azaleasource/WPILibCProgramming/trunk/WPILib/Preferences.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2011. All Rights Reserved.							  */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in $(WIND_BASE)/WPILib.  */
/*----------------------------------------------------------------------------*/

#ifndef __PREFERENCES_H__
#define __PREFERENCES_H__

#include "ErrorBase.h"
#include "Task.h"
#include <map>
#include <semLib.h>
#include <string>
#include <vector>
#include "tables/ITableListener.h"
#include "networktables/NetworkTable.h"

/**
 * The preferences class provides a relatively simple way to save important values to
 * the cRIO to access the next time the cRIO is booted.
 *
 * <p>This class loads and saves from a file
 * inside the cRIO.  The user can not access the file directly, but may modify values at specific
 * fields which will then be saved to the file when {@link Preferences#Save() Save()} is called.</p>
 *
 * <p>This class is thread safe.</p>
 *
 * <p>This will also interact with {@link NetworkTable} by creating a table called "Preferences" with all the
 * key-value pairs.  To save using {@link NetworkTable}, simply set the boolean at position "~S A V E~" to true.
 * Also, if the value of any variable is " in the {@link NetworkTable}, then that represents non-existence in the
 * {@link Preferences} table</p>
 */
class Preferences : public ErrorBase, public ITableListener
{
public:
	static Preferences *GetInstance();

	std::vector<std::string> GetKeys();
	std::string GetString(const char *key, const char *defaultValue = "");
	int GetString(const char *key, char *value, int valueSize, const char *defaultValue = "");
	int GetInt(const char *key, int defaultValue = 0);
	double GetDouble(const char *key, double defaultValue = 0.0);
	float GetFloat(const char *key, float defaultValue = 0.0);
	bool GetBoolean(const char *key, bool defaultValue = false);
	INT64 GetLong(const char *key, INT64 defaultValue = 0);
	void PutString(const char *key, const char *value);
	void PutInt(const char *key, int value);
	void PutDouble(const char *key, double value);
	void PutFloat(const char *key, float value);
	void PutBoolean(const char *key, bool value);
	void PutLong(const char *key, INT64 value);
	void Save();
	bool ContainsKey(const char *key);
	void Remove(const char *key);
	
	void ValueChanged(ITable* source, const std::string& key, EntryValue value, bool isNew);

protected:
	Preferences();
	virtual ~Preferences();

private:
	std::string Get(const char *key);
	void Put(const char *key, std::string value);

	void ReadTaskRun();
	void WriteTaskRun();

	static int InitReadTask(Preferences *obj) {obj->ReadTaskRun();return 0;}
	static int InitWriteTask(Preferences *obj) {obj->WriteTaskRun();return 0;}

	static Preferences *_instance;

	/** The semaphore for accessing the file */
	SEM_ID m_fileLock;
	/** The semaphore for beginning reads and writes to the file */
	SEM_ID m_fileOpStarted;
	/** The semaphore for reading from the table */
	SEM_ID m_tableLock;
	typedef std::map<std::string, std::string> StringMap;
	/** The actual values (String->String) */
	StringMap m_values;
	/** The keys in the order they were read from the file */
	std::vector<std::string> m_keys;
	/** The comments that were in the file sorted by which key they appeared over (String->Comment) */
	StringMap m_comments;
	/** The comment at the end of the file */
	std::string m_endComment;
	Task m_readTask;
	Task m_writeTask;
};

#endif