Add flag isUsingBlockchainContext to ErgoTree

core/shared/src/main/scala/sigma/serialization/CoreByteReader.scala

@@ -157,4 +157,12 @@ class CoreByteReader(val r: Reader, val maxTreeDepth: Int = CoreSerializer.MaxTr
   @inline final def wasDeserialize_=(v: Boolean): Unit = {
     _wasDeserialize = v
   }
+
+  private var _wasUsingBlockchainContext: Boolean = false
+  /** Helper property which is used to track operations using the blockchain context during parsing. */
+  @inline final def wasUsingBlockchainContext: Boolean = _wasUsingBlockchainContext
+
+  @inline final def wasUsingBlockchainContext_=(v: Boolean): Unit = {
+    _wasUsingBlockchainContext = v
+  }
 }

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

@@ -90,7 +90,8 @@ case class ErgoTree private[sigma](
     root: Either[UnparsedErgoTree, SigmaPropValue],
     private val givenComplexity: Int,
     private val propositionBytes: Array[Byte],
-    private val givenDeserialize: Option[Boolean]
+    private val givenDeserialize: Option[Boolean],
+    private val givenIsUsingBlockchainContext: Option[Boolean]
 ) {
   def this(
       header: HeaderType,
@@ -99,9 +100,10 @@ case class ErgoTree private[sigma](
     this(
       header, constants, root, 0,
       propositionBytes = DefaultSerializer.serializeErgoTree(
-        ErgoTree(header, constants, root, 0, null, None)
+        ErgoTree(header, constants, root, 0, null, None, None)
       ),
-      givenDeserialize = None
+      givenDeserialize = None,
+      givenIsUsingBlockchainContext = None
     )
 
   require(isConstantSegregation || constants.isEmpty)
@@ -163,6 +165,20 @@ case class ErgoTree private[sigma](
     _hasDeserialize.get
   }
 
+  private[sigma] var _isUsingBlockchainContext: Option[Boolean] = givenIsUsingBlockchainContext
+
+  /** Returns true if the tree depends on the blockchain context.
+   */
+  lazy val isUsingBlockchainContext: Boolean = {
+    if (_isUsingBlockchainContext.isEmpty) {
+      _isUsingBlockchainContext = Some(root match {
+        case Right(p) => Value.isUsingBlockchainContext(p)
+        case _ => false
+      })
+    }
+    _isUsingBlockchainContext.get
+  }
+
   /** Serialized proposition expression of SigmaProp type with
     * ConstantPlaceholder nodes not replaced by Constant nodes.
     */

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

@@ -1408,6 +1408,13 @@ case object SContextMethods extends MonoTypeMethods {
     dataInputsMethod, headersMethod, preHeaderMethod, inputsMethod, outputsMethod, heightMethod, selfMethod,
     selfBoxIndexMethod, lastBlockUtxoRootHashMethod, minerPubKeyMethod, getVarMethod
   )
+
+  /** Names of methods which provide blockchain context.
+   * This value can be reused where necessary to avoid allocations. */
+  val BlockchainContextMethodNames: IndexedSeq[String] = Array(
+    headersMethod.name, preHeaderMethod.name, heightMethod.name,
+    lastBlockUtxoRootHashMethod.name, minerPubKeyMethod.name
+  )
 }
 
 /** Type descriptor of `Header` type of ErgoTree. */

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

@@ -210,6 +210,25 @@ object Value {
     c > 0
   }
 
+  /** Traverses the given expression tree and counts the number of operations
+   * which read the blockchain context. If it is non-zero, returns true. */
+  def isUsingBlockchainContext(exp: SValue): Boolean = {
+    val blockchainContextNode: PartialFunction[Any, Int] = {
+      case Height => 1
+      case LastBlockUtxoRootHash => 1
+      case MinerPubkey => 1
+      case MethodCall(_, method, _, _) =>
+        method.objType match {
+          case SContextMethods =>
+            if (SContextMethods.BlockchainContextMethodNames.contains(method.name)) 1 else 0
+          case _ => 0
+        }
+      case _ => 0
+    }
+    val c = count(blockchainContextNode)(exp)
+    c > 0
+  }
+
   def typeError(node: SValue, evalResult: Any) = {
     val tpe = node.tpe
     throw new InterpreterException(

