Use smart casts in the AST deobfuscator

Many of the old is/as calls were left over from the original Java code.

Signed-off-by: Graham <gpe@openrs2.dev>

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/AddSubTransformer.kt

@@ -88,14 +88,14 @@ class AddSubTransformer : Transformer() {
     }
 
     private fun Expression.isNegative(): Boolean {
-        return when {
+        return when (this) {
-            isUnaryExpr -> asUnaryExpr().operator == UnaryExpr.Operator.MINUS
+            is UnaryExpr -> operator == UnaryExpr.Operator.MINUS
-            isIntegerLiteralExpr -> when (val n = asIntegerLiteralExpr().asNumber()) {
+            is IntegerLiteralExpr -> when (val n = asNumber()) {
                 IntegerLiteralExpr.MAX_31_BIT_UNSIGNED_VALUE_AS_LONG -> false
                 is Int -> n < 0
                 else -> error("Invalid IntegerLiteralExpr type")
             }
-            isLongLiteralExpr -> when (val n = asLongLiteralExpr().asNumber()) {
+            is LongLiteralExpr -> when (val n = asNumber()) {
                 LongLiteralExpr.MAX_63_BIT_UNSIGNED_VALUE_AS_BIG_INTEGER -> false
                 is Long -> n < 0
                 else -> error("Invalid LongLiteralExpr type")

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.kt

@@ -3,6 +3,8 @@ package dev.openrs2.deob.ast.transform
 import com.github.javaparser.ast.CompilationUnit
 import com.github.javaparser.ast.expr.BinaryExpr
 import com.github.javaparser.ast.expr.Expression
+import com.github.javaparser.ast.expr.LiteralExpr
+import com.github.javaparser.ast.expr.ThisExpr
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
 import dev.openrs2.deob.ast.util.flip
@@ -32,5 +34,5 @@ class BinaryExprOrderTransformer : Transformer() {
     }
 
     private val Expression.isLiteralOrThisExpr: Boolean
-        get() = isLiteralExpr || isThisExpr
+        get() = this is LiteralExpr || this is ThisExpr
 }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BitMaskTransformer.kt

@@ -3,11 +3,11 @@ package dev.openrs2.deob.ast.transform
 import com.github.javaparser.ast.CompilationUnit
 import com.github.javaparser.ast.expr.BinaryExpr
 import com.github.javaparser.ast.expr.IntegerLiteralExpr
+import com.github.javaparser.ast.expr.LongLiteralExpr
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
 import dev.openrs2.deob.ast.util.checkedAsInt
 import dev.openrs2.deob.ast.util.checkedAsLong
-import dev.openrs2.deob.ast.util.isIntegerOrLongLiteral
 import dev.openrs2.deob.ast.util.toLongLiteralExpr
 import dev.openrs2.deob.ast.util.walk
 import javax.inject.Singleton
@@ -17,25 +17,25 @@ class BitMaskTransformer : Transformer() {
     override fun transformUnit(group: LibraryGroup, library: Library, unit: CompilationUnit) {
         unit.walk { expr: BinaryExpr ->
             val shiftOp = expr.operator
-            val left = expr.left
+            val bitwiseExpr = expr.left
             val shamtExpr = expr.right
 
-            if (shiftOp !in SHIFT_OPS || !left.isBinaryExpr || !shamtExpr.isIntegerLiteralExpr) {
+            if (shiftOp !in SHIFT_OPS || bitwiseExpr !is BinaryExpr || shamtExpr !is IntegerLiteralExpr) {
                 return@walk
             }
 
-            val bitwiseExpr = left.asBinaryExpr()
             val bitwiseOp = bitwiseExpr.operator
             val argExpr = bitwiseExpr.left
             var maskExpr = bitwiseExpr.right
 
-            if (bitwiseOp !in BITWISE_OPS || !maskExpr.isIntegerOrLongLiteral()) {
+            if (bitwiseOp !in BITWISE_OPS) {
                 return@walk
             }
 
