react-native/React/Base/RCTLog.h

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

#import <Foundation/Foundation.h>

#import "RCTAssert.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Thresholds for logs to raise an assertion, or display redbox, respectively.
 * You can override these values when debugging in order to tweak the default
 * logging behavior.
 */
#define RCTLOG_FATAL_LEVEL RCTLogLevelMustFix
#define RCTLOG_REDBOX_LEVEL RCTLogLevelError

/**
 * A regular expression that can be used to selectively limit the throwing of
 * a exception to specific log contents.
 */
#define RCTLOG_FATAL_REGEX nil

/**
 * An enum representing the severity of the log message.
 */
typedef NS_ENUM(NSInteger, RCTLogLevel) {
  RCTLogLevelInfo = 1,
  RCTLogLevelWarning = 2,
  RCTLogLevelError = 3,
  RCTLogLevelMustFix = 4
};

/**
 * A block signature to be used for custom logging functions. In most cases you
 * will want to pass these arguments to the RCTFormatLog function in order to
 * generate a string, or use the RCTSimpleLogFunction() constructor to register
 * a simple function that does not use all of the arguments.
 */
typedef void (^RCTLogFunction)(
  RCTLogLevel level,
  NSString *fileName,
  NSNumber *lineNumber,
  NSString *message
);

/**
 * A method to generate a string from a collection of log data. To omit any
 * particular data from the log, just pass nil or zero for the argument.
 */
NSString *RCTFormatLog(
  NSDate *timestamp,
  NSThread *thread,
  RCTLogLevel level,
  NSString *fileName,
  NSNumber *lineNumber,
  NSString *message
);

/**
 * A method to generate a log function from a block with a much simpler
 * template. The message passed to the simpler block is equivalent to the
 * output of the RCTFormatLog() function.
 */
RCTLogFunction RCTSimpleLogFunction(void (^logFunction)(RCTLogLevel level, NSString *message));

/**
 * The default logging function used by RCTLogXX.
 */
extern RCTLogFunction RCTDefaultLogFunction;

/**
 * These methods get and set the current logging threshold. This is the level
 * below which logs will be ignored. Default is RCTLogLevelInfo for debug and
 * RCTLogLevelError for production.
 */
void RCTSetLogThreshold(RCTLogLevel threshold);
RCTLogLevel RCTGetLogThreshold(void);

/**
 * These methods get and set the current logging function called by the RCTLogXX
 * macros. You can use these to replace the standard behavior with custom log
 * functionality.
 */
void RCTSetLogFunction(RCTLogFunction logFunction);
RCTLogFunction RCTGetLogFunction(void);

/**
 * This appends additional code to the existing log function, without replacing
 * the existing functionality. Useful if you just want to forward logs to an
 * extra service without changing the default behavior.
 */
void RCTAddLogFunction(RCTLogFunction logFunction);

/**
 * This method adds a conditional prefix to any messages logged within the scope
 * of the passed block. This is useful for adding additional context to log
 * messages. The block will be performed synchronously on the current thread.
 */
void RCTPerformBlockWithLogPrefix(void (^block)(void), NSString *prefix);

/**
 * Private logging functions - ignore these.
 */
void _RCTLogFormat(RCTLogLevel, const char *, int, NSString *, ...) NS_FORMAT_FUNCTION(4,5);
#define _RCTLog(lvl, ...) do { \
  NSString *msg = [NSString stringWithFormat:__VA_ARGS__]; \
  if (lvl >= RCTLOG_FATAL_LEVEL) { \
    BOOL fail = YES; \
    if (RCTLOG_FATAL_REGEX) { \
      if ([msg rangeOfString:RCTLOG_FATAL_REGEX options:NSRegularExpressionSearch].length) { \
        fail = NO; \
      } \
    } \
    RCTCAssert(!fail, @"FATAL ERROR: %@", msg); \
  }\
  _RCTLogFormat(lvl, __FILE__, __LINE__, __VA_ARGS__); \
} while (0)

/**
 * Legacy injection function - don't use this.
 */
void RCTInjectLogFunction(void (^)(NSString *msg));

/**
 * Logging macros. Use these to log information, warnings and errors in your
 * own code.
 */
#define RCTLog(...) _RCTLog(RCTLogLevelInfo, __VA_ARGS__)
#define RCTLogInfo(...) _RCTLog(RCTLogLevelInfo, __VA_ARGS__)
#define RCTLogWarn(...) _RCTLog(RCTLogLevelWarning, __VA_ARGS__)
#define RCTLogError(...) _RCTLog(RCTLogLevelError, __VA_ARGS__)
#define RCTLogMustFix(...) _RCTLog(RCTLogLevelMustFix, __VA_ARGS__)

#ifdef __cplusplus
}
#endif