integration/Source/Integration/DebugPrint.h

#pragma once

//////////////////////////////////////////////////////////////
//
// Namespace DebugPrint
//
// This namespace contains the function "DPrint",
// which is short for debugging print.  This
// is what you should use if you want to print
// a debugging message.
//
// Messages printed using "DPrint" will
// be routed to several destinations.  These
// might include a logfile, the unreal console,
// and the visual studio debugging log.
//
// In order for "DPrint" to work, you have to
// configure them once, at program initialization
// time.  This is done using the functions in
// namespace DebugPrintConfig, below.
//
// We promise that namespace DebugPrint will
// only ever contain one function, 'DPrint.'
// that way, it's safe for you to put
// 'using namespace DebugPrint' in your code.
//
// All DPrint-related functionality is
// thread-safe.  A single 'DPrint' is meant to
// be output atomically.
//
// It is fine for the content of the DPrint
// string to contain newlines.
// 
//////////////////////////////////////////////////////////////

namespace DebugPrint {
	// Print text into the debug log.
	void DPrint(const FString& fs);

	// Print text into the debug log.
	void DPrint(const char* msg);

	// Print text into the debug log.
	void DPrint(const char* msg, size_t len);
};

//////////////////////////////////////////////////////////////
//
// namespace DebugPrintControl
//
// This namespace contains the functions
// necessary to initialize "DPrint", and
// route its output to several destinations.
//
// "DPrint" is a callback-based design.
// Initialization might consist of: register a
// callback that sends a string to a logfile,
// register another callback that sends a string
// to visual studio's debug console, and register
// a third one that sends a string to the
// unreal console. Each time somebody calls
// 'DPrint', all three callbacks will get invoked.
// 
// There is also a 'collect' option where you
// can ask "DPrint" to save the messages in a
// buffer, which you can then collect at
// your leisure.  You can use buffering and
// callbacks at the same time.  Note that
// buffering is inherently less than ideal for
// messages that warn of imminent program aborts.
// So it is recommended that you use at least one
// callback that sends its output without delay.
//
//////////////////////////////////////////////////////////////

namespace DebugPrintControl {
	// The prototype for a callback function.
	//
	using DPrintCallback = void (*)(const FString& fs);

	// Register a callback.
	//
	// Registering a callback that is already
	// registered is a no-op.
	//
	void RegisterCallback(DPrintCallback f);

	// Enable collection in a buffer.
	//
	// If collection is already enabled, this is a no-op.
	//
	void EnableCollection();

	// Collect all the stored messages, and clear the storage.
	//
	TArray<FString> GetStored();
};

//////////////////////////////////////////////////////////////
//
// ConsoleOutput
//
// This class stores the text that's in the unreal console.
// It stores it as one great big string, which contains
// newlines to denote line breaks.
//
// This class also contains a 'dirty' bit.  Each time somebody
// appends a line of text to the console, the dirty bit is
// automatically set.  The bit can be checked using 'IsDirty'
// and cleared using 'ClearDirty'.  This makes it so that
// you don't have to update the unreal widget unless the
// text has actually changed.
//
//////////////////////////////////////////////////////////////

class FlxConsoleOutput {
private:
	FString Content;
	bool Dirty;

	// Truncate the console to a reasonable number of
	// lines.  The length is hardwired.
	void Truncate();

	// Add a newline if there isn't one.  Returns true if it changed anything.
	bool MaybeAppendNewline();

	// Append text.  Returns true if it changed anything.
	bool MaybeAppendText(const FString& text);

public:
	// Append a line of text to the console.
	void Append(const FString& text);

	// Append a line of text to the console on a line by itself.
	void AppendLine(const FString& text);

	// Get the console text as a string.
	const FString& Get() const { return Content;  }
	
	// Return if the dirty flag is set.
	bool IsDirty() const { return Dirty; }

	// Clear the dirty flag.
	void ClearDirty() { Dirty = false;  }
};