@Override
public void visit(ExpressionList el) {
for (Iterator iter = el.getExpressions().iterator(); iter.hasNext(); ) {
Expression expression = (Expression) iter.next();
expression.accept(this);
}
}
@Override
public void visit(Function function) {
// all aggregate functions (SUM, AVG, COUNT, MAX, MIN) have only one parameter (Expression)
// although COUNT(*) has no parameters
// EXTRACT_YEAR has one parameter
// if you change this method, NameProjectVisitor.visit(Function) has to be changed as well
ExpressionList params = function.getParameters();
int numParams = 0;
if (params != null) {
params.accept(this);
// in order to determine the size
List<Expression> listParams = params.getExpressions();
numParams = listParams.size();
}
List<ValueExpression> expressions = new ArrayList<ValueExpression>();
for (int i = 0; i < numParams; i++) {
expressions.add(_exprStack.pop());
}
Collections.reverse(expressions); // at the stack top is the lastly added VE
String fnName = function.getName();
if (fnName.equalsIgnoreCase("EXTRACT_YEAR")) {
if (numParams != 1) {
throw new RuntimeException("EXTRACT_YEAR function has exactly one parameter!");
}
ValueExpression expr = expressions.get(0);
ValueExpression ve = new IntegerYearFromDate(expr);
_exprStack.push(ve);
}
}
@Override
public void visit(Function function) {
// all aggregate functions (SUM, AVG, COUNT, MAX, MIN) have only one parameter (Expression)
// although COUNT(*) has no parameters
// EXTRACT_YEAR has one parameter
ExpressionList params = function.getParameters();
if (params != null) {
List<Expression> listParams = params.getExpressions();
for (Expression param : listParams) {
param.accept(this);
}
}
}
/*
* Has to be separate because ExpressionList does not extend Expression
*/
private boolean isRecognized(ExpressionList params) {
if (params == null) return true;
final List<Expression> exprs = params.getExpressions();
if (exprs == null || exprs.isEmpty()) return true;
// if any of the children is not recognized, we have to go to super
// if some of exprs are recognized and some not, we will have some extra
// elements on stack
for (final Expression expr : exprs) if (!isRecognized(expr)) return false;
// all exprs recognized
return true;
}
// my VISITOR methods
@Override
public void visit(Function function) {
// all aggregate functions (SUM, AVG, COUNT, MAX, MIN) have only one parameter (Expression)
// although COUNT(*) has no parameters
// EXTRACT_YEAR has one parameter
ExpressionList params = function.getParameters();
int numParams = 0;
if (params != null) {
List<Expression> listParams = params.getExpressions();
numParams = listParams.size();
for (Expression param : listParams) {
param.accept(this);
}
}
List<ValueExpression> expressions = new ArrayList<ValueExpression>();
for (int i = 0; i < numParams; i++) {
expressions.add(_exprStack.pop());
}
String fnName = function.getName();
if (fnName.equalsIgnoreCase("SUM")) {
// there must be only one parameter, if not SQL parser will raise an exception
ValueExpression expr = expressions.get(0);
NumericConversion numConv = (NumericConversion) expr.getType();
_agg = new AggregateSumOperator(numConv, expr, _map);
// DISTINCT and agg are stored on the same component.
if (function.isDistinct()) {
DistinctOperator distinct = new DistinctOperator(_map, expressions);
_agg.setDistinct(distinct);
}
} else if (fnName.equalsIgnoreCase("COUNT")) {
// COUNT(R.A) and COUNT(1) have the same semantics as COUNT(*), since we do not have NULLs in
// R.A
_agg = new AggregateCountOperator(_map);
// DISTINCT and agg are stored on the same component.
