private static boolean buildIff()

in src/org/jetbrains/java/decompiler/modules/decompiler/SimplifyExprentsHelper.java [640:742]
80 lines of code
36 McCabe index (conditional complexity)

  private static boolean buildIff(Statement stat, SSAConstructorSparseEx ssa) {
    if (stat.type == StatementType.IF && stat.getExprents() == null) {
      IfStatement statement = (IfStatement)stat;
      Exprent ifHeadExpr = statement.getHeadexprent();
      BitSet ifHeadExprBytecode = (ifHeadExpr == null ? null : ifHeadExpr.bytecode);

      if (statement.iftype == IfStatement.IFTYPE_IFELSE) {
        Statement ifStatement = statement.getIfstat();
        Statement elseStatement = statement.getElsestat();

        if (ifStatement.getExprents() != null && ifStatement.getExprents().size() == 1 &&
            elseStatement.getExprents() != null && elseStatement.getExprents().size() == 1 &&
            ifStatement.getAllSuccessorEdges().size() == 1 && elseStatement.getAllSuccessorEdges().size() == 1 &&
            ifStatement.getAllSuccessorEdges().get(0).getDestination() == elseStatement.getAllSuccessorEdges().get(0).getDestination()) {
          Exprent ifExpr = ifStatement.getExprents().get(0);
          Exprent elseExpr = elseStatement.getExprents().get(0);

          if (ifExpr.type == Exprent.EXPRENT_ASSIGNMENT && elseExpr.type == Exprent.EXPRENT_ASSIGNMENT) {
            AssignmentExprent ifAssign = (AssignmentExprent)ifExpr;
            AssignmentExprent elseAssign = (AssignmentExprent)elseExpr;

            if (ifAssign.getLeft().type == Exprent.EXPRENT_VAR && elseAssign.getLeft().type == Exprent.EXPRENT_VAR) {
              VarExprent ifVar = (VarExprent)ifAssign.getLeft();
              VarExprent elseVar = (VarExprent)elseAssign.getLeft();

              if (ifVar.getIndex() == elseVar.getIndex() && ifVar.isStack()) { // ifVar.getIndex() >= VarExprent.STACK_BASE) {
                boolean found = false;

                for (Entry<VarVersion, FastSparseSet<Integer>> ent : ssa.getPhi().entrySet()) {
                  if (ent.getKey().var == ifVar.getIndex()) {
                    if (ent.getValue().contains(ifVar.getVersion()) && ent.getValue().contains(elseVar.getVersion())) {
                      found = true;
                      break;
                    }
                  }
                }

                if (found) {
                  List<Exprent> data = new ArrayList<>(statement.getFirst().getExprents());

                  List<Exprent> operands = Arrays.asList(statement.getHeadexprent().getCondition(), ifAssign.getRight(), elseAssign.getRight());
                  data.add(new AssignmentExprent(ifVar, new FunctionExprent(FunctionExprent.FUNCTION_IIF, operands, ifHeadExprBytecode), ifHeadExprBytecode));
                  statement.setExprents(data);

                  if (statement.getAllSuccessorEdges().isEmpty()) {
                    StatEdge ifEdge = ifStatement.getAllSuccessorEdges().get(0);
                    StatEdge edge = new StatEdge(ifEdge.getType(), statement, ifEdge.getDestination());

                    statement.addSuccessor(edge);
                    if (ifEdge.closure != null) {
                      ifEdge.closure.addLabeledEdge(edge);
                    }
                  }

                  SequenceHelper.destroyAndFlattenStatement(statement);

                  return true;
                }
              }
            }
          }
          else if (ifExpr.type == Exprent.EXPRENT_EXIT && elseExpr.type == Exprent.EXPRENT_EXIT) {
            ExitExprent ifExit = (ExitExprent)ifExpr;
            ExitExprent elseExit = (ExitExprent)elseExpr;

            if (ifExit.getExitType() == elseExit.getExitType() && ifExit.getValue() != null && elseExit.getValue() != null &&
                ifExit.getExitType() == ExitExprent.EXIT_RETURN) {
              // throw is dangerous, because of implicit casting to a common superclass
              // e.g. throws IOException and throw true?new RuntimeException():new IOException(); won't work
              if (ifExit.getExitType() == ExitExprent.EXIT_THROW &&
                  !ifExit.getValue().getExprType().equals(elseExit.getValue().getExprType())) {  // note: getExprType unreliable at this point!
                return false;
              }

              // avoid flattening to 'iff' if any of the branches is an 'iff' already
              if (isIff(ifExit.getValue()) || isIff(elseExit.getValue())) {
                return false;
              }

              List<Exprent> data = new ArrayList<>(statement.getFirst().getExprents());

              data.add(new ExitExprent(ifExit.getExitType(), new FunctionExprent(FunctionExprent.FUNCTION_IIF,
                                                                               Arrays.asList(
                                                                                 statement.getHeadexprent().getCondition(),
                                                                                 ifExit.getValue(),
                                                                                 elseExit.getValue()), ifHeadExprBytecode), ifExit.getRetType(), ifHeadExprBytecode, ifExit.getMethodDescriptor()));
              statement.setExprents(data);

              StatEdge retEdge = ifStatement.getAllSuccessorEdges().get(0);
              Statement closure = retEdge.closure == statement ? statement.getParent() : retEdge.closure;
              statement.addSuccessor(new StatEdge(EdgeType.BREAK, statement, retEdge.getDestination(), closure));

              SequenceHelper.destroyAndFlattenStatement(statement);

              return true;
            }
          }
        }
      }
    }

    return false;
  }