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Public Member Functions | Public Attributes | Protected Member Functions | Private Attributes
nsPrefBranch Class Reference

#include <nsPrefBranch.h>

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List of all members.

Public Member Functions

NS_DECL_ISUPPORTS
NS_DECL_NSIPREFBRANCH
NS_DECL_NSIPREFBRANCH2
NS_DECL_NSISECURITYPREF
NS_DECL_NSIOBSERVER 
nsPrefBranch (const char *aPrefRoot, PRBool aDefaultBranch)
virtual ~nsPrefBranch ()
PRInt32 GetRootLength ()
void addObserver (in string aDomain, in nsIObserver aObserver, in boolean aHoldWeak)
 Add a preference change observer.
void removeObserver (in string aDomain, in nsIObserver aObserver)
 Remove a preference change observer.
long getPrefType (in string aPrefName)
 Called to determine the type of a specific preference.
boolean getBoolPref (in string aPrefName)
 Called to get the state of an individual boolean preference.
void setBoolPref (in string aPrefName, in long aValue)
 Called to set the state of an individual boolean preference.
string getCharPref (in string aPrefName)
 Called to get the state of an individual string preference.
void setCharPref (in string aPrefName, in string aValue)
 Called to set the state of an individual string preference.
long getIntPref (in string aPrefName)
 Called to get the state of an individual integer preference.
void setIntPref (in string aPrefName, in long aValue)
 Called to set the state of an individual integer preference.
void getComplexValue (in string aPrefName, in nsIIDRef aType,[iid_is(aType), retval] out nsQIResult aValue)
 Called to get the state of an individual complex preference.
void setComplexValue (in string aPrefName, in nsIIDRef aType, in nsISupports aValue)
 Called to set the state of an individual complex preference.
void clearUserPref (in string aPrefName)
 Called to clear a user set value from a specific preference.
void lockPref (in string aPrefName)
 Called to lock a specific preference.
boolean prefHasUserValue (in string aPrefName)
 Called to check if a specific preference has a user value associated to it.
boolean prefIsLocked (in string aPrefName)
 Called to check if a specific preference is locked.
void unlockPref (in string aPrefName)
 Called to unlock a specific preference.
void deleteBranch (in string aStartingAt)
 Called to remove all of the preferences referenced by this branch.
void getChildList (in string aStartingAt, out unsigned long aCount,[array, size_is(aCount), retval] out string aChildArray)
 Returns an array of strings representing the child preferences of the root of this branch.
void resetBranch (in string aStartingAt)
 Called to reset all of the preferences referenced by this branch to their default values.
boolean securityGetBoolPref (in string pref)
 Called to get the state of a "capability" boolean preference.
void securitySetBoolPref (in string pref, in boolean value)
 Called to set the state of a "capability" boolean preference.
string securityGetCharPref (in string pref)
 Called to get the state of a "capability" string preference.
void securitySetCharPref (in string pref, in string value)
 Called to set the state of a "capability" string preference.
long securityGetIntPref (in string pref)
 Called to get the state of a "capability" integer preference.
void securitySetIntPref (in string pref, in long value)
 Called to set the state of a "capability" integer preference.
void securityClearUserPref (in string pref_name)
 Called to clear a user set value from a "capability" preference.
void observe (in nsISupports aSubject, in string aTopic, in wstring aData)
 Observe will be called when there is a notification for the topic |aTopic|.

Public Attributes

const long PREF_INVALID = 0
 Values describing the basic preference types.
const long PREF_STRING = 32
const long PREF_INT = 64
const long PREF_BOOL = 128
readonly attribute string root
 Called to get the root on which this branch is based, such as "browser.startup.".

Protected Member Functions

 nsPrefBranch ()
nsresult GetDefaultFromPropertiesFile (const char *aPrefName, PRUnichar **return_buf)
const char * getPrefName (const char *aPrefName)
nsresult getValidatedPrefName (const char *aPrefName, const char **_retval)
void freeObserverList (void)

Private Attributes

PRInt32 mPrefRootLength
nsAutoVoidArray * mObservers
nsCString mPrefRoot
nsCStringArray mObserverDomains
PRBool mIsDefault

Detailed Description

Definition at line 56 of file nsPrefBranch.h.


Constructor & Destructor Documentation

nsPrefBranch::nsPrefBranch ( const char *  aPrefRoot,
PRBool  aDefaultBranch 
)

Definition at line 88 of file nsPrefBranch.cpp.