if (function.isDistinct()) {
DistinctOperator distinct = new DistinctOperator(_map, expressions);
_agg.setDistinct(distinct);
}
} else if (fnName.equalsIgnoreCase("EXTRACT_YEAR")) {
if (numParams != 1) {
throw new RuntimeException("EXTRACT_YEAR function has exactly one parameter!");
}
ValueExpression expr = expressions.get(0);
ValueExpression ve = new IntegerYearFromDate(expr);
_exprStack.push(ve);
}
}
/**
* Recursive methods to create a {@link Function} starting from a {@link BinaryExpression} We
* consider all possible values of the left and right expressions
*
* @param pred
* @param lookupTable
* @return
*/
private Function getFunction(Expression pred, LookupTable lookupTable) {
if (pred instanceof BinaryExpression) {
return getFunction((BinaryExpression) pred, lookupTable);
} else if (pred instanceof IsNullExpression) {
return getFunction((IsNullExpression) pred, lookupTable);
} else if (pred instanceof Parenthesis) {
Expression inside = ((Parenthesis) pred).getExpression();
return getFunction(inside, lookupTable);
} else if (pred instanceof Between) {
Between between = (Between) pred;
Expression left = between.getLeftExpression();
Expression e1 = between.getBetweenExpressionStart();
Expression e2 = between.getBetweenExpressionEnd();
GreaterThanEquals gte = new GreaterThanEquals();
gte.setLeftExpression(left);
gte.setRightExpression(e1);
MinorThanEquals mte = new MinorThanEquals();
mte.setLeftExpression(left);
mte.setRightExpression(e2);
AndExpression ande = new AndExpression(gte, mte);
return getFunction(ande, lookupTable);
} else if (pred instanceof InExpression) {
InExpression inExpr = (InExpression) pred;
Expression left = inExpr.getLeftExpression();
ExpressionList ilist = (ExpressionList) inExpr.getRightItemsList();
List<EqualsTo> eqList = new ArrayList<EqualsTo>();
for (Expression item : ilist.getExpressions()) {
EqualsTo eq = new EqualsTo();
eq.setLeftExpression(left);
eq.setRightExpression(item);
eqList.add(eq);
}
int size = eqList.size();
if (size > 1) {
OrExpression or = new OrExpression(eqList.get(size - 1), eqList.get(size - 2));
for (int i = size - 3; i >= 0; i--) {
OrExpression orexpr = new OrExpression(eqList.get(i), or);
or = orexpr;
}
return getFunction(or, lookupTable);
} else {
return getFunction(eqList.get(0), lookupTable);
}
} else return null;
}
@Override
public void visit(Function function) {
boolean recognized = isRecognized(function);
if (!recognized) {
// try to extract SUM
// parameters for COUNT are ignored, as explained in super
final String fnName = function.getName();
if (fnName.equalsIgnoreCase("SUM")) {
recognized = isRecognized(function.getParameters());
if (recognized) {
final ValueExpression expr = popFromExprStack();
createSum(expr, function.isDistinct());
}
} else if (fnName.equalsIgnoreCase("COUNT")) {
final List<ValueExpression> expressions = new ArrayList<ValueExpression>();
if (function.isDistinct()) {
// putting something on stack only if isDistinct is set to
// true
recognized = isRecognized(function.getParameters());
// it might happen that we put on stack something we don't
// use
// this is the case only when some exprs are recognized and
// the others not
if (recognized) {
// create a list of expressions
int numParams = 0;
final ExpressionList params = function.getParameters();
if (params != null) numParams = params.getExpressions().size();
for (int i = 0; i < numParams; i++) expressions.add(popFromExprStack());
}
} else recognized = true;
if (recognized)
// finally, create CountAgg out of expressions (empty if
// nonDistinct)
createCount(expressions, function.isDistinct());
}
}
if (!recognized)
// normal call to parent
super.visit(function);
}
public void visit(ExpressionList expressionList) throws Exception {
for (Iterator iter = expressionList.getExpressions().iterator(); iter.hasNext(); ) {
Expression expression = (Expression) iter.next();
expression.accept(this);
}
}