io.dahgan.stream.Streams.kt Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
Core Module
The newest version!
package io.dahgan.stream

import java.util.*

/**
 * Wraps the given byte arrays, detects its encoding and finally converts it to characters.
 */
class ByteStream(private val input: ByteArray, private val offset: Int = 0) : Stream {
    companion object {
        private val X00 = 0x00.toByte()
        private val XFE = 0xFE.toByte()
        private val XFF = 0xFF.toByte()
        private val XEF = 0xEF.toByte()
        private val XBB = 0xBB.toByte()
        private val XBF = 0xBF.toByte()

        private val decoders = mapOf(
                Encoding.UTF8 to UTF8Decoder(),
                Encoding.UTF16LE to UTF16Decoder.le(),
                Encoding.UTF16BE to UTF16Decoder.be(),
                Encoding.UTF32LE to UTF32Decoder.le(),
                Encoding.UTF32BE to UTF32Decoder.be()
        )
    }

    private val encoding: Encoding by lazy {
        when {
            input.size >= 4 && input[0] == X00 && input[1] == X00 && input[2] == XFE && input[3] == XFF -> Encoding.UTF32BE
            input.size >= 4 && input[0] == X00 && input[1] == X00 && input[2] == X00 -> Encoding.UTF32BE
            input.size >= 4 && input[0] == XFF && input[1] == XFE && input[2] == X00 && input[3] == X00 -> Encoding.UTF32LE
            input.size >= 4 && input[1] == X00 && input[2] == X00 && input[3] == X00 -> Encoding.UTF32LE
            input.size >= 2 && input[0] == XFE && input[1] == XFF -> Encoding.UTF16BE
            input.size >= 1 && input[0] == X00 -> Encoding.UTF16BE
            input.size >= 2 && input[0] == XFF && input[1] == XFE -> Encoding.UTF16LE
            input.size >= 2 && input[1] == X00 -> Encoding.UTF16LE
            input.size >= 4 && input[0] == XEF && input[1] == XBB && input[2] == XBF -> Encoding.UTF8
            else -> Encoding.UTF8
        }
    }

    private val head: UniChar by lazy {
        decoders[encoding]!!.decode(input, offset)
    }

    /**
     * @see Stream#encoding()
     */
    override fun encoding(): Encoding = encoding

    /**
     * @see Stream#head()
     */
    override fun head(): UniChar = head

    /**
     * @see Stream#tail()
     */
    override fun tail(): ByteStream = ByteStream(this.input, head.offset)

    /**
     * @see Stream#isEmpty()
     */
    override fun isEmpty(): Boolean = input.size <= offset

    /**
     * @see Stream#isNotEmpty()
     */
    override fun isNotEmpty(): Boolean = !isEmpty()

    /**
     * @see Stream#push(head)
     */
    override fun push(head: UniChar): Stream = PushedStream(head, this)

    /**
     * @see Stream#codes()
     */
    override fun codes(): IntArray {
        val destination = ArrayList()

        var current = this
        while (current.isNotEmpty()) {
            destination.add(current.head.code)
            current = current.tail()
        }

        return destination.toIntArray()
    }
}

/**
 * A PushedStream adds the given decoded character as head to the given Stream.
 */
class PushedStream(private val head: UniChar, private val tail: Stream) : Stream {
    /**
     * @see Stream#encoding()
     */
    override fun encoding(): Encoding = tail.encoding()

    /**
     * @see Stream#head()
     */
    override fun head(): UniChar = head

    /**
     * @see Stream#tail()
     */
    override fun tail(): Stream = tail

    /**
     * @see Stream#isEmpty()
     */
    override fun isEmpty(): Boolean = false

    /**
     * @see Stream#isNotEmpty()
     */
    override fun isNotEmpty(): Boolean = true

    /**
     * @see Stream#push(head)
     */
    override fun push(head: UniChar): Stream = PushedStream(head, this)

    /**
     * @see Stream#codes()
     */
    override fun codes(): IntArray = intArrayOf(head.code, *tail.codes())
}