  : mObservers(nsnull)
{
  mPrefRoot = aPrefRoot;
  mPrefRootLength = mPrefRoot.Length();
  mIsDefault = aDefaultBranch;

  nsCOMPtr<nsIObserverService> observerService = 
           do_GetService("@mozilla.org/observer-service;1");
  if (observerService) {
    ++mRefCnt;    // Our refcnt must be > 0 when we call this, or we'll get deleted!
    // add weak so we don't have to clean up at shutdown
    observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, PR_TRUE);
    --mRefCnt;
  }
}

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Definition at line 105 of file nsPrefBranch.cpp.

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nsPrefBranch::nsPrefBranch ( ) [inline, protected]

Definition at line 74 of file nsPrefBranch.h.

    { };

Member Function Documentation

void nsIPrefBranch2::addObserver ( in string  aDomain,
in nsIObserver  aObserver,
in boolean  aHoldWeak 
) [inherited]

Add a preference change observer.

On preference changes, the following arguments will be passed to the nsIObserver.observe() method: aSubject - The nsIPrefBranch object (this) aTopic - The string defined by NS_PREFBRANCH_PREFCHANGE_TOPIC_ID aData - The preference which has changed

Parameters:
aDomainThe preference on which to listen for changes. This can be the name of an entire branch to observe. e.g. Holding the "root" prefbranch and calling addObserver("foo.bar.", ...) will observe changes to foo.bar.baz and foo.bar.bzip
aObserverThe object to be notified if the preference changes.
aHoldWeaktrue Hold a weak reference to |aObserver|. The object must implement the nsISupportsWeakReference interface or this will fail. false Hold a strong reference to |aObserver|.
Note:
Registering as a preference observer can open an object to potential cyclical references which will cause memory leaks. These cycles generally occur because an object both registers itself as an observer (causing the branch to hold a reference to the observer) and holds a reference to the branch object for the purpose of getting/setting preference values. There are 3 approaches which have been implemented in an attempt to avoid these situations. 1) The nsPrefBranch object supports nsISupportsWeakReference. Any consumer may hold a weak reference to it instead of a strong one. 2) The nsPrefBranch object listens for xpcom-shutdown and frees all of the objects currently in its observer list. This insures that long lived objects (services for example) will be freed correctly. 3) The observer can request to be held as a weak reference when it is registered. This insures that shorter lived objects (say one tied to an open window) will not fall into the cyclical reference trap.
The list of registered observers may be changed during the dispatch of nsPref:changed notification. However, the observers are not guaranteed to be notified in any particular order, so you can't be sure whether the added/removed observer will be called during the notification when it is added/removed.
It is possible to change preferences during the notification.
It is not safe to change observers during this callback in Gecko releases before 1.9. If you want a safe way to remove a pref observer, please use an nsITimer.
See also:
nsIObserver
removeObserver
void nsIPrefBranch::clearUserPref ( in string  aPrefName) [inherited]

Called to clear a user set value from a specific preference.

This will, in effect, reset the value to the default value. If no default value exists the preference will cease to exist.

Parameters:
aPrefNameThe preference to be cleared.
Note:
This method does nothing if this object is a default branch.
Returns:
NS_OK The user preference was successfully cleared.
Other The preference does not exist or have a user set value.
void nsIPrefBranch::deleteBranch ( in string  aStartingAt) [inherited]

Called to remove all of the preferences referenced by this branch.

Parameters:
aStartingAtThe point on the branch at which to start the deleting preferences. Pass in "" to remove all preferences referenced by this branch.
Note:
This method can be called on either a default or user branch but, in effect, always operates on both.
Returns:
NS_OK The preference(s) were successfully removed.
Other The preference(s) do not exist or an error occurred.

Definition at line 764 of file nsPrefBranch.cpp.

