remove Nop ast node.

codeGenCpu6502/src/prog8/codegen/cpu6502/AsmGen.kt

@@ -837,7 +837,6 @@ class AsmGen(private val program: Program,
         outputSourceLine(stmt)
         when(stmt) {
             is VarDecl -> translate(stmt)
-            is Nop -> {}
             is Directive -> translate(stmt)
             is Return -> translate(stmt)
             is Subroutine -> translateSubroutine(stmt)
@@ -859,7 +858,7 @@ class AsmGen(private val program: Program,
             is GoSub -> translate(stmt)
             is PostIncrDecr -> postincrdecrAsmGen.translate(stmt)
             is Label -> translate(stmt)
-            is Branch -> translate(stmt)
+            is ConditionalBranch -> translate(stmt)
             is IfElse -> translate(stmt)
             is ForLoop -> forloopsAsmGen.translate(stmt)
             is RepeatLoop -> translate(stmt)
@@ -1536,7 +1535,7 @@ $repeatLabel    lda  $counterVar
         scope.statements.forEach{ translate(it) }
     }
 
-    private fun translate(stmt: Branch) {
+    private fun translate(stmt: ConditionalBranch) {
         if(stmt.truepart.isEmpty() && stmt.elsepart.isNotEmpty())
             throw AssemblyError("only else part contains code, shoud have been switched already")
 

compiler/src/prog8/compiler/astprocessing/AstChecker.kt

@@ -205,8 +205,7 @@ internal class AstChecker(private val program: Program,
                 is Label,
                 is VarDecl,
                 is InlineAssembly,
-                is IStatementContainer,
+                is IStatementContainer -> true
-                is Nop -> true
                 is Assignment -> {
                     val target = statement.target.identifier!!.targetStatement(program)
                     target === statement.previousSibling()      // an initializer assignment is okay

compiler/src/prog8/compiler/astprocessing/BeforeAsmAstChanger.kt

@@ -324,7 +324,7 @@ internal class BeforeAsmAstChanger(val program: Program, private val options: Co
                     complexArrayIndexedExpressions.add(arrayIndexedExpression)
             }
 
-            override fun visit(branch: Branch) {}
+            override fun visit(branch: ConditionalBranch) {}
 
             override fun visit(forLoop: ForLoop) {}
 

compiler/src/prog8/compiler/astprocessing/ParentNodeChecker.kt

@@ -47,7 +47,7 @@ internal class ParentNodeChecker: AstWalker() {
         return noModifications
     }
 
-    override fun before(branch: Branch, parent: Node): Iterable<IAstModification> {
+    override fun before(branch: ConditionalBranch, parent: Node): Iterable<IAstModification> {
         if(branch.parent!==parent)
             throw FatalAstException("parent node mismatch at $branch")
         return noModifications
@@ -233,12 +233,6 @@ internal class ParentNodeChecker: AstWalker() {
         return noModifications
     }
 
-    override fun before(nop: Nop, parent: Node): Iterable<IAstModification> {
-        if(nop.parent!==parent)
-            throw FatalAstException("parent node mismatch at $nop")
-        return noModifications
-    }
-
     override fun before(scope: AnonymousScope, parent: Node): Iterable<IAstModification> {
         if(scope.parent!==parent)
             throw FatalAstException("parent node mismatch at $scope")

compiler/src/prog8/compiler/astprocessing/VariousCleanups.kt

@@ -17,10 +17,6 @@ import prog8.compilerinterface.IErrorReporter
 
 internal class VariousCleanups(val program: Program, val errors: IErrorReporter, val options: CompilationOptions): AstWalker() {
 
