rjson

README

This is just a fork of the original rjson package at http://launchpad.net/rjson to ease use if you don't have Bazaar or don't want to depend on launchpad.

Documentation

Overview

Package rjson implements a backwardly compatible version of JSON with the aim of making it easier for humans to read and write.

The data model is exactly that of JSON's and this package implements all the marshalling and unmarshalling operations supported by the standard library's json package.

The three principal differences are:

• Quotes may be omitted for some object key values (see below).
• Commas are automatically inserted when a newline is encountered after a value (but not an object key).
• Commas are optional at the end of an array or object.

The quotes around an object key may be omitted if the key matches the following regular expression:

[a-zA-Z][a-zA-Z0-9\-_]*

This rule will be relaxed in the future to allow unicode characters, probably following the same rules as Go's identifiers, and probably a few more non-alphabetical characters.

Index

• func Compact(dst *bytes.Buffer, src []byte) error
• func HTMLEscape(dst *bytes.Buffer, src []byte)
• func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error
• func Marshal(v interface{}) ([]byte, error)
• func MarshalIndent(v interface{}, prefix, indent string) ([]byte, error)
• func Unmarshal(data []byte, v interface{}) error
• type Decoder
  • func NewDecoder(r io.Reader) *Decoder
  • func (dec *Decoder) Decode(v interface{}) error
  • func (dec *Decoder) UseNumber()
• type Encoder
  • func NewEncoder(w io.Writer) *Encoder
  • func (enc *Encoder) Encode(v interface{}) error
• type InvalidUTF8Error
  • func (e *InvalidUTF8Error) Error() string
• type InvalidUnmarshalError
  • func (e *InvalidUnmarshalError) Error() string
• type Marshaler
• type MarshalerError
  • func (e *MarshalerError) Error() string
• type Number
  • func (n Number) Float64() (float64, error)
  • func (n Number) Int64() (int64, error)
  • func (n Number) String() string
• type RawMessage
  • func (m *RawMessage) MarshalJSON() ([]byte, error)
  • func (m *RawMessage) UnmarshalRJSON(data []byte) error
• type SyntaxError
  • func (e *SyntaxError) Error() string
• type UnmarshalFieldError
  • func (e *UnmarshalFieldError) Error() string
• type UnmarshalTypeError
  • func (e *UnmarshalTypeError) Error() string
• type Unmarshaler
• type UnsupportedTypeError
  • func (e *UnsupportedTypeError) Error() string
• type UnsupportedValueError
  • func (e *UnsupportedValueError) Error() string

Functions

func Compact

func Compact(dst *bytes.Buffer, src []byte) error

Compact appends to dst the rjson-encoded src with insignificant space characters elided. Note that calling Compact on the result of Indent can be smaller still, as Compact does not current omit quotes from strings that can be represented as identifiers.

func HTMLEscape

func HTMLEscape(dst *bytes.Buffer, src []byte)

HTMLEscape appends to dst the JSON-encoded src with <, >, and & characters inside string literals changed to \u003c, \u003e, \u0026 so that the JSON will be safe to embed inside HTML <script> tags. For historical reasons, web browsers don't honor standard HTML escaping within <script> tags, so an alternative JSON encoding must be used.

func Indent

func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error

Indent appends to dst an indented form of the rjson-encoded src. Each element in a rjson object or array begins on a new, indented line beginning with prefix followed by one or more copies of indent according to the indentation nesting. The data appended to dst has no trailing newline, to make it easier to embed inside other formatted rjson data. Strings are formatted as identifiers whenever possible; commas are elided.

func Marshal

func Marshal(v interface{}) ([]byte, error)

Marshal returns the JSON encoding of v. Note that despite the fact that this is the rjson package, this function does returns JSON. MarshalIndent and Indent can be used to produce rjson-specific output.

Marshal traverses the value v recursively. If an encountered value implements the Marshaler interface and is not a nil pointer, Marshal calls its MarshalJSON method to produce JSON. The nil pointer exception is not strictly necessary but mimics a similar, necessary exception in the behavior of UnmarshalJSON.

Otherwise, Marshal uses the following type-dependent default encodings:

Boolean values encode as JSON booleans.

Floating point, integer, and Number values encode as JSON numbers.

