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Copy pathvalue_source.go
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257 lines (207 loc) · 5.77 KB
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package cli
import (
"fmt"
"os"
"strings"
)
// ValueSource is a source which can be used to look up a value,
// typically for use with a cli.Flag
type ValueSource interface {
fmt.Stringer
fmt.GoStringer
// Lookup returns the value from the source and if it was found
// or returns an empty string and false
Lookup() (string, bool)
}
// EnvValueSource is to specifically detect env sources when
// printing help text
type EnvValueSource interface {
IsFromEnv() bool
Key() string
}
// MapSource is a source which can be used to look up a value
// based on a key
// typically for use with a cli.Flag
type MapSource interface {
fmt.Stringer
fmt.GoStringer
// Lookup returns the value from the source based on key
// and if it was found
// or returns an empty string and false
Lookup(string) (any, bool)
}
// ValueSourceChain contains an ordered series of ValueSource that
// allows for lookup where the first ValueSource to resolve is
// returned
type ValueSourceChain struct {
Chain []ValueSource
}
func NewValueSourceChain(src ...ValueSource) ValueSourceChain {
return ValueSourceChain{
Chain: src,
}
}
func (vsc *ValueSourceChain) Append(other ValueSourceChain) {
vsc.Chain = append(vsc.Chain, other.Chain...)
}
func (vsc *ValueSourceChain) EnvKeys() []string {
vals := []string{}
for _, src := range vsc.Chain {
if v, ok := src.(EnvValueSource); ok && v.IsFromEnv() {
vals = append(vals, v.Key())
}
}
return vals
}
func (vsc *ValueSourceChain) String() string {
s := []string{}
for _, vs := range vsc.Chain {
s = append(s, vs.String())
}
return strings.Join(s, ",")
}
func (vsc *ValueSourceChain) GoString() string {
s := []string{}
for _, vs := range vsc.Chain {
s = append(s, vs.GoString())
}
return fmt.Sprintf("&ValueSourceChain{Chain:{%[1]s}}", strings.Join(s, ","))
}
func (vsc *ValueSourceChain) Lookup() (string, bool) {
s, _, ok := vsc.LookupWithSource()
return s, ok
}
func (vsc *ValueSourceChain) LookupWithSource() (string, ValueSource, bool) {
for _, src := range vsc.Chain {
if value, found := src.Lookup(); found {
return value, src, true
}
}
return "", nil, false
}
// envVarValueSource encapsulates a ValueSource from an environment variable
type envVarValueSource struct {
key string
}
func (e *envVarValueSource) Lookup() (string, bool) {
return os.LookupEnv(strings.TrimSpace(string(e.key)))
}
func (e *envVarValueSource) IsFromEnv() bool {
return true
}
func (e *envVarValueSource) Key() string {
return e.key
}
func (e *envVarValueSource) String() string { return fmt.Sprintf("environment variable %[1]q", e.key) }
func (e *envVarValueSource) GoString() string {
return fmt.Sprintf("&envVarValueSource{Key:%[1]q}", e.key)
}
func EnvVar(key string) ValueSource {
return &envVarValueSource{
key: key,
}
}
// EnvVars is a helper function to encapsulate a number of
// envVarValueSource together as a ValueSourceChain
func EnvVars(keys ...string) ValueSourceChain {
vsc := ValueSourceChain{Chain: []ValueSource{}}
for _, key := range keys {
vsc.Chain = append(vsc.Chain, EnvVar(key))
}
return vsc
}
// fileValueSource encapsulates a ValueSource from a file
type fileValueSource struct {
Path string
}
func (f *fileValueSource) Lookup() (string, bool) {
data, err := os.ReadFile(f.Path)
return string(data), err == nil
}
func (f *fileValueSource) String() string { return fmt.Sprintf("file %[1]q", f.Path) }
func (f *fileValueSource) GoString() string {
return fmt.Sprintf("&fileValueSource{Path:%[1]q}", f.Path)
}
func File(path string) ValueSource {
return &fileValueSource{Path: path}
}
// Files is a helper function to encapsulate a number of
// fileValueSource together as a ValueSourceChain
func Files(paths ...string) ValueSourceChain {
vsc := ValueSourceChain{Chain: []ValueSource{}}
for _, path := range paths {
vsc.Chain = append(vsc.Chain, File(path))
}
return vsc
}
type mapSource struct {
name string
m map[any]any
}
func NewMapSource(name string, m map[any]any) MapSource {
return &mapSource{
name: name,
m: m,
}
}
func (ms *mapSource) String() string { return fmt.Sprintf("map source %[1]q", ms.name) }
func (ms *mapSource) GoString() string {
return fmt.Sprintf("&mapSource{name:%[1]q}", ms.name)
}
// Lookup returns a value from the map source. The lookup name may be a dot-separated path into the map.
// If that is the case, it will recursively traverse the map based on the '.' delimited sections to find
// a nested value for the key.
func (ms *mapSource) Lookup(name string) (any, bool) {
sections := strings.Split(name, ".")
if name == "" || len(sections) == 0 {
return nil, false
}
node := ms.m
// traverse into the map based on the dot-separated sections
if len(sections) >= 2 { // the last section is the value we want, we will return it directly at the end
for _, section := range sections[:len(sections)-1] {
child, ok := node[section]
if !ok {
return nil, false
}
switch child := child.(type) {
case map[string]any:
node = make(map[any]any, len(child))
for k, v := range child {
node[k] = v
}
case map[any]any:
node = child
default:
return nil, false
}
}
}
if val, ok := node[sections[len(sections)-1]]; ok {
return val, true
}
return nil, false
}
type mapValueSource struct {
key string
ms MapSource
}
func NewMapValueSource(key string, ms MapSource) ValueSource {
return &mapValueSource{
key: key,
ms: ms,
}
}
func (mvs *mapValueSource) String() string {
return fmt.Sprintf("key %[1]q from %[2]s", mvs.key, mvs.ms.String())
}
func (mvs *mapValueSource) GoString() string {
return fmt.Sprintf("&mapValueSource{key:%[1]q, src:%[2]s}", mvs.key, mvs.ms.GoString())
}
func (mvs *mapValueSource) Lookup() (string, bool) {
if v, ok := mvs.ms.Lookup(mvs.key); !ok {
return "", false
} else {
return fmt.Sprintf("%+v", v), true
}
}