-            val shamt = shamtExpr.asIntegerLiteralExpr().checkedAsInt()
+            val shamt = shamtExpr.checkedAsInt()
-            if (maskExpr.isIntegerLiteralExpr) {
+            when (maskExpr) {
-                var mask = maskExpr.asIntegerLiteralExpr().checkedAsInt()
+                is IntegerLiteralExpr -> {
+                    var mask = maskExpr.checkedAsInt()
 
                     mask = when (shiftOp) {
                         BinaryExpr.Operator.SIGNED_RIGHT_SHIFT -> mask shr shamt
@@ -44,8 +44,9 @@ class BitMaskTransformer : Transformer() {
                     }
 
                     maskExpr = IntegerLiteralExpr(mask.toString())
-            } else {
+                }
-                var mask = maskExpr.asLongLiteralExpr().checkedAsLong()
+                is LongLiteralExpr -> {
+                    var mask = maskExpr.checkedAsLong()
 
                     mask = when (shiftOp) {
                         BinaryExpr.Operator.SIGNED_RIGHT_SHIFT -> mask shr shamt
@@ -55,6 +56,8 @@ class BitMaskTransformer : Transformer() {
 
                     maskExpr = mask.toLongLiteralExpr()
                 }
+                else -> return@walk
+            }
 
             expr.replace(BinaryExpr(BinaryExpr(argExpr.clone(), shamtExpr.clone(), shiftOp), maskExpr, bitwiseOp))
         }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/ComplementTransformer.kt

@@ -4,6 +4,7 @@ import com.github.javaparser.ast.CompilationUnit
 import com.github.javaparser.ast.expr.BinaryExpr
 import com.github.javaparser.ast.expr.Expression
 import com.github.javaparser.ast.expr.IntegerLiteralExpr
+import com.github.javaparser.ast.expr.LongLiteralExpr
 import com.github.javaparser.ast.expr.UnaryExpr
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
@@ -34,7 +35,7 @@ class ComplementTransformer : Transformer() {
 
     private companion object {
         private fun Expression.isComplement(): Boolean {
-            return isUnaryExpr && asUnaryExpr().operator == UnaryExpr.Operator.BITWISE_COMPLEMENT
+            return this is UnaryExpr && operator == UnaryExpr.Operator.BITWISE_COMPLEMENT
         }
 
         private fun Expression.isComplementOrLiteral(): Boolean {
@@ -53,10 +54,10 @@ class ComplementTransformer : Transformer() {
         }
 
         private fun Expression.complement(): Expression {
-            return when {
+            return when (this) {
-                isUnaryExpr -> asUnaryExpr().expression
+                is UnaryExpr -> expression
-                isIntegerLiteralExpr -> IntegerLiteralExpr(asIntegerLiteralExpr().checkedAsInt().inv().toString())
+                is IntegerLiteralExpr -> IntegerLiteralExpr(checkedAsInt().inv().toString())
-                isLongLiteralExpr -> asLongLiteralExpr().checkedAsLong().inv().toLongLiteralExpr()
+                is LongLiteralExpr -> checkedAsLong().inv().toLongLiteralExpr()
                 else -> throw IllegalArgumentException()
             }
         }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/EncloseTransformer.kt

@@ -1,9 +1,19 @@
 package dev.openrs2.deob.ast.transform
 
 import com.github.javaparser.ast.CompilationUnit
+import com.github.javaparser.ast.expr.ArrayAccessExpr
+import com.github.javaparser.ast.expr.ArrayCreationExpr
+import com.github.javaparser.ast.expr.AssignExpr
 import com.github.javaparser.ast.expr.BinaryExpr
+import com.github.javaparser.ast.expr.CastExpr
+import com.github.javaparser.ast.expr.ConditionalExpr
 import com.github.javaparser.ast.expr.EnclosedExpr
 import com.github.javaparser.ast.expr.Expression
+import com.github.javaparser.ast.expr.FieldAccessExpr
+import com.github.javaparser.ast.expr.InstanceOfExpr
+import com.github.javaparser.ast.expr.MethodCallExpr
+import com.github.javaparser.ast.expr.ObjectCreationExpr
+import com.github.javaparser.ast.expr.UnaryExpr
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
 import dev.openrs2.deob.ast.util.walk
@@ -45,12 +55,12 @@ class EncloseTransformer : Transformer() {
 
