gecko-dev/modules/libpref/prefapi.h

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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
// <pre>
*/
#ifndef PREFAPI_H
#define PREFAPI_H
#include "nscore.h"
#include "PLDHashTable.h"
#ifdef __cplusplus
extern "C" {
#endif
// 1 MB should be enough for everyone.
static const uint32_t MAX_PREF_LENGTH = 1 * 1024 * 1024;
// Actually, 4kb should be enough for everyone.
static const uint32_t MAX_ADVISABLE_PREF_LENGTH = 4 * 1024;
typedef union
{
char* stringVal;
int32_t intVal;
bool boolVal;
} PrefValue;
/*
// <font color=blue>
// The Init function initializes the preference context and creates
// the preference hashtable.
// </font>
*/
void PREF_Init();
/*
// Cleanup should be called at program exit to free the
// list of registered callbacks.
*/
void PREF_Cleanup();
void PREF_CleanupPrefs();
/*
// <font color=blue>
// Preference flags, including the native type of the preference. Changing any of these
// values will require modifying the code inside of PrefTypeFlags class.
// </font>
*/
enum class PrefType {
Invalid = 0,
String = 1,
Int = 2,
Bool = 3,
};
// Keep the type of the preference, as well as the flags guiding its behaviour.
class PrefTypeFlags
{
public:
PrefTypeFlags() : mValue(AsInt(PrefType::Invalid)) {}
explicit PrefTypeFlags(PrefType aType) : mValue(AsInt(aType)) {}
PrefTypeFlags& Reset() { mValue = AsInt(PrefType::Invalid); return *this; }
bool IsTypeValid() const { return !IsPrefType(PrefType::Invalid); }
bool IsTypeString() const { return IsPrefType(PrefType::String); }
bool IsTypeInt() const { return IsPrefType(PrefType::Int); }
bool IsTypeBool() const { return IsPrefType(PrefType::Bool); }
bool IsPrefType(PrefType type) const { return GetPrefType() == type; }
PrefTypeFlags& SetPrefType(PrefType aType) {
mValue = mValue - AsInt(GetPrefType()) + AsInt(aType);
return *this;
}
PrefType GetPrefType() const {
return (PrefType)(mValue & (AsInt(PrefType::String) |
AsInt(PrefType::Int) |
AsInt(PrefType::Bool)));
}
bool HasDefault() const { return mValue & PREF_FLAG_HAS_DEFAULT; }
PrefTypeFlags& SetHasDefault(bool aSetOrUnset) { return SetFlag(PREF_FLAG_HAS_DEFAULT, aSetOrUnset); }
bool HasStickyDefault() const { return mValue & PREF_FLAG_STICKY_DEFAULT; }
PrefTypeFlags& SetHasStickyDefault(bool aSetOrUnset) { return SetFlag(PREF_FLAG_STICKY_DEFAULT, aSetOrUnset); }
bool IsLocked() const { return mValue & PREF_FLAG_LOCKED; }
PrefTypeFlags& SetLocked(bool aSetOrUnset) { return SetFlag(PREF_FLAG_LOCKED, aSetOrUnset); }
bool HasUserValue() const { return mValue & PREF_FLAG_USERSET; }
PrefTypeFlags& SetHasUserValue(bool aSetOrUnset) { return SetFlag(PREF_FLAG_USERSET, aSetOrUnset); }
private:
static uint16_t AsInt(PrefType aType) { return (uint16_t)aType; }
PrefTypeFlags& SetFlag(uint16_t aFlag, bool aSetOrUnset) {
mValue = aSetOrUnset ? mValue | aFlag : mValue & ~aFlag;
return *this;
}
// Pack both the value of type (PrefType) and flags into the same int. This is why
// the flag enum starts at 4, as PrefType occupies the bottom two bits.
enum {
PREF_FLAG_LOCKED = 4,
PREF_FLAG_USERSET = 8,
PREF_FLAG_CONFIG = 16,
PREF_FLAG_REMOTE = 32,
PREF_FLAG_LILOCAL = 64,
PREF_FLAG_HAS_DEFAULT = 128,
PREF_FLAG_STICKY_DEFAULT = 256,
};
uint16_t mValue;
};
struct PrefHashEntry : PLDHashEntryHdr
{
PrefTypeFlags prefFlags; // This field goes first to minimize struct size on 64-bit.
const char *key;
PrefValue defaultPref;
PrefValue userPref;
};
/*
// <font color=blue>
// Set the various types of preferences. These functions take a dotted
// notation of the preference name (e.g. "browser.startup.homepage").
