org.hibernate.community.dialect.SybaseLegacySqlAstTranslator Maven / Gradle / Ivy

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later
 * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
 */
package org.hibernate.community.dialect;

import java.util.List;
import java.util.function.Consumer;

import org.hibernate.LockMode;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.query.sqm.ComparisonOperator;
import org.hibernate.sql.ast.SqlAstNodeRenderingMode;
import org.hibernate.sql.ast.spi.AbstractSqlAstTranslator;
import org.hibernate.sql.ast.spi.SqlSelection;
import org.hibernate.sql.ast.tree.Statement;
import org.hibernate.sql.ast.tree.cte.CteStatement;
import org.hibernate.sql.ast.tree.expression.BinaryArithmeticExpression;
import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
import org.hibernate.sql.ast.tree.expression.CaseSimpleExpression;
import org.hibernate.sql.ast.tree.expression.Expression;
import org.hibernate.sql.ast.tree.expression.Literal;
import org.hibernate.sql.ast.tree.expression.SqlTuple;
import org.hibernate.sql.ast.tree.expression.Summarization;
import org.hibernate.sql.ast.tree.from.NamedTableReference;
import org.hibernate.sql.ast.tree.select.QueryPart;
import org.hibernate.sql.ast.tree.select.QuerySpec;
import org.hibernate.sql.exec.spi.JdbcOperation;

/**
 * A SQL AST translator for Sybase.
 *
 * @author Christian Beikov
 */
public class SybaseLegacySqlAstTranslator extends AbstractSqlAstTranslator {

	public SybaseLegacySqlAstTranslator(SessionFactoryImplementor sessionFactory, Statement statement) {
		super( sessionFactory, statement );
	}

	@Override
	protected boolean supportsWithClause() {
		return false;
	}

	// Sybase does not allow CASE expressions where all result arms contain plain parameters.
	// At least one result arm must provide some type context for inference,
	// so we cast the first result arm if we encounter this condition

	@Override
	protected void visitAnsiCaseSearchedExpression(
			CaseSearchedExpression caseSearchedExpression,
			Consumer resultRenderer) {
		if ( getParameterRenderingMode() == SqlAstNodeRenderingMode.DEFAULT && areAllResultsParameters( caseSearchedExpression ) ) {
			final List whenFragments = caseSearchedExpression.getWhenFragments();
			final Expression firstResult = whenFragments.get( 0 ).getResult();
			super.visitAnsiCaseSearchedExpression(
					caseSearchedExpression,
					e -> {
						if ( e == firstResult ) {
							renderCasted( e );
						}
						else {
							resultRenderer.accept( e );
						}
					}
			);
		}
		else {
			super.visitAnsiCaseSearchedExpression( caseSearchedExpression, resultRenderer );
		}
	}

	@Override
	protected void visitAnsiCaseSimpleExpression(
			CaseSimpleExpression caseSimpleExpression,
			Consumer resultRenderer) {
		if ( getParameterRenderingMode() == SqlAstNodeRenderingMode.DEFAULT && areAllResultsParameters( caseSimpleExpression ) ) {
			final List whenFragments = caseSimpleExpression.getWhenFragments();
			final Expression firstResult = whenFragments.get( 0 ).getResult();
			super.visitAnsiCaseSimpleExpression(
					caseSimpleExpression,
					e -> {
						if ( e == firstResult ) {
							renderCasted( e );
						}
						else {
							resultRenderer.accept( e );
						}
					}
			);
		}
		else {
			super.visitAnsiCaseSimpleExpression( caseSimpleExpression, resultRenderer );
		}
	}

	@Override
	protected boolean renderNamedTableReference(NamedTableReference tableReference, LockMode lockMode) {
		super.renderNamedTableReference( tableReference, lockMode );
		if ( LockMode.READ.lessThan( lockMode ) ) {
			appendSql( " holdlock" );
		}
		return true;
	}

	@Override
	protected void renderForUpdateClause(QuerySpec querySpec, ForUpdateClause forUpdateClause) {
		// Sybase does not support the FOR UPDATE clause
	}

	@Override
	public void visitOffsetFetchClause(QueryPart queryPart) {
		assertRowsOnlyFetchClauseType( queryPart );
		if ( !queryPart.isRoot() && queryPart.getOffsetClauseExpression() != null ) {
			throw new IllegalArgumentException( "Can't emulate offset clause in subquery" );
		}
	}

	@Override
	protected void renderComparison(Expression lhs, ComparisonOperator operator, Expression rhs) {
		renderComparisonEmulateIntersect( lhs, operator, rhs );
	}

	@Override
	protected void renderSelectTupleComparison(
			List lhsExpressions,
			SqlTuple tuple,
			ComparisonOperator operator) {
		emulateSelectTupleComparison( lhsExpressions, tuple.getExpressions(), operator, true );
	}

	@Override
	protected void renderPartitionItem(Expression expression) {
		if ( expression instanceof Literal ) {
			// Note that this depends on the SqmToSqlAstConverter to add a dummy table group
			appendSql( "dummy_.x" );
		}
		else if ( expression instanceof Summarization ) {
			// This could theoretically be emulated by rendering all grouping variations of the query and
			// connect them via union all but that's probably pretty inefficient and would have to happen
			// on the query spec level
			throw new UnsupportedOperationException( "Summarization is not supported by DBMS" );
		}
		else {
			expression.accept( this );
		}
	}

	@Override
	public void visitBinaryArithmeticExpression(BinaryArithmeticExpression arithmeticExpression) {
		appendSql( OPEN_PARENTHESIS );
		arithmeticExpression.getLeftHandOperand().accept( this );
		appendSql( arithmeticExpression.getOperator().getOperatorSqlTextString() );
		arithmeticExpression.getRightHandOperand().accept( this );
		appendSql( CLOSE_PARENTHESIS );
	}

	@Override
	protected boolean supportsRowValueConstructorSyntax() {
		return false;
	}

	@Override
	protected boolean supportsRowValueConstructorSyntaxInInList() {
		return false;
	}

	@Override
	protected boolean supportsRowValueConstructorSyntaxInQuantifiedPredicates() {
		return false;
	}

	@Override
	protected boolean needsRowsToSkip() {
		return true;
	}

	@Override
	protected boolean needsMaxRows() {
		return true;
	}
}