updated examples to new combinator library

1 files changed, 33 insertions, 0 deletions

diff --git a/docs/examples/parsing/ListParser.scala b/docs/examples/parsing/ListParser.scala
new file mode 100644
index 0000000000..65354482f3
--- /dev/null
+++ b/docs/examples/parsing/ListParser.scala
@@ -0,0 +1,33 @@
+package examples.parsing
+
+import scala.util.parsing.combinator.{Parsers, ImplicitConversions, ~, mkTilde}
+import scala.util.parsing.input.CharArrayReader
+
+object listParser {
+  abstract class Tree
+  case class Id(s: String)          extends Tree
+  case class Num(n: Int)            extends Tree
+  case class Lst(elems: List[Tree]) extends Tree
+
+  import Character.{isLetter, isLetterOrDigit, isDigit}
+  def mkString(cs: List[Any]) = cs.mkString("")
+
+  class ListParsers extends Parsers {
+    type Elem = Char
+
+    lazy val ident = rep1(elem("letter", isLetter), elem("letter or digit", isLetterOrDigit)) ^^ {cs => Id(mkString(cs))}
+    lazy val number = chainl1(elem("digit", isDigit) ^^ (_ - '0'), success ^^ {(accum: Int, d: Int) => accum * 10 + d}) ^^ Num
+    lazy val list = '(' ~ repsep(expr, ',') ~ ')' ^^ Lst
+    lazy val expr: Parser[Tree] = list | ident | number
+  }
+
+  def main(args: Array[String]) {
+    println(
+      if (args.length == 1) {
+        (new ListParsers).expr(new CharArrayReader(args(0).toCharArray()))
+      }
+      else
+        "usage: scala examples.parsing.listParser <list-string>"
+    )
+  }
+}