class Pos private val prog String val offs Int val line Int val col In

  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
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
class Pos private(val prog: String, val offs: Int, val line: Int, val col: Int) {
def this(prog: String) = this(prog, 0, 1, 1)
def ch = if (offs == prog.length) -1 else prog(offs)
def inc = ch match {
case '\n' => new Pos(prog, offs+1, line+1, 1)
case -1 => this
case _ => new Pos(prog, offs+1, line, col+1)
}
override def toString = "(" + line + ", " + col + ")"
}
object DomainTags extends Enumeration {
type Tag = Value
val STRLITER, NUMBER, IDENT, END_OF_PROGRAM = Value
}
import DomainTags._
class Scanner {
def scan(start: Pos): (Tag, Pos) =
sys.error("syntax error at " + start)
}
class Token(val start: Pos, scanner: Scanner) {
val (tag, follow) = start.ch match {
case -1 => (END_OF_PROGRAM, start)
case _ => scanner.scan(start)
}
def image = start.prog.substring(start.offs, follow.offs)
def next = new Token(follow, scanner)
}
trait StrLiters extends Scanner {
private def missStrLiter(pos: Pos): Pos = pos.ch match {
case '\'' => missStrLiterInside(pos.inc)
case _ => pos
}
private def missStrLiterInside(pos: Pos): Pos = pos.ch match {
case '\'' => meetApostrophe(pos.inc)
case _ => pos
}
private def meetApostrophe(pos: Pos): Pos = pos.ch match {
case '\'' => missStrLiterInside(pos.inc)
case _ => pos
}
override def scan(start: Pos) = {
val follow = missStrLiter(start)
if (start == follow) super.scan(start)
else (STRLITER, follow)
}
}
trait Numbers extends Scanner {
private def missNumber(pos: Pos): Pos = pos.ch match {
case '-' => missNumberMod(pos.inc)
case a if (a >= '0' && a <= '9') => missNumberMod(pos.inc)
case _ => pos
}
private def missNumberMod(pos: Pos): Pos = pos.ch match {
case a if (a >= '0' && a <= '9') => missNumberDot(pos.inc)
case _ => pos
}
private def missNumberDot(pos: Pos): Pos = pos.ch match {
case a if (a >= '0' && a <= '9') => missNumberDot(pos.inc)
case '.' => missNumberEnd(pos.inc)
case _ => pos
}
private def missNumberEnd(pos: Pos): Pos = pos.ch match {
case a if (a >= '0' && a <= '9') => missNumberEnd(pos.inc)
case _ => pos
}
override def scan(start: Pos) = {
val follow = missNumber(start)
if (start == follow) super.scan(start)
else (NUMBER, follow)
}
}
trait Idents extends Scanner {
private def missIdent(pos: Pos): Pos = pos.ch match {
case a if (a >= 'a' && a <= 'z') => missIdentInside(pos.inc)
case a if (a >= 'A' && a <= 'Z') => missIdentInside(pos.inc)
case _ => pos
}
private def missIdentInside(pos: Pos): Pos = pos.ch match {
case a if (a >= 'a' && a <= 'z') => missIdentInside(pos.inc)
case a if (a >= 'A' && a <= 'Z') => missIdentInside(pos.inc)
case a if (a >= '0' && a <= '9') => missIdentInside(pos.inc)
case '.' => missIdentInside(pos.inc)
case _ => pos
}
override def scan(start: Pos) = {
val follow = missIdent(start)
if (start == follow) super.scan(start)
else (IDENT, follow)
}
}
var t = new Token(
new Pos("-123.4\n 'alp''ha'"),
new Scanner with Numbers with StrLiters
)
while (t.tag != END_OF_PROGRAM) {
println(t.tag.toString + " " + t.start + "-" + t.follow + ": " + t.image)
t = t.next
}