/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.sql.planner.assertions;
import com.facebook.presto.Session;
import com.facebook.presto.metadata.Metadata;
import com.facebook.presto.sql.parser.SqlParser;
import com.facebook.presto.sql.planner.Symbol;
import com.facebook.presto.sql.planner.plan.ApplyNode;
import com.facebook.presto.sql.planner.plan.PlanNode;
import com.facebook.presto.sql.planner.plan.ProjectNode;
import com.facebook.presto.sql.tree.Expression;
import com.google.common.collect.ImmutableList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.stream.Collectors;
import static com.facebook.presto.sql.ExpressionUtils.rewriteIdentifiersToSymbolReferences;
import static com.google.common.base.Preconditions.checkState;
import static java.util.Objects.requireNonNull;
public class ExpressionMatcher
implements RvalueMatcher
{
private final String sql;
private final Expression expression;
public ExpressionMatcher(String expression)
{
this.sql = requireNonNull(expression);
this.expression = expression(requireNonNull(expression));
}
private Expression expression(String sql)
{
SqlParser parser = new SqlParser();
return rewriteIdentifiersToSymbolReferences(parser.createExpression(sql));
}
@Override
public Optional<Symbol> getAssignedSymbol(PlanNode node, Session session, Metadata metadata, SymbolAliases symbolAliases)
{
Optional<Symbol> result = Optional.empty();
ImmutableList.Builder<Expression> matchesBuilder = ImmutableList.builder();
Map<Symbol, Expression> assignments = getAssignments(node);
if (assignments == null) {
return result;
}
ExpressionVerifier verifier = new ExpressionVerifier(symbolAliases);
for (Map.Entry<Symbol, Expression> assignment : assignments.entrySet()) {
if (verifier.process(assignment.getValue(), expression)) {
result = Optional.of(assignment.getKey());
matchesBuilder.add(assignment.getValue());
}
}
List<Expression> matches = matchesBuilder.build();
checkState(matches.size() < 2, "Ambiguous expression %s matches multiple assignments", expression,
(matches.stream().map(Expression::toString).collect(Collectors.joining(", "))));
return result;
}
private static Map<Symbol, Expression> getAssignments(PlanNode node)
{
if (node instanceof ProjectNode) {
ProjectNode projectNode = (ProjectNode) node;
return projectNode.getAssignments().getMap();
}
else if (node instanceof ApplyNode) {
ApplyNode applyNode = (ApplyNode) node;
return applyNode.getSubqueryAssignments().getMap();
}
else {
return null;
}
}
@Override
public String toString()
{
return sql;
}
}