protected ExpQuery(
Type resultType, VarDeclList elemVarDecls, Expression rangeExp, Expression queryExp)
throws ExpInvalidException {
super(resultType, rangeExp, queryExp);
fElemVarDecls = elemVarDecls;
fRangeExp = rangeExp;
fQueryExp = queryExp;
// type of rangeExp must be a subtype of Collection, i.e. Set,
// Sequence or Bag
if (!fRangeExp.type().isCollection(false))
throw new ExpInvalidException(
"Range expression must be of type " + "`Collection', found `" + fRangeExp.type() + "'.");
// assert that declard element variables are equal or
// supertypes of range element type
Type rangeElemType = ((CollectionType) fRangeExp.type()).elemType();
for (int i = 0; i < fElemVarDecls.size(); i++) {
VarDecl vd = fElemVarDecls.varDecl(i);
if (!rangeElemType.isSubtypeOf(vd.type()))
throw new ExpInvalidException(
"Type `"
+ vd.type()
+ "' of range variable `"
+ vd.name()
+ "' does not match type `"
+ rangeElemType
+ "' of collection elements.");
}
}
/** Evaluate collect expressions. */
protected final Value evalCollectNested(EvalContext ctx) {
// evaluate range
Value v = fRangeExp.eval(ctx);
if (v.isUndefined()) return UndefinedValue.instance;
CollectionValue rangeVal = (CollectionValue) v;
// prepare result value
ArrayList<Value> resValues = new ArrayList<Value>();
// loop over range elements
for (Value elemVal : rangeVal) {
// bind element variable to range element, if variable was
// declared
if (!fElemVarDecls.isEmpty()) ctx.pushVarBinding(fElemVarDecls.varDecl(0).name(), elemVal);
// evaluate collect expression
Value val = fQueryExp.eval(ctx);
// add element to result
resValues.add(val);
if (!fElemVarDecls.isEmpty()) ctx.popVarBinding();
}
// result is collection with mapped values
if (fRangeExp.type().isSequence() || fRangeExp.type().isOrderedSet())
return new SequenceValue(fQueryExp.type(), resValues);
else return new BagValue(fQueryExp.type(), resValues);
}
protected void assertBooleanQuery() throws ExpInvalidException {
// queryExp must be a boolean expression
if (!fQueryExp.type().isBoolean())
throw new ExpInvalidException(
"Argument expression of `"
+ name()
+ "' must have boolean type, found `"
+ fQueryExp.type()
+ "'.");
}
/** Evaluate sortedBy expressions. */
protected final Value evalSortedBy(EvalContext ctx) {
// evaluate range
Value v = fRangeExp.eval(ctx);
if (v.isUndefined()) return UndefinedValue.instance;
CollectionValue rangeVal = (CollectionValue) v;
ArrayList<KeyValPair> keyValList = new ArrayList<KeyValPair>();
// loop over range elements
for (Value elemVal : rangeVal) {
// bind element variable to range element, if variable was
// declared
if (!fElemVarDecls.isEmpty()) ctx.pushVarBinding(fElemVarDecls.varDecl(0).name(), elemVal);
// evaluate sortedBy expression and store the result as a
// key together with elemVal
Value key = fQueryExp.eval(ctx);
keyValList.add(new KeyValPair(key, elemVal));
if (!fElemVarDecls.isEmpty()) ctx.popVarBinding();
}
// sort elements by key
Collections.sort(
keyValList,
new Comparator<KeyValPair>() {
public int compare(KeyValPair o1, KeyValPair o2) {
return o1.fKey.compareTo(o2.fKey);
}
});
// drop the keys from the list
ListIterator<KeyValPair> listIter = keyValList.listIterator();
Collection<Value> result = new ArrayList<Value>(keyValList.size());
while (listIter.hasNext()) {
KeyValPair kvp = listIter.next();
result.add(kvp.fElem);
}
Type rangeElemType = ((CollectionType) fRangeExp.type()).elemType();
return new SequenceValue(rangeElemType, result);
}
