/**
* 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.qp.operator;
import com.foundationdb.qp.row.ProjectedRow;
import com.foundationdb.qp.row.Row;
import com.foundationdb.qp.rowtype.ProjectedRowType;
import com.foundationdb.qp.rowtype.ProjectedTableRowType;
import com.foundationdb.qp.rowtype.RowType;
import com.foundationdb.server.explain.*;
import com.foundationdb.server.types.TInstance;
import com.foundationdb.server.types.texpressions.TEvaluatableExpression;
import com.foundationdb.server.types.texpressions.TPreparedExpression;
import com.foundationdb.util.ArgumentValidation;
import com.foundationdb.util.tap.InOutTap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.*;
/**
<h1>Overview</h1>
Project_Default computes fields from input rows. It only operates on rows of one specified type. Rows of other
types are passed through without modification. A common usage is to keep some columns from rows of the specified
type and to discard others, but the projection is on expressions, not columns.
<h1>Arguments</h1>
<li><b>RowType rowType:</b> Type of rows to be projected. Must be non-null.
<li><b>List<Expression> projections:</b> Expressions computing fields of output rows. Must be non-null and non-empty.
<h1>Behavior</h1>
A row of the specified rowType is projected. Each expression is evaluted using the row as input. The
(scalar) outputs from these expressions form a row which is passed to the output stream.
Rows of other types are passed through from the input stream to the output stream.
<h1>Output</h1>
A projected row has a null hkey.
<h1>Assumptions</h1>
None.
<h1>Performance</h1>
Project_Default does no IO. For each input row, the type is checked and each output field is computed.
<h1>Memory Requirements</h1>
None.
*/
class Project_Default extends Operator
{
// Object interface
@Override
public String toString()
{
if (projectType.hasTable()) {
return String.format("project to table %s (%s)", projectType.table(), pExpressions.toString());
} else {
return String.format("project(%s)", pExpressions.toString());
}
}
// Operator interface
@Override
protected Cursor cursor(QueryContext context, QueryBindingsCursor bindingsCursor)
{
return new Execution(context, inputOperator.cursor(context, bindingsCursor));
}
@Override
public ProjectedRowType rowType()
{
return projectType;
}
@Override
public void findDerivedTypes(Set<RowType> derivedTypes)
{
inputOperator.findDerivedTypes(derivedTypes);
derivedTypes.add(projectType);
}
@Override
public List<Operator> getInputOperators()
{
return Collections.singletonList(inputOperator);
}
@Override
public String describePlan()
{
return describePlan(inputOperator);
}
// Project_Default interface
public Project_Default(Operator inputOperator, RowType rowType, List<? extends TPreparedExpression> pExpressions)
{
ArgumentValidation.notNull("rowType", rowType);
ArgumentValidation.notEmpty("new projections", pExpressions);
this.inputOperator = inputOperator;
this.rowType = rowType;
this.pExpressions = pExpressions;
this.projectType = rowType.schema().newProjectType(pExpressions);
}
// Project_Default constructor, returns ProjectedTableRowType rows
public Project_Default(Operator inputOperator, RowType inputRowType,
RowType projectTableRowType, List<? extends TPreparedExpression> pExpressions)
{
ArgumentValidation.notNull("inputRowType", inputRowType);
ArgumentValidation.notEmpty("new projections", pExpressions);
this.inputOperator = inputOperator;
this.rowType = inputRowType;
ArgumentValidation.notNull("projectRowType", projectTableRowType);
ArgumentValidation.isTrue("RowType has Table", projectTableRowType.hasTable());
projectType = new ProjectedTableRowType(projectTableRowType.schema(),
projectTableRowType.table(),
pExpressions);
this.pExpressions = pExpressions; // TODO defensively copy once the old expressions are gone (until then, this may NPE)
}
// Class state
private static final InOutTap TAP_OPEN = OPERATOR_TAP.createSubsidiaryTap("operator: Project_Default open");
private static final InOutTap TAP_NEXT = OPERATOR_TAP.createSubsidiaryTap("operator: Project_Default next");
private static final Logger LOG = LoggerFactory.getLogger(Project_Default.class);
// Object state
protected final Operator inputOperator;
protected final RowType rowType;
private final List<? extends TPreparedExpression> pExpressions;
protected ProjectedRowType projectType;
@Override
public CompoundExplainer getExplainer(ExplainContext context)
{
Attributes att = new Attributes();
att.put(Label.NAME, PrimitiveExplainer.getInstance(getName()));
if (projectType.hasTable())
att.put(Label.PROJECT_OPTION, projectType.getExplainer(context));
att.put(Label.INPUT_OPERATOR, inputOperator.getExplainer(context));
for (TPreparedExpression ex : pExpressions)
att.put(Label.PROJECTION, ex.getExplainer(context));
if (context.hasExtraInfo(this))
att.putAll(context.getExtraInfo(this).get());
return new CompoundExplainer(Type.PROJECT, att);
}
// Inner classes
private class Execution extends ChainedCursor
{
// Cursor interface
@Override
public void open()
{
TAP_OPEN.in();
try {
super.open();
} finally {
TAP_OPEN.out();
}
}
@Override
public Row next()
{
if (TAP_NEXT_ENABLED) {
TAP_NEXT.in();
}
try {
if (CURSOR_LIFECYCLE_ENABLED) {
CursorLifecycle.checkIdleOrActive(this);
}
checkQueryCancelation();
Row projectedRow = null;
Row inputRow;
if ((inputRow = input.next()) != null) {
projectedRow =
inputRow.rowType() == rowType
? new ProjectedRow(projectType, inputRow, context, bindings, pEvalExpr)
: inputRow;
}
if (projectedRow == null) {
setIdle();
}
if (LOG_EXECUTION) {
LOG.debug("Project_Default: yield {}", projectedRow);
}
return projectedRow;
} finally {
if (TAP_NEXT_ENABLED) {
TAP_NEXT.out();
}
}
}
// Execution interface
Execution(QueryContext context, Cursor input)
{
super(context, input);
// one list of evaluatables per execution
if (pExpressions != null)
pEvalExpr = ProjectedRow.createTEvaluatableExpressions(pExpressions);
else
pEvalExpr = null;
}
// Object state
private List<TEvaluatableExpression> pEvalExpr = null;
}
}