data/shared/src/main/scala/sigma/serialization/CaseObjectSerialization.scala

@@ -1,12 +1,20 @@
 package sigma.serialization
 
-import sigma.ast.SType
-import sigma.ast.{Value, ValueCompanion}
+import sigma.ast.{Height, LastBlockUtxoRootHash, MinerPubkey, SType, Value, ValueCompanion}
 
 case class CaseObjectSerialization[V <: Value[SType]](override val opDesc: ValueCompanion, obj: V)
   extends ValueSerializer[V] {
 
   override def serialize(obj: V, w: SigmaByteWriter): Unit = ()
 
-  override def parse(r: SigmaByteReader): V = obj
+  override def parse(r: SigmaByteReader): V = {
+    opDesc match {
+      case Height => r.wasUsingBlockchainContext = true
+      case LastBlockUtxoRootHash => r.wasUsingBlockchainContext = true
+      case MinerPubkey => r.wasUsingBlockchainContext = true
+      case _ =>
+    }
+
+    obj
+  }
 }

data/shared/src/main/scala/sigma/serialization/ErgoTreeSerializer.scala

@@ -150,10 +150,16 @@ class ErgoTreeSerializer {
         val wasDeserialize_saved = r.wasDeserialize
         r.wasDeserialize = false
 
+        val wasUsingBlockchainContext_saved = r.wasUsingBlockchainContext
+        r.wasUsingBlockchainContext = false
+
         val root = ValueSerializer.deserialize(r)
         val hasDeserialize = r.wasDeserialize  // == true if there was deserialization node
         r.wasDeserialize = wasDeserialize_saved
 
+        val isUsingBlockchainContext = r.wasUsingBlockchainContext // == true if there was a node using the blockchain context
+        r.wasUsingBlockchainContext = wasUsingBlockchainContext_saved
+
         if (checkType) {
           CheckDeserializedScriptIsSigmaProp(root)
         }
@@ -168,7 +174,7 @@ class ErgoTreeSerializer {
 
         new ErgoTree(
           h, cs, Right(root.asSigmaProp), complexity,
-          propositionBytes, Some(hasDeserialize))
+          propositionBytes, Some(hasDeserialize), Some(isUsingBlockchainContext))
       }
       catch {
         case e: ReaderPositionLimitExceeded =>
@@ -183,7 +189,7 @@ class ErgoTreeSerializer {
             r.position = startPos
             val bytes = r.getBytes(numBytes)
             val complexity = ComplexityTable.OpCodeComplexity(Constant.opCode)
-            new ErgoTree(ErgoTree.DefaultHeader, EmptyConstants, Left(UnparsedErgoTree(bytes, ve)), complexity, bytes, None)
+            new ErgoTree(ErgoTree.DefaultHeader, EmptyConstants, Left(UnparsedErgoTree(bytes, ve)), complexity, bytes, None, None)
           case None =>
             throw new SerializerException(
               s"Cannot handle ValidationException, ErgoTree serialized without size bit.", Some(ve))

data/shared/src/main/scala/sigma/serialization/MethodCallSerializer.scala

@@ -1,11 +1,11 @@
 package sigma.serialization
 
 import sigma.ast.syntax._
-import sigma.ast.MethodCall
+import sigma.ast.{ComplexityTable, MethodCall, SContextMethods, SMethod, SType, STypeSubst, Value, ValueCompanion}
 import sigma.util.safeNewArray
 import SigmaByteWriter._
 import debox.cfor
-import sigma.ast.{ComplexityTable, SMethod, SType, STypeSubst, Value, ValueCompanion}
+import sigma.ast.SContextMethods.BlockchainContextMethodNames
 import sigma.serialization.CoreByteWriter.{ArgInfo, DataInfo}
 
 case class MethodCallSerializer(cons: (Value[SType], SMethod, IndexedSeq[Value[SType]], STypeSubst) => Value[SType])
@@ -60,6 +60,11 @@ case class MethodCallSerializer(cons: (Value[SType], SMethod, IndexedSeq[Value[S
       }
 
     val specMethod = method.specializeFor(obj.tpe, types)
+
+    var isUsingBlockchainContext = specMethod.objType == SContextMethods &&
+      BlockchainContextMethodNames.contains(method.name)
+    r.wasUsingBlockchainContext ||= isUsingBlockchainContext
+
     cons(obj, specMethod, args, Map.empty)
   }
 }

sc/shared/src/test/scala/sigmastate/ErgoTreeSpecification.scala

@@ -140,6 +140,104 @@ class ErgoTreeSpecification extends SigmaDslTesting with ContractsTestkit {
     }
   }
 
