Introduce new StringProperties object that can encode and decode properties from a string #2303
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,291 @@ | ||
| /* | ||
| * Copyright 2017-2023 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license. | ||
| */ | ||
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| package kotlinx.serialization.properties | ||
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| import kotlinx.serialization.* | ||
| import kotlinx.serialization.descriptors.* | ||
| import kotlinx.serialization.encoding.* | ||
| import kotlinx.serialization.internal.* | ||
| import kotlinx.serialization.modules.* | ||
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| /** | ||
| * Transforms a [Serializable] class' properties into a single flat [String] representing the class data | ||
| * in the properties format. | ||
| * | ||
| * If the given class has non-primitive property `d` of arbitrary type `D`, `D` values are inserted | ||
| * into the same map; keys for such values are prefixed with string `d.`: | ||
| * | ||
| * ``` | ||
| * @Serializable | ||
| * class Data(val property1: String) | ||
| * | ||
| * @Serializable | ||
| * class DataHolder(val data: Data, val property2: String) | ||
| * | ||
| * val string = StringProperties.encodeToString(properties) | ||
| * // string contents will be the following: | ||
| * """ | ||
| * property2 = value2 | ||
| * data.property1 = value1 | ||
| * """ | ||
| * ``` | ||
| * | ||
| * If the given class has a [List] property `l`, each value from the list | ||
| * would be prefixed with `l.N.`, where N is an index for a particular value. | ||
| * [Map] is treated as a `[key,value,...]` list. | ||
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| * Conversely, this class can convert a properties string into a [Serializable] class instance. | ||
| * ``` | ||
| * @Serializable | ||
| * class Data(val property1: String) | ||
| * | ||
| * @Serializable | ||
| * class DataHolder(val data: Data, val property2: String) | ||
| * | ||
| * val string = """ | ||
| * property2 = value2 | ||
| * data.property1 = value1 | ||
| * """ | ||
| * val data = StringProperties.decodeToString(string, DataHolder.serializer()) | ||
| * // data contents will be the following: | ||
| * // DataHolder(data = Data(property1 = "value1"), property2 = "value2") | ||
| * ``` | ||
| * | ||
| * @param conf A [PropertiesConf] which contain configuration for customising the output string. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| @Suppress("UNUSED_PARAMETER") | ||
| public sealed class StringProperties( | ||
| private val conf: PropertiesConf, | ||
| private val properties: Properties = Properties(conf.serializersModule), | ||
| ) : SerialFormat by properties, StringFormat { | ||
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| /** | ||
| * Encodes properties from the given [value] to a properties String using the given [serializer]. | ||
| * `null` values are omitted from the output. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public override fun <T> encodeToString(serializer: SerializationStrategy<T>, value: T): String { | ||
| val map = properties.encodeToMap(serializer, value) | ||
| val builder = StringBuilder() | ||
| for ((k, v) in map) { | ||
| builder.append(k) | ||
| repeat(conf.spacesBeforeSeparator) { | ||
| builder.append(' ') | ||
| } | ||
| builder.append(conf.keyValueSeparator.char()) | ||
| repeat(conf.spacesAfterSeparator) { | ||
| builder.append(' ') | ||
| } | ||
| builder.append(v) | ||
| builder.append(conf.lineSeparator.chars()) | ||
| } | ||
| return builder.toString() | ||
| } | ||
|
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| /** | ||
| * Decodes properties from the given [string] to a value of type [T] using the given [deserializer]. | ||
| * [String] values are converted to respective primitive types using default conversion methods. | ||
| * [T] may contain properties of nullable types; they will be filled by non-null values from the [map], if present. | ||
| */ | ||
| public override fun <T> decodeFromString(deserializer: DeserializationStrategy<T>, string: String): T { | ||
| val result = mutableMapOf<String, String>() | ||
| for (line in string.logicalLines()) { | ||
| val parsedLine = line.unescaped() | ||
| var keyEnd = parsedLine.length | ||
| for (i in parsedLine.indices) { | ||
| if (parsedLine[i] in separators) { | ||
| keyEnd = i | ||
| break | ||
| } | ||
| } | ||
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| var valueBegin = parsedLine.length | ||
| var separatorFound = false | ||
| for (i in keyEnd..parsedLine.lastIndex) { | ||
| if (separatorFound && parsedLine[i] != ' ') { | ||
| valueBegin = i | ||
| break | ||
| } | ||
| if (parsedLine[i] in nonBlankSeparators) { | ||
| separatorFound = true | ||
| } | ||
| if (parsedLine[i] !in separators) { | ||
| valueBegin = i | ||
| break | ||
| } | ||
| } | ||
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| result[parsedLine.substring(0, keyEnd)] = parsedLine.substring(valueBegin) | ||
| } | ||
| return properties.decodeFromStringMap(deserializer, result) | ||
|
There was a problem hiding this comment. Same here, I would add an overload to get the input string as |
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| } | ||
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| /** | ||
| * A [Properties] instance that can be used as default and does not have any [SerializersModule] installed. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public companion object Default : StringProperties(PropertiesConf()) | ||
| } | ||
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| @OptIn(ExperimentalSerializationApi::class) | ||
| private class StringPropertiesImpl(conf: PropertiesConf) : StringProperties(conf) | ||
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| /** | ||
| * Creates an instance of [StringProperties] with a given [builderAction]. | ||
| * TODO: doc | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public fun StringProperties(builderAction: StringPropertiesBuilder.() -> Unit = {}): StringProperties { | ||
| val builder = StringPropertiesBuilder(PropertiesConf()) | ||
