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76 lines
1.6 KiB
76 lines
1.6 KiB
package jsonstream
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import (
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"bufio"
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"encoding/json"
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"errors"
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"io"
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)
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// Reader is used for reading newline delimited JSON objects from an input io.Reader
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type Reader struct {
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buffer *bufio.Reader
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keys map[string]bool
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}
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// NewReader will create a new Reader from the provided io.Reader and keys
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// k, when not an empty slice, will tell the Reader to only include the provided keys from the input JSON object
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func NewReader(r io.Reader, k []string) *Reader {
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var keys map[string]bool
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keys = make(map[string]bool, 0)
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for _, key := range k {
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keys[key] = true
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}
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return &Reader{
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buffer: bufio.NewReader(r),
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keys: keys,
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}
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}
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func (reader *Reader) processData(data interface{}) (processed map[string]interface{}, err error) {
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var fields map[string]interface{}
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fields, err = getAsMap(data)
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if err != nil {
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return processed, err
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}
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processed = make(map[string]interface{})
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for key, value := range fields {
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if _, ok := reader.keys[key]; ok {
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processed[key] = value
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}
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}
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return processed, err
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}
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// ReadLine will read the next JSON object from the input io.Reader
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func (reader *Reader) ReadLine() (data interface{}, err error) {
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var line []byte
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var isPrefix bool
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line, isPrefix, err = reader.buffer.ReadLine()
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if isPrefix {
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err = errors.New("Line exceeds the length of the buffer")
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}
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if err != nil {
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return data, err
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}
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// skip empty lines, we'll fail at processing them anyways
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if len(line) == 0 {
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return reader.ReadLine()
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}
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err = json.Unmarshal(line, &data)
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if err != nil {
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return data, err
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}
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if len(reader.keys) > 0 {
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data, err = reader.processData(data)
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}
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return data, err
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}
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