-    override fun before(nop: Nop, parent: Node): Iterable<IAstModification> {
-        return listOf(IAstModification.Remove(nop, parent as IStatementContainer))
-    }
-
     override fun after(scope: AnonymousScope, parent: Node): Iterable<IAstModification> {
         return if(parent is IStatementContainer)
             listOf(ScopeFlatten(scope, parent as IStatementContainer))

compilerAst/src/prog8/ast/AstToSourceTextConverter.kt

@@ -2,13 +2,11 @@ package prog8.ast
 
 import prog8.ast.antlr.escape
 import prog8.ast.base.DataType
-import prog8.ast.base.FatalAstException
 import prog8.ast.base.NumericDatatypes
 import prog8.ast.base.VarDeclType
 import prog8.ast.expressions.*
 import prog8.ast.statements.*
 import prog8.ast.walk.IAstVisitor
-import prog8.compilerinterface.Encoding
 
 
 /**
@@ -259,7 +257,7 @@ class AstToSourceTextConverter(val output: (text: String) -> Unit, val program:
         }
     }
 
-    override fun visit(branch: Branch) {
+    override fun visit(branch: ConditionalBranch) {
         output("if_${branch.condition.toString().lowercase()} ")
         branch.truepart.accept(this)
         if(branch.elsepart.statements.isNotEmpty()) {

compilerAst/src/prog8/ast/AstToplevel.kt

@@ -92,7 +92,7 @@ interface IStatementContainer {
                     if(found!=null)
                         return found
                 }
-                is Branch -> {
+                is ConditionalBranch -> {
                     val found = stmt.truepart.searchSymbol(name) ?: stmt.elsepart.searchSymbol(name)
                     if(found!=null)
                         return found

compilerAst/src/prog8/ast/antlr/Antlr2Kotlin.kt

@@ -518,14 +518,14 @@ private fun Prog8ANTLRParser.Else_partContext.toAst(): MutableList<Statement> {
     return statement_block()?.toAst() ?: mutableListOf(statement().toAst())
 }
 
-private fun Prog8ANTLRParser.Branch_stmtContext.toAst(): Branch {
+private fun Prog8ANTLRParser.Branch_stmtContext.toAst(): ConditionalBranch {
     val branchcondition = branchcondition().toAst()
     val trueStatements = statement_block()?.toAst() ?: mutableListOf(statement().toAst())
     val elseStatements = else_part()?.toAst() ?: mutableListOf()
     val trueScope = AnonymousScope(trueStatements, statement_block()?.toPosition()
             ?: statement().toPosition())
     val elseScope = AnonymousScope(elseStatements, else_part()?.toPosition() ?: toPosition())
-    return Branch(branchcondition, trueScope, elseScope, toPosition())
+    return ConditionalBranch(branchcondition, trueScope, elseScope, toPosition())
 }
 
 private fun Prog8ANTLRParser.BranchconditionContext.toAst() = BranchCondition.valueOf(

compilerAst/src/prog8/ast/statements/AstStatements.kt

@@ -639,19 +639,6 @@ class AnonymousScope(override var statements: MutableList<Statement>,
     override fun accept(visitor: AstWalker, parent: Node) = visitor.visit(this, parent)
 }
 
-class Nop(override val position: Position): Statement() {
-    override lateinit var parent: Node
-
-    override fun linkParents(parent: Node) {
-        this.parent = parent
-    }
-
-    override fun replaceChildNode(node: Node, replacement: Node) = throw FatalAstException("can't replace here")
-    override fun copy() = Nop(position)
-    override fun accept(visitor: IAstVisitor) = visitor.visit(this)
-    override fun accept(visitor: AstWalker, parent: Node) = visitor.visit(this, parent)
-}
-
 class AsmGenInfo {
     // This class contains various attributes that influence the assembly code generator.
     // Conceptually it should be part of any INameScope.
@@ -818,10 +805,10 @@ class IfElse(var condition: Expression,
 
