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SQL support for Querydsl
There is a newer version: 6.9
/*
 * Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
 *
 * 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.querydsl.sql;

import com.querydsl.core.types.EntityPath;
import com.querydsl.core.types.Path;
import java.io.Serializable;
import java.util.Objects;

/** Provides metadata like the column name, JDBC type and constraints */
public final class ColumnMetadata implements Serializable {

  private static final long serialVersionUID = -5678865742525938470L;

  /**
   * Returns this path's column metadata if present. Otherwise returns default metadata where the
   * column name is equal to the path's name.
   */
  public static ColumnMetadata getColumnMetadata(Path path) {
    Path parent = path.getMetadata().getParent();
    if (parent instanceof EntityPath) {
      Object columnMetadata = ((EntityPath) parent).getMetadata(path);
      if (columnMetadata instanceof ColumnMetadata) {
        return (ColumnMetadata) columnMetadata;
      }
    }
    return ColumnMetadata.named(path.getMetadata().getName());
  }

  /**
   * Extract the column name for the given path, returns the path name, if no ColumnMetadata is
   * attached
   *
   * @param path patch
   * @return column name or path name
   */
  public static String getName(Path path) {
    Path parent = path.getMetadata().getParent();
    if (parent instanceof EntityPath) {
      Object columnMetadata = ((EntityPath) parent).getMetadata(path);
      if (columnMetadata instanceof ColumnMetadata) {
        return ((ColumnMetadata) columnMetadata).getName();
      }
    }
    return path.getMetadata().getName();
  }

  /**
   * Creates default column meta data with the given column name, but without any type or constraint
   * information. Use the fluent builder methods to further configure it.
   *
   * @throws NullPointerException if the name is null
   */
  public static ColumnMetadata named(String name) {
    return new ColumnMetadata(null, name, null, true, UNDEFINED, UNDEFINED);
  }

  private static final int UNDEFINED = -1;

  private final String name;

  private final Integer index;

  private final Integer jdbcType;

  private final boolean nullable;

  private final int size;

  private final int decimalDigits;

  private ColumnMetadata(
      Integer index, String name, Integer jdbcType, boolean nullable, int size, int decimalDigits) {
    this.index = index;
    this.name = name;
    this.jdbcType = jdbcType;
    this.nullable = nullable;
    this.size = size;
    this.decimalDigits = decimalDigits;
  }

  public String getName() {
    return name;
  }

  public int getIndex() {
    return index;
  }

  public ColumnMetadata withIndex(int index) {
    return new ColumnMetadata(index, name, jdbcType, nullable, size, decimalDigits);
  }

  public int getJdbcType() {
    return jdbcType;
  }

  public boolean hasJdbcType() {
    return jdbcType != null;
  }

  public ColumnMetadata ofType(int jdbcType) {
    return new ColumnMetadata(index, name, jdbcType, nullable, size, decimalDigits);
  }

  public boolean isNullable() {
    return nullable;
  }

  public ColumnMetadata notNull() {
    return new ColumnMetadata(index, name, jdbcType, false, size, decimalDigits);
  }

  /**
   * For char or date types this is the maximum number of characters, for numeric or decimal types
   * this is precision.
   *
   * @return size
   */
  public int getSize() {
    return size;
  }

  public boolean hasSize() {
    return size != UNDEFINED;
  }

  public ColumnMetadata withSize(int size) {
    return new ColumnMetadata(index, name, jdbcType, nullable, size, decimalDigits);
  }

  /**
   * the number of fractional digits
   *
   * @return digits
   */
  public int getDigits() {
    return decimalDigits;
  }

  public boolean hasDigits() {
    return decimalDigits != UNDEFINED;
  }

  public ColumnMetadata withDigits(int decimalDigits) {
    return new ColumnMetadata(index, name, jdbcType, nullable, size, decimalDigits);
  }

  @Override
  public boolean equals(Object o) {
    if (o == this) {
      return true;
    } else if (o instanceof ColumnMetadata) {
      ColumnMetadata md = (ColumnMetadata) o;
      return name.equals(md.name)
          && Objects.equals(jdbcType, md.jdbcType)
          && nullable == md.nullable
          && size == md.size
          && decimalDigits == md.decimalDigits;
    } else {
      return false;
    }
  }

  @Override
  public int hashCode() {
    return name.hashCode();
  }
}