| builder.builderAction() | ||
| return StringPropertiesImpl(builder.build()) | ||
| } | ||
|
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| /** | ||
| * Encodes properties from given [value] to a string using serializer for reified type [T] and returns this string. | ||
| * Converts all primitive types to [String] using [toString] method. | ||
| * `null` values are omitted from the output. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public inline fun <reified T> StringProperties.encodeToString(value: T): String = | ||
| encodeToString(serializersModule.serializer(), value) | ||
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| /** | ||
| * Decodes properties from given [propertiesString], assigns them to an object using serializer for reified type [T] and returns this object. | ||
| * [String] values are converted to respective primitive types using default conversion methods. | ||
| * [T] may contain properties of nullable types; they will be filled by non-null values from the [map], if present. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public inline fun <reified T> StringProperties.decodeFromString(propertiesString: String): T = | ||
| decodeFromString(serializersModule.serializer(), propertiesString) | ||
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| /** | ||
| * Builder of the [StringProperties] instance provided by `StringProperties { ... }` factory function. | ||
| */ | ||
| @ExperimentalSerializationApi | ||
| public class StringPropertiesBuilder internal constructor(from: PropertiesConf) { | ||
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| /** | ||
| * A [LineSeparator] to be used for separating lines when encoding to a string. | ||
| * Default value is [LineSeparator.LF]. | ||
| */ | ||
| public var lineSeparator: LineSeparator = from.lineSeparator | ||
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| /** | ||
| * A [KeyValueSeparator] to be used for separating keys and values when encoding to a string. | ||
| * Default value is [KeyValueSeparator.EQUALS]. | ||
| */ | ||
| public var keyValueSeparator: KeyValueSeparator = from.keyValueSeparator | ||
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| /** | ||
| * A number of spaces to be inserted before the [keyValueSeparator] when encoding to a string. | ||
| * Default value is `0`. | ||
| */ | ||
| public var spacesBeforeSeparator: Int = from.spacesBeforeSeparator | ||
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| /** | ||
| * A number of spaces to be inserted after the [keyValueSeparator] when encoding to a string. | ||
| * Default value is `0`. | ||
| */ | ||
| public var spacesAfterSeparator: Int = from.spacesAfterSeparator | ||
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| /** | ||
| * A [SerializersModule] to be used for encoding and decoding. | ||
| * Default value is [EmptySerializersModule]. | ||
| */ | ||
| public var module: SerializersModule = from.serializersModule | ||
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| internal fun build(): PropertiesConf { | ||
| return PropertiesConf( | ||
| lineSeparator, | ||
| keyValueSeparator, | ||
| spacesBeforeSeparator, | ||
| spacesAfterSeparator, | ||
| module | ||
| ) | ||
| } | ||
| } | ||
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| @ExperimentalSerializationApi | ||
| internal data class PropertiesConf( | ||
| val lineSeparator: LineSeparator = LineSeparator.LF, | ||
| val keyValueSeparator: KeyValueSeparator = KeyValueSeparator.EQUALS, | ||
| val spacesBeforeSeparator: Int = 0, | ||
| val spacesAfterSeparator: Int = 0, | ||
| val serializersModule: SerializersModule = EmptySerializersModule() | ||
| ) | ||
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| @ExperimentalSerializationApi | ||
| public enum class LineSeparator(private val s: String) { | ||
| LF("\n"), | ||
| CR("\r"), | ||
| CRLF("\r\n"); | ||
|
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| public fun chars(): CharArray { | ||
| return s.toCharArray() | ||
| } | ||
| } | ||
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| @ExperimentalSerializationApi | ||
| public enum class KeyValueSeparator(private val c: Char) { | ||
| EQUALS('='), | ||
| COLON(':'); | ||
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| public fun char(): Char = c | ||
| } | ||
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| private val nonBlankSeparators = setOf('=', ':') | ||
| private val separators = nonBlankSeparators + ' ' | ||
| private val wellKnownEscapeChars = mapOf( | ||
| '\\' to '\\', | ||
| 'n' to '\n', | ||
| 'r' to '\r', | ||
| 't' to '\t' | ||
| ) | ||
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| private fun String.unescaped(): String { | ||
| val sb = StringBuilder(this.length) | ||
| var i = 0 | ||
| while (i < this.length) { | ||
| if (i < this.length - 1 && this[i] == '\\') { | ||
| if (this[i + 1] in wellKnownEscapeChars) { | ||
| sb.append(wellKnownEscapeChars[this[i + 1]]) | ||
| i += 2 | ||
| } else { | ||
| i++ | ||
| } | ||
| } else { | ||
| sb.append(this[i]) | ||
| i++ | ||
| } | ||
| } | ||
| return sb.toString() | ||
| } | ||
|
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| private fun String.logicalLines(): List<String> { | ||
| val commentFilter = "[ \\t\\f]*[#!].*".toRegex() | ||
| val lines = lines() | ||
| .filterNot { it.isBlank() || commentFilter.matches(it) } | ||
| .toMutableList() | ||
| val logicalLines = mutableListOf<String>() | ||
|
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| var currentLine = "" | ||
| for (line in lines) { | ||
| val trimmedLine = line.trimStart() | ||
| if (trimmedLine.endsWith("\\")) { | ||
| currentLine += trimmedLine.dropLast(1) | ||
| } else { | ||
| currentLine += trimmedLine | ||
| logicalLines.add(currentLine) | ||
| currentLine = "" | ||
| } | ||
| } | ||
| if (currentLine.isNotBlank()) { | ||
| logicalLines.add(currentLine) | ||
| } | ||
|
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| return logicalLines | ||
| } | ||
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I would extract the actual output renderer into another function taking a map overload to encode a giving String map to a Properties file