package org.basex.query.expr;
import static org.basex.query.QueryText.*;
import static org.basex.query.util.Err.*;
import java.io.IOException;
import org.basex.io.serial.Serializer;
import org.basex.query.QueryContext;
import org.basex.query.QueryException;
import org.basex.query.func.Function;
import org.basex.query.item.AtomType;
import org.basex.query.item.Bln;
import org.basex.query.item.Item;
import org.basex.query.item.SeqType;
import org.basex.query.item.SeqType.Occ;
import org.basex.util.InputInfo;
import org.basex.util.Token;
/**
* Value comparison.
*
* @author BaseX Team 2005-12, BSD License
* @author Christian Gruen
*/
public final class CmpV extends Cmp {
/** Comparators. */
public enum Op {
/** Item comparison:less or equal. */
LE("le") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
final int v = a.diff(ii, b);
return v != Item.UNDEF && v <= 0;
}
@Override
public Op swap() { return GE; }
@Override
public Op invert() { return GT; }
},
/** Item comparison:less. */
LT("lt") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
final int v = a.diff(ii, b);
return v != Item.UNDEF && v < 0;
}
@Override
public Op swap() { return GT; }
@Override
public Op invert() { return GE; }
},
/** Item comparison:greater of equal. */
GE("ge") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
final int v = a.diff(ii, b);
return v != Item.UNDEF && v >= 0;
}
@Override
public Op swap() { return LE; }
@Override
public Op invert() { return LT; }
},
/** Item comparison:greater. */
GT("gt") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
final int v = a.diff(ii, b);
return v != Item.UNDEF && v > 0;
}
@Override
public Op swap() { return LT; }
@Override
public Op invert() { return LE; }
},
/** Item comparison:equal. */
EQ("eq") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
return a.eq(ii, b);
}
@Override
public Op swap() { return EQ; }
@Override
public Op invert() { return NE; }
},
/** Item comparison:not equal. */
NE("ne") {
@Override
public boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException {
return !a.eq(ii, b);
}
@Override
public Op swap() { return NE; }
@Override
public Op invert() { return EQ; }
};
/** String representation. */
public final String name;
/**
* Constructor.
* @param n string representation
*/
Op(final String n) { name = n; }
/**
* Evaluates the expression.
* @param ii input info
* @param a first item
* @param b second item
* @return result
* @throws QueryException query exception
*/
public abstract boolean eval(final InputInfo ii, final Item a, final Item b)
throws QueryException;
/**
* Swaps the comparator.
* @return swapped comparator
*/
public abstract Op swap();
/**
* Inverts the comparator.
* @return inverted comparator
*/
public abstract Op invert();
@Override
public String toString() { return name; }
}
/** Comparator. */
Op op;
/**
* Constructor.
* @param ii input info
* @param e1 first expression
* @param e2 second expression
* @param o operator
*/
public CmpV(final InputInfo ii, final Expr e1, final Expr e2, final Op o) {
super(ii, e1, e2);
op = o;
}
@Override
public Expr comp(final QueryContext ctx) throws QueryException {
super.comp(ctx);
// swap expressions; add text() to location paths to simplify optimizations
if(swap()) {
op = op.swap();
ctx.compInfo(OPTSWAP, this);
}
for(int e = 0; e != expr.length; ++e) expr[e] = expr[e].addText(ctx);
final Expr e1 = expr[0];
final Expr e2 = expr[1];
type = SeqType.get(AtomType.BLN, e1.size() == 1 && e2.size() == 1 ?
Occ.O : Occ.ZO);
Expr e = this;
if(oneIsEmpty()) {
e = optPre(null, ctx);
} else if(allAreValues()) {
e = preEval(ctx);
} else if(e1.isFunction(Function.COUNT)) {
e = compCount(op);
if(e != this) ctx.compInfo(e instanceof Bln ? OPTPRE : OPTWRITE, this);
} else if(e1.isFunction(Function.POSITION)) {
// position() CMP number
e = Pos.get(op, e2, e, input);
if(e != this) ctx.compInfo(OPTWRITE, this);
} else if(e1.type().eq(SeqType.BLN) && (op == Op.EQ && e2 == Bln.FALSE ||
op == Op.NE && e2 == Bln.TRUE)) {
// (A eq false()) -> not(A)
e = Function.NOT.get(input, e1);
}
return e;
}
@Override
public Expr compEbv(final QueryContext ctx) {
// e.g.: if($x eq true()) -> if($x)
// checking one direction is sufficient, as operators may have been swapped
return (op == Op.EQ && expr[1] == Bln.TRUE ||
op == Op.NE && expr[1] == Bln.FALSE) &&
expr[0].type().eq(SeqType.BLN) ? expr[0] : this;
}
@Override
public Bln item(final QueryContext ctx, final InputInfo ii)
throws QueryException {
final Item a = expr[0].item(ctx, input);
if(a == null) return null;
final Item b = expr[1].item(ctx, input);
if(b == null) return null;
if(a.comparable(b)) return Bln.get(op.eval(input, a, b));
if(a.type.isFunction()) FNEQ.thrw(input, a);
if(b.type.isFunction()) FNEQ.thrw(input, b);
throw XPTYPECMP.thrw(input, a.type, b.type);
}
@Override
public CmpV invert() {
return expr[0].size() != 1 || expr[1].size() != 1 ? this :
new CmpV(input, expr[0], expr[1], op.invert());
}
@Override
public void plan(final Serializer ser) throws IOException {
ser.openElement(this, OP, Token.token(op.name));
for(final Expr e : expr) e.plan(ser);
ser.closeElement();
}
@Override
public String description() {
return "'" + op + "' expression";
}
@Override
public String toString() {
return toString(" " + op + ' ');
}
}