Rudimentary support for string ranges

MoeOrganization · Feb 13, 2013 · c9fa8f4 · c9fa8f4
1 parent ee66b6b
commit c9fa8f4
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Showing 3 changed files with 61 additions and 7 deletions.
diff --git a/src/main/scala/org/moe/interpreter/Interpreter.scala b/src/main/scala/org/moe/interpreter/Interpreter.scala
@@ -137,11 +137,35 @@ object Interpreter {
       }
 
       case RangeLiteralNode(start, end) => {
-        val range_start  = Utils.objToInteger(eval(runtime, env, start))
-        val range_end    = Utils.objToInteger(eval(runtime, env, end))
-        val range: Range = new Range(range_start, range_end + 1, 1)
-        val array: List[MoeObject] = range.toList.map(runtime.NativeObjects.getInt(_))
-        runtime.NativeObjects.getArray(array)
+        val s = eval(runtime, env, start)
+        val e = eval(runtime, env, end)
+        (s, e) match {
+          case (s: MoeIntObject, e: MoeIntObject) => {
+            val range_start  = Utils.objToInteger(s)
+            val range_end    = Utils.objToInteger(e)
+            val range: Range = new Range(range_start, range_end + 1, 1)
+            val array: List[MoeObject] = range.toList.map(runtime.NativeObjects.getInt(_))
+            runtime.NativeObjects.getArray(array)
+          }
+          case (s: MoeStringObject, e: MoeStringObject) => {
+            val range_start = Utils.objToString(s)
+            val range_end   = Utils.objToString(e)
+
+            // return the successor of the string ("abc" => "abd")
+            def succ(str: String) = str.init + (str.last.toInt + 1).toChar
+
+            // this is totally non-functional, imperative style code,
+            // not in Scala spirit; but will do, for now
+            var elems: List[String] = List()
+            var str = range_start
+            while (str <= range_end) {
+              elems = elems :+ str
+              str = succ(str)
+            }
+            runtime.NativeObjects.getArray(elems.map(runtime.NativeObjects.getString(_)))
+          }
+          case _ => throw new MoeErrors.UnexpectedType("Pair of MoeIntObject or MoeStringObject expected")
+        }
       }
 
       // unary operators

diff --git a/src/test/scala/org/moe/interpreter/RangeLiteralNodeTestSuite.scala b/src/test/scala/org/moe/interpreter/RangeLiteralNodeTestSuite.scala
@@ -7,7 +7,7 @@ import org.scalatest.FunSuite
 
 class RangeLiteralNodeTestSuite extends FunSuite with InterpreterTestUtils {
 
-  test("... basic test with Range") {
+  test("... basic test with Integer Range") {
     val ast = wrapSimpleAST(
       List(
         RangeLiteralNode(
@@ -26,4 +26,23 @@ class RangeLiteralNodeTestSuite extends FunSuite with InterpreterTestUtils {
     assert(array(2).asInstanceOf[MoeIntObject].getNativeValue === 3)
   }
 
+  test("... basic test with String Range") {
+    val ast = wrapSimpleAST(
+      List(
+        RangeLiteralNode(
+          StringLiteralNode("a"),
+          StringLiteralNode("c")
+        )
+      )
+    )
+    val result = Interpreter.eval(runtime, runtime.getRootEnv, ast)
+
+    val array: List[MoeObject] = result.asInstanceOf[MoeArrayObject].getNativeValue
+
+    assert(array.size === 3)
+    assert(array(0).asInstanceOf[MoeStringObject].getNativeValue === "a")
+    assert(array(1).asInstanceOf[MoeStringObject].getNativeValue === "b")
+    assert(array(2).asInstanceOf[MoeStringObject].getNativeValue === "c")
+  }
+
 }
diff --git a/src/test/scala/org/moe/parser/RangeLiteralTestSuite.scala b/src/test/scala/org/moe/parser/RangeLiteralTestSuite.scala
@@ -10,7 +10,7 @@ import org.moe.parser._
 
 class RangeLiteralTestSuite extends FunSuite with BeforeAndAfter with ParserTestUtils {
 
-  test("... basic test with a simple range") {
+  test("... basic test with a simple integer range") {
     val result = interpretCode("1 .. 3")
 
     val array: List[MoeObject] = result.asInstanceOf[MoeArrayObject].getNativeValue
@@ -21,4 +21,15 @@ class RangeLiteralTestSuite extends FunSuite with BeforeAndAfter with ParserTest
     assert(array(2).asInstanceOf[MoeIntObject].getNativeValue === 3)
   }
 
+  test("... basic test with a simple string range") {
+    val result = interpretCode(""" "a" .. "c" """)
+
+    val array: List[MoeObject] = result.asInstanceOf[MoeArrayObject].getNativeValue
+
+    assert(array.size === 3)
+    assert(array(0).asInstanceOf[MoeStringObject].getNativeValue === "a")
+    assert(array(1).asInstanceOf[MoeStringObject].getNativeValue === "b")
+    assert(array(2).asInstanceOf[MoeStringObject].getNativeValue === "c")
+  }
+
 }