blob: 15dc0ce9efbcd477834b5a9b87b6513a2ea64e44 (
plain) (
blame)
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
|
package examples
abstract class Parsers {
type inputType
trait Parser[a] {
type Result = Option[Pair[a, inputType]];
def apply(in: inputType): Result;
def filter(pred: a => boolean) = new Parser[a] {
def apply(in: inputType): Result = Parser.this.apply(in) match {
case None => None
case Some(Pair(x, in1)) => if (pred(x)) Some(Pair(x, in1)) else None
}
}
def map[b](f: a => b) = new Parser[b] {
def apply(in: inputType): Result = Parser.this.apply(in) match {
case None => None
case Some(Pair(x, in1)) => Some(Pair(f(x), in1))
}
}
def flatMap[b](f: a => Parser[b]) = new Parser[b] {
def apply(in: inputType): Result = Parser.this.apply(in) match {
case None => None
case Some(Pair(x, in1)) => f(x).apply(in1)
}
}
def ||| (p: => Parser[a]) = new Parser[a] {
def apply(in: inputType): Result = Parser.this.apply(in) match {
case None => p(in)
case s => s
}
}
def &&& [b](p: => Parser[b]): Parser[b] =
for (val _ <- this; val x <- p) yield x
}
def succeed[a](x: a) = new Parser[a] {
def apply(in: inputType): Result = Some(Pair(x, in))
}
def rep[a](p: Parser[a]): Parser[List[a]] =
rep1(p) ||| succeed(List())
def rep1[a](p: Parser[a]): Parser[List[a]] =
for (val x <- p; val xs <- rep(p)) yield x :: xs
def opt[a](p: Parser[a]): Parser[List[a]] =
(for (val x <- p) yield List(x)) ||| succeed(List())
}
class Tokenizer(in: Iterator[char], delimiters: String) extends Iterator[String] {
val EOI: char = 0;
def nextChar() =
if (in.hasNext) in.next else EOI;
private var ch = nextChar();
def isDelimiter(ch: Char) = {
var i = 0;
while (i < delimiters.length() && delimiters.charAt(i) != ch) { i = i + 1 }
i < delimiters.length()
}
def hasNext: boolean = ch != EOI
private val buf = new StringBuffer
def next: String = {
while (ch <= ' ' && ch != EOI) nextChar();
if (ch == EOI) ""
else {
if (isDelimiter(ch)) ch.toString()
else {
buf.setLength(0); buf append ch
while (ch > ' ' && ch != EOI && !isDelimiter(ch)) {
buf append ch; nextChar();
}
buf.toString()
}
}
}
}
trait TokenParsers extends Parsers {
type inputType = Stream[String]
def nextToken() = new Parser[String] {
def apply(in: inputType): Result =
if (in.isEmpty) None else Some(Pair(in.head, in.tail))
}
}
trait CharParsers extends Parsers {
def any: Parser[char]
def chr(ch: char) =
for (val c <- any; c == ch) yield c
def chr(p: char => boolean) =
for (val c <- any; p(c)) yield c
}
|
