are sorted in
// insertion order
func (l *List) String() string {
var o []string
for _, key := range l.sort {
cap := l.m[Capability(key)]
if len(cap.Values) == 0 {
o = append(o, key)
continue
}
for _, value := range cap.Values {
o = append(o, fmt.Sprintf("%s=%s", key, value))
}
}
return strings.Join(o, " ")
}
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