icejoywoo · June 25, 2019 06:14 · Jun 25, 2019 · Jun 25, 2019 · Jun 25, 2019 · Jun 13, 2019
diff --git a/EvalDemo.scala b/EvalDemo.scala
@@ -0,0 +1,14 @@
+import com.twitter.util.Eval
+
+object EvalDemo {
+  def main(args: Array[String]): Unit = {
+    val eval = new Eval
+    eval.compile(
+      """
+        |object Env {
+        |    val a = 5
+        |}
+      """.stripMargin)
+    println(eval.inPlace[Int]("import Env._; a"))
+  }
+}
diff --git a/calculator.scala b/calculator.scala
@@ -25,7 +25,7 @@ class Arith extends JavaTokenParsers {
       case "+"~v => v.toDouble
     }, { i => s"unexpected error [$i]" })
   | ident                                ^? ({ case i if env.contains(i) => env(i) }, { i => s"$i is not found in context"})
-  | ("-" | "+")~identifier               ^? ({
+  | ("-" | "+")~ident                    ^? ({
       case "-"~v if env.contains(v) => -env(v)
       case "+"~v if env.contains(v) => env(v)
     }, { case _~i => s"$i is not found in context" })

diff --git a/calculator.scala b/calculator.scala
@@ -4,8 +4,6 @@ import scala.util.parsing.combinator._
 class Arith extends JavaTokenParsers {
   var env: mutable.Map[String, Double] = mutable.Map.empty
 
-  def identifier: Parser[String] = """[a-zA-Z_]+""".r
-
   def expr: Parser[Double] = term~rep("+"~term | "-"~term) ^^ {
     case term~ops =>
       ops.foldLeft(term) {
@@ -26,14 +24,12 @@ class Arith extends JavaTokenParsers {
       case "-"~v => -v.toDouble
       case "+"~v => v.toDouble
     }, { i => s"unexpected error [$i]" })
-  | identifier                           ^? ({ case i if env.contains(i) => env(i) }, { i => s"$i is not found in context"})
+  | ident                                ^? ({ case i if env.contains(i) => env(i) }, { i => s"$i is not found in context"})
   | ("-" | "+")~identifier               ^? ({
       case "-"~v if env.contains(v) => -env(v)
       case "+"~v if env.contains(v) => env(v)
     }, { case _~i => s"$i is not found in context" })
-  | "("~expr~")"        ^? ({
-      case "("~v~")" => v
-    }, { i => s"unexpected error [$i]"})
+  | "(" ~> expr <~ ")"
   )
 }
 

diff --git a/calculator.scala b/calculator.scala
@@ -22,16 +22,15 @@ class Arith extends JavaTokenParsers {
   }
   def factor: Parser[Double] = (
     floatingPointNumber                  ^^ { _.toDouble }
-  | ("-" | "+")~floatingPointNumber      ^^ {
+  | ("-" | "+")~floatingPointNumber      ^? ({
       case "-"~v => -v.toDouble
       case "+"~v => v.toDouble
-      case _     => sys.error("unexpected error")
-    }
+    }, { i => s"unexpected error [$i]" })
   | identifier                           ^? ({ case i if env.contains(i) => env(i) }, { i => s"$i is not found in context"})
   | ("-" | "+")~identifier               ^? ({
       case "-"~v if env.contains(v) => -env(v)
       case "+"~v if env.contains(v) => env(v)
-    }, { i => s"$i is not found in context"})
+    }, { case _~i => s"$i is not found in context" })
   | "("~expr~")"        ^? ({
       case "("~v~")" => v
     }, { i => s"unexpected error [$i]"})

diff --git a/calculator.scala b/calculator.scala
@@ -31,7 +31,7 @@ class Arith extends JavaTokenParsers {
   | ("-" | "+")~identifier               ^? ({
       case "-"~v if env.contains(v) => -env(v)
       case "+"~v if env.contains(v) => env(v)
-    }, { i => s"unexpected error [$i]"})
+    }, { i => s"$i is not found in context"})
   | "("~expr~")"        ^? ({
       case "("~v~")" => v
     }, { i => s"unexpected error [$i]"})

