/**
* Copyright (C) 2009-2013 FoundationDB, LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.foundationdb.server.types.mcompat.mfuncs;
import com.foundationdb.server.types.LazyList;
import com.foundationdb.server.types.TClass;
import com.foundationdb.server.types.TExecutionContext;
import com.foundationdb.server.types.TInstance;
import com.foundationdb.server.types.TScalar;
import com.foundationdb.server.types.TOverloadResult;
import com.foundationdb.server.types.mcompat.mtypes.MApproximateNumber;
import com.foundationdb.server.types.mcompat.mtypes.MNumeric;
import com.foundationdb.server.types.mcompat.mtypes.MString;
import com.foundationdb.server.types.value.ValueSource;
import com.foundationdb.server.types.value.ValueTarget;
import com.foundationdb.server.types.texpressions.TInputSetBuilder;
import com.foundationdb.server.types.texpressions.TScalarBase;
public final class MField extends TScalarBase {
public static final TScalar[] exactOverloads = new TScalar[] {
// From the MySQL docs:
//
// If all arguments to FIELD() are strings, all arguments are compared as strings.
// If all arguments are numbers, they are compared as numbers.
// Otherwise, the arguments are compared as double.
//
// We can accomplish this by having three ScalarsGroups. The first consist of VARCHAR and CHAR. We want
// more than one TScalar in this group, so that same-type-at is false and it's not automatically picked.
// Only the various string types are strongly castable to either of these, so that takes care of the first
// sentence in the FIELD spec (as quoted above). The second ScalarsGroup consists of exact numbers. We
// provide these in four flavors: signed and unsigned of BIGINT and DECIMAL. This lets us cover all of the
// exact precision types without expensive casts (casts between non-DECIMAL ints are cheap). Finally,
// the DOUBLE overload is in a ScalarsGroup by itself, so that same-type-at is true and the scalar
// is always picked.
new MField(MString.VARCHAR, false, 1),
new MField(MString.CHAR, false, 1),
new MField(MNumeric.BIGINT, false, 2),
new MField(MNumeric.BIGINT_UNSIGNED, false, 2),
new MField(MNumeric.DECIMAL, false, 2),
new MField(MNumeric.DECIMAL_UNSIGNED, false, 2),
new MField(MApproximateNumber.DOUBLE, false, 3)
};
@Override
protected void buildInputSets(TInputSetBuilder builder) {
builder.setExact(exact).vararg(targetClass, 0, 1);
}
@Override
protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output) {
ValueSource needle = inputs.get(0);
int result = 0;
if (!needle.isNull()) {
TInstance needleInstance = context.inputTypeAt(0);
for (int i = 1, size = inputs.size(); i < size; ++i) {
ValueSource arg = inputs.get(i);
if (!arg.isNull()) {
TInstance argInstance = context.inputTypeAt(i);
int cmp = TClass.compare(needleInstance, needle, argInstance, arg);
if (cmp == 0) {
result = i;
break;
}
}
}
}
output.putInt32(result);
}
@Override
public String displayName() {
return "FIELD";
}
@Override
public TOverloadResult resultType() {
return TOverloadResult.fixed(MNumeric.INT, 3);
}
@Override
public int[] getPriorities() {
return new int[] { priority };
}
@Override
protected boolean nullContaminates(int inputIndex) {
return false;
}
private MField(TClass targetClass, boolean exact, int maxPriority) {
this.targetClass = targetClass;
this.exact = exact;
this.priority = maxPriority;
}
private final TClass targetClass;
private final int priority;
private final boolean exact;
}