blob: 016e07e20f4de1817dffe24af8e47473429c45ab (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
package kotlinx.serialization.encoding
import kotlinx.serialization.ExperimentalSerializationApi
/**
* This interface indicates that decoder supports consuming large strings by chunks via consumeChunk method.
* Currently, only streaming json decoder implements this interface.
* Please note that this interface is only applicable to streaming decoders. That means that it is not possible to use
* some JsonTreeDecoder features like polymorphism with this interface.
*/
@ExperimentalSerializationApi
public interface ChunkedDecoder {
/**
* Method allows decoding a string value by fixed-size chunks.
* Usable for handling very large strings that may not fit in memory.
* Chunk size is guaranteed to not exceed 16384 chars (but it may be smaller than that).
* Feeds string chunks to the provided consumer.
*
* @param consumeChunk - lambda function to handle string chunks
*
* Example usage:
* ```
* @Serializable(with = LargeStringSerializer::class)
* data class LargeStringData(val largeString: String)
*
* @Serializable
* data class ClassWithLargeStringDataField(val largeStringField: LargeStringData)
*
* object LargeStringSerializer : KSerializer<LargeStringData> {
* override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("LargeStringContent", PrimitiveKind.STRING)
*
* override fun deserialize(decoder: Decoder): LargeStringData {
* require(decoder is ChunkedDecoder) { "Only chunked decoder supported" }
*
* val tmpFile = createTempFile()
* val writer = FileWriter(tmpFile.toFile()).use {
* decoder.decodeStringChunked { chunk ->
* writer.append(chunk)
* }
* }
* return LargeStringData("file://${tmpFile.absolutePathString()}")
* }
* }
* ```
*
* In this sample, we need to be able to handle a huge string coming from json. Instead of storing it in memory,
* we offload it into a file and return the file name instead
*/
@ExperimentalSerializationApi
public fun decodeStringChunked(consumeChunk: (chunk: String) -> Unit)
}
|