         companion object {
             fun from(expr: Expression): Op? {
-                return when {
+                return when (expr) {
-                    expr.isArrayAccessExpr || expr.isFieldAccessExpr -> ACCESS_PARENS
+                    is ArrayAccessExpr, is FieldAccessExpr -> ACCESS_PARENS
-                    expr.isMethodCallExpr || expr.isEnclosedExpr -> ACCESS_PARENS
+                    is MethodCallExpr, is EnclosedExpr -> ACCESS_PARENS
-                    expr.isUnaryExpr -> if (expr.asUnaryExpr().operator.isPostfix) POSTFIX else UNARY
+                    is UnaryExpr -> if (expr.operator.isPostfix) POSTFIX else UNARY
-                    expr.isCastExpr || expr.isObjectCreationExpr || expr.isArrayCreationExpr -> CAST_NEW
+                    is CastExpr, is ObjectCreationExpr, is ArrayCreationExpr -> CAST_NEW
-                    expr.isBinaryExpr -> when (expr.asBinaryExpr().operator) {
+                    is BinaryExpr -> when (expr.operator) {
                         BinaryExpr.Operator.MULTIPLY -> MULTIPLICATIVE
                         BinaryExpr.Operator.DIVIDE, BinaryExpr.Operator.REMAINDER -> MULTIPLICATIVE
                         BinaryExpr.Operator.PLUS, BinaryExpr.Operator.MINUS -> ADDITIVE
@@ -66,9 +76,9 @@ class EncloseTransformer : Transformer() {
                         BinaryExpr.Operator.OR -> LOGICAL_OR
                         else -> null
                     }
-                    expr.isInstanceOfExpr -> RELATIONAL
+                    is InstanceOfExpr -> RELATIONAL
-                    expr.isConditionalExpr -> TERNARY
+                    is ConditionalExpr -> TERNARY
-                    expr.isAssignExpr -> ASSIGNMENT
+                    is AssignExpr -> ASSIGNMENT
                     else -> null
                 }
             }
@@ -77,49 +87,34 @@ class EncloseTransformer : Transformer() {
 
     override fun transformUnit(group: LibraryGroup, library: Library, unit: CompilationUnit) {
         unit.walk { expr: Expression ->
-            when {
+            when (expr) {
-                expr.isArrayAccessExpr -> {
+                is ArrayAccessExpr -> encloseLeft(expr, expr.name)
-                    val accessExpr = expr.asArrayAccessExpr()
+                is FieldAccessExpr -> encloseLeft(expr, expr.scope)
-                    encloseLeft(expr, accessExpr.name)
+                is MethodCallExpr -> {
-                }
+                    expr.scope.ifPresent { scope ->
-                expr.isFieldAccessExpr -> {
-                    encloseLeft(expr, expr.asFieldAccessExpr().scope)
-                }
-                expr.isMethodCallExpr -> {
-                    expr.asMethodCallExpr().scope.ifPresent { scope ->
                         encloseLeft(expr, scope)
                     }
                 }
-                expr.isUnaryExpr -> {
+                is UnaryExpr -> encloseRight(expr, expr.expression)
-                    val unaryExpr = expr.asUnaryExpr()
+                is CastExpr -> encloseRight(expr, expr.expression)
-                    encloseRight(expr, unaryExpr.expression)
+                is ObjectCreationExpr -> {
-                }
+                    expr.scope.ifPresent { scope ->
-                expr.isCastExpr -> {
-                    encloseRight(expr, expr.asCastExpr().expression)
-                }
-                expr.isObjectCreationExpr -> {
-                    expr.asObjectCreationExpr().scope.ifPresent { scope ->
                         encloseLeft(expr, scope)
                     }
                 }
-                expr.isBinaryExpr -> {
+                is BinaryExpr -> {
-                    val binaryExpr = expr.asBinaryExpr()
+                    encloseLeft(expr, expr.left)
-                    encloseLeft(expr, binaryExpr.left)
+                    encloseRight(expr, expr.right)
-                    encloseRight(expr, binaryExpr.right)
-                }
-                expr.isInstanceOfExpr -> {
-                    encloseLeft(expr, expr.asInstanceOfExpr().expression)
                 }
-                expr.isConditionalExpr -> {
+                is InstanceOfExpr -> encloseLeft(expr, expr.expression)
-                    val conditionalExpr = expr.asConditionalExpr()
+                is ConditionalExpr -> {
-                    encloseLeft(expr, conditionalExpr.condition)
+                    encloseLeft(expr, expr.condition)
-                    encloseLeft(expr, conditionalExpr.thenExpr)
+                    encloseLeft(expr, expr.thenExpr)
-                    encloseRight(expr, conditionalExpr.elseExpr)
+                    encloseRight(expr, expr.elseExpr)
                 }
-                expr.isAssignExpr -> {
+                is AssignExpr -> {
-                    val assignExpr = expr.asAssignExpr()
+                    encloseLeft(expr, expr.target)
-                    encloseLeft(expr, assignExpr.target)
+                    encloseRight(expr, expr.value)
-                    encloseRight(expr, assignExpr.value)
                 }
             }
         }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/ForLoopConditionTransformer.kt

