helpers.go

Documentation: github.com/mailru/easyjson

     1  // Package easyjson contains marshaler/unmarshaler interfaces and helper functions.
     2  package easyjson
     3  
     4  import (
     5  	"io"
     6  	"io/ioutil"
     7  	"net/http"
     8  	"strconv"
     9  	"unsafe"
    10  
    11  	"github.com/mailru/easyjson/jlexer"
    12  	"github.com/mailru/easyjson/jwriter"
    13  )
    14  
    15  // Marshaler is an easyjson-compatible marshaler interface.
    16  type Marshaler interface {
    17  	MarshalEasyJSON(w *jwriter.Writer)
    18  }
    19  
    20  // Marshaler is an easyjson-compatible unmarshaler interface.
    21  type Unmarshaler interface {
    22  	UnmarshalEasyJSON(w *jlexer.Lexer)
    23  }
    24  
    25  // MarshalerUnmarshaler is an easyjson-compatible marshaler/unmarshaler interface.
    26  type MarshalerUnmarshaler interface {
    27  	Marshaler
    28  	Unmarshaler
    29  }
    30  
    31  // Optional defines an undefined-test method for a type to integrate with 'omitempty' logic.
    32  type Optional interface {
    33  	IsDefined() bool
    34  }
    35  
    36  // UnknownsUnmarshaler provides a method to unmarshal unknown struct fileds and save them as you want
    37  type UnknownsUnmarshaler interface {
    38  	UnmarshalUnknown(in *jlexer.Lexer, key string)
    39  }
    40  
    41  // UnknownsMarshaler provides a method to write additional struct fields
    42  type UnknownsMarshaler interface {
    43  	MarshalUnknowns(w *jwriter.Writer, first bool)
    44  }
    45  
    46  func isNilInterface(i interface{}) bool {
    47  	return (*[2]uintptr)(unsafe.Pointer(&i))[1] == 0
    48  }
    49  
    50  // Marshal returns data as a single byte slice. Method is suboptimal as the data is likely to be copied
    51  // from a chain of smaller chunks.
    52  func Marshal(v Marshaler) ([]byte, error) {
    53  	if isNilInterface(v) {
    54  		return nullBytes, nil
    55  	}
    56  
    57  	w := jwriter.Writer{}
    58  	v.MarshalEasyJSON(&w)
    59  	return w.BuildBytes()
    60  }
    61  
    62  // MarshalToWriter marshals the data to an io.Writer.
    63  func MarshalToWriter(v Marshaler, w io.Writer) (written int, err error) {
    64  	if isNilInterface(v) {
    65  		return w.Write(nullBytes)
    66  	}
    67  
    68  	jw := jwriter.Writer{}
    69  	v.MarshalEasyJSON(&jw)
    70  	return jw.DumpTo(w)
    71  }
    72  
    73  // MarshalToHTTPResponseWriter sets Content-Length and Content-Type headers for the
    74  // http.ResponseWriter, and send the data to the writer. started will be equal to
    75  // false if an error occurred before any http.ResponseWriter methods were actually
    76  // invoked (in this case a 500 reply is possible).
    77  func MarshalToHTTPResponseWriter(v Marshaler, w http.ResponseWriter) (started bool, written int, err error) {
    78  	if isNilInterface(v) {
    79  		w.Header().Set("Content-Type", "application/json")
    80  		w.Header().Set("Content-Length", strconv.Itoa(len(nullBytes)))
    81  		written, err = w.Write(nullBytes)
    82  		return true, written, err
    83  	}
    84  
    85  	jw := jwriter.Writer{}
    86  	v.MarshalEasyJSON(&jw)
    87  	if jw.Error != nil {
    88  		return false, 0, jw.Error
    89  	}
    90  	w.Header().Set("Content-Type", "application/json")
    91  	w.Header().Set("Content-Length", strconv.Itoa(jw.Size()))
    92  
    93  	started = true
    94  	written, err = jw.DumpTo(w)
    95  	return
    96  }
    97  
    98  // Unmarshal decodes the JSON in data into the object.
    99  func Unmarshal(data []byte, v Unmarshaler) error {
   100  	l := jlexer.Lexer{Data: data}
   101  	v.UnmarshalEasyJSON(&l)
   102  	return l.Error()
   103  }
   104  
   105  // UnmarshalFromReader reads all the data in the reader and decodes as JSON into the object.
   106  func UnmarshalFromReader(r io.Reader, v Unmarshaler) error {
   107  	data, err := ioutil.ReadAll(r)
   108  	if err != nil {
   109  		return err
   110  	}
   111  	l := jlexer.Lexer{Data: data}
   112  	v.UnmarshalEasyJSON(&l)
   113  	return l.Error()
   114  }
   115
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