/**
* 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.common.funcs;
import com.foundationdb.server.types.LazyList;
import com.foundationdb.server.types.TClass;
import com.foundationdb.server.types.TCustomOverloadResult;
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.TPreptimeContext;
import com.foundationdb.server.types.TPreptimeValue;
import com.foundationdb.server.types.common.types.StringAttribute;
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;
import java.util.List;
public abstract class Substring extends TScalarBase
{
public static TScalar[] create(TClass strType, TClass intType)
{
return new TScalar[]
{
new Substring(strType, intType, new int[] {1}) // 2 args: SUBSTR(<STRING>, <OFFSET>)
{
@Override
protected Integer getLength(LazyList<? extends ValueSource> inputs)
{
return null;
}
},
new Substring(strType, intType, new int[] {1, 2}) // 3 args: SUBSTR(<STRING>, <OFFSET>, <LENGTH>)
{
@Override
protected Integer getLength(LazyList<? extends ValueSource> inputs)
{
return inputs.get(2).getInt32();
}
},
};
}
protected abstract Integer getLength (LazyList<? extends ValueSource> inputs);
private final TClass strType;
private final TClass intType;
private final int covering[];
private Substring(TClass strType, TClass intType, int covering[])
{
this.strType = strType;
this.intType = intType;
this.covering = covering;
}
@Override
protected void buildInputSets(TInputSetBuilder builder)
{
builder.covers(strType, 0).covers(intType, covering);
}
@Override
protected void doEvaluate(TExecutionContext context, LazyList<? extends ValueSource> inputs, ValueTarget output)
{
output.putString(getSubstr(inputs.get(0).getString(),
inputs.get(1).getInt32(),
getLength(inputs)),
null);
}
@Override
public String displayName()
{
return "SUBSTRING";
}
@Override
public String[] registeredNames()
{
return new String[] {"SUBSTRING", "SUBSTR", "MID"};
}
@Override
public TOverloadResult resultType()
{
return TOverloadResult.custom(new TCustomOverloadResult()
{
@Override
public TInstance resultInstance(List<TPreptimeValue> inputs, TPreptimeContext context)
{
int strLength = inputs.get(0).type().attribute(StringAttribute.MAX_LENGTH);
// usage: SUBSTR (<STRING> , <OFFSET> [, <LENGTH>] )
int length = strLength;
ValueSource lenArg;
// check if <LENGTH> is available
if (inputs.size() == 3 && (lenArg = inputs.get(2).value()) != null
&& !lenArg.isNull()) {
length = lenArg.getInt32();
}
return strType.instance(length > strLength ? strLength : length, anyContaminatingNulls(inputs));
}
});
}
private static String getSubstr(String st, int from, Integer length) {
// if str is empty or <from> and <length> is outside of reasonable index
//
// Note negative index is acceptable for <from>, but its absolute value has
// to be within [1, str.length] (mysql index starts at 1)
if (st.isEmpty() || from == 0 || (length != null && length <= 0)) {
return "";
}
try {
if (from < 0) {
from = st.offsetByCodePoints(st.length(), from);
} else {
from = st.offsetByCodePoints(0, from - 1);
}
}
catch (IndexOutOfBoundsException ex) {
return "";
}
if (length == null) {
return st.substring(from);
}
int to;
try {
to = st.offsetByCodePoints(from, length);
} catch (IndexOutOfBoundsException ex) {
to = st.length();
}
return st.substring(from, to);
}
}