HHH-14728 Include CamelCaseToUnderscoresNamingStrategy from Spring Boot

hibernate-core/src/main/java/org/hibernate/boot/model/naming/CamelCaseToUnderscoresNamingStrategy.java

@@ -0,0 +1,92 @@
+/*
+ * 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.boot.model.naming;
+
+import java.util.Locale;
+
+import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;
+
+/**
+ * Originally copied from Spring Boot as this strategy is popular there
+ * (original name is SpringPhysicalNamingStrategy).
+ *
+ * @author Phillip Webb
+ * @author Madhura Bhave
+ */
+public class CamelCaseToUnderscoresNamingStrategy implements PhysicalNamingStrategy {
+
+	@Override
+	public Identifier toPhysicalCatalogName(Identifier name, JdbcEnvironment jdbcEnvironment) {
+		return apply( name, jdbcEnvironment );
+	}
+
+	@Override
+	public Identifier toPhysicalSchemaName(Identifier name, JdbcEnvironment jdbcEnvironment) {
+		return apply( name, jdbcEnvironment );
+	}
+
+	@Override
+	public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment jdbcEnvironment) {
+		return apply( name, jdbcEnvironment );
+	}
+
+	@Override
+	public Identifier toPhysicalSequenceName(Identifier name, JdbcEnvironment jdbcEnvironment) {
+		return apply( name, jdbcEnvironment );
+	}
+
+	@Override
+	public Identifier toPhysicalColumnName(Identifier name, JdbcEnvironment jdbcEnvironment) {
+		return apply( name, jdbcEnvironment );
+	}
+
+	private Identifier apply(final Identifier name, final JdbcEnvironment jdbcEnvironment) {
+		if ( name == null ) {
+			return null;
+		}
+		StringBuilder builder = new StringBuilder( name.getText().replace( '.', '_' ) );
+		for ( int i = 1; i < builder.length() - 1; i++ ) {
+			if ( isUnderscoreRequired( builder.charAt( i - 1 ), builder.charAt( i ), builder.charAt( i + 1 ) ) ) {
+				builder.insert( i++, '_' );
+			}
+		}
+		return getIdentifier( builder.toString(), name.isQuoted(), jdbcEnvironment );
+	}
+
+	/**
+	 * Get an identifier for the specified details. By default this method will return an identifier
+	 * with the name adapted based on the result of {@link #isCaseInsensitive(JdbcEnvironment)}
+	 *
+	 * @param name the name of the identifier
+	 * @param quoted if the identifier is quoted
+	 * @param jdbcEnvironment the JDBC environment
+	 *
+	 * @return an identifier instance
+	 */
+	protected Identifier getIdentifier(String name, final boolean quoted, final JdbcEnvironment jdbcEnvironment) {
+		if ( isCaseInsensitive( jdbcEnvironment ) ) {
+			name = name.toLowerCase( Locale.ROOT );
+		}
+		return new Identifier( name, quoted );
+	}
+
+	/**
+	 * Specify whether the database is case sensitive.
+	 *
+	 * @param jdbcEnvironment the JDBC environment which can be used to determine case
+	 *
+	 * @return true if the database is case insensitive sensitivity
+	 */
+	protected boolean isCaseInsensitive(JdbcEnvironment jdbcEnvironment) {
+		return true;
+	}
+
+	private boolean isUnderscoreRequired(final char before, final char current, final char after) {
+		return Character.isLowerCase( before ) && Character.isUpperCase( current ) && Character.isLowerCase( after );
+	}
+
+}