/
json.go
255 lines (210 loc) · 4.81 KB
/
json.go
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package document
import (
"bufio"
"bytes"
"encoding/json"
"fmt"
"io"
"math"
"strconv"
)
// ToJSON encodes d to w in JSON.
func ToJSON(w io.Writer, d Document) error {
return json.NewEncoder(w).Encode(jsonDocument{d})
}
// ArrayToJSON encodes a to w in JSON.
func ArrayToJSON(w io.Writer, a Array) error {
return json.NewEncoder(w).Encode(jsonArray{a})
}
type jsonArray struct {
Array
}
func (j jsonArray) MarshalJSON() ([]byte, error) {
var buf bytes.Buffer
buf.WriteByte('[')
var notFirst bool
err := j.Array.Iterate(func(i int, v Value) error {
if notFirst {
buf.WriteByte(',')
}
notFirst = true
data, err := v.MarshalJSON()
if err != nil {
return err
}
_, err = buf.Write(data)
return err
})
if err != nil {
return nil, err
}
buf.WriteByte(']')
return buf.Bytes(), nil
}
type jsonDocument struct {
Document
}
func (j jsonDocument) MarshalJSON() ([]byte, error) {
var buf bytes.Buffer
buf.WriteByte('{')
var notFirst bool
err := j.Document.Iterate(func(f string, v Value) error {
if notFirst {
buf.WriteByte(',')
}
notFirst = true
buf.WriteString(strconv.Quote(f))
buf.WriteRune(':')
data, err := v.MarshalJSON()
if err != nil {
return err
}
_, err = buf.Write(data)
return err
})
if err != nil {
return nil, err
}
buf.WriteByte('}')
return buf.Bytes(), nil
}
func parseJSONValue(dec *json.Decoder) (Value, error) {
// ensure the decoder parses numbers as the json.Number type
dec.UseNumber()
// parse the first token to determine which type is it
t, err := dec.Token()
if err != nil {
return Value{}, err
}
switch tt := t.(type) {
case string:
return NewTextValue(tt), nil
case bool:
return NewBoolValue(tt), nil
case nil:
return NewNullValue(), nil
case json.Number:
i, err := tt.Int64()
if err != nil {
// if it's too big to fit in an int64, let's try parsing this as a floating point number
f, err := tt.Float64()
if err != nil {
return Value{}, err
}
return NewFloat64Value(f), nil
}
switch {
case i >= math.MinInt8 && i <= math.MaxInt8:
return NewInt8Value(int8(i)), nil
case i >= math.MinInt16 && i <= math.MaxInt16:
return NewInt16Value(int16(i)), nil
case i >= math.MinInt32 && i <= math.MaxInt32:
return NewInt32Value(int32(i)), nil
default:
return NewInt64Value(int64(i)), nil
}
case json.Delim:
switch tt {
case ']', '}':
return Value{}, fmt.Errorf("found %q, expected '{' or '['", tt)
case '[':
buf := NewValueBuffer()
err := parseJSONArray(dec, t, &buf)
if err != nil {
return Value{}, err
}
return NewArrayValue(buf), nil
case '{':
buf := NewFieldBuffer()
err = parseJSONDocument(dec, t, buf)
if err != nil {
return Value{}, err
}
return NewDocumentValue(buf), nil
}
}
return Value{}, nil
}
func parseJSONDocument(dec *json.Decoder, currToken json.Token, buf *FieldBuffer) error {
var err error
// expecting a '{'
if d, ok := currToken.(json.Delim); !ok || d.String() != "{" {
return fmt.Errorf("found %q, expected '{'", d.String())
}
for dec.More() {
// parse the key, it must be a string
t, err := dec.Token()
if err != nil {
return err
}
k, ok := t.(string)
if !ok {
return fmt.Errorf("found %q, expected string", t)
}
v, err := parseJSONValue(dec)
if err != nil {
return err
}
buf.Add(k, v)
}
currToken, err = dec.Token()
if err == io.EOF {
return fmt.Errorf("found %q, expected '}'", err)
}
// expecting a '}'
if d, ok := currToken.(json.Delim); !ok || d.String() != "}" {
return fmt.Errorf("found %q, expected '}'", d.String())
}
return nil
}
func parseJSONArray(dec *json.Decoder, currToken json.Token, buf *ValueBuffer) error {
// expecting a '['
if d, ok := currToken.(json.Delim); !ok || d.String() != "[" {
return fmt.Errorf("found %q, expected '['", d.String())
}
for dec.More() {
v, err := parseJSONValue(dec)
if err != nil {
return err
}
*buf = buf.Append(v)
}
// expecting ']'
t, err := dec.Token()
if err != nil {
return err
}
if d, ok := t.(json.Delim); !ok || d != ']' {
return fmt.Errorf("found %q, expected ']'", t)
}
return nil
}
// IteratorToJSON encodes all the documents of an iterator to JSON stream.
func IteratorToJSON(w io.Writer, s Iterator) error {
enc := json.NewEncoder(w)
enc.SetIndent("", " ")
return s.Iterate(func(d Document) error {
return enc.Encode(jsonDocument{d})
})
}
// IteratorToJSONArray encodes all the documents of an iterator to a JSON array.
func IteratorToJSONArray(w io.Writer, s Iterator) error {
buf := bufio.NewWriter(w)
buf.WriteByte('[')
enc := json.NewEncoder(w)
enc.SetIndent("", " ")
first := true
err := s.Iterate(func(d Document) error {
if !first {
buf.WriteByte(',')
} else {
first = false
}
return ToJSON(buf, d)
})
if err != nil {
return err
}
buf.WriteByte(']')
return buf.Flush()
}