mirror of https://github.com/docker/cli.git
69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
package formatter
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import (
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"encoding/json"
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"reflect"
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"unicode"
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"github.com/pkg/errors"
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)
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// MarshalJSON marshals x into json
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// It differs a bit from encoding/json MarshalJSON function for formatter
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func MarshalJSON(x any) ([]byte, error) {
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m, err := marshalMap(x)
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if err != nil {
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return nil, err
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}
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return json.Marshal(m)
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}
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// marshalMap marshals x to map[string]any
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func marshalMap(x any) (map[string]any, error) {
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val := reflect.ValueOf(x)
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if val.Kind() != reflect.Ptr {
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return nil, errors.Errorf("expected a pointer to a struct, got %v", val.Kind())
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}
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if val.IsNil() {
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return nil, errors.Errorf("expected a pointer to a struct, got nil pointer")
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}
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valElem := val.Elem()
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if valElem.Kind() != reflect.Struct {
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return nil, errors.Errorf("expected a pointer to a struct, got a pointer to %v", valElem.Kind())
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}
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typ := val.Type()
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m := make(map[string]any)
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for i := 0; i < val.NumMethod(); i++ {
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k, v, err := marshalForMethod(typ.Method(i), val.Method(i))
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if err != nil {
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return nil, err
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}
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if k != "" {
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m[k] = v
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}
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}
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return m, nil
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}
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var unmarshallableNames = map[string]struct{}{"FullHeader": {}}
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// marshalForMethod returns the map key and the map value for marshalling the method.
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// It returns ("", nil, nil) for valid but non-marshallable parameter. (e.g. "unexportedFunc()")
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func marshalForMethod(typ reflect.Method, val reflect.Value) (string, any, error) {
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if val.Kind() != reflect.Func {
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return "", nil, errors.Errorf("expected func, got %v", val.Kind())
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}
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name, numIn, numOut := typ.Name, val.Type().NumIn(), val.Type().NumOut()
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_, blackListed := unmarshallableNames[name]
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// FIXME: In text/template, (numOut == 2) is marshallable,
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// if the type of the second param is error.
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marshallable := unicode.IsUpper(rune(name[0])) && !blackListed &&
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numIn == 0 && numOut == 1
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if !marshallable {
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return "", nil, nil
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}
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result := val.Call(make([]reflect.Value, numIn))
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intf := result[0].Interface()
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return name, intf, nil
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}
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