1 files changed, 70 insertions, 0 deletions
diff --git a/docs/examples/parsing/ArithmeticParsers.scala b/docs/examples/parsing/ArithmeticParsers.scala
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+++ b/docs/examples/parsing/ArithmeticParsers.scala
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+package examples.parsing
+
+import scala.util.parsing.combinator1.syntactical.StandardTokenParsers
+
+object ArithmeticParsers extends StandardTokenParsers {
+  lexical.delimiters ++= List("(", ")", "+", "-", "*", "/")
+
+  def expr: Parser[Any] = term ~ rep("+" ~ term | "-" ~ term)
+  def term = factor ~ rep("*" ~ factor | "/" ~ factor)
+  def factor: Parser[Any] = "(" ~ expr ~ ")" | numericLit
+
+  def main(args: Array[String]) {
+    val tokens = new lexical.Scanner(args(0))
+    println(args(0))
+    println(phrase(expr)(tokens))
+  }
+}
+
+object ArithmeticParsers1 extends StandardTokenParsers {
+  lexical.delimiters ++= List("(", ")", "+", "-", "*", "/")
+
+  val reduceList: Int ~ List[String ~ Int] => Int = {
+    case i ~ ps => (i /: ps)(reduce)
+  }
+
+  def reduce(x: Int, r: String ~ Int) = (r: @unchecked) match {
+    case "+" ~ y => x + y
+    case "-" ~ y => x - y
+    case "*" ~ y => x * y
+    case "/" ~ y => x / y
+  }
+
+  def expr  : Parser[Int] = term ~ rep ("+" ~ term | "-" ~ term) ^^ reduceList
+  def term  : Parser[Int] = factor ~ rep ("*" ~ factor | "/" ~ factor) ^^ reduceList
+  def factor: Parser[Int] = "(" ~> expr <~ ")" | numericLit ^^ (_.toInt)
+
+  def main(args: Array[String]) {
+    val tokens = new lexical.Scanner(args(0))
+    println(args(0))
+    println(phrase(expr)(tokens))
+  }
+}
+
+class Expr
+case class BinOp(op: String, l: Expr, r: Expr) extends Expr
+case class Num(n: Int) extends Expr
+
+object ArithmeticParsers2 extends StandardTokenParsers {
+  lexical.delimiters ++= List("(", ")", "+", "-", "*", "/")
+
+  val reduceList: Expr ~ List[String ~ Expr] => Expr = {
+    case i ~ ps => (i /: ps)(reduce)
+  }
+
+  def reduce(l: Expr, r: String ~ Expr) = BinOp(r._1, l, r._2)
+  def mkNum(s: String) = Num(s.toInt)
+
+  def expr  : Parser[Expr] = term ~ rep ("+" ~ term | "-" ~ term) ^^ reduceList
+  def term  : Parser[Expr] = factor ~ rep ("*" ~ factor | "/" ~ factor) ^^ reduceList
+  def factor: Parser[Expr] = "(" ~> expr <~ ")" | numericLit ^^ ((s: String) => Num(s.toInt))
+
+  def main(args: Array[String]) {
+    val parse = phrase(expr)
+    val tokens = new lexical.Scanner(args(0))
+    println(args(0))
+    println(parse(tokens))
+  }
+}
+
+