platform/boot/src/com/intellij/lang/properties/charset/Native2AsciiCharsetEncoder.java

/*
 * Copyright 2000-2012 JetBrains s.r.o.
 *
 * 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.intellij.lang.properties.charset;

/**
 * @author Alexey
 */

import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.nio.charset.Charset;
import java.nio.CharBuffer;
import java.nio.ByteBuffer;
import java.nio.BufferUnderflowException;
import java.nio.BufferOverflowException;

class Native2AsciiCharsetEncoder extends CharsetEncoder {

  @SuppressWarnings("UseOfArchaicSystemPropertyAccessors")
  private static final char ANCHOR = Boolean.getBoolean("idea.native2ascii.lowercase") ? 'a' : 'A';
  
  private final Charset myBaseCharset;

  public Native2AsciiCharsetEncoder(Native2AsciiCharset charset) {
    super(charset, 1, 6);
    myBaseCharset = charset.getBaseCharset();
  }

  protected CoderResult encodeLoop(CharBuffer in, ByteBuffer out) {
    while (in.position() < in.limit()) {
      in.mark();
      try {
        char c = in.get();
        if (c < '\u0080') {
          ByteBuffer byteBuffer = myBaseCharset.encode(Character.toString(c));
          out.put(byteBuffer);
        }
        else {
          if (out.remaining() < 6) throw new BufferOverflowException();
          out.put((byte)'\\');
          out.put((byte)'u');
          out.put(toHexChar(c >> 12));
          out.put(toHexChar((c >> 8) & 0xf));
          out.put(toHexChar((c >> 4) & 0xf));
          out.put(toHexChar(c & 0xf));
        }
      }
      catch (BufferUnderflowException e) {
        in.reset();
      }
      catch (BufferOverflowException e) {
        in.reset();
        return CoderResult.OVERFLOW;
      }
    }
    return CoderResult.UNDERFLOW;
  }

  private static byte toHexChar(int digit) {
    if (digit < 10) {
      return (byte)('0' + digit);
    }
    return (byte)(ANCHOR - 10 + digit);
  }
}