@@ -23,13 +23,10 @@ class ForLoopConditionTransformer : Transformer() {
         unit.walk { stmt: ForStmt ->
             val updatedExprs = stmt.update.mapNotNull { it.getUpdatedExpr() }
 
-            stmt.compare.ifPresent { compare ->
+            stmt.compare.ifPresent { expr ->
-                if (!compare.isBinaryExpr) {
+                if (expr !is BinaryExpr) {
                     return@ifPresent
-                }
+                } else if (expr.hasSideEffects()) {
-
-                val expr = compare.asBinaryExpr()
-                if (expr.hasSideEffects()) {
                     return@ifPresent
                 }
 

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/GlTransformer.kt

@@ -9,13 +9,17 @@ import com.github.javaparser.ast.body.Parameter
 import com.github.javaparser.ast.body.TypeDeclaration
 import com.github.javaparser.ast.body.VariableDeclarator
 import com.github.javaparser.ast.expr.BinaryExpr
+import com.github.javaparser.ast.expr.ConditionalExpr
 import com.github.javaparser.ast.expr.Expression
 import com.github.javaparser.ast.expr.FieldAccessExpr
+import com.github.javaparser.ast.expr.IntegerLiteralExpr
 import com.github.javaparser.ast.expr.MethodCallExpr
 import com.github.javaparser.ast.expr.NameExpr
 import com.github.javaparser.ast.expr.SimpleName
 import com.github.javaparser.ast.type.PrimitiveType
+import com.github.javaparser.resolution.types.ResolvedArrayType
 import com.github.javaparser.resolution.types.ResolvedPrimitiveType
+import com.github.javaparser.resolution.types.ResolvedReferenceType
 import com.github.javaparser.resolution.types.ResolvedType
 import com.github.michaelbull.logging.InlineLogger
 import dev.openrs2.deob.ast.Library
@@ -65,11 +69,11 @@ class GlTransformer @Inject constructor(private val registry: GlRegistry) : Tran
     }
 
     private fun transformFramebufferStatus(unit: CompilationUnit, expr: Expression) {
-        if (!expr.isIntegerLiteralExpr) {
+        if (expr !is IntegerLiteralExpr) {
             return
         }
 
-        val value = expr.asIntegerLiteralExpr().checkedAsInt()
+        val value = expr.checkedAsInt()
         if (value.toLong() != GL_FRAMEBUFFER_COMPLETE.value) {
             return
         }
@@ -92,8 +96,8 @@ class GlTransformer @Inject constructor(private val registry: GlRegistry) : Tran
 
     private fun ResolvedType.isFollowedByOffset(): Boolean {
         return when {
-            isArray && asArrayType().componentType.isPrimitive -> true
+            this is ResolvedArrayType && componentType.isPrimitive -> true
-            isReferenceType && asReferenceType().qualifiedName == "java.lang.Object" -> true
+            this is ResolvedReferenceType && qualifiedName == "java.lang.Object" -> true
             else -> false
         }
     }
@@ -164,11 +168,11 @@ class GlTransformer @Inject constructor(private val registry: GlRegistry) : Tran
 
             expr.scope.ifPresent { scope ->
                 val type = scope.calculateResolvedType()
-                if (!type.isReferenceType) {
+                if (type !is ResolvedReferenceType) {
                     return@ifPresent
                 }
 
