External Lab - Mauricio Molina

project/plugins.sbt

@@ -0,0 +1 @@
+addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.5.0")

src/main/scala/calculator/ir/AST.scala

@@ -18,3 +18,6 @@ sealed abstract class Expr extends AST
 
 case class Num(n: Int) extends Expr
 case class Plus(left: Expr, right: Expr) extends Expr
+case class Minus(left: Expr, right: Expr) extends Expr
+case class Mult(left: Expr, right: Expr) extends Expr
+case class Div(left: Expr, right: Expr) extends Expr

src/main/scala/calculator/ir/sugar.scala

@@ -16,5 +16,8 @@ package object ir {
   //   take the right operand and returns the appropriate Expr 
   implicit class ExprBuilder(val left: Expr) {
     def |+|(right: Expr) = Plus(left, right)
+    def |-| (right: Expr) = Minus(left, right)
+    def |*| (right: Expr) = Mult(left, right)
+    def |/| (right: Expr) = Div(left, right)
   }
 }

src/main/scala/calculator/parser/Parser.scala

@@ -11,8 +11,13 @@ object CalcParser extends JavaTokenParsers with PackratParsers {
     // expressions
     lazy val expr: PackratParser[Expr] = 
       (   expr~"+"~fact ^^ {case l~"+"~r ⇒ l |+| r}
+        | expr~"-"~fact ^^ {case l~"-"~r ⇒ l |-| r}
+        | expr~"*"~fact ^^ {case l~"*"~r ⇒ l |*| r}
+        | expr~"/"~fact ^^ {case l~"/"~r ⇒ l |/| r}
         | fact )
 
+
+
     // factors
     lazy val fact: PackratParser[Expr] =
       number

src/main/scala/calculator/semantics/Interpreter.scala

@@ -6,5 +6,8 @@ package object semantics {
   def eval(ast: AST): Int = ast match {
     case Num(i) ⇒ i
     case Plus(left, right) ⇒ eval(left) + eval(right)
+    case Minus(left, right) ⇒ eval(left) - eval(right)
+    case Mult(left, right) ⇒ eval(left) * eval(right)
+    case Div(left, right) ⇒ eval(left) / eval(right)
   }
 }

src/test/scala/calculator/parser/ParserTest.scala

@@ -42,5 +42,41 @@ class CalcParserTests extends FunSpec with LangParseMatchers[AST] {
       program("1 + 2 + 100") should parseAs ( (1 |+| 2) |+| 100 )
     }
 
+  }
+
+    describe("Subtraction") {
+
+    it("can subtract two numbers") {
+      program("1-1") should parseAs ( 1 |-| 1 )
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("1 - 2 - 100") should parseAs ( (1 |-| 2) |-| 100 )
+    }
+
+  }
+
+      describe("Multiplication") {
+
+    it("can multiply two numbers") {
+      program("1*1") should parseAs ( 1 |*| 1 )
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("1 * 2 * 100") should parseAs ( (1 |*| 2) |*| 100 )
+    }
+
+  }
+
+    describe("Division") {
+
+    it("can add divide numbers") {
+      program("1/1") should parseAs ( 1 |/| 1 )
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("1 / 2 / 100") should parseAs ( (1 |/| 2) |/| 100 )
+    }
+
   }
 }

src/test/scala/calculator/semantics/SemanticsTest.scala

@@ -39,5 +39,50 @@ class NumSemanticsTests extends FunSpec
     }
 
   }
+  describe("Subtraction") {
 
+    it("can subtract two numbers") {
+      program("1-1") should compute (0)
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("100 - 2 - 1") should compute (97)
+    }
+
+    it("can handle negative numbers") {
+      program("1 - -1") should compute (2)
+    }
+
+  }
+
+    describe("Multiplication") {
+
+    it("can add multiply numbers") {
+      program("3*5") should compute (15)
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("1 * 3 * 150") should compute (450)
+    }
+
+    it("can handle negative numbers") {
+      program("6 * -1") should compute (-6)
+    }
+
+  }
+      describe("Division") {
+
+    it("can add divide numbers") {
+      program("100/10") should compute (10)
+    }
+
+    it("can be chained (and is left-associative)") {
+      program("100/10/2") should compute (5)
+    }
+
+    it("can handle negative numbers") {
+      program("60/-5") should compute (-12)
+    }
+
+  }
 }