/*
 * The JastAdd Extensible Java Compiler (http://jastadd.org) is covered
 * by the modified BSD License. You should have received a copy of the
 * modified BSD license with this compiler.
 * 
 * Copyright (c) 2005-2008, Torbjorn Ekman
 * All rights reserved.
 */

aspect UnreachableStatements {

  void ASTNode.checkUnreachableStmt() {
  }
  void Stmt.checkUnreachableStmt() {
    if(!reachable() && reportUnreachable())
      error("statement is unreachable");
  }
  void StaticInitializer.checkUnreachableStmt() {
    if(!getBlock().canCompleteNormally())
      error("static initializer in " + hostType().fullName() + " can not complete normally");
  }
  void InstanceInitializer.checkUnreachableStmt() {
    if(!getBlock().canCompleteNormally())
      error("instance initializer in " + hostType().fullName() + " can not complete normally");
  }

  inh boolean Stmt.reachable();
  inh boolean Block.reachable();
  syn lazy boolean Stmt.canCompleteNormally() = true;
  
  eq ConstructorDecl.getConstructorInvocation().reachable() = true;
  eq ConstructorDecl.getBlock().reachable() = !hasConstructorInvocation() ? true : getConstructorInvocation().canCompleteNormally();
  eq MethodDecl.getBlock().reachable() = true;
  eq StaticInitializer.getBlock().reachable() = true;
  eq InstanceInitializer.getBlock().reachable() = true;

  eq Block.canCompleteNormally() = getNumStmt() == 0 ? reachable() : getStmt(getNumStmt() - 1).canCompleteNormally();
  eq Block.getStmt().reachable() = childIndex == 0 ? reachable() : getStmt(childIndex-1).canCompleteNormally();
  
  eq LocalClassDeclStmt.canCompleteNormally() = reachable();
  
  eq VarDeclStmt.canCompleteNormally() = reachable();

  eq EmptyStmt.canCompleteNormally() = reachable();

  eq LabeledStmt.canCompleteNormally() = getStmt().canCompleteNormally() || reachableBreak();
  eq LabeledStmt.getStmt().reachable() = reachable();

  syn lazy boolean BranchTargetStmt.reachableBreak() {
    for(Iterator iter = targetBreaks().iterator(); iter.hasNext(); ) {
      BreakStmt stmt = (BreakStmt)iter.next();
      if(stmt.reachable())
        return true;
    }
    return false;
  }
  
  eq ExprStmt.canCompleteNormally() = reachable();

  syn boolean SwitchStmt.lastStmtCanCompleteNormally() = getBlock().canCompleteNormally();

  syn boolean SwitchStmt.noStmts() {
    for(int i = 0; i < getBlock().getNumStmt(); i++)
      if(!(getBlock().getStmt(i) instanceof Case))
        return false;
    return true;
  }

  syn boolean SwitchStmt.noStmtsAfterLastLabel() = 
    getBlock().getNumStmt() > 0 && getBlock().getStmt(getBlock().getNumStmt()-1) instanceof Case;

  syn boolean SwitchStmt.noDefaultLabel() {
    for(int i = 0; i < getBlock().getNumStmt(); i++)
      if(getBlock().getStmt(i) instanceof DefaultCase)
        return false;
    return true;
  }

  eq SwitchStmt.canCompleteNormally() =
    lastStmtCanCompleteNormally() || noStmts() || noStmtsAfterLastLabel() || noDefaultLabel() || reachableBreak();

  eq SwitchStmt.getBlock().reachable() = reachable();
  syn boolean Case.reachable() = getParent().getParent() instanceof Block && ((Block)getParent().getParent()).reachable();
  
  eq WhileStmt.canCompleteNormally() = reachable() && (!getCondition().isConstant() || !getCondition().isTrue()) || reachableBreak();
  eq WhileStmt.getStmt().reachable() = reachable() && !getCondition().isFalse();

