1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef LIBTEXTCLASSIFIER_UTIL_BASE_LOGGING_H_
18#define LIBTEXTCLASSIFIER_UTIL_BASE_LOGGING_H_
19
20#include <cassert>
21#include <sstream>
22#include <string>
23
24#include "util/base/logging_levels.h"
25#include "util/base/port.h"
26
27namespace libtextclassifier {
28namespace logging {
29
30// The class that does all the work behind our TC_LOG(severity) macros.  Each
31// TC_LOG(severity) << obj1 << obj2 << ...; logging statement creates a
32// LogMessage temporary object containing a stringstream.  Each operator<< adds
33// info to that stringstream and the LogMessage destructor performs the actual
34// logging.  The reason this works is that in C++, "all temporary objects are
35// destroyed as the last step in evaluating the full-expression that (lexically)
36// contains the point where they were created."  For more info, see
37// http://en.cppreference.com/w/cpp/language/lifetime.  Hence, the destructor is
38// invoked after the last << from that logging statement.
39class LogMessage {
40 public:
41  LogMessage(LogSeverity severity, const char *file_name,
42             int line_number) TC_ATTRIBUTE_NOINLINE;
43
44  ~LogMessage() TC_ATTRIBUTE_NOINLINE;
45
46  // Returns the stream associated with the logger object.
47  std::stringstream &stream() { return stream_; }
48
49 private:
50  const LogSeverity severity_;
51
52  // Stream that "prints" all info into a string (not to a file).  We construct
53  // here the entire logging message and next print it in one operation.
54  std::stringstream stream_;
55};
56
57#define TC_LOG(severity)                                          \
58  ::libtextclassifier::logging::LogMessage(                       \
59      ::libtextclassifier::logging::severity, __FILE__, __LINE__) \
60      .stream()
61
62// If condition x is true, does nothing.  Otherwise, crashes the program (liek
63// LOG(FATAL)) with an informative message.  Can be continued with extra
64// messages, via <<, like any logging macro, e.g.,
65//
66// TC_CHECK(my_cond) << "I think we hit a problem";
67#define TC_CHECK(x)                                                           \
68  (x) || TC_LOG(FATAL) << __FILE__ << ":" << __LINE__ << ": check failed: \"" \
69                       << #x
70
71#define TC_CHECK_EQ(x, y) TC_CHECK((x) == (y))
72#define TC_CHECK_LT(x, y) TC_CHECK((x) < (y))
73#define TC_CHECK_GT(x, y) TC_CHECK((x) > (y))
74#define TC_CHECK_LE(x, y) TC_CHECK((x) <= (y))
75#define TC_CHECK_GE(x, y) TC_CHECK((x) >= (y))
76#define TC_CHECK_NE(x, y) TC_CHECK((x) != (y))
77
78// Debug checks: a TC_DCHECK<suffix> macro should behave like TC_CHECK<suffix>
79// in debug mode an don't check / don't print anything in non-debug mode.
80#ifdef NDEBUG
81
82// Pseudo-stream that "eats" the tokens <<-pumped into it, without printing
83// anything.
84class NullStream {
85 public:
86  NullStream() {}
87  NullStream &stream() { return *this; }
88};
89template <typename T>
90inline NullStream &operator<<(NullStream &str, const T &) {
91  return str;
92}
93
94#define TC_NULLSTREAM ::libtextclassifier::logging::NullStream().stream()
95#define TC_DCHECK(x) TC_NULLSTREAM
96#define TC_DCHECK_EQ(x, y) TC_NULLSTREAM
97#define TC_DCHECK_LT(x, y) TC_NULLSTREAM
98#define TC_DCHECK_GT(x, y) TC_NULLSTREAM
99#define TC_DCHECK_LE(x, y) TC_NULLSTREAM
100#define TC_DCHECK_GE(x, y) TC_NULLSTREAM
101#define TC_DCHECK_NE(x, y) TC_NULLSTREAM
102
103#else  // NDEBUG
104
105// In debug mode, each TC_DCHECK<suffix> is equivalent to TC_CHECK<suffix>,
106// i.e., a real check that crashes when the condition is not true.
107#define TC_DCHECK(x) TC_CHECK(x)
108#define TC_DCHECK_EQ(x, y) TC_CHECK_EQ(x, y)
109#define TC_DCHECK_LT(x, y) TC_CHECK_LT(x, y)
110#define TC_DCHECK_GT(x, y) TC_CHECK_GT(x, y)
111#define TC_DCHECK_LE(x, y) TC_CHECK_LE(x, y)
112#define TC_DCHECK_GE(x, y) TC_CHECK_GE(x, y)
113#define TC_DCHECK_NE(x, y) TC_CHECK_NE(x, y)
114
115#endif  // NDEBUG
116}  // namespace logging
117}  // namespace libtextclassifier
118
119#endif  // LIBTEXTCLASSIFIER_UTIL_BASE_LOGGING_H_
120