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PostgreSQL JDBC - NG - Driver
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/**
 * Copyright (c) 2013, impossibl.com
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  * Neither the name of impossibl.com nor the names of its contributors may
 *    be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package com.impossibl.postgres.system;

public class Identifier {

  /**
   * Quote an identifier if its required.
   *
   * Attempts to do so creating no garbage when not needing a quote.
   *
   * @param ident Identifier to quote, if necessary
   * @return Quoted version of {@code ident}
   */
  public static String quoteIfNeeded(String ident) {

    int first = ident.codePointAt(0);
    int firstType = Character.getType(first);
    StringBuilder bldr = null;
    if (firstType != Character.LOWERCASE_LETTER && first != '_') {
      bldr = new StringBuilder("\"").appendCodePoint(first);
    }

    for (int idx = 1; idx < ident.length(); ++idx) {
      int ch = ident.codePointAt(idx);
      switch (Character.getType(ch)) {
        case Character.LOWERCASE_LETTER:
        case Character.DECIMAL_DIGIT_NUMBER:
          if (bldr == null) continue;
        default:
          switch (ch) {
            case '_':
              if (bldr == null) continue;
              bldr.appendCodePoint(ch);
              break;
            case '"':
              if (bldr == null) bldr = new StringBuilder("\"").append(ident, 0, idx);
              bldr.append('"').append('"');
              break;
            default:
              if (bldr == null) bldr = new StringBuilder("\"").append(ident, 0, idx);
              bldr.appendCodePoint(ch);
          }
      }
    }

    return bldr == null ? ident : bldr.append('"').toString();
  }

}