  eq DoStmt.canCompleteNormally() = getStmt().canCompleteNormally() && (!getCondition().isConstant() || !getCondition().isTrue())
    || reachableContinue() && (!getCondition().isConstant() || !getCondition().isTrue()) || reachableBreak();

  syn lazy boolean BranchTargetStmt.reachableContinue() {
    for(Iterator iter = targetContinues().iterator(); iter.hasNext(); ) {
      Stmt stmt = (Stmt)iter.next();
      if(stmt.reachable())
        return true;
    }
    return false;
  }
  
  eq DoStmt.getStmt().reachable() = reachable();

  eq ForStmt.canCompleteNormally() = reachable() && hasCondition() && (!getCondition().isConstant() || !getCondition().isTrue()) || reachableBreak();
  eq ForStmt.getStmt().reachable() = reachable() && (!hasCondition() || (!getCondition().isConstant() || !getCondition().isFalse()));
  
  eq BreakStmt.canCompleteNormally() = false;
  eq ContinueStmt.canCompleteNormally() = false;
  eq ReturnStmt.canCompleteNormally() = false;
  eq ThrowStmt.canCompleteNormally() = false;

  eq SynchronizedStmt.canCompleteNormally() = getBlock().canCompleteNormally();
  eq SynchronizedStmt.getBlock().reachable() = reachable();

  eq TryStmt.canCompleteNormally() {
     boolean anyCatchClauseCompleteNormally = false;
     for(int i = 0; i < getNumCatchClause() && !anyCatchClauseCompleteNormally; i++)
       anyCatchClauseCompleteNormally = getCatchClause(i).getBlock().canCompleteNormally();
     return (getBlock().canCompleteNormally() || anyCatchClauseCompleteNormally) &&
       (!hasFinally() || getFinally().canCompleteNormally());
  }
  eq TryStmt.getBlock().reachable() = reachable();
  eq TryStmt.getFinally().reachable() = reachable();
  eq CatchClause.getBlock().reachable() = reachableCatchClause();

  inh lazy boolean CatchClause.reachableCatchClause();
  eq TryStmt.getCatchClause(int childIndex).reachableCatchClause() {
    TypeDecl type = getCatchClause(childIndex).getParameter().type();
    for(int i = 0; i < childIndex; i++)
      if(getCatchClause(i).handles(type))
        return false;
    if(reachableThrow(getCatchClause(childIndex)))
      return true;
    if(type.mayCatch(typeError()) || type.mayCatch(typeRuntimeException()))
      return true;
    return false;
  }
  inh lazy TypeDecl TryStmt.typeError();
  inh lazy TypeDecl TryStmt.typeRuntimeException();
  
  eq IfStmt.canCompleteNormally() = (reachable() && !hasElse()) || (getThen().canCompleteNormally() ||
    (hasElse() && getElse().canCompleteNormally()));
  eq IfStmt.getThen().reachable() = reachable();
  eq IfStmt.getElse().reachable() = reachable();


  inh boolean Stmt.reportUnreachable();
  eq Block.getStmt(int i).reportUnreachable() = i == 0 ? reachable() : getStmt(i-1).reachable();
  eq IfStmt.getThen().reportUnreachable() = reachable();
  eq IfStmt.getElse().reportUnreachable() = reachable();
  eq ForStmt.getStmt().reportUnreachable() = reachable();
  eq DoStmt.getStmt().reportUnreachable() = reachable();
  eq WhileStmt.getStmt().reportUnreachable() = reachable();
  eq TryStmt.getBlock().reportUnreachable() = reachable();
  eq TryStmt.getCatchClause().reportUnreachable() = reachable();
  eq TryStmt.getFinally().reportUnreachable() = reachable();
  eq SynchronizedStmt.getBlock().reportUnreachable() = reachable();
  eq SwitchStmt.getBlock().reportUnreachable() = reachable();
  eq TypeDecl.getChild().reportUnreachable() = true;
  eq Program.getCompilationUnit().reportUnreachable() = true;

}