Add TransformerLogger

Author: oxinabox

src/transformer.jl

@@ -0,0 +1,36 @@
+"""
+    TransformerLogger(f, logger)
+Preprocesses log messages, using the function `f`, before passing them to the
+`logger` that is wrapped.
+This can be used, for example, to truncate a log message.
+to conditionally change the log level of logs from a given module
+(which depending on the wrappped `logger`, might cause the message to be dropped).
+
+The transforming function `f` is given a named tuple with the fields:
+`(level, message, _module, group, id, file, line, kwargs)`
+and should return the same.
+See `?LoggingExtra.handle_message_args` for more information on what each is.
+"""
+struct TransformerLogger{T<:AbstractLogger, F} <: AbstractLogger
+    transform::F
+	logger::T
+end
+
+
+function handle_message(transformer::TransformerLogger, args...; kwargs...)
+	log_args = handle_message_args(args...; kwargs...)
+    new_log_args = transformer.transform(log_args)
+    
+    args = Tuple(new_log_args)[1:end-1]
+    kwargs = new_log_args.kwargs
+
+    if comp_handle_message_check(transformer.logger, args...; kwargs...)
+		handle_message(transformer.logger, args...; kwargs...)
+	end
+end
+
+shouldlog(transformer::TransformerLogger, args...) = true
+
+min_enabled_level(transformer::TransformerLogger) = BelowMinLevel
+
+catch_exceptions(transformer::TransformerLogger) = catch_exceptions(transformer.logger)