xpcom/ds/nsStringEnumerator.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsStringEnumerator_h
   8 #define nsStringEnumerator_h
   9
  10 #include "nsIStringEnumerator.h"
  11 #include "nsStringFwd.h"
  12 #include "nsTArrayForwardDeclare.h"
  13
  14 class nsStringEnumeratorBase : public nsIStringEnumerator,
  15                                public nsIUTF8StringEnumerator {
  16  public:
  17   NS_DECL_NSISTRINGENUMERATORBASE
  18
  19   NS_IMETHOD GetNext(nsAString&) override;
  20
  21   using nsIUTF8StringEnumerator::GetNext;
  22
  23  protected:
  24   virtual ~nsStringEnumeratorBase() = default;
  25 };
  26
  27 // nsIStringEnumerator/nsIUTF8StringEnumerator implementations
  28 //
  29 // Currently all implementations support both interfaces. The
  30 // constructors below provide the most common interface for the given
  31 // type (i.e. nsIStringEnumerator for char16_t* strings, and so
  32 // forth) but any resulting enumerators can be queried to the other
  33 // type. Internally, the enumerators will hold onto the type that was
  34 // passed in and do conversion if GetNext() for the other type of
  35 // string is called.
  36
  37 // There are a few different types of enumerators:
  38
  39 //
  40 // These enumerators hold a pointer to the array. Be careful
  41 // because modifying the array may confuse the iterator, especially if
  42 // you insert or remove elements in the middle of the array.
  43 //
  44
  45 // The non-adopting enumerator requires that the array sticks around
  46 // at least as long as the enumerator does. These are for constant
  47 // string arrays that the enumerator does not own, this could be used
  48 // in VERY specialized cases such as when the provider KNOWS that the
  49 // string enumerator will be consumed immediately, or will at least
  50 // outlast the array.
  51 // For example:
  52 //
  53 // nsTArray<nsCString> array;
  54 // array.AppendCString("abc");
  55 // array.AppendCString("def");
  56 // NS_NewStringEnumerator(&enumerator, &array, true);
  57 //
  58 // // call some internal method which iterates the enumerator
  59 // InternalMethod(enumerator);
  60 // NS_RELEASE(enumerator);
  61 //
  62 [[nodiscard]] nsresult NS_NewStringEnumerator(nsIStringEnumerator** aResult,
  63                                               const nsTArray<nsString>* aArray,
  64                                               nsISupports* aOwner);
  65 [[nodiscard]] nsresult NS_NewUTF8StringEnumerator(
  66     nsIUTF8StringEnumerator** aResult, const nsTArray<nsCString>* aArray);
  67
  68 [[nodiscard]] nsresult NS_NewStringEnumerator(nsIStringEnumerator** aResult,
  69                                               const nsTArray<nsString>* aArray);
  70
  71 // Adopting string enumerators assume ownership of the array and will
  72 // call |operator delete| on the array when the enumerator is destroyed
  73 // this is useful when the provider creates an array solely for the
  74 // purpose of creating the enumerator.
  75 // For example:
  76 //
  77 // nsTArray<nsCString>* array = new nsTArray<nsCString>;
  78 // array->AppendString("abcd");
  79 // NS_NewAdoptingStringEnumerator(&result, array);
  80 [[nodiscard]] nsresult NS_NewAdoptingStringEnumerator(
  81     nsIStringEnumerator** aResult, nsTArray<nsString>* aArray);
  82
  83 [[nodiscard]] nsresult NS_NewAdoptingUTF8StringEnumerator(
  84     nsIUTF8StringEnumerator** aResult, nsTArray<nsCString>* aArray);
  85
  86 // these versions take a refcounted "owner" which will be addreffed
  87 // when the enumerator is created, and destroyed when the enumerator
  88 // is released. This allows providers to give non-owning pointers to
  89 // ns*StringArray member variables without worrying about lifetime
  90 // issues
  91 // For example:
  92 //
  93 // nsresult MyClass::Enumerate(nsIUTF8StringEnumerator** aResult) {
  94 //     mCategoryList->AppendString("abcd");
  95 //     return NS_NewStringEnumerator(aResult, mCategoryList, this);
  96 // }
  97 //
  98 [[nodiscard]] nsresult NS_NewUTF8StringEnumerator(
  99     nsIUTF8StringEnumerator** aResult, const nsTArray<nsCString>* aArray,
 100     nsISupports* aOwner);
 101
 102 #endif  // defined nsStringEnumerator_h