modules/libpref/nsIPrefBranch.idl
author Michael Comella <michael.l.comella@gmail.com>
Thu, 28 Sep 2017 14:09:48 -0700
changeset 672179 24a1c13c077ff73b0699219074d5b7c7e97041ef
parent 560957 84fda80ad9997f82d4c70052b68220aae3262aea
child 685889 3d0093f961eec929caa370444cd0f7fcbfbc82bc
permissions -rw-r--r--
Bug 1403755: Rm code to insert blanks into top sites. r=liuche This code was being mistakenly activated when getting top sites for Activity Stream. This is the first removal of old top sites code and will mean we can't go back to old top sites by flipping the `ActivityStream.isEnabled` flag. Since we're planning to ship AS, this shouldn't matter. If we wanted to preserve support, we could create a branch but deleting the code is much simpler. MozReview-Commit-ID: 9VB0RqNHmE0

/* -*- Mode: IDL; tab-width: 2; 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/. */

#include "nsISupports.idl"

interface nsIObserver;

/**
 * The nsIPrefBranch interface is used to manipulate the preferences data. This
 * object may be obtained from the preferences service (nsIPrefService) and
 * used to get and set default and/or user preferences across the application.
 *
 * This object is created with a "root" value which describes the base point in
 * the preferences "tree" from which this "branch" stems. Preferences are
 * accessed off of this root by using just the final portion of the preference.
 * For example, if this object is created with the root "browser.startup.",
 * the preferences "browser.startup.page", "browser.startup.homepage",
 * and "browser.startup.homepage_override" can be accessed by simply passing
 * "page", "homepage", or "homepage_override" to the various Get/Set methods.
 *
 * @see nsIPrefService
 */

[scriptable, uuid(55d25e49-793f-4727-a69f-de8b15f4b985)]
interface nsIPrefBranch : nsISupports
{

  /**
   * Values describing the basic preference types.
   *
   * @see getPrefType
   */
  const long PREF_INVALID = 0;
  const long PREF_STRING = 32;
  const long PREF_INT = 64;
  const long PREF_BOOL = 128;

  /**
   * Called to get the root on which this branch is based, such as
   * "browser.startup."
   */
  readonly attribute string root;

  /**
   * Called to determine the type of a specific preference.
   *
   * @param aPrefName The preference to get the type of.
   *
   * @return long     A value representing the type of the preference. This
   *                  value will be PREF_STRING, PREF_INT, or PREF_BOOL.
   */
  long getPrefType(in string aPrefName);

  /**
   * Called to get the state of an individual boolean preference.
   *
   * @param aPrefName The boolean preference to get the state of.
   * @param aDefaultValue The value to return if the preference is not set.
   *
   * @return boolean  The value of the requested boolean preference.
   *
   * @see setBoolPref
   */
  [optional_argc,binaryname(GetBoolPrefWithDefault)]
  boolean getBoolPref(in string aPrefName, [optional] in boolean aDefaultValue);
  [noscript,binaryname(GetBoolPref)]
  boolean getBoolPrefXPCOM(in string aPrefName);

  /**
   * Called to set the state of an individual boolean preference.
   *
   * @param aPrefName The boolean preference to set the state of.
   * @param aValue    The boolean value to set the preference to.
   *
   * @throws Error if setting failed or the preference has a default
             value of a type other than boolean.
   *
   * @see getBoolPref
   */
  void setBoolPref(in string aPrefName, in boolean aValue);

  /**
   * Called to get the state of an individual floating-point preference.
   * "Floating point" preferences are really string preferences that
   * are converted to floating point numbers.
   *
   * @param aPrefName The floating point preference to get the state of.
   * @param aDefaultValue The value to return if the preference is not set.
   *
   * @return float  The value of the requested floating point preference.
   *
   * @see setCharPref
   */
  [optional_argc,binaryname(GetFloatPrefWithDefault)]
  float getFloatPref(in string aPrefName, [optional] in float aDefaultValue);
  [noscript,binaryname(GetFloatPref)]
  float getFloatPrefXPCOM(in string aPrefName);

