src/main/kotlin/SizedInteger.kt


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

import java.math.BigInteger

/**
 * [SizedInteger] represents an unsigned integer number of arbitrary yet fixed length. It's useful for storing integers
 * got from a connection as message fields.
 *
 * @param size The size of the field, measured in bytes.
 * @param value The value of the field.
 *
 * @throws IllegalArgumentException if the size required to store the provided value is bigger than the provided size.
 */
class SizedInteger(val size: ULong, value: BigInteger) {
    init {
        if (!this.sizeOk(size, value)) {
            throw IllegalArgumentException()
        }
    }

    constructor(size: ULong) : this(size, 0.toBigInteger())

    /**
     * @throws IllegalStateException on set if the declared size is not enough for the new value.
     */
    var value = value
        set(value) {
            if (!this.sizeOk(value)) {
                throw IllegalStateException()
            }
        }

    private fun sizeOk(size: ULong, value: BigInteger): Boolean {
        val requiredSize = value.toByteArray().size.toUInt()
        return requiredSize <= size
    }
    private fun sizeOk(value: BigInteger): Boolean = sizeOk(this.size, value)
}