-                val name = type.asReferenceType().qualifiedName
+                val name = type.qualifiedName
                 if (name in GL_CLASSES) {
                     transformArguments(unit, expr)
                 }
@@ -235,26 +239,28 @@ class GlTransformer @Inject constructor(private val registry: GlRegistry) : Tran
         parameter: GlParameter,
         expr: Expression
     ) {
-        if (expr.isBinaryExpr) {
+        when (expr) {
-            val binaryExpr = expr.asBinaryExpr()
+            is BinaryExpr -> {
-            transformExpr(unit, command, parameter, binaryExpr.left)
+                transformExpr(unit, command, parameter, expr.left)
-            transformExpr(unit, command, parameter, binaryExpr.right)
+                transformExpr(unit, command, parameter, expr.right)
-        } else if (expr.isConditionalExpr) {
+            }
-            val conditionalExpr = expr.asConditionalExpr()
+            is ConditionalExpr -> {
-            transformExpr(unit, command, parameter, conditionalExpr.thenExpr)
+                transformExpr(unit, command, parameter, expr.thenExpr)
-            transformExpr(unit, command, parameter, conditionalExpr.elseExpr)
+                transformExpr(unit, command, parameter, expr.elseExpr)
-        } else if (expr.isIntegerLiteralExpr) {
+            }
+            is IntegerLiteralExpr -> {
                 transformIntegerLiteralExpr(unit, command, parameter, expr)
             }
         }
+    }
 
     private fun transformIntegerLiteralExpr(
         unit: CompilationUnit,
         command: GlCommand,
         parameter: GlParameter,
-        expr: Expression
+        expr: IntegerLiteralExpr
     ) {
-        var value = expr.asIntegerLiteralExpr().checkedAsInt()
+        var value = expr.checkedAsInt()
         val group = parameter.group ?: return
 
         if (parameter.bitfield) {
@@ -320,21 +326,21 @@ class GlTransformer @Inject constructor(private val registry: GlRegistry) : Tran
 
         private val FIELD_METHOD_COMPARATOR = Comparator<BodyDeclaration<*>> { a, b ->
             when {
-                a.isFieldDeclaration && !b.isFieldDeclaration -> -1
+                a is FieldDeclaration && b !is FieldDeclaration -> -1
-                !a.isFieldDeclaration && b.isFieldDeclaration -> 1
+                a !is FieldDeclaration && b is FieldDeclaration -> 1
                 else -> 0
             }
         }
 
         private fun BodyDeclaration<*>.getIntValue(): Int? {
-            if (!isFieldDeclaration) {
+            if (this !is FieldDeclaration) {
                 return null
             }
 
-            val variable = asFieldDeclaration().variables.firstOrNull() ?: return null
+            val variable = variables.firstOrNull() ?: return null
             return variable.initializer.map {
-                if (it.isIntegerLiteralExpr) {
+                if (it is IntegerLiteralExpr) {
-                    it.asIntegerLiteralExpr().checkedAsInt()
+                    it.checkedAsInt()
                 } else {
                     null
                 }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/IdentityTransformer.kt

@@ -3,6 +3,8 @@ package dev.openrs2.deob.ast.transform
 import com.github.javaparser.ast.CompilationUnit
 import com.github.javaparser.ast.expr.BinaryExpr
 import com.github.javaparser.ast.expr.Expression
+import com.github.javaparser.ast.expr.IntegerLiteralExpr
+import com.github.javaparser.ast.expr.LongLiteralExpr
 import com.github.javaparser.ast.expr.UnaryExpr
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
@@ -47,17 +49,17 @@ class IdentityTransformer : Transformer() {
     }
 
     private fun Expression.isZero(): Boolean {
-        return when {
+        return when (this) {
-            isIntegerLiteralExpr -> asIntegerLiteralExpr().asNumber() == 0
+            is IntegerLiteralExpr -> asNumber() == 0
-            isLongLiteralExpr -> asLongLiteralExpr().asNumber() == 0L
+            is LongLiteralExpr -> asNumber() == 0L
             else -> false
         }
     }
 
     private fun Expression.isOne(): Boolean {
-        return when {
+        return when (this) {
-            isIntegerLiteralExpr -> asIntegerLiteralExpr().asNumber() == 1
+            is IntegerLiteralExpr -> asNumber() == 1
-            isLongLiteralExpr -> asLongLiteralExpr().asNumber() == 1L
+            is LongLiteralExpr -> asNumber() == 1L
             else -> false
         }
     }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/IfElseTransformer.kt