String values encode as JSON strings, with each invalid UTF-8 sequence replaced by the encoding of the Unicode replacement character U+FFFD. The angle brackets "<" and ">" are escaped to "\u003c" and "\u003e" to keep some browsers from misinterpreting JSON output as HTML.

Array and slice values encode as JSON arrays, except that []byte encodes as a base64-encoded string, and a nil slice encodes as the null JSON object.

Struct values encode as JSON objects. Each exported struct field becomes a member of the object unless

• the field's tag is "-", or
• the field is empty and its tag specifies the "omitempty" option.

The empty values are false, 0, any nil pointer or interface value, and any array, slice, map, or string of length zero. The object's default key string is the struct field name but can be specified in the struct field's tag value. The "json" key in the struct field's tag value is the key name, followed by an optional comma and options. Examples:

// Field is ignored by this package.
Field int `json:"-"`

// Field appears in JSON as key "myName".
Field int `json:"myName"`

// Field appears in JSON as key "myName" and
// the field is omitted from the object if its value is empty,
// as defined above.
Field int `json:"myName,omitempty"`

// Field appears in JSON as key "Field" (the default), but
// the field is skipped if empty.
// Note the leading comma.
Field int `json:",omitempty"`

The "string" option signals that a field is stored as JSON inside a JSON-encoded string. This extra level of encoding is sometimes used when communicating with JavaScript programs:

Int64String int64 `json:",string"`

The key name will be used if it's a non-empty string consisting of only Unicode letters, digits, dollar signs, percent signs, hyphens, underscores and slashes.

Anonymous struct fields are usually marshaled as if their inner exported fields were fields in the outer struct, subject to the usual Go visibility rules. An anonymous struct field with a name given in its JSON tag is treated as having that name instead of as anonymous.

Handling of anonymous struct fields is new in Go 1.1. Prior to Go 1.1, anonymous struct fields were ignored. To force ignoring of an anonymous struct field in both current and earlier versions, give the field a JSON tag of "-".

Map values encode as JSON objects. The map's key type must be string; the object keys are used directly as map keys.

Pointer values encode as the value pointed to. A nil pointer encodes as the null JSON object.

Interface values encode as the value contained in the interface. A nil interface value encodes as the null JSON object.

Channel, complex, and function values cannot be encoded in JSON. Attempting to encode such a value causes Marshal to return an UnsupportedTypeError.

JSON cannot represent cyclic data structures and Marshal does not handle them. Passing cyclic structures to Marshal will result in an infinite recursion.

func MarshalIndent

func MarshalIndent(v interface{}, prefix, indent string) ([]byte, error)

MarshalIndent is like Marshal but applies Indent to format the output.

func Unmarshal

func Unmarshal(data []byte, v interface{}) error

Unmarshal parses the JSON- or rjson-encoded data and stores the result in the value pointed to by v. As the data models are the same, "JSON" is used to refer to both JSON and rjson.

Unmarshal uses the inverse of the encodings that Marshal uses, allocating maps, slices, and pointers as necessary, with the following additional rules:

To unmarshal rjson into a pointer, Unmarshal first handles the case of the JSON being the JSON literal null. In that case, Unmarshal sets the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into the value pointed at by the pointer. If the pointer is nil, Unmarshal allocates a new value for it to point to.

To unmarshal JSON into an interface value, Unmarshal unmarshals the JSON into the concrete value contained in the interface value. If the interface value is nil, that is, has no concrete value stored in it, Unmarshal stores one of these in the interface value:

bool, for JSON booleans
float64, for JSON numbers
string, for JSON strings
[]interface{}, for JSON arrays
map[string]interface{}, for JSON objects
nil for JSON null

If a JSON value is not appropriate for a given target type, or if a JSON number overflows the target type, Unmarshal skips that field and completes the unmarshalling as best it can. If no more serious errors are encountered, Unmarshal returns an UnmarshalTypeError describing the earliest such error.

Types

type Decoder

type Decoder struct {
	// contains filtered or unexported fields
}

A Decoder reads and decodes rjson objects from an input stream.

func NewDecoder

func NewDecoder(r io.Reader) *Decoder

NewDecoder returns a new decoder that reads from r.

The decoder introduces its own buffering and may read data from r beyond the rjson values requested.

func (*Decoder) Decode

func (dec *Decoder) Decode(v interface{}) error

Decode reads the next rjson-encoded value from its input and stores it in the value pointed to by v.

