[6.0.0] Conversion from Long-encoded nBits representation to BigInt and back

data/shared/src/main/scala/sigma/ast/methods.scala

@@ -2,7 +2,7 @@ package sigma.ast
 
 import org.ergoplatform._
 import org.ergoplatform.validation._
-import sigma._
+import sigma.{VersionContext, _}
 import sigma.ast.SCollection.{SBooleanArray, SBoxArray, SByteArray, SByteArray2, SHeaderArray}
 import sigma.ast.SMethod.{MethodCallIrBuilder, MethodCostFunc, javaMethodOf}
 import sigma.ast.SType.TypeCode
@@ -53,7 +53,7 @@ sealed trait MethodsContainer {
   protected def getMethods(): Seq[SMethod] = Nil
 
   /** Returns all the methods of this type. */
-  lazy val methods: Seq[SMethod] = {
+  def methods: Seq[SMethod] = {                        //todo: consider versioned caching
     val ms = getMethods().toArray
     assert(ms.map(_.name).distinct.length == ms.length, s"Duplicate method names in $this")
     ms.groupBy(_.objType).foreach { case (comp, ms) =>
@@ -303,6 +303,18 @@ case object SIntMethods extends SNumericTypeMethods {
 case object SLongMethods extends SNumericTypeMethods {
   /** Type for which this container defines methods. */
   override def ownerType: SMonoType = SLong
+
+  lazy val DecodeNBitsMethod: SMethod = SMethod(
+    this, "DecodeNBits", SFunc(this.ownerType, SBigInt), 8, FixedCost(JitCost(5)))
+    .withInfo(PropertyCall, "Consider this Long value as nbits-encoded BigInt value and decode it to BigInt")
+
+  protected override def getMethods(): Seq[SMethod] = {
+    if (VersionContext.current.isV6SoftForkActivated) {
+      super.getMethods() ++ Seq(DecodeNBitsMethod)
+    } else {
+      super.getMethods()
+    }
+  }
 }
 
 /** Methods of BigInt type. Implemented using [[java.math.BigInteger]]. */