+  property("ErgoTree.isUsingBlockchainContext") {
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 0.toByte,
+        Array[Constant[SType]](),
+        Right(TrueSigmaProp))
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe false
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Array(IntConstant(1)),
+        Right(BoolToSigmaProp(GT(Height, ConstantPlaceholder(0, SInt))))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          LastBlockUtxoRootHash, SAvlTreeMethods.getMethod,
+          IndexedSeq(ExtractId(GetVarBox(22: Byte).get), GetVarByteArray(23: Byte).get)).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(BoolToSigmaProp(EQ(MinerPubkey, ErgoLikeContextTesting.dummyPubkey)))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          Context, SContextMethods.headersMethod, Vector()).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          Context, SContextMethods.preHeaderMethod, Vector()).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          Context, SContextMethods.heightMethod, Vector()).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          Context, SContextMethods.lastBlockUtxoRootHashMethod, Vector()).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+
+    {
+      val t = new ErgoTree(
+        HeaderType @@ 16.toByte,
+        Vector(),
+        Right(OptionIsDefined(IR.builder.mkMethodCall(
+          Context, SContextMethods.minerPubKeyMethod, Vector()).asOption[SByteArray]))
+      )
+      t._isUsingBlockchainContext shouldBe None
+      t.isUsingBlockchainContext shouldBe true
+    }
+  }
+
   property("ErgoTree equality") {
     val t1 = new ErgoTree(
       HeaderType @@ 16.toByte,
@@ -728,7 +826,7 @@ class ErgoTreeSpecification extends SigmaDslTesting with ContractsTestkit {
       val addr = ErgoAddressEncoder.Mainnet.fromString("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").getOrThrow
       val tree = addr.script
       tree match {
-        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _) =>
+        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _, _) =>
       }
     }
 
@@ -741,7 +839,7 @@ class ErgoTreeSpecification extends SigmaDslTesting with ContractsTestkit {
       val addr = ErgoAddressEncoder.Mainnet.fromString("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").getOrThrow
       val tree = addr.script
       tree match {
-        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _) =>
+        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _, _) =>
       }
     }
 
@@ -765,7 +863,7 @@ class ErgoTreeSpecification extends SigmaDslTesting with ContractsTestkit {
       val addr = ErgoAddressEncoder.Mainnet.fromString("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").getOrThrow
       val tree = addr.script
       tree match {
-        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _) =>
+        case ErgoTree(_, _, Right(BlockValueWithInvalidBoolToSigmaProp(_)), _, _, _, _) =>
       }
       val lines = SigmaPPrint.tokenize(tree, 150, 300)
       if (printDebugInfo) {

sc/shared/src/test/scala/sigmastate/serialization/ErgoTreeSerializerSpecification.scala

@@ -217,7 +217,7 @@ class ErgoTreeSerializerSpecification extends SerializationSpecification
   property("SigmaProp.propBytes vs ErgoTree.serializer equivalence") {
     forAll(MinSuccessful(100)) { sp: SigmaProp =>
       val propBytes = sp.propBytes
-      val ergoTree = new ErgoTree(ErgoTree.DefaultHeader, EmptyConstants, Right(sp.toSigmaBoolean.toSigmaPropValue), 0, null, None)
+      val ergoTree = new ErgoTree(ErgoTree.DefaultHeader, EmptyConstants, Right(sp.toSigmaBoolean.toSigmaPropValue), 0, null, None, None)
       val treeBytes = DefaultSerializer.serializeErgoTree(ergoTree)
       treeBytes shouldBe propBytes.toArray
     }