private void analyzeCall(RexCall call, Constancy callConstancy) { parentCallTypeStack.add(call.getOperator()); // visit operands, pushing their states onto stack super.visitCall(call); // look for NON_CONSTANT operands int nOperands = call.getOperands().length; List<Constancy> operandStack = stack.subList(stack.size() - nOperands, stack.size()); for (Constancy operandConstancy : operandStack) { if (operandConstancy == Constancy.NON_CONSTANT) { callConstancy = Constancy.NON_CONSTANT; } } // Even if all operands are constant, the call itself may // be non-deterministic. if (!call.getOperator().isDeterministic()) { callConstancy = Constancy.NON_CONSTANT; } else if (call.getOperator().isDynamicFunction()) { // We can reduce the call to a constant, but we can't // cache the plan if the function is dynamic preparingStmt.disableStatementCaching(); } // Row operator itself can't be reduced to a literal, but if // the operands are constants, we still want to reduce those if ((callConstancy == Constancy.REDUCIBLE_CONSTANT) && (call.getOperator() instanceof SqlRowOperator)) { callConstancy = Constancy.NON_CONSTANT; } if (callConstancy == Constancy.NON_CONSTANT) { // any REDUCIBLE_CONSTANT children are now known to be maximal // reducible subtrees, so they can be added to the result // list for (int iOperand = 0; iOperand < nOperands; ++iOperand) { Constancy constancy = operandStack.get(iOperand); if (constancy == Constancy.REDUCIBLE_CONSTANT) { addResult(call.getOperands()[iOperand]); } } // if this cast expression can't be reduced to a literal, // then see if we can remove the cast if (call.getOperator() == SqlStdOperatorTable.castFunc) { reduceCasts(call); } } // pop operands off of the stack operandStack.clear(); // pop this parent call operator off the stack parentCallTypeStack.remove(parentCallTypeStack.size() - 1); // push constancy result for this call onto stack stack.add(callConstancy); }
public void analyze(RexNode exp) { assert (stack.isEmpty()); exp.accept(this); // Deal with top of stack assert (stack.size() == 1); assert (parentCallTypeStack.isEmpty()); Constancy rootConstancy = stack.get(0); if (rootConstancy == Constancy.REDUCIBLE_CONSTANT) { // The entire subtree was constant, so add it to the result. addResult(exp); } stack.clear(); }