{
  const char *pref;
  PrefCallbackData *pCallback;

  if (mObservers) {
    // unregister the observers
    PRInt32 count;

    count = mObservers->Count();
    if (count > 0) {
      PRInt32 i;
      nsCAutoString domain;
      for (i = 0; i < count; ++i) {
        pCallback = (PrefCallbackData *)mObservers->ElementAt(i);
        if (pCallback) {
          mObserverDomains.CStringAt(i, domain);
          // We must pass a fully qualified preference name to remove the callback
          pref = getPrefName(domain.get()); // can't fail because domain must be valid
          // Remove this observer from our array so that nobody else can remove
          // what we're trying to remove right now.
          mObservers->ReplaceElementAt(nsnull, i);
          PREF_UnregisterCallback(pref, NotifyObserver, pCallback);
          NS_RELEASE(pCallback->pObserver);
          nsMemory::Free(pCallback);
        }
      }

      // now empty the observer domains array in bulk
      mObserverDomains.Clear();
    }
    delete mObservers;
    mObservers = 0;
  }
}

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boolean nsIPrefBranch::getBoolPref ( in string  aPrefName) [inherited]

Called to get the state of an individual boolean preference.

Parameters:
aPrefNameThe boolean preference to get the state of.
Returns:
boolean The value of the requested boolean preference.
See also:
setBoolPref
string nsIPrefBranch::getCharPref ( in string  aPrefName) [inherited]

Called to get the state of an individual string preference.

Parameters:
aPrefNameThe string preference to retrieve.
Returns:
string The value of the requested string preference.
See also:
setCharPref
void nsIPrefBranch::getChildList ( in string  aStartingAt,
out unsigned long  aCount,
[array, size_is(aCount), retval] out string  aChildArray 
) [inherited]

Returns an array of strings representing the child preferences of the root of this branch.

Parameters:
aStartingAtThe point on the branch at which to start enumerating the child preferences. Pass in "" to enumerate all preferences referenced by this branch.
aCountReceives the number of elements in the array.
aChildArrayReceives the array of child preferences.
Note:
This method can be called on either a default or user branch but, in effect, always operates on both.
Returns:
NS_OK The preference list was successfully retrieved.
Other The preference(s) do not exist or an error occurred.
void nsIPrefBranch::getComplexValue ( in string  aPrefName,
in nsIIDRef  aType,
[iid_is(aType), retval] out nsQIResult  aValue 
) [inherited]

Called to get the state of an individual complex preference.

A complex preference is a preference which represents an XPCOM object that can not be easily represented using a standard boolean, integer or string value.

Parameters:
aPrefNameThe complex preference to get the value of.
aTypeThe XPCOM interface that this complex preference represents. Interfaces currently supported are:
aValueThe XPCOM object into which to the complex preference value should be retrieved.
Returns:
NS_OK The value was successfully retrieved.
Other The value does not exist or is the wrong type.
See also:
setComplexValue
nsresult nsPrefBranch::GetDefaultFromPropertiesFile ( const char *  aPrefName,
PRUnichar **  return_buf 
) [protected]

Definition at line 800 of file nsPrefBranch.cpp.

{
  nsresult rv;

  // the default value contains a URL to a .properties file
    
  nsXPIDLCString propertyFileURL;
  rv = PREF_CopyCharPref(aPrefName, getter_Copies(propertyFileURL), PR_TRUE);
  if (NS_FAILED(rv))
    return rv;
    
  nsCOMPtr<nsIStringBundleService> bundleService =
      do_GetService(NS_STRINGBUNDLE_CONTRACTID, &rv);
  if (NS_FAILED(rv))
    return rv;

  nsCOMPtr<nsIStringBundle> bundle;
  rv = bundleService->CreateBundle(propertyFileURL,
                                   getter_AddRefs(bundle));
  if (NS_FAILED(rv))
    return rv;

  // string names are in unicode
  nsAutoString stringId;
  stringId.AssignASCII(aPrefName);

  return bundle->GetStringFromName(stringId.get(), return_buf);
}

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long nsIPrefBranch::getIntPref ( in string  aPrefName) [inherited]

Called to get the state of an individual integer preference.

Parameters:
aPrefNameThe integer preference to get the value of.
Returns:
long The value of the requested integer preference.
See also:
setIntPref
const char * nsPrefBranch::getPrefName ( const char *  aPrefName) [protected]

Definition at line 829 of file nsPrefBranch.cpp.

{
  // for speed, avoid strcpy if we can:
  if (mPrefRoot.IsEmpty())
    return aPrefName;

  // isn't there a better way to do this? this is really kind of gross.
  mPrefRoot.Truncate(mPrefRootLength);

  // only append if anything to append
  if ((nsnull != aPrefName) && (*aPrefName != '\0'))
    mPrefRoot.Append(aPrefName);

  return mPrefRoot.get();
}

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long nsIPrefBranch::getPrefType ( in string  aPrefName) [inherited]

Called to determine the type of a specific preference.