  /**
   * Called to get the state of an individual ascii string preference.
   *
   * @param aPrefName The string preference to retrieve.
   * @param aDefaultValue The string to return if the preference is not set.
   *
   * @return string   The value of the requested string preference.
   *
   * @see setCharPref
   */
  [optional_argc,binaryname(GetCharPrefWithDefault)]
  string getCharPref(in string aPrefName, [optional] in string aDefaultValue);
  [noscript,binaryname(GetCharPref)]
  string getCharPrefXPCOM(in string aPrefName);

  /**
   * Called to set the state of an individual ascii string preference.
   *
   * @param aPrefName The string preference to set.
   * @param aValue    The string value to set the preference to.
   *
   * @throws Error if setting failed or the preference has a default
             value of a type other than string.
   *
   * @see getCharPref
   */
  void setCharPref(in string aPrefName, in string aValue);

  /**
   * Called to get the state of an individual unicode string preference.
   *
   * @param aPrefName The string preference to retrieve.
   * @param aDefaultValue The string to return if the preference is not set.
   *
   * @return string   The value of the requested string preference.
   *
   * @see setStringPref
   */
  [optional_argc]
  AUTF8String getStringPref(in string aPrefName,
                            [optional] in AUTF8String aDefaultValue);

  /**
   * Called to set the state of an individual unicode string preference.
   *
   * @param aPrefName The string preference to set.
   * @param aValue    The string value to set the preference to.
   *
   * @throws Error if setting failed or the preference has a default
             value of a type other than string.
   *
   * @see getStringPref
   */
  void setStringPref(in string aPrefName, in AUTF8String aValue);

  /**
   * Called to get the state of an individual integer preference.
   *
   * @param aPrefName The integer preference to get the value of.
   * @param aDefaultValue The value to return if the preference is not set.
   *
   * @return long     The value of the requested integer preference.
   *
   * @see setIntPref
   */
  [optional_argc,binaryname(GetIntPrefWithDefault)]
  long getIntPref(in string aPrefName, [optional] in long aDefaultValue);
  [noscript,binaryname(GetIntPref)]
  long getIntPrefXPCOM(in string aPrefName);

  /**
   * Called to set the state of an individual integer preference.
   *
   * @param aPrefName The integer preference to set the value of.
   * @param aValue    The integer value to set the preference to.
   *
   * @throws Error if setting failed or the preference has a default
             value of a type other than integer.
   *
   * @see getIntPref
   */
  void setIntPref(in string aPrefName, in long aValue);

  /**
   * 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.
   *
   * @param aPrefName The complex preference to get the value of.
   * @param aType     The XPCOM interface that this complex preference
   *                  represents. Interfaces currently supported are:
   *                    - nsIFile
   *                    - nsISupportsString (UniChar)
   *                      (deprecated; see getStringPref)
   *                    - nsIPrefLocalizedString (Localized UniChar)
   * @param aValue    The XPCOM object into which to the complex preference 
   *                  value should be retrieved.
   *
   * @throws Error The value does not exist or is the wrong type.
   *
   * @see setComplexValue
   */
  void getComplexValue(in string aPrefName, in nsIIDRef aType,
                       [iid_is(aType), retval] out nsQIResult aValue);

  /**
   * 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.
   *
   * @param aPrefName The complex preference to set the value of.
   * @param aType     The XPCOM interface that this complex preference
   *                  represents. Interfaces currently supported are:
   *                    - nsIFile
   *                    - nsISupportsString (UniChar)
   *                      (deprecated; see setStringPref)
   *                    - nsIPrefLocalizedString (Localized UniChar)
   * @param aValue    The XPCOM object from which to set the complex preference 
   *                  value.
   *
   * @throws Error if setting failed or the value is the wrong type.
   *
   * @see getComplexValue
   */
  void setComplexValue(in string aPrefName, in nsIIDRef aType, in nsISupports aValue);

  /**
   * 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.
   *
   * @param aPrefName The preference to be cleared.
   *
   * @note
   * This method does nothing if this object is a default branch.
   */
  void clearUserPref(in string aPrefName);