// Note that this will cause the preference to be saved to the file if
// it is different from the default. In other words, these are used
// to set the _user_ preferences.
//
// If set_default is set to true however, it sets the default value.
// This will only affect the program behavior if the user does not have a value
// saved over it for the particular preference. In addition, these will never
// be saved out to disk.
//
// Each set returns PREF_VALUECHANGED if the user value changed
// (triggering a callback), or PREF_NOERROR if the value was unchanged.
// </font>
*/
nsresult PREF_SetCharPref(const char *pref,const char* value, bool set_default = false);
nsresult PREF_SetIntPref(const char *pref,int32_t value, bool set_default = false);
nsresult PREF_SetBoolPref(const char *pref,bool value, bool set_default = false);
bool PREF_HasUserPref(const char* pref_name);
/*
// <font color=blue>
// Get the various types of preferences. These functions take a dotted
// notation of the preference name (e.g. "browser.startup.homepage")
//
// They also take a pointer to fill in with the return value and return an
// error value. At the moment, this is simply an int but it may
// be converted to an enum once the global error strategy is worked out.
//
// They will perform conversion if the type doesn't match what was requested.
// (if it is reasonably possible)
// </font>
*/
nsresult PREF_GetIntPref(const char *pref,
int32_t * return_int, bool get_default);
nsresult PREF_GetBoolPref(const char *pref, bool * return_val, bool get_default);
/*
// <font color=blue>
// These functions are similar to the above "Get" version with the significant
// difference that the preference module will alloc the memory (e.g. XP_STRDUP) and
// the caller will need to be responsible for freeing it...
// </font>
*/
nsresult PREF_CopyCharPref(const char *pref, char ** return_buf, bool get_default);
/*
// <font color=blue>
// bool function that returns whether or not the preference is locked and therefore
// cannot be changed.
// </font>
*/
bool PREF_PrefIsLocked(const char *pref_name);
/*
// <font color=blue>
// Function that sets whether or not the preference is locked and therefore
// cannot be changed.
// </font>
*/
nsresult PREF_LockPref(const char *key, bool lockIt);
PrefType PREF_GetPrefType(const char *pref_name);
/*
* Delete a branch of the tree
*/
nsresult PREF_DeleteBranch(const char *branch_name);
/*
* Clears the given pref (reverts it to its default value)
*/
nsresult PREF_ClearUserPref(const char *pref_name);
/*
* Clears all user prefs
*/
nsresult PREF_ClearAllUserPrefs();
/*
// <font color=blue>
// The callback function will get passed the pref_node which triggered the call
// and the void * instance_data which was passed to the register callback function.
// Return a non-zero result (nsresult) to pass an error up to the caller.
// </font>
*/
/* Temporarily conditionally compile PrefChangedFunc typedef.
** During migration from old libpref to nsIPref we need it in
** both header files. Eventually prefapi.h will become a private
** file. The two types need to be in sync for now. Certain
** compilers were having problems with multiple definitions.
*/
#ifndef have_PrefChangedFunc_typedef
typedef void (*PrefChangedFunc) (const char *, void *);
#define have_PrefChangedFunc_typedef
#endif
/*
// <font color=blue>
// Register a callback. This takes a node in the preference tree and will
// call the callback function if anything below that node is modified.
// Unregister returns PREF_NOERROR if a callback was found that
// matched all the parameters; otherwise it returns PREF_ERROR.
// </font>
*/
void PREF_RegisterCallback(const char* domain,
PrefChangedFunc callback, void* instance_data );
nsresult PREF_UnregisterCallback(const char* domain,
PrefChangedFunc callback, void* instance_data );
/*
* Used by nsPrefService as the callback function of the 'pref' parser
*/
void PREF_ReaderCallback( void *closure,
const char *pref,
PrefValue value,
PrefType type,
bool isDefault,
bool isStickyDefault);
#ifdef __cplusplus
}
#endif
#endif