Parameters:
aPrefNameThe preference to get the type of.
Returns:
long A value representing the type of the preference. This value will be PREF_STRING, PREF_INT, or PREF_BOOL.

Definition at line 71 of file nsPrefBranch.h.

{ return mPrefRootLength; }
nsresult nsPrefBranch::getValidatedPrefName ( const char *  aPrefName,
const char **  _retval 
) [protected]

Definition at line 845 of file nsPrefBranch.cpp.

{
  static const char capabilityPrefix[] = "capability.";

  NS_ENSURE_ARG_POINTER(aPrefName);
  const char *fullPref = getPrefName(aPrefName);

  // now that we have the pref, check it against the ScriptSecurityManager
  if ((fullPref[0] == 'c') &&
    PL_strncmp(fullPref, capabilityPrefix, sizeof(capabilityPrefix)-1) == 0)
  {
    nsresult rv;
    nsCOMPtr<nsIPrefSecurityCheck> secCheck = 
             do_GetService(NS_GLOBAL_PREF_SECURITY_CHECK, &rv);

    if (NS_FAILED(rv))
      return NS_ERROR_FAILURE;

    PRBool enabled;
    rv = secCheck->CanAccessSecurityPreferences(&enabled);
    if (NS_FAILED(rv) || !enabled)
      return NS_ERROR_FAILURE;
  }

  *_retval = fullPref;
  return NS_OK;
}

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void nsIPrefBranch::lockPref ( in string  aPrefName) [inherited]

Called to lock a specific preference.

Locking a preference will cause the preference service to always return the default value regardless of whether there is a user set value or not.

Parameters:
aPrefNameThe preference to be locked.
Note:
This method can be called on either a default or user branch but, in effect, always operates on the default branch.
Returns:
NS_OK The preference was successfully locked.
Other The preference does not exist or an error occurred.
See also:
unlockPref
void nsIObserver::observe ( in nsISupports  aSubject,
in string  aTopic,
in wstring  aData 
) [inherited]

Observe will be called when there is a notification for the topic |aTopic|.

This assumes that the object implementing this interface has been registered with an observer service such as the nsIObserverService.

If you expect multiple topics/subjects, the impl is responsible for filtering.

You should not modify, add, remove, or enumerate notifications in the implemention of observe.

Parameters:
aSubject: Notification specific interface pointer.
aTopic: The notification topic or subject.
aData: Notification specific wide string. subject event.
boolean nsIPrefBranch::prefHasUserValue ( in string  aPrefName) [inherited]

Called to check if a specific preference has a user value associated to it.

Parameters:
aPrefNameThe preference to be tested.
Note:
This method can be called on either a default or user branch but, in effect, always operates on the user branch.
Returns:
boolean true The preference has a user set value. false The preference only has a default value.
boolean nsIPrefBranch::prefIsLocked ( in string  aPrefName) [inherited]

Called to check if a specific preference is locked.

If a preference is locked calling its Get method will always return the default value.

Parameters:
aPrefNameThe preference to be tested.
Note:
This method can be called on either a default or user branch but, in effect, always operates on the default branch.
Returns:
boolean true The preference is locked. false The preference is not locked.
See also:
lockPref
unlockPref
void nsIPrefBranch2::removeObserver ( in string  aDomain,
in nsIObserver  aObserver 
) [inherited]

Remove a preference change observer.

Parameters:
aDomainThe preference which is being observed for changes.
aObserverAn observer previously registered with addObserver().
See also:
nsIObserver
addObserver
void nsIPrefBranch::resetBranch ( in string  aStartingAt) [inherited]

Called to reset all of the preferences referenced by this branch to their default values.

Parameters:
aStartingAtThe point on the branch at which to start the resetting preferences to their default values. Pass in "" to reset all preferences referenced by this branch.
Note:
This method can be called on either a default or user branch but, in effect, always operates on the user branch.
Returns:
NS_OK The preference(s) were successfully reset.
Other The preference(s) do not exist or an error occurred.

Called to clear a user set value from a "capability" preference.

This will, in effect, reset the value to the default value. If no default value exists the preference will cease to exist.