@@ -7,6 +7,7 @@ import com.github.javaparser.ast.stmt.BlockStmt
 import com.github.javaparser.ast.stmt.IfStmt
 import com.github.javaparser.ast.stmt.ReturnStmt
 import com.github.javaparser.ast.stmt.Statement
+import com.github.javaparser.ast.stmt.ThrowStmt
 import dev.openrs2.deob.ast.Library
 import dev.openrs2.deob.ast.LibraryGroup
 import dev.openrs2.deob.ast.util.countNots
@@ -78,7 +79,7 @@ class IfElseTransformer : Transformer() {
                 val notCondition = condition.not()
                 if (notCondition.countNots() < condition.countNots()) {
                     stmt.condition = notCondition
-                    if (elseStmt.isIfStmt) {
+                    if (elseStmt is IfStmt) {
                         val block = BlockStmt()
                         block.statements.add(elseStmt.clone())
                         stmt.thenStmt = block
@@ -136,23 +137,19 @@ class IfElseTransformer : Transformer() {
         unit.walk { stmt: IfStmt ->
             stmt.elseStmt.ifPresent { elseStmt ->
                 // match
-                if (!elseStmt.isBlockStmt) {
+                if (elseStmt !is BlockStmt) {
                     return@ifPresent
                 }
 
-                val blockStmt = elseStmt.asBlockStmt()
+                val statements = elseStmt.statements
-                val statements = blockStmt.statements
                 if (statements.isEmpty()) {
                     return@ifPresent
                 }
 
-                val head = statements[0]
+                val ifStmt = statements[0]
-                if (!head.isIfStmt) {
+                if (ifStmt !is IfStmt) {
                     return@ifPresent
-                }
+                } else if (ifStmt.elseStmt.isPresent) {
-
-                val ifStmt = head.asIfStmt()
-                if (ifStmt.elseStmt.isPresent) {
                     return@ifPresent
                 }
 
@@ -164,7 +161,7 @@ class IfElseTransformer : Transformer() {
                 // rewrite
                 val condition = ifStmt.condition.not()
 
-                val tail = blockStmt.clone()
+                val tail = elseStmt.clone()
                 tail.statements.removeAt(0)
 
                 elseStmt.replace(IfStmt(condition, tail, thenStmt.clone()))
@@ -213,44 +210,47 @@ class IfElseTransformer : Transformer() {
     }
 
     private fun Statement.isIf(): Boolean {
-        return when {
+        return when (this) {
             is IfStmt -> true
             is BlockStmt -> {
-                val stmts = asBlockStmt().statements
+                val stmts = statements
-                stmts.size == 1 && stmts[0].isIfStmt
+                stmts.size == 1 && stmts[0] is IfStmt
             }
             else -> false
         }
     }
 
     private fun Statement.getIf(): Statement {
-        if (isIfStmt) {
+        when (this) {
+            is IfStmt -> {
                 return clone()
-        } else if (isBlockStmt) {
+            }
-            val stmts = asBlockStmt().statements
+            is BlockStmt -> {
+                val stmts = statements
                 if (stmts.size == 1) {
                     val head = stmts[0]
-                if (head.isIfStmt) {
+                    if (head is IfStmt) {
                         return head.clone()
                     }
                 }
             }
+        }
         throw IllegalArgumentException()
     }
 
     private fun Statement.isTailThrowOrReturn(): Boolean {
-        return if (isThrowStmt || isReturnStmt) {
+        return when (this) {
-            true
+            is ThrowStmt, is ReturnStmt -> true
-        } else if (isBlockStmt) {
+            is BlockStmt -> {
-            val stmts = asBlockStmt().statements
+                val stmts = statements
                 if (stmts.isEmpty()) {
                     return false
                 }
 
                 val tail = stmts[stmts.size - 1]
-            tail.isThrowStmt || tail.isReturnStmt
+                tail is ThrowStmt || tail is ReturnStmt
-        } else {
+            }
-            false
+            else -> false
         }
     }
 }