 }
 
-class Branch(var condition: BranchCondition,
+class ConditionalBranch(var condition: BranchCondition,
-             var truepart: AnonymousScope,
+                        var truepart: AnonymousScope,
-             var elsepart: AnonymousScope,
+                        var elsepart: AnonymousScope,
-             override val position: Position) : Statement() {
+                        override val position: Position) : Statement() {
     override lateinit var parent: Node
 
     override fun linkParents(parent: Node) {

compilerAst/src/prog8/ast/walk/AstWalker.kt

@@ -85,7 +85,7 @@ abstract class AstWalker {
     open fun before(assignTarget: AssignTarget, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(assignment: Assignment, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(block: Block, parent: Node): Iterable<IAstModification> = noModifications
-    open fun before(branch: Branch, parent: Node): Iterable<IAstModification> = noModifications
+    open fun before(branch: ConditionalBranch, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(breakStmt: Break, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(containment: ContainmentCheck, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(decl: VarDecl, parent: Node): Iterable<IAstModification> = noModifications
@@ -105,7 +105,6 @@ abstract class AstWalker {
     open fun before(memread: DirectMemoryRead, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(memwrite: DirectMemoryWrite, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(module: Module, parent: Node): Iterable<IAstModification> = noModifications
-    open fun before(nop: Nop, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(numLiteral: NumericLiteralValue, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(postIncrDecr: PostIncrDecr, parent: Node): Iterable<IAstModification> = noModifications
     open fun before(program: Program): Iterable<IAstModification> = noModifications
@@ -129,7 +128,7 @@ abstract class AstWalker {
     open fun after(assignTarget: AssignTarget, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(assignment: Assignment, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(block: Block, parent: Node): Iterable<IAstModification> = noModifications
-    open fun after(branch: Branch, parent: Node): Iterable<IAstModification> = noModifications
+    open fun after(branch: ConditionalBranch, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(breakStmt: Break, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(containment: ContainmentCheck, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(builtinFunctionPlaceholder: BuiltinFunctionPlaceholder, parent: Node): Iterable<IAstModification> = noModifications
@@ -150,7 +149,6 @@ abstract class AstWalker {
     open fun after(memread: DirectMemoryRead, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(memwrite: DirectMemoryWrite, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(module: Module, parent: Node): Iterable<IAstModification> = noModifications
-    open fun after(nop: Nop, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(numLiteral: NumericLiteralValue, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(postIncrDecr: PostIncrDecr, parent: Node): Iterable<IAstModification> = noModifications
     open fun after(program: Program): Iterable<IAstModification> = noModifications
@@ -299,7 +297,7 @@ abstract class AstWalker {
         track(after(ifElse, parent), ifElse, parent)
     }
 
-    fun visit(branch: Branch, parent: Node) {
+    fun visit(branch: ConditionalBranch, parent: Node) {
         track(before(branch, parent), branch, parent)
         branch.truepart.accept(this, branch)
         branch.elsepart.accept(this, branch)
@@ -443,11 +441,6 @@ abstract class AstWalker {
         track(after(inlineAssembly, parent), inlineAssembly, parent)
     }
 
-    fun visit(nop: Nop, parent: Node) {
-        track(before(nop, parent), nop, parent)
-        track(after(nop, parent), nop, parent)
-    }
-
     fun visit(whenStmt: When, parent: Node) {
         track(before(whenStmt, parent), whenStmt, parent)
         whenStmt.condition.accept(this, whenStmt)

compilerAst/src/prog8/ast/walk/IAstVisitor.kt

@@ -71,7 +71,7 @@ interface IAstVisitor {
         ifElse.elsepart.accept(this)
     }
 
-    fun visit(branch: Branch) {
+    fun visit(branch: ConditionalBranch) {
         branch.truepart.accept(this)
         branch.elsepart.accept(this)
     }
@@ -169,9 +169,6 @@ interface IAstVisitor {
     fun visit(inlineAssembly: InlineAssembly) {
     }
 
-    fun visit(nop: Nop) {
-    }
-
     fun visit(whenStmt: When) {
         whenStmt.condition.accept(this)
         whenStmt.choices.forEach { it.accept(this) }