Parameters:
pref_nameThe preference to be cleared.
Note:
This method does nothing if this object is a default branch.
Returns:
NS_OK The user preference was successfully cleared.
Other The preference does not exist or have a user set value.

Called to get the state of a "capability" boolean preference.

Parameters:
prefThe boolean preference to get the state of.
Returns:
boolean The value of the requested boolean preference.
See also:
securitySetBoolPref

Called to get the state of a "capability" string preference.

Parameters:
prefThe string preference to retrieve.
Returns:
string The value of the requested string preference.
See also:
securitySetCharPref

Called to get the state of a "capability" integer preference.

Parameters:
prefThe integer preference to get the value of.
Returns:
long The value of the requested integer preference.
See also:
securitySetIntPref
void nsISecurityPref::securitySetBoolPref ( in string  pref,
in boolean  value 
) [inherited]

Called to set the state of a "capability" boolean preference.

Parameters:
prefThe boolean preference to set the state of.
valueThe boolean value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
securityGetBoolPref
void nsISecurityPref::securitySetCharPref ( in string  pref,
in string  value 
) [inherited]

Called to set the state of a "capability" string preference.

Parameters:
prefThe string preference to set.
valueThe string value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
securityGetCharPref
void nsISecurityPref::securitySetIntPref ( in string  pref,
in long  value 
) [inherited]

Called to set the state of a "capability" integer preference.

Parameters:
prefThe integer preference to set the value of.
valueThe integer value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
securityGetIntPref
void nsIPrefBranch::setBoolPref ( in string  aPrefName,
in long  aValue 
) [inherited]

Called to set the state of an individual boolean preference.

Parameters:
aPrefNameThe boolean preference to set the state of.
aValueThe boolean value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
getBoolPref
void nsIPrefBranch::setCharPref ( in string  aPrefName,
in string  aValue 
) [inherited]

Called to set the state of an individual string preference.

Parameters:
aPrefNameThe string preference to set.
aValueThe string value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
getCharPref
void nsIPrefBranch::setComplexValue ( in string  aPrefName,
in nsIIDRef  aType,
in nsISupports  aValue 
) [inherited]

Called to set the state of an individual complex preference.

A complex preference is a preference which represents an XPCOM object that can not be easily represented using a standard boolean, integer or string value.

Parameters:
aPrefNameThe complex preference to set the value of.
aTypeThe XPCOM interface that this complex preference represents. Interfaces currently supported are:
aValueThe XPCOM object from which to set the complex preference value.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
getComplexValue
void nsIPrefBranch::setIntPref ( in string  aPrefName,
in long  aValue 
) [inherited]

Called to set the state of an individual integer preference.

Parameters:
aPrefNameThe integer preference to set the value of.
aValueThe integer value to set the preference to.
Returns:
NS_OK The value was successfully set.
Other The value was not set or is the wrong type.
See also:
getIntPref
void nsIPrefBranch::unlockPref ( in string  aPrefName) [inherited]

Called to unlock a specific preference.

Unlocking a previously locked preference allows the preference service to once again return the user set value of the preference.

Parameters:
aPrefNameThe preference to be unlocked.
Note:
This method can be called on either a default or user branch but, in effect, always operates on the default branch.
Returns:
NS_OK The preference was successfully unlocked.
Other The preference does not exist or an error occurred.
See also:
lockPref

Member Data Documentation

Definition at line 87 of file nsPrefBranch.h.

nsCStringArray nsPrefBranch::mObserverDomains [private]

Definition at line 86 of file nsPrefBranch.h.

nsAutoVoidArray* nsPrefBranch::mObservers [private]

Definition at line 84 of file nsPrefBranch.h.

Definition at line 85 of file nsPrefBranch.h.

Definition at line 83 of file nsPrefBranch.h.

const long nsIPrefBranch::PREF_BOOL = 128 [inherited]

Definition at line 72 of file nsIPrefBranch.idl.

Definition at line 71 of file nsIPrefBranch.idl.

Values describing the basic preference types.

See also:
getPrefType

Definition at line 69 of file nsIPrefBranch.idl.

Definition at line 70 of file nsIPrefBranch.idl.

readonly attribute string nsIPrefBranch::root [inherited]

Called to get the root on which this branch is based, such as "browser.startup.".

Definition at line 78 of file nsIPrefBranch.idl.


The documentation for this class was generated from the following files: