| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.flink.table.operations.utils; |
| |
| import org.apache.flink.annotation.Internal; |
| import org.apache.flink.table.api.TableException; |
| import org.apache.flink.table.api.ValidationException; |
| import org.apache.flink.table.catalog.ResolvedSchema; |
| import org.apache.flink.table.expressions.CallExpression; |
| import org.apache.flink.table.expressions.Expression; |
| import org.apache.flink.table.expressions.FieldReferenceExpression; |
| import org.apache.flink.table.expressions.LocalReferenceExpression; |
| import org.apache.flink.table.expressions.ResolvedExpression; |
| import org.apache.flink.table.expressions.TableReferenceExpression; |
| import org.apache.flink.table.expressions.ValueLiteralExpression; |
| import org.apache.flink.table.expressions.resolver.ExpressionResolver; |
| import org.apache.flink.table.expressions.utils.ResolvedExpressionDefaultVisitor; |
| import org.apache.flink.table.functions.BuiltInFunctionDefinitions; |
| import org.apache.flink.table.functions.FunctionDefinition; |
| import org.apache.flink.table.operations.ProjectQueryOperation; |
| import org.apache.flink.table.operations.QueryOperation; |
| import org.apache.flink.table.types.DataType; |
| import org.apache.flink.table.types.logical.LogicalType; |
| |
| import java.util.LinkedHashSet; |
| import java.util.List; |
| import java.util.Optional; |
| import java.util.Set; |
| import java.util.stream.Collectors; |
| import java.util.stream.IntStream; |
| |
| import static org.apache.flink.table.functions.BuiltInFunctionDefinitions.AS; |
| import static org.apache.flink.table.functions.BuiltInFunctionDefinitions.CAST; |
| import static org.apache.flink.table.functions.BuiltInFunctionDefinitions.GET; |
| import static org.apache.flink.table.operations.utils.OperationExpressionsUtils.extractName; |
| import static org.apache.flink.table.operations.utils.OperationExpressionsUtils.extractNames; |
| import static org.apache.flink.table.types.logical.LogicalTypeRoot.INTEGER; |
| |
| /** Utility class for creating valid {@link ProjectQueryOperation} operation. */ |
| @Internal |
| final class ProjectionOperationFactory { |
| |
| private final TransitiveExtractNameVisitor extractTransitiveNameVisitor = |
| new TransitiveExtractNameVisitor(); |
| private final StripAliases stripAliases = new StripAliases(); |
| private int currentFieldIndex = 0; |
| |
| QueryOperation create( |
| List<ResolvedExpression> projectList, |
| QueryOperation child, |
| boolean explicitAlias, |
| ExpressionResolver.PostResolverFactory postResolverFactory) { |
| |
| final NamingVisitor namingVisitor = new NamingVisitor(postResolverFactory); |
| |
| final List<ResolvedExpression> namedExpressions = |
| nameExpressions(namingVisitor, projectList); |
| String[] fieldNames = validateAndGetUniqueNames(namedExpressions); |
| |
| final List<ResolvedExpression> finalExpression; |
| if (explicitAlias) { |
| finalExpression = namedExpressions; |
| } else { |
| finalExpression = |
| namedExpressions.stream() |
| .map(expr -> expr.accept(stripAliases)) |
| .collect(Collectors.toList()); |
| } |
| |
| DataType[] fieldTypes = |
| namedExpressions.stream() |
| .map(ResolvedExpression::getOutputDataType) |
| .toArray(DataType[]::new); |
| |
| return new ProjectQueryOperation( |
| finalExpression, child, ResolvedSchema.physical(fieldNames, fieldTypes)); |
| } |
| |
| private String[] validateAndGetUniqueNames(List<ResolvedExpression> namedExpressions) { |
| // we need to maintain field names order to match with types |
| final Set<String> names = new LinkedHashSet<>(); |
| |
| extractNames(namedExpressions).stream() |
| .map( |
| name -> |
| name.orElseThrow( |
| () -> |
| new TableException( |
| "Could not name a field in a projection."))) |
| .forEach( |
| name -> { |
| if (!names.add(name)) { |
| throw new ValidationException("Ambiguous column name: " + name); |
| } |
| }); |
| |
| return names.toArray(new String[0]); |
| } |
| |
| /** |
| * Ensures that all expressions have a derivable name. There is a few categories and naming |
| * rules that apply: |
| * |
| * <ul> |
| * <li>{@link FieldReferenceExpression}, {@link TableReferenceExpression}, {@link |
| * LocalReferenceExpression} and {@link BuiltInFunctionDefinitions#AS} are already named} |
