JsonFormatter.java

/*******************************************************************************
 * Copyright (c) 2012, 2016, 2017 PDT Extension Group and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     PDT Extension Group - initial API and implementation
 *     Kaloyan Raev - [501269] externalize strings
 *******************************************************************************/
package org.eclipse.php.composer.api.json;

import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.google.gson.Gson;

public class JsonFormatter {

	public static String format(final Object object) {
		final JsonVisitor visitor = new JsonVisitor(1, '\t');
		visitor.visit(object, 0);
		return JsonFormatter.postProcessing(visitor.toString());
	}

	private static String postProcessing(String json) {
		json = json.replace("[\n{", "[{"); //$NON-NLS-1$ //$NON-NLS-2$
		json = json.replace("},\n{", "}, {"); //$NON-NLS-1$ //$NON-NLS-2$
		return json;
	}

	private static class JsonVisitor {

		private Gson gson = new Gson();
		private final StringBuilder builder = new StringBuilder();
		private final int indentationSize;
		private final char indentationChar;

		public JsonVisitor(final int indentationSize, final char indentationChar) {
			this.indentationSize = indentationSize;
			this.indentationChar = indentationChar;
		}

		private void visit(final List<Object> array, final int indent) {
			final int length = array.size();
			if (length == 0) {
				write("[]", 0); //$NON-NLS-1$
			} else {
				writeln("[", 0); //$NON-NLS-1$
				for (int i = 0; i < length; i++) {
					visit(array.get(i), indent + 1);
					if (i < length - 1) {
						writeln(",", 0); //$NON-NLS-1$
					}
				}
				writeln("", 0); //$NON-NLS-1$
				write("]", indent); //$NON-NLS-1$
			}

		}

		private void visit(final Map<String, Object> obj, int indent) {
			final int length = obj.size();
			if (length == 0) {
				write("{}", 0); //$NON-NLS-1$
			} else {
				writeln("{", 0); //$NON-NLS-1$
				final Iterator<String> keys = ((Set<String>) obj.keySet()).iterator();
				while (keys.hasNext()) {
					final String key = keys.next();
					write("\"" + escape(key) + "\" : ", indent + 1); //$NON-NLS-1$ //$NON-NLS-2$
					visit(obj.get(key), indent + 1);
					if (keys.hasNext()) {
						writeln(",", 0); //$NON-NLS-1$
					}
				}
				writeln("", 0); //$NON-NLS-1$
				write("}", indent); //$NON-NLS-1$
			}

		}

		@SuppressWarnings("unchecked")
		private void visit(final Object object, int indent) {
			if (object instanceof List) {
				visit((List<Object>) object, indent);
			} else if (object instanceof Map) {
				visit((Map<String, Object>) object, indent);
			} else {
				if (builder.charAt(builder.length() - 1) != '\n') {
					indent = 0;
				}
				if (object instanceof String) {
					write("\"" + escape(String.valueOf(object)) + "\"", indent); //$NON-NLS-1$ //$NON-NLS-2$
				} else if (object instanceof Boolean || object instanceof Number) {
					write(String.valueOf(object), indent);
				} else {
					write(gson.toJson(String.valueOf(object)), indent);
				}
			}
		}

		private void writeln(final String data, final int indent) {
			write(data, indent);
			builder.append('\n');
		}

		private void write(final String data, final int indent) {
			for (int i = 0; i < (indent * indentationSize); i++) {
				builder.append(indentationChar);
			}
			builder.append(data);
		}

		@Override
		public String toString() {
			return builder.toString();
		}

		private static String escape(String s) {
			if (s == null || s.isEmpty()) {
				return ""; //$NON-NLS-1$
			}
			StringBuilder sb = new StringBuilder();

			for (int i = 0; i < s.length(); i++) {
				char ch = s.charAt(i);
				switch (ch) {
				case '"':
					sb.append("\\\""); //$NON-NLS-1$
					break;
				case '\\':
					sb.append("\\\\"); //$NON-NLS-1$
					break;
				case '\b':
					sb.append("\\b"); //$NON-NLS-1$
					break;
				case '\f':
					sb.append("\\f"); //$NON-NLS-1$
					break;
				case '\n':
					sb.append("\\n"); //$NON-NLS-1$
					break;
				case '\r':
					sb.append("\\r"); //$NON-NLS-1$
					break;
				case '\t':
					sb.append("\\t"); //$NON-NLS-1$
					break;
				// see
				// https://github.com/pulse00/Composer-Eclipse-Plugin/issues/51
				/*
				 * case '/': sb.append("\\/"); break;
				 */
				default:
					// Reference: http://www.unicode.org/versions/Unicode5.1.0/
					if ((ch >= '\u0000' && ch <= '\u001F') || (ch >= '\u007F' && ch <= '\u009F')
							|| (ch >= '\u2000' && ch <= '\u20FF')) {
						String ss = Integer.toHexString(ch);
						sb.append("\\u"); //$NON-NLS-1$
						for (int k = 0; k < 4 - ss.length(); k++) {
							sb.append('0');
						}
						sb.append(ss.toUpperCase());
					} else {
						sb.append(ch);
					}
				}
			}
			return sb.toString();
		}
	}
}