See the documentation for Unmarshal for details about the conversion of rjson into a Go value.

func (*Decoder) UseNumber

func (dec *Decoder) UseNumber()

UseNumber causes the Decoder to unmarshal a number into an interface{} as a Number instead of as a float64.

type Encoder

type Encoder struct {
	// contains filtered or unexported fields
}

An Encoder writes JSON objects to an output stream.

func NewEncoder

func NewEncoder(w io.Writer) *Encoder

NewEncoder returns a new encoder that writes to w.

func (*Encoder) Encode

func (enc *Encoder) Encode(v interface{}) error

Encode writes the JSON encoding of v to the connection. Note that this does use the JSON encoding, not rjson.

See the documentation for Marshal for details about the conversion of Go values to JSON.

type InvalidUTF8Error

type InvalidUTF8Error struct {
	S string
}

func (*InvalidUTF8Error) Error

func (e *InvalidUTF8Error) Error() string

type InvalidUnmarshalError

type InvalidUnmarshalError struct {
	Type reflect.Type
}

An InvalidUnmarshalError describes an invalid argument passed to Unmarshal. (The argument to Unmarshal must be a non-nil pointer.)

func (*InvalidUnmarshalError) Error

func (e *InvalidUnmarshalError) Error() string

type Marshaler

type Marshaler interface {
	MarshalJSON() ([]byte, error)
}

Marshaler is the interface implemented by objects that can marshal themselves into valid JSON (and hence valid rjson)

type MarshalerError

type MarshalerError struct {
	Type reflect.Type
	Err  error
}

func (*MarshalerError) Error

func (e *MarshalerError) Error() string

type Number

type Number string

A Number represents a JSON number literal.

func (Number) Float64

func (n Number) Float64() (float64, error)

Float64 returns the number as a float64.

func (Number) Int64

func (n Number) Int64() (int64, error)

Int64 returns the number as an int64.

func (Number) String

func (n Number) String() string

String returns the literal text of the number.

type RawMessage

type RawMessage []byte

RawMessage is a raw encoded JSON object. It implements Marshaler and Unmarshaler and can be used to delay JSON decoding or precompute a JSON encoding.

func (*RawMessage) MarshalJSON

func (m *RawMessage) MarshalJSON() ([]byte, error)

MarshalJSON returns *m as the JSON encoding of m.

func (*RawMessage) UnmarshalRJSON

func (m *RawMessage) UnmarshalRJSON(data []byte) error

UnmarshalRJSON sets *m to a copy of data.

type SyntaxError

type SyntaxError struct {
	Offset int64 // error occurred after reading Offset bytes
	// contains filtered or unexported fields
}

A SyntaxError is a description of a JSON syntax error.

func (*SyntaxError) Error

func (e *SyntaxError) Error() string

type UnmarshalFieldError

type UnmarshalFieldError struct {
	Key   string
	Type  reflect.Type
	Field reflect.StructField
}

An UnmarshalFieldError describes a JSON object key that led to an unexported (and therefore unwritable) struct field.

func (*UnmarshalFieldError) Error

func (e *UnmarshalFieldError) Error() string

type UnmarshalTypeError

type UnmarshalTypeError struct {
	Value string       // description of JSON value - "bool", "array", "number -5"
	Type  reflect.Type // type of Go value it could not be assigned to
}

An UnmarshalTypeError describes a JSON value that was not appropriate for a value of a specific Go type.

func (*UnmarshalTypeError) Error

func (e *UnmarshalTypeError) Error() string

type Unmarshaler

type Unmarshaler interface {
	UnmarshalRJSON([]byte) error
}

Unmarshaler is the interface implemented by objects that can unmarshal a rjson description of themselves. The input can be assumed to be a valid rjson object encoding. UnmarshalRJSON must copy the rjson data if it wishes to retain the data after returning. Note: I plan to honour UnmarshalJSON methods in the future.

type UnsupportedTypeError

type UnsupportedTypeError struct {
	Type reflect.Type
}

An UnsupportedTypeError is returned by Marshal when attempting to encode an unsupported value type.

func (*UnsupportedTypeError) Error

func (e *UnsupportedTypeError) Error() string

type UnsupportedValueError

type UnsupportedValueError struct {
	Value reflect.Value
	Str   string
}

func (*UnsupportedValueError) Error

func (e *UnsupportedValueError) Error() string