| * <li>{@link BuiltInFunctionDefinitions#CAST} use the name of underlying expression appended |
| * with the name of the type |
| * <li>{@link BuiltInFunctionDefinitions#GET} uses pattern <i>[underlying name][$fieldName]{1, |
| * }</i> |
| * <li>if none of the above apply a name <i>[_c(idx)]</i> is used where idx is the index |
| * within given expressions |
| * </ul> |
| */ |
| private List<ResolvedExpression> nameExpressions( |
| NamingVisitor namingVisitor, List<ResolvedExpression> expression) { |
| return IntStream.range(0, expression.size()) |
| .mapToObj( |
| idx -> { |
| currentFieldIndex = idx; |
| return expression.get(idx).accept(namingVisitor); |
| }) |
| .collect(Collectors.toList()); |
| } |
| |
| private class NamingVisitor extends ResolvedExpressionDefaultVisitor<ResolvedExpression> { |
| |
| private ExpressionResolver.PostResolverFactory postResolverFactory; |
| |
| public NamingVisitor(ExpressionResolver.PostResolverFactory postResolverFactory) { |
| this.postResolverFactory = postResolverFactory; |
| } |
| |
| @Override |
| public ResolvedExpression visit(CallExpression call) { |
| FunctionDefinition functionDefinition = call.getFunctionDefinition(); |
| final Optional<String> rename; |
| if (functionDefinition == CAST) { |
| rename = nameForCast(call); |
| } else if (functionDefinition == GET) { |
| rename = nameForGet(call); |
| } else if (functionDefinition == AS) { |
| rename = Optional.empty(); |
| } else { |
| rename = Optional.of(getUniqueName()); |
| } |
| |
| return rename.map(name -> postResolverFactory.as(call, name)).orElse(call); |
| } |
| |
| private Optional<String> nameForGet(CallExpression call) { |
| return Optional.of( |
| call.accept(extractTransitiveNameVisitor) |
| .orElseGet(ProjectionOperationFactory.this::getUniqueName)); |
| } |
| |
| private Optional<String> nameForCast(CallExpression call) { |
| Optional<String> innerName = |
| call.getChildren().get(0).accept(extractTransitiveNameVisitor); |
| Expression type = call.getChildren().get(1); |
| return Optional.of( |
| innerName |
| .map(n -> String.format("%s-%s", n, type)) |
| .orElseGet(ProjectionOperationFactory.this::getUniqueName)); |
| } |
| |
| @Override |
| public ResolvedExpression visit(ValueLiteralExpression valueLiteral) { |
| return postResolverFactory.as(valueLiteral, getUniqueName()); |
| } |
| |
| @Override |
| public ResolvedExpression visit(ResolvedExpression other) { |
| return postResolverFactory.as(other, getUniqueName()); |
| } |
| |
| @Override |
| protected ResolvedExpression defaultMethod(ResolvedExpression expression) { |
| return expression; |
| } |
| } |
| |
| private static class StripAliases extends ResolvedExpressionDefaultVisitor<ResolvedExpression> { |
| |
| @Override |
| public ResolvedExpression visit(CallExpression call) { |
| if (call.getFunctionDefinition() == AS) { |
| return call.getResolvedChildren().get(0).accept(this); |
| } else { |
| return call; |
| } |
| } |
| |
| @Override |
| protected ResolvedExpression defaultMethod(ResolvedExpression expression) { |
| return expression; |
| } |
| } |
| |
| private static class TransitiveExtractNameVisitor |
| extends ResolvedExpressionDefaultVisitor<Optional<String>> { |
| |
| @Override |
| public Optional<String> visit(CallExpression call) { |
| if (call.getFunctionDefinition() == GET) { |
| return extractNameFromGet(call); |
| } else { |
| return defaultMethod(call); |
| } |
| } |
| |
| @Override |
| protected Optional<String> defaultMethod(ResolvedExpression expression) { |
| return extractName(expression); |
| } |
| |
| private Optional<String> extractNameFromGet(CallExpression call) { |
| Expression child = call.getChildren().get(0); |
| ValueLiteralExpression key = (ValueLiteralExpression) call.getChildren().get(1); |
| |
| final LogicalType keyType = key.getOutputDataType().getLogicalType(); |
| |
| final String keySuffix; |
| if (keyType.is(INTEGER)) { |
| keySuffix = |
| "$_" |
| + key.getValueAs(Integer.class) |
| .orElseThrow( |
| () -> |
| new TableException( |
| "Integer constant excepted.")); |
| } else { |
| keySuffix = |
| "$" |
| + key.getValueAs(String.class) |
| .orElseThrow( |
| () -> |
| new TableException( |
| "Integer constant excepted.")); |
| } |
| return child.accept(this).map(p -> p + keySuffix); |
| } |
| } |
| |
| private String getUniqueName() { |
| return "_c" + currentFieldIndex++; |
| } |
| } |
