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/* NSC -- new Scala compiler
* Copyright 2006-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala
package reflect
package internal
import scala.annotation.{ tailrec, switch }
import java.lang.{ Character => JCharacter }
import scala.language.postfixOps
/** Contains constants and classifier methods for characters */
trait Chars {
// Be very careful touching these.
// Apparently trivial changes to the way you write these constants
// will cause Scanners.scala to go from a nice efficient switch to
// a ghastly nested if statement which will bring the type checker
// to its knees. See ticket #1456
// Martin: (this should be verified now that the pattern rules have been redesigned).
final val LF = '\u000A'
final val FF = '\u000C'
final val CR = '\u000D'
final val SU = '\u001A'
/** Convert a character digit to an Int according to given base,
* -1 if no success
*/
def digit2int(ch: Char, base: Int): Int = {
val num = (
if (ch <= '9') ch - '0'
else if ('a' <= ch && ch <= 'z') ch - 'a' + 10
else if ('A' <= ch && ch <= 'Z') ch - 'A' + 10
else -1
)
if (0 <= num && num < base) num else -1
}
/** Buffer for creating '\ u XXXX' strings. */
private[this] val char2uescapeArray = Array[Char]('\\', 'u', 0, 0, 0, 0)
/** Convert a character to a backslash-u escape */
def char2uescape(c: Char): String = {
@inline def hexChar(ch: Int): Char =
( if (ch < 10) '0' else 'A' - 10 ) + ch toChar
char2uescapeArray(2) = hexChar((c >> 12) )
char2uescapeArray(3) = hexChar((c >> 8) % 16)
char2uescapeArray(4) = hexChar((c >> 4) % 16)
char2uescapeArray(5) = hexChar((c ) % 16)
new String(char2uescapeArray)
}
/** Is character a line break? */
def isLineBreakChar(c: Char) = (c: @switch) match {
case LF|FF|CR|SU => true
case _ => false
}
/** Is character a whitespace character (but not a new line)? */
def isWhitespace(c: Char) =
c == ' ' || c == '\t' || c == CR
/** Can character form part of a doc comment variable $xxx? */
def isVarPart(c: Char) =
'0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'
/** Can character start an alphanumeric Scala identifier? */
def isIdentifierStart(c: Char): Boolean =
(c == '_') || (c == '$') || Character.isUnicodeIdentifierStart(c)
/** Can character form part of an alphanumeric Scala identifier? */
def isIdentifierPart(c: Char) =
(c == '$') || Character.isUnicodeIdentifierPart(c)
/** Is character a math or other symbol in Unicode? */
def isSpecial(c: Char) = {
val chtp = Character.getType(c)
chtp == Character.MATH_SYMBOL.toInt || chtp == Character.OTHER_SYMBOL.toInt
}
private final val otherLetters = Set[Char]('\u0024', '\u005F') // '$' and '_'
private final val letterGroups = {
import JCharacter._
Set[Byte](LOWERCASE_LETTER, UPPERCASE_LETTER, OTHER_LETTER, TITLECASE_LETTER, LETTER_NUMBER)
}
def isScalaLetter(ch: Char) = letterGroups(JCharacter.getType(ch).toByte) || otherLetters(ch)
/** Can character form part of a Scala operator name? */
def isOperatorPart(c : Char) : Boolean = (c: @switch) match {
case '~' | '!' | '@' | '#' | '%' |
'^' | '*' | '+' | '-' | '<' |
'>' | '?' | ':' | '=' | '&' |
'|' | '/' | '\\' => true
case c => isSpecial(c)
}
}
object Chars extends Chars { }
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