JavaParser/com/github/javaparser/utils/Log.java

1	/*
2	* Copyright (C) 2007-2010 Júlio Vilmar Gesser.
3	* Copyright (C) 2011, 2013-2020 The JavaParser Team.
4	*
5	* This file is part of JavaParser.
6	*
7	* JavaParser can be used either under the terms of
8	* a) the GNU Lesser General Public License as published by
9	* the Free Software Foundation, either version 3 of the License, or
10	* (at your option) any later version.
11	* b) the terms of the Apache License
12	*
13	* You should have received a copy of both licenses in LICENCE.LGPL and
14	* LICENCE.APACHE. Please refer to those files for details.
15	*
16	* JavaParser is distributed in the hope that it will be useful,
17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19	* GNU Lesser General Public License for more details.
20	*/
21
22	package com.github.javaparser.utils;
23
24	import java.io.IOException;
25	import java.io.PrintWriter;
26	import java.io.StringWriter;
27	import java.util.function.Supplier;
28
29	import static com.github.javaparser.utils.CodeGenerationUtils.f;
30
31	/**
32	* To avoid dependencies on logging frameworks, we have invented yet another logging framework :-)
33	* <p>
34	* See <a href="http://javaparser.org/javaparsers-logging-framework-in-one-file/">a blog about this</a>
35	*/
36	public class Log {
37	/**
38	* This adapter logs to standard out and standard error.
39	*/
40	public static class StandardOutStandardErrorAdapter implements Adapter {
41	@Override
42	public void info(Supplier<String> messageSupplier) {
43	System.out.println(messageSupplier.get());
44	}
45
46	@Override
47	public void trace(Supplier<String> messageSupplier) {
48	System.out.println(messageSupplier.get());
49	}
50
51	@Override
52	public void error(Supplier<Throwable> throwableSupplier, Supplier<String> messageSupplier) {
53	Throwable throwable = throwableSupplier.get();
54	String message = messageSupplier.get();
55	if (message == null) {
56	System.err.println(throwable.getMessage());
57	printStackTrace(throwable);
58	} else if (throwable == null) {
59	System.err.println(message);
60	} else {
61	System.err.println(message + ":" + throwable.getMessage());
62	printStackTrace(throwable);
63	}
64	}
65
66	private void printStackTrace(Throwable throwable) {
67	try (StringWriter sw = new StringWriter(); PrintWriter pw = new PrintWriter(sw)) {
68	throwable.printStackTrace(pw);
69	trace(sw::toString);
70	} catch (IOException e) {
71	throw new AssertionError("Error in logging library");
72	}
73	}
74	}
75
76	/**
77	* This adapter logs nothing.
78	*/
79	public static class SilentAdapter implements Adapter {
80	@Override
81	public void info(Supplier<String> messageSupplier) {
82	}
83
84	@Override
85	public void trace(Supplier<String> messageSupplier) {
86	}
87
88	@Override
89	public void error(Supplier<Throwable> throwableSupplier, Supplier<String> messageSupplier) {
90	}
91	}
92
93	public interface Adapter {
94
95	void info(Supplier<String> message);
96
97	void trace(Supplier<String> message);
98
99	/**
100	* Both can supply a null.
101	*/
102	void error(Supplier<Throwable> throwableSupplier, Supplier<String> messageSupplier);
103	}
104
105	private static Adapter CURRENT_ADAPTER = new SilentAdapter();
106
107	/**
108	* Change how logging is handled. You can set your own implementation that forwards to your logging library.
109	*/
110	public static void setAdapter(Adapter adapter) {
111	CURRENT_ADAPTER = adapter;
112	}
113
114	/**
115	* For logging information that may help solving a problem.
116	*/
117	@SafeVarargs
118	public static void trace(String format, Supplier<Object>... args) {
119	CURRENT_ADAPTER.trace(makeFormattingSupplier(format, args));
120	}
121
122	private static Supplier<String> makeFormattingSupplier(String format, Supplier<Object>[] args) {
123	return () -> {
124	Object[] objects = new Object[args.length];
125	for (int i = 0; i < args.length; i++) {
126	objects[i] = args[i].get();
127	}
128	return f(format, objects);
129	};
130	}
131
132
133	/**
134	* For logging things that are nice to see scrolling by.
135	*/
136	@SafeVarargs
137	public static void info(String format, Supplier<Object>... args) {
138	CURRENT_ADAPTER.info(makeFormattingSupplier(format, args));
139	}
140
141	/**
142	* For drawing attention to an error.
143	*/
144	public static void error(Throwable throwable) {
145	CURRENT_ADAPTER.error(() -> throwable, null);
146	}
147
148	/**
149	* For drawing attention to an error that you don't have an exception for.
150	*/
151	@SafeVarargs
152	public static void error(Throwable throwable, String format, Supplier<Object>... args) {
153	CURRENT_ADAPTER.error(() -> throwable, makeFormattingSupplier(format, args));
154	}
155
156	/**
157	* For drawing attention to an error that you don't have an exception for.
158	*/
159	@SafeVarargs
160	public static void error(String format, Supplier<Object>... args) {
161	CURRENT_ADAPTER.error(() -> null, makeFormattingSupplier(format, args));
162	}
163	}
164