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/IncrementTransformer.kt

@@ -13,22 +13,21 @@ import javax.inject.Singleton
 class IncrementTransformer : Transformer() {
     override fun transformUnit(group: LibraryGroup, library: Library, unit: CompilationUnit) {
         unit.walk { stmt: ExpressionStmt ->
-            if (!stmt.expression.isUnaryExpr) {
+            val expr = stmt.expression
+            if (expr !is UnaryExpr) {
                 return@walk
             }
 
-            val unaryExpr = stmt.expression.asUnaryExpr()
+            expr.operator = expr.operator.toPostfix()
-            unaryExpr.operator = unaryExpr.operator.toPostfix()
         }
 
         unit.walk { stmt: ForStmt ->
             for (expr in stmt.update) {
-                if (!expr.isUnaryExpr) {
+                if (expr !is UnaryExpr) {
                     continue
                 }
 
-                val unaryExpr = expr.asUnaryExpr()
+                expr.operator = expr.operator.toPostfix()
-                unaryExpr.operator = unaryExpr.operator.toPostfix()
             }
         }
     }

deob-ast/src/main/java/dev/openrs2/deob/ast/util/ExprUtils.kt

@@ -37,7 +37,7 @@ fun Long.toHexLiteralExpr(): LongLiteralExpr {
 }
 
 fun Expression.isIntegerOrLongLiteral(): Boolean {
-    return isIntegerLiteralExpr || isLongLiteralExpr
+    return this is IntegerLiteralExpr || this is LongLiteralExpr
 }
 
 fun Long.toLongLiteralExpr(): LongLiteralExpr {
@@ -66,19 +66,15 @@ fun Expression.negate(): Expression {
 }
 
 fun Expression.not(): Expression {
-    if (isUnaryExpr) {
+    when (this) {
-        val unary = asUnaryExpr()
+        is UnaryExpr -> {
-        if (unary.operator == UnaryExpr.Operator.LOGICAL_COMPLEMENT) {
+            if (operator == UnaryExpr.Operator.LOGICAL_COMPLEMENT) {
-            return unary.expression.clone()
+                return expression.clone()
             }
-    } else if (isBinaryExpr) {
+        }
-        val binary = asBinaryExpr()
+        is BinaryExpr -> {
-
-        val left = binary.left
-        val right = binary.right
-
             @Suppress("NON_EXHAUSTIVE_WHEN")
-        when (binary.operator) {
+            when (operator) {
                 BinaryExpr.Operator.EQUALS ->
                     return BinaryExpr(left.clone(), right.clone(), BinaryExpr.Operator.NOT_EQUALS)
                 BinaryExpr.Operator.NOT_EQUALS ->
@@ -96,18 +92,19 @@ fun Expression.not(): Expression {
                 BinaryExpr.Operator.OR ->
                     return BinaryExpr(left.not(), right.not(), BinaryExpr.Operator.AND)
             }
-    } else if (isBooleanLiteralExpr) {
-        return BooleanLiteralExpr(!asBooleanLiteralExpr().value)
         }
+        is BooleanLiteralExpr -> return BooleanLiteralExpr(!value)
+    }
+
     return UnaryExpr(clone(), UnaryExpr.Operator.LOGICAL_COMPLEMENT)
 }
 
 fun Expression.countNots(): Int {
     var count = 0
 
-    if (isUnaryExpr && asUnaryExpr().operator == UnaryExpr.Operator.LOGICAL_COMPLEMENT) {
+    if (this is UnaryExpr && operator == UnaryExpr.Operator.LOGICAL_COMPLEMENT) {
         count++
-    } else if (isBinaryExpr && asBinaryExpr().operator == BinaryExpr.Operator.NOT_EQUALS) {
+    } else if (this is BinaryExpr && operator == BinaryExpr.Operator.NOT_EQUALS) {
         count++
     }