WriterCharAppender.java
/*******************************************************************************
* Copyright 2014 Univocity Software Pty Ltd
*
* 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.univocity.parsers.common.input;
import com.univocity.parsers.common.*;
import java.io.*;
/**
* Extension of the {@link DefaultCharAppender} class to include facilities for writing to an output. Used by writers extending {@link AbstractWriter}.
*
* <p> This class introduces the handling of the normalized newline character defined in {@link Format#getNormalizedNewline()} and converts it to the newline sequence in {@link Format#getLineSeparator()}
* <p> It also introduces methods to write to an instance of {@link java.io.Writer} directly to avoid unnecessary String instantiations.
*
* @author Univocity Software Pty Ltd - <a href="mailto:parsers@univocity.com">parsers@univocity.com</a>
* @see com.univocity.parsers.common.Format
* @see com.univocity.parsers.common.AbstractWriter
*/
public class WriterCharAppender extends ExpandingCharAppender {
private final char lineSeparator1;
private final char lineSeparator2;
private final char newLine;
private boolean denormalizeLineEndings = true;
/**
* Creates a WriterCharAppender with:
* <ul>
* <li>a maximum limit of characters to append</li>
* <li>the default value to return when no characters have been accumulated.</li>
* <li>the basic {@link Format} specification for handling newlines</li>
* </ul>
*
* The padding character is defaulted to a whitespace character ' '.
*
* @param maxLength maximum limit of characters to append
* @param emptyValue default value to return when no characters have been accumulated
* @param whitespaceRangeStart starting range of characters considered to be whitespace.
* @param format output format specification used for newline handling
*/
public WriterCharAppender(int maxLength, String emptyValue, int whitespaceRangeStart, Format format) {
super(maxLength == -1 ? 8192 : maxLength, emptyValue, whitespaceRangeStart);
char[] lineSeparator = format.getLineSeparator();
this.lineSeparator1 = lineSeparator[0];
this.lineSeparator2 = lineSeparator.length > 1 ? lineSeparator[1] : '\0';
newLine = format.getNormalizedNewline();
}
/**
* Appends the given character and marks it as ignored if it is a whitespace ({@code ch <= ' '})
*
* <p>If the given character is equal to {@link Format#getNormalizedNewline()}, then the character sequence returned by {@link Format#getLineSeparator()} is going to be appended.
*
* @param ch character to append
*/
@Override
public final void appendIgnoringWhitespace(char ch) {
if (ch == newLine && denormalizeLineEndings) {
super.appendIgnoringWhitespace(lineSeparator1);
if (lineSeparator2 != '\0') {
super.appendIgnoringWhitespace(lineSeparator2);
}
} else {
super.appendIgnoringWhitespace(ch);
}
}
/**
* Appends the given character and marks it as ignored if it is a padding character
*
* <p>If the given character is equal to {@link Format#getNormalizedNewline()}, then the character sequence returned by {@link Format#getLineSeparator()} is going to be appended.
*
* @param ch character to append
* @param padding the padding character
*/
@Override
public final void appendIgnoringPadding(char ch, char padding) {
if (ch == newLine && denormalizeLineEndings) {
super.appendIgnoringPadding(lineSeparator1, padding);
if (lineSeparator2 != '\0') {
super.appendIgnoringPadding(lineSeparator2, padding);
}
} else {
super.appendIgnoringPadding(ch, padding);
}
}
/**
* Appends the given character and marks it as ignored if it is a whitespace ({@code ch <= ' '}) or a padding character
*
* <p>If the given character is equal to {@link Format#getNormalizedNewline()}, then the character sequence returned by {@link Format#getLineSeparator()} is going to be appended.
*
* @param ch character to append
* @param padding the padding character
*/
@Override
public final void appendIgnoringWhitespaceAndPadding(char ch, char padding) {
if (ch == newLine && denormalizeLineEndings) {
super.appendIgnoringWhitespaceAndPadding(lineSeparator1, padding);
if (lineSeparator2 != '\0') {
super.appendIgnoringWhitespaceAndPadding(lineSeparator2, padding);
}
} else {
super.appendIgnoringWhitespaceAndPadding(ch, padding);
}
}
/**
* Appends the given character.
*
* <p>If the given character is equal to {@link Format#getNormalizedNewline()}, then the character sequence returned by {@link Format#getLineSeparator()} is going to be appended.
*
* @param ch the character to append
*/
@Override
public final void append(char ch) {
if (ch == newLine && denormalizeLineEndings) {
appendNewLine();
} else {
super.append(ch);
}
}
/**
* Writes the accumulated value to the {@link java.io.Writer}, discarding any trailing whitespace characters identified when using
* {@link WriterCharAppender#appendIgnoringWhitespace(char)}, {@link WriterCharAppender#appendIgnoringPadding(char, char)} or {@link WriterCharAppender#appendIgnoringWhitespaceAndPadding(char, char)}
* <p> The internal accumulated value is discarded after invoking this method (as in {@link DefaultCharAppender#reset()})
* <p> If the accumulated value is empty (i.e. no characters were appended, or all appended characters where ignored as whitespace or padding), then the written value will be the {@link DefaultCharAppender#emptyValue} attribute defined in the constructor of this class.
*
* @param writer the output writer
*
* @throws IOException if an error occurs while writing to the output.
*/
public final void writeCharsAndReset(Writer writer) throws IOException {
if (index - whitespaceCount > 0) {
writer.write(chars, 0, index - whitespaceCount);
} else if (emptyChars != null) {
writer.write(emptyChars, 0, emptyChars.length);
}
index = 0;
whitespaceCount = 0;
}
/**
* Appends the newline character sequence specified in {@link Format#getLineSeparator()}
*/
public final void appendNewLine() {
if (index + 2 >= chars.length) {
expand();
}
chars[index++] = lineSeparator1;
if (lineSeparator2 != '\0') {
chars[index++] = lineSeparator2;
}
}
/**
* Configures the appender to allow line ending sequences to be appended as-is, without replacing them by the
* normalized line separator character.
*
* @param enableDenormalizedLineEndings flag indicating whether denormalized line endings are allowed. The writer
* won't convert line separators automatically.
*/
public final void enableDenormalizedLineEndings(boolean enableDenormalizedLineEndings) {
this.denormalizeLineEndings = enableDenormalizedLineEndings;
}
}