EqlQueryIntrospector.java

/*
 * Copyright 2024-2025 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.data.jpa.repository.query;

import static org.springframework.data.jpa.repository.query.QueryTokens.*;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.jspecify.annotations.Nullable;

/**
 * {@link ParsedQueryIntrospector} for EQL queries.
 *
 * @author Mark Paluch
 * @author Christoph Strobl
 */
@SuppressWarnings("UnreachableCode")
class EqlQueryIntrospector extends EqlBaseVisitor<Void> implements ParsedQueryIntrospector<QueryInformation> {

	private final EqlQueryRenderer renderer = new EqlQueryRenderer();

	private @Nullable String primaryFromAlias = null;
	private @Nullable List<QueryToken> projection;
	private boolean projectionProcessed;
	private boolean hasConstructorExpression = false;

	@Override
	public QueryInformation getParsedQueryInformation() {
		return new QueryInformation(primaryFromAlias, projection == null ? Collections.emptyList() : projection,
				hasConstructorExpression);
	}

	@Override
	public Void visitSelect_clause(EqlParser.Select_clauseContext ctx) {

		if (!projectionProcessed) {
			projection = captureSelectItems(ctx.select_item(), renderer);
			projectionProcessed = true;
		}

		return super.visitSelect_clause(ctx);
	}

	@Override
	public Void visitRange_variable_declaration(EqlParser.Range_variable_declarationContext ctx) {

		if (primaryFromAlias == null && ctx.identification_variable() != null && !EqlQueryRenderer.isSubquery(ctx)
				&& !EqlQueryRenderer.isSetQuery(ctx)) {
			primaryFromAlias = ctx.identification_variable().getText();
		}

		return super.visitRange_variable_declaration(ctx);
	}

	@Override
	public Void visitConstructor_expression(EqlParser.Constructor_expressionContext ctx) {

		hasConstructorExpression = true;
		return super.visitConstructor_expression(ctx);
	}

	private static List<QueryToken> captureSelectItems(List<EqlParser.Select_itemContext> selections,
			EqlQueryRenderer itemRenderer) {

		List<QueryToken> selectItemTokens = new ArrayList<>(selections.size() * 2);
		for (EqlParser.Select_itemContext selection : selections) {

			if (!selectItemTokens.isEmpty()) {
				selectItemTokens.add(TOKEN_COMMA);
			}

			selectItemTokens.add(QueryTokens.token(QueryRenderer.from(itemRenderer.visitSelect_item(selection)).render()));
		}
		return selectItemTokens;
	}

}