  /**
   * 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.
   *
   * @param aPrefName The 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.
   *
   * @throws Error The preference does not exist or an error occurred.
   *
   * @see unlockPref
   */
  void lockPref(in string aPrefName);

  /**
   * Called to check if a specific preference has a user value associated to
   * it.
   *
   * @param aPrefName The 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.
   *
   * @note
   * If a preference was manually set to a value that equals the default value,
   * then the preference no longer has a user set value, i.e. it is
   * considered reset to its default value.
   * In particular, this method will return false for such a preference and
   * the preference will not be saved to a file by nsIPrefService.savePrefFile.
   *
   * @return boolean  true  The preference has a user set value.
   *                  false The preference only has a default value.
   */
  boolean prefHasUserValue(in string aPrefName);

  /**
   * Called to check if a specific preference is locked. If a preference is
   * locked calling its Get method will always return the default value.
   *
   * @param aPrefName The 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.
   *
   * @return boolean  true  The preference is locked.
   *                  false The preference is not locked.
   *
   * @see lockPref
   * @see unlockPref
   */
  boolean prefIsLocked(in string aPrefName);

  /**
   * 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.
   *
   * @param aPrefName The 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.
   *
   * @throws Error The preference does not exist or an error occurred.
   *
   * @see lockPref
   */
  void    unlockPref(in string aPrefName);


  /**
   * Called to remove all of the preferences referenced by this branch.
   *
   * @param aStartingAt The 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.
   *
   * @throws Error The preference(s) do not exist or an error occurred.
   */
  void deleteBranch(in string aStartingAt);

  /**
   * Returns an array of strings representing the child preferences of the
   * root of this branch.
   * 
   * @param aStartingAt The point on the branch at which to start enumerating
   *                    the child preferences. Pass in "" to enumerate all
   *                    preferences referenced by this branch.
   * @param aCount      Receives the number of elements in the array.
   * @param aChildArray Receives 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.
   *
   * @throws Error The preference(s) do not exist or an error occurred.
   */
  void getChildList(in string aStartingAt,
                    [optional] out unsigned long aCount,
                    [array, size_is(aCount), retval] out string aChildArray);

  /**
   * Called to reset all of the preferences referenced by this branch to their
   * default values.
   *
   * @param aStartingAt The 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.
   *
   * @throws Error The preference(s) do not exist or an error occurred.
   */
  void resetBranch(in string aStartingAt);

  /**
   * 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 name of the preference which has changed, relative to
   *              the |root| of the aSubject branch.
   *
   * aSubject.get*Pref(aData) will get the new value of the modified
   * preference. For example, if your observer is registered with
   * addObserver("bar.", ...) on a branch with root "foo.", modifying
   * the preference "foo.bar.baz" will trigger the observer, and aData
   * parameter will be "bar.baz".
   *
   * @param aDomain   The 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
   * @param aObserver The object to be notified if the preference changes.
   * @param aHoldWeak true  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 ensures 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.
   *
   * @note
   * 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.
   *
   * @note
   * It is possible to change preferences during the notification.
   *
   * @note
   * 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 nsIObserver
   * @see removeObserver
   */
  void addObserver(in string aDomain, in nsIObserver aObserver,
                   [optional] in boolean aHoldWeak);

  /**
   * Remove a preference change observer.
   *
   * @param aDomain   The preference which is being observed for changes.
   * @param aObserver An observer previously registered with addObserver().
   *
   * @note
   * Note that you must call removeObserver() on the same nsIPrefBranch
   * instance on which you called addObserver() in order to remove aObserver;
   * otherwise, the observer will not be removed.
   *
   * @see nsIObserver
   * @see addObserver
   */
  void removeObserver(in string aDomain, in nsIObserver aObserver);
};


%{C++

#define NS_PREFBRANCH_CONTRACTID "@mozilla.org/preferencesbranch;1"
/**
 * Notification sent when a preference changes.
 */
#define NS_PREFBRANCH_PREFCHANGE_TOPIC_ID "nsPref:changed"

%}