KaperD / Shallow-Size-Kotlin-Plugin

Shallow Size Kotlin Compiler Plugin

Plugin adds shallowSize(): Int method to all data classes at compile time

This method returns sum of all data class fields sizes in bytes

Pointer size is considered as 4 bytes, Boolean size as 1 byte, other primitive types have SIZE_BYTES field in their companion object

Using with Gradle

Requirements

• JDK 8
• Kotlin 1.5.0

Steps

1. Get plugin shallow-size-plugin.jar file
   • Download it from GitHub Releases
   • Or clone this repo, run ./gradlew shallow-size-plugin:jar and get jar from shallow-size-plugin/build/libs/
2. Add this to your build.gradle.kts:

tasks.withType<KotlinCompile> {
    kotlinOptions.freeCompilerArgs += "-Xplugin=${rootDir}/path/to/shallow-size-plugin.jar"
}

Or if you use build.gradle:

compileKotlin {
    kotlinOptions {
        freeCompilerArgs += ["-Xplugin=${rootDir}/path/to/shallow-size-plugin.jar"]
    }
}

Example of plugin usage with gradle

You can see it in use-plugin folder. It also contains some plugin tests

Example of plugin work

open class Base(var a: Short)

data class A(val b: Int) : Base(42) {
    val c: Int // don't have field
        get() = 1
}

fun main() {
    val a = A(3)
    println(a.shallowSize()) // 6
}