diff --git a/calculator.scala b/calculator.scala
@@ -27,16 +27,14 @@ class Arith extends JavaTokenParsers {
       case "+"~v => v.toDouble
       case _     => sys.error("unexpected error")
     }
-  | identifier                           ^^ { env(_) }
-  | ("-" | "+")~identifier               ^^ {
-      case "-"~v => -env(v)
-      case "+"~v => env(v)
-      case _     => sys.error("unexpected error")
-    }
-  | "("~expr~")"        ^^ {
+  | identifier                           ^? ({ case i if env.contains(i) => env(i) }, { i => s"$i is not found in context"})
+  | ("-" | "+")~identifier               ^? ({
+      case "-"~v if env.contains(v) => -env(v)
+      case "+"~v if env.contains(v) => env(v)
+    }, { i => s"unexpected error [$i]"})
+  | "("~expr~")"        ^? ({
       case "("~v~")" => v
-      case _         => sys.error("unexpected error")
-    }
+    }, { i => s"unexpected error [$i]"})
   )
 }
 

diff --git a/calculator.scala b/calculator.scala
@@ -0,0 +1,92 @@
+import scala.collection.mutable
+import scala.util.parsing.combinator._
+
+class Arith extends JavaTokenParsers {
+  var env: mutable.Map[String, Double] = mutable.Map.empty
+
+  def identifier: Parser[String] = """[a-zA-Z_]+""".r
+
+  def expr: Parser[Double] = term~rep("+"~term | "-"~term) ^^ {
+    case term~ops =>
+      ops.foldLeft(term) {
+        case (a, "+"~b) => a + b
+        case (a, "-"~b) => a - b
+      }
+  }
+  def term: Parser[Double] = factor~rep("*"~factor | "/"~factor) ^^ {
+    case factor~ops =>
+      ops.foldLeft(factor) {
+        case (a, "*"~b) => a * b
+        case (a, "/"~b) => a / b
+      }
+  }
+  def factor: Parser[Double] = (
+    floatingPointNumber                  ^^ { _.toDouble }
+  | ("-" | "+")~floatingPointNumber      ^^ {
+      case "-"~v => -v.toDouble
+      case "+"~v => v.toDouble
+      case _     => sys.error("unexpected error")
+    }
+  | identifier                           ^^ { env(_) }
+  | ("-" | "+")~identifier               ^^ {
+      case "-"~v => -env(v)
+      case "+"~v => env(v)
+      case _     => sys.error("unexpected error")
+    }
+  | "("~expr~")"        ^^ {
+      case "("~v~")" => v
+      case _         => sys.error("unexpected error")
+    }
+  )
+}
+
+object TestArith extends Arith {
+  def main(args: Array[String]): Unit = {
+    env += "a" -> 5
+    env += "b" -> 6
+    env += "c" -> 7
+
+    assert(parseAll(expr, "2 * (3 + 7) * a + (b + c) * c").get == 191.0)
+    assert(parseAll(expr, "2 * (3 + 7) * (a + (b + c) * c)").get == 1920.0)
+    assert(parseAll(expr, "a + 4").get == 9.0)
+    assert(parseAll(expr, "((a) + (4))").get == 9.0)
+    assert(parseAll(expr, "a / 20 + 10 + a * b + c * 10").get == 110.25)
+    assert(parseAll(expr, "+5").get == 5.0)
+    assert(parseAll(expr, "-a").get == -5.0)
+
+    parseAll(expr, "2 * (3 + 7)") match {
+      case Success(matched,_) => println(matched)
+      case Failure(msg,_) => println("FAILURE: " + msg)
+      case Error(msg,_) => println("ERROR: " + msg)
+    }
+
+    parseAll(expr, "2 * (3 + 7))") match {
+      case Success(matched,_) => println(matched)
+      case Failure(msg,_) => println("FAILURE: " + msg)
+      case Error(msg,_) => println("ERROR: " + msg)
+    }
+
+    assert(!parseAll(expr, "2 * (3 + 7))").successful)
+    assert(!parseAll(expr, "(2 * (3 + 7)").successful)
+  }
+}
+
+object TestArith2 {
+  def main(args: Array[String]): Unit = {
+    val a = new Arith
+    a.env ++= Map(
+      "a" -> 5,
+      "b" -> 6,
+      "c" -> 7
+    )
+
+    assert(a.parseAll(a.expr, "2 * (3 + 7) * a + (b + c) * c").get == 191.0)
+    assert(a.parseAll(a.expr, "2 * (3 + 7) * (a + (b + c) * c)").get == 1920.0)
+    assert(a.parseAll(a.expr, "a + 4").get == 9.0)
+    assert(a.parseAll(a.expr, "((a) + (4))").get == 9.0)
+    assert(a.parseAll(a.expr, "a / 20 + 10 + a * b + c * 10").get == 110.25)
+
+    assert(!a.parseAll(a.expr, "2 * (3 + 7))").successful)
+    assert(!a.parseAll(a.expr, "(2 * (3 + 7)").successful)
+  }
+}