package org.basex.query.expr;
import static org.basex.query.QueryText.*;
import java.io.IOException;
import org.basex.io.serial.Serializer;
import org.basex.query.QueryContext;
import org.basex.query.QueryException;
import org.basex.query.item.Value;
import org.basex.query.iter.Iter;
import org.basex.query.iter.ValueIter;
import org.basex.query.util.Var;
import org.basex.util.InputInfo;
import org.basex.util.Token;
import org.basex.util.TokenBuilder;
/**
* Case expression for typeswitch.
*
* @author BaseX Team 2005-12, BSD License
* @author Christian Gruen
*/
public final class TypeCase extends Single {
/** Variable. */
final Var var;
/**
* Constructor.
* @param ii input info
* @param v variable
* @param r return expression
*/
public TypeCase(final InputInfo ii, final Var v, final Expr r) {
super(ii, r);
var = v;
}
@Override
public TypeCase comp(final QueryContext ctx) throws QueryException {
return comp(ctx, null);
}
/**
* Compiles the expression.
* @param ctx query context
* @param v value to be bound
* @return resulting item
* @throws QueryException query exception
*/
TypeCase comp(final QueryContext ctx, final Value v) throws QueryException {
if(var.name == null) {
super.comp(ctx);
} else {
final int s = ctx.vars.size();
ctx.vars.add(v == null ? var : var.bind(v, ctx).copy());
super.comp(ctx);
ctx.vars.size(s);
}
type = expr.type();
return this;
}
@Override
public boolean uses(final Use u) {
return u == Use.VAR || super.uses(u);
}
/**
* Evaluates the expression.
* @param ctx query context
* @param seq sequence to be checked
* @return resulting item
* @throws QueryException query exception
*/
Iter iter(final QueryContext ctx, final Value seq)
throws QueryException {
if(var.type != null && !var.type.instance(seq)) return null;
if(var.name == null) return ctx.iter(expr);
final int s = ctx.vars.size();
ctx.vars.add(var.bind(seq, ctx).copy());
final ValueIter ic = ctx.value(expr).iter();
ctx.vars.size(s);
return ic;
}
@Override
public void plan(final Serializer ser) throws IOException {
ser.openElement(this, VAR, var.name != null ? var.name.string() :
Token.EMPTY);
expr.plan(ser);
ser.closeElement();
}
@Override
public String toString() {
final TokenBuilder tb = new TokenBuilder(var.type == null ? DEFAULT : CASE);
if(var.name != null) tb.add(' ');
return tb.add(var + " " + RETURN + ' ' + expr).toString();
}
@Override
public TypeCase markTailCalls() {
expr = expr.markTailCalls();
return this;
}
}