packrat parsing

1 files changed, 58 insertions, 0 deletions

diff --git a/test/files/run/packrat2.scala b/test/files/run/packrat2.scala
new file mode 100644
index 0000000000..3361552561
--- /dev/null
+++ b/test/files/run/packrat2.scala
@@ -0,0 +1,58 @@
+import scala.util.parsing.combinator._
+
+import scala.util.parsing.combinator.syntactical.StandardTokenParsers
+import scala.util.parsing.input._
+import scala.util.parsing.syntax._
+
+import scala.collection.mutable.HashMap
+
+object Test extends Application{
+  import grammars2._
+
+  val head = phrase(exp)
+
+  println(extractResult(head(new lexical.Scanner("1"))))
+  println(extractResult(head(new lexical.Scanner("1+2"))))
+  println(extractResult(head(new lexical.Scanner("9*9"))))
+  println(extractResult(head(new lexical.Scanner("4*9+7"))))
+  println(extractResult(head(new lexical.Scanner("4*9+7*2+3*3"))))
+  println(extractResult(head(new lexical.Scanner("4*9+7*2+3*3+9*5+7*6*2"))))
+  println(extractResult(head(new lexical.Scanner("4*(9+7)*(2+3)*3"))))
+
+}
+
+object grammars2 extends StandardTokenParsers with PackratParsers{
+
+  def extractResult(r : ParseResult[_]) = r match{
+    case Success(a,_) => a
+    case Failure(a,_) => a
+    case Error(a,_) => a
+  }
+
+  lexical.delimiters ++= List("+","-","*","/","(",")")
+  lexical.reserved ++= List("Hello","World")
+
+  /*
+   * exp = sum | prod | num
+   * sum = exp ~ "+" ~ num
+   * prod = exp ~ "*" ~ num
+   */
+
+  val exp : PackratParser[Int] = sum | prod | numericLit ^^{_.toInt} | "("~>exp<~")"
+  val sum : PackratParser[Int] = exp~("+"~>exp) ^^ {case x~y => x+y}
+  val prod: PackratParser[Int] = exp~("*"~>(numericLit ^^{_.toInt} | exp)) ^^ {case x~y => x*y}
+
+
+ /* lexical.reserved ++= List("a","b", "c")
+  val a : PackratParser[Any] = numericLit^^{x => primeFactors(x.toInt)}
+  val b : PackratParser[Any] = memo("b")
+  val c : PackratParser[Any] = memo("c")
+  val AnBnCn : PackratParser[Any] =
+    parseButDontEat(repMany1(a,b))~not(b)~>rep1(a)~repMany1(b,c)// ^^{case x~y => x:::y}
+  //val c : PackratParser[Any] = parseButDontEat(a)~a~a
+  //println(c((new PackratReader(new lexical.Scanner("45 24")))))
+  val r = new PackratReader(new lexical.Scanner("45 b c"))
+  println(AnBnCn(r))
+  println(r.getCache.size)
+*/
+}
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