basis.text.String2.scala Maven / Gradle / Ivy
/* ____ ___ *\
** / __ | ___ ____ /__/___ A library of building blocks **
** / __ / __ |/ ___|/ / ___| **
** / /_/ / /_/ /\__ \/ /\__ \ (c) 2012 Chris Sachs **
** |_____/\_____\____/__/\____/ http://basis.reify.it **
\* */
package basis.text
import basis.collections._
import basis.util._
/** A UTF-16 string.
*
* @define collection string
*/
final class String2(codeUnits: Array[Char]) extends UTF16 {
override def size: Int = codeUnits.length
override def get(index: Int): Int = codeUnits(index)
}
/** A factory for [[String2 UTF-16 strings]]. */
object String2 {
val empty: String2 = new String2(new Array[Char](0))
def apply(chars: CharSequence): String2 = {
val s = new String2Builder
s.append(chars)
s.state
}
implicit def Builder: StringBuilder[Any] { type State = String2 } = new String2Builder
}
/** A builder for 16-bit Unicode strings in the UTF-16 encoding form.
* Produces only well-formed code unit sequences. */
private[text] final class String2Builder extends StringBuilder[Any] {
override type State = String2
private[this] var codeUnits: Array[Char] = _
private[this] var aliased: Boolean = true
private[this] var size: Int = 0
private[this] def expand(base: Int, size: Int): Int = {
var n = (base max size) - 1
n |= n >> 1; n |= n >> 2; n |= n >> 4; n |= n >> 8; n |= n >> 16
n + 1
}
private[this] def resize(size: Int) {
val newCodeUnits = new Array[Char](size)
if (codeUnits != null) java.lang.System.arraycopy(codeUnits, 0, newCodeUnits, 0, codeUnits.length min size)
codeUnits = newCodeUnits
}
private[this] def prepare(size: Int) {
if (aliased || size > codeUnits.length) {
resize(expand(16, size))
aliased = false
}
}
override def append(c: Int) {
val n = size
if ((c >= 0x0000 && c <= 0xD7FF) ||
(c >= 0xE000 && c <= 0xFFFF)) { // U+0000..U+D7FF | U+E000..U+FFFF
prepare(n + 1)
codeUnits(n) = c.toChar
size = n + 1
}
else if (c >= 0x10000 && c <= 0x10FFFF) { // U+10000..U+10FFFF
prepare(n + 2)
val u = c - 0x10000
codeUnits(n) = (0xD800 | (u >>> 10)).toChar
codeUnits(n + 1) = (0xDC00 | (u & 0x3FF)).toChar
size = n + 2
}
else { // invalid code point
prepare(n + 1)
codeUnits(n) = 0xFFFD.toChar
size = n + 1
}
}
override def expect(count: Int): this.type = {
if (codeUnits == null || size + count > codeUnits.length) {
resize(size + count)
aliased = false
}
this
}
override def state: String2 = {
if (codeUnits == null || size != codeUnits.length) resize(size)
aliased = true
new String2(codeUnits)
}
override def clear() {
codeUnits = null
aliased = true
size = 0
}
}