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Merge pull request #223 from rsteube/generic-macro
macro: extract generic macro
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| package macro | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "reflect" | ||
| "regexp" | ||
| "strings" | ||
|
|
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| "gopkg.in/yaml.v3" | ||
| ) | ||
|
|
||
| type Macro[T any] struct { | ||
| f func(string) (*T, error) | ||
| s func() string | ||
| } | ||
|
|
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| type Default[T any] interface { | ||
| Default() T | ||
| } | ||
|
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| func (m Macro[T]) Parse(s string) (*T, error) { | ||
| r := regexp.MustCompile(`^\$(?P<macro>[^(]*)(\((?P<arg>.*)\))?$`) | ||
| matches := r.FindStringSubmatch(s) | ||
| if matches == nil { | ||
| return nil, fmt.Errorf("malformed macro: '%v'", s) | ||
| } | ||
| return m.f(matches[3]) | ||
| } | ||
|
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| func (m Macro[T]) Signature() string { return m.s() } | ||
|
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| // MacroN creates a macro without an argument | ||
| func MacroN[T any](f func() (*T, error)) Macro[T] { | ||
| return Macro[T]{ | ||
| f: func(s string) (*T, error) { | ||
| return f() | ||
| }, | ||
| s: func() string { return "" }, | ||
| } | ||
| } | ||
|
|
||
| // MacroI creates a macro with an argument | ||
| func MacroI[A, T any](f func(arg A) (*T, error)) Macro[T] { | ||
| return Macro[T]{ | ||
| f: func(s string) (*T, error) { | ||
| var arg A | ||
| switch reflect.TypeOf(arg).Kind() { | ||
| case reflect.String: | ||
| reflect.ValueOf(&arg).Elem().SetString(s) | ||
|
|
||
| default: | ||
| if err := yaml.Unmarshal([]byte(s), &arg); err != nil { | ||
| return nil, err | ||
| } | ||
| if s == "" { | ||
| if v, ok := interface{}(arg).(Default[A]); ok { | ||
| arg = v.Default() | ||
| } | ||
| } | ||
| } | ||
| return f(arg) | ||
| }, | ||
| s: func() string { return signature(new(A)) }, | ||
| } | ||
| } | ||
|
|
||
| // MacroV creates a macro with a variable argument | ||
| func MacroV[A, T any](f func(args ...A) (*T, error)) Macro[T] { | ||
| return Macro[T]{ | ||
| f: func(s string) (*T, error) { | ||
| if s == "" { | ||
| return f() | ||
| } | ||
|
|
||
| var args []A | ||
| if err := yaml.Unmarshal([]byte(s), &args); err != nil { | ||
| return nil, fmt.Errorf("malformed macro arg: '%v', expected '%v'", s, reflect.TypeOf(args)) | ||
| } | ||
| return f(args...) | ||
| }, | ||
| s: func() string { return fmt.Sprintf("[%v]", signature(new(A))) }, | ||
| } | ||
| } | ||
|
|
||
| func signature(i interface{}) string { | ||
| elem := reflect.ValueOf(i).Elem() | ||
| switch elem.Kind() { | ||
| case reflect.Struct: | ||
| out, err := yaml.Marshal(i) | ||
| if err != nil { | ||
| return err.Error() | ||
| } | ||
| lines := strings.Split(string(out), "\n") | ||
| return fmt.Sprintf("{%v}", strings.Join(lines[:len(lines)-1], ", ")) | ||
|
|
||
| case reflect.Slice: | ||
| ptr := reflect.New(elem.Type().Elem()).Interface() | ||
| return fmt.Sprintf("[%v]", signature(ptr)) | ||
|
|
||
| case reflect.String: | ||
| return `""` | ||
|
|
||
| default: | ||
| return fmt.Sprintf("%v", reflect.ValueOf(i).Elem()) | ||
| } | ||
| } |