Generate range downTos with templates DSL

libraries/tools/kotlin-stdlib-gen/src/generators/GenerateDownTos.kt

@@ -1,71 +0,0 @@
-package generators
-
-import java.io.File
-import java.io.FileWriter
-import java.io.PrintWriter
-
-private fun generateDownTos(outputFile: File, header: String) {
-
-    fun getMaxType(fromType: String, toType: String): String {
-        return when {
-            fromType == "Double" || toType == "Double" -> "Double"
-            fromType == "Float"  || toType == "Float"  -> "Float"
-            fromType == "Long"   || toType == "Long"   -> "Long"
-            fromType == "Int"    || toType == "Int"    -> "Int"
-            fromType == "Short"  || toType == "Short"  -> "Short"
-            fromType == "Char"   || toType == "Char"   -> "Char"
-            else -> "Byte"
-        }
-    }
-
-    fun generateDownTo(writer: PrintWriter, fromType: String, toType: String) {
-        val elementType = getMaxType(fromType, toType)
-        val progressionType = elementType + "Progression"
-
-        val fromExpr = if (elementType == fromType) "this" else "this.to$elementType()"
-        val toExpr = if (elementType == toType) "to" else "to.to$elementType()"
-        val incrementExpr = when (elementType) {
-            "Long" -> "-1.toLong()"
-            "Float" -> "-1.toFloat()"
-            "Double" -> "-1.0"
-            else -> "-1"
-        }
-
-        val deprecated =
-        if ((fromType == "Char") != (toType == "Char")) {
-            """deprecated("This operation doesn't make sense and shall be removed in M13. Consider converting Char operand to Int or other operand to Char.")"""
-        } else ""
-
-        writer.println("""
-/**
- * Returns a progression from this value down to the specified [to] value.
- *
- * The [to] value has to be less than this value.
- */
-$deprecated
-public fun $fromType.downTo(to: $toType): $progressionType {
-    return $progressionType($fromExpr, $toExpr, $incrementExpr)
-}""".replace("\n\n","\n"))
-    }
-
-    println("Writing $outputFile")
-
-    outputFile.getParentFile()?.mkdirs()
-    val writer = PrintWriter(FileWriter(outputFile))
-    try {
-        writer.println(header)
-
-        writer.println("""
-$COMMON_AUTOGENERATED_WARNING
-""")
-
-        val types = arrayOf("Byte", "Char", "Short", "Int", "Long", "Float", "Double")
-        for (fromType in types) {
-            for (toType in types) {
-                generateDownTo(writer, fromType, toType)
-            }
-        }
-    } finally {
-        writer.close()
-    }
-}

libraries/tools/kotlin-stdlib-gen/src/generators/GenerateStandardLib.kt

@@ -28,7 +28,6 @@ fun main(args: Array<String>) {
     generateCollectionsAPI(outDir)
     generateCollectionsJsAPI(jsCoreDir)
 
-    generateDownTos(File(outDir, "_DownTo.kt"), "package kotlin")
 }
 
 fun List<GenericFunction>.writeTo(file: File, builder: GenericFunction.() -> String) {

libraries/tools/kotlin-stdlib-gen/src/templates/Engine.kt

@@ -44,7 +44,13 @@ enum class PrimitiveType {
 
     companion object {
         val defaultPrimitives = PrimitiveType.values().toSet()
-        val numericPrimitives = setOf(PrimitiveType.Int, PrimitiveType.Long, PrimitiveType.Byte, PrimitiveType.Short, PrimitiveType.Double, PrimitiveType.Float)
+        val numericPrimitives = setOf(Int, Long, Byte, Short, Double, Float)
+
+        val descendingByDomainCapacity = listOf(Double, Float, Long, Int, Short, Char, Byte)
+
+        fun getMaxCapacityType(fromType: PrimitiveType, toType: PrimitiveType): PrimitiveType = descendingByDomainCapacity.first { it == fromType || it == toType }
+
+        val primitivePermutations = numericPrimitives.flatMap { fromType -> numericPrimitives map { toType -> fromType to toType } } + (Char to Char)
     }
 }
 

libraries/tools/kotlin-stdlib-gen/src/templates/Ranges.kt

@@ -46,5 +46,32 @@ fun ranges(): List<GenericFunction> {
         }
     }
 
+    fun downTo(fromType: PrimitiveType, toType: PrimitiveType) = f("downTo(to: $toType)") {
+        only(Primitives)
+        only(fromType)
+        val elementType = PrimitiveType.getMaxCapacityType(fromType, toType)
+        val progressionType = elementType.name + "Progression"
+        returns(progressionType)
+
+        doc {
+            """
+            Returns a progression from this value down to the specified [to] value with the increment -1.
+            The [to] value has to be less than this value.
+            """
+        }
+
+        val fromExpr = if (elementType == fromType) "this" else "this.to$elementType()"
+        val toExpr = if (elementType == toType) "to" else "to.to$elementType()"
+        val incrementExpr = when (elementType) {
+            PrimitiveType.Long -> "-1L"
+            PrimitiveType.Float -> "-1.0F"
+            PrimitiveType.Double -> "-1.0"
+            else -> "-1"
+        }
+        body { "return $progressionType($fromExpr, $toExpr, $incrementExpr)" }
+    }
+
+    templates addAll PrimitiveType.primitivePermutations.map { downTo(it.first, it.second) }
+
     return templates
-}
+}