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PlantUML is a component that allows to quickly write diagrams from text.
There is a newer version: 1.2024.8
// THIS FILE HAS BEEN GENERATED BY A PREPROCESSOR.
/* +=======================================================================
 * |
 * |      PlantUML : a free UML diagram generator
 * |
 * +=======================================================================
 *
 * (C) Copyright 2009-2024, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
 *
 * If you like this project or if you find it useful, you can support us at:
 *
 * https://plantuml.com/patreon (only 1$ per month!)
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 *
 *
 * PlantUML is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * PlantUML distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see .
 *
 * PlantUML can occasionally display sponsored or advertising messages. Those
 * messages are usually generated on welcome or error images and never on
 * functional diagrams.
 * See https://plantuml.com/professional if you want to remove them
 *
 * Images (whatever their format : PNG, SVG, EPS...) generated by running PlantUML
 * are owned by the author of their corresponding sources code (that is, their
 * textual description in PlantUML language). Those images are not covered by
 * this LGPL license.
 *
 * The generated images can then be used without any reference to the LGPL license.
 * It is not even necessary to stipulate that they have been generated with PlantUML,
 * although this will be appreciated by the PlantUML team.
 *
 * There is an exception : if the textual description in PlantUML language is also covered
 * by any license, then the generated images are logically covered
 * by the very same license.
 *
 * This is the IGY distribution (Install GraphViz by Yourself).
 * You have to install GraphViz and to setup the GRAPHVIZ_DOT environment variable
 * (see https://plantuml.com/graphviz-dot )
 *
 * Icons provided by OpenIconic :  https://useiconic.com/open
 * Archimate sprites provided by Archi :  http://www.archimatetool.com
 * Stdlib AWS provided by https://github.com/milo-minderbinder/AWS-PlantUML
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 * ASCIIMathML (c) Peter Jipsen http://www.chapman.edu/~jipsen
 * ASCIIMathML (c) David Lippman http://www.pierce.ctc.edu/dlippman
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 * Brotli (c) by the Brotli Authors https://github.com/google/brotli
 * Themes (c) by Brett Schwarz https://github.com/bschwarz/puml-themes
 * Twemoji (c) by Twitter at https://twemoji.twitter.com/
 *
 */
package net.sourceforge.plantuml.json;

import java.io.IOException;
import java.io.Writer;

class JsonWriter {

	private static final int CONTROL_CHARACTERS_END = 0x001f;

	private static final char[] QUOT_CHARS = { '\\', '"' };
	private static final char[] BS_CHARS = { '\\', '\\' };
	private static final char[] LF_CHARS = { '\\', 'n' };
	private static final char[] CR_CHARS = { '\\', 'r' };
	private static final char[] TAB_CHARS = { '\\', 't' };
	// In JavaScript, U+2028 and U+2029 characters count as line endings and must be
	// encoded.
	// http://stackoverflow.com/questions/2965293/javascript-parse-error-on-u2028-unicode-character
	private static final char[] UNICODE_2028_CHARS = { '\\', 'u', '2', '0', '2', '8' };
	private static final char[] UNICODE_2029_CHARS = { '\\', 'u', '2', '0', '2', '9' };
	private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
			'e', 'f' };

	protected final Writer writer;

	JsonWriter(Writer writer) {
		this.writer = writer;
	}

	protected void writeLiteral(String value) throws IOException {
		writer.write(value);
	}

	protected void writeNumber(String string) throws IOException {
		writer.write(string);
	}

	protected void writeString(String string) throws IOException {
		writer.write('"');
		writeJsonString(string);
		writer.write('"');
	}

	protected void writeArrayOpen() throws IOException {
		writer.write('[');
	}

	protected void writeArrayClose() throws IOException {
		writer.write(']');
	}

	protected void writeArraySeparator() throws IOException {
		writer.write(',');
	}

	protected void writeObjectOpen() throws IOException {
		writer.write('{');
	}

	protected void writeObjectClose() throws IOException {
		writer.write('}');
	}

	protected void writeMemberName(String name) throws IOException {
		writer.write('"');
		writeJsonString(name);
		writer.write('"');
	}

	protected void writeMemberSeparator() throws IOException {
		writer.write(':');
	}

	protected void writeObjectSeparator() throws IOException {
		writer.write(',');
	}

	protected void writeJsonString(String string) throws IOException {
		int length = string.length();
		int start = 0;
		for (int index = 0; index < length; index++) {
			char[] replacement = getReplacementChars(string.charAt(index));
			if (replacement != null) {
				writer.write(string, start, index - start);
				writer.write(replacement);
				start = index + 1;
			}
		}
		writer.write(string, start, length - start);
	}

	private static char[] getReplacementChars(char ch) {
		if (ch > '\\') {
			if (ch < '\u2028' || ch > '\u2029') {
				// The lower range contains 'a' .. 'z'. Only 2 checks required.
				return null;
			}
			return ch == '\u2028' ? UNICODE_2028_CHARS : UNICODE_2029_CHARS;
		}
		if (ch == '\\') {
			return BS_CHARS;
		}
		if (ch > '"') {
			// This range contains '0' .. '9' and 'A' .. 'Z'. Need 3 checks to get here.
			return null;
		}
		if (ch == '"') {
			return QUOT_CHARS;
		}
		if (ch > CONTROL_CHARACTERS_END) {
			return null;
		}
		if (ch == '\n') {
			return LF_CHARS;
		}
		if (ch == '\r') {
			return CR_CHARS;
		}
		if (ch == '\t') {
			return TAB_CHARS;
		}
		return new char[] { '\\', 'u', '0', '0', HEX_DIGITS[ch >> 4 & 0x000f], HEX_DIGITS[ch & 0x000f] };
	}

}