gecko-dev/xpcom/glue/nsTArray.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is C++ array template.
*
* The Initial Developer of the Original Code is Google Inc.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@meer.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsTArray_h__
#define nsTArray_h__
#include "prtypes.h"
#include "nsQuickSort.h"
#include "nsDebug.h"
#include NEW_H
//
// This class serves as a base class for nsTArray. It shouldn't be used
// directly. It holds common implementation code that does not depend on the
// element type of the nsTArray.
//
class NS_COM_GLUE nsTArray_base {
public:
typedef PRUint32 size_type;
typedef PRUint32 index_type;
// A special value that is used to indicate an invalid or unknown index
// into the array.
enum {
NoIndex = index_type(-1)
};
// @return The number of elements in the array.
size_type Length() const {
return mHdr->mLength;
}
// @return True if the array is empty or false otherwise.
PRBool IsEmpty() const {
return Length() == 0;
}
// @return The number of elements that can fit in the array without forcing
// the array to be re-allocated. The length of an array is always less
// than or equal to its capacity.
size_type Capacity() const {
return mHdr->mCapacity;
}
protected:
nsTArray_base()
: mHdr(NS_CONST_CAST(Header *, &sEmptyHdr)) {
}
// Resize the storage if necessary to achieve the requested capacity.
// @param capacity The requested number of array elements.
// @param elementSize The size of an array element.
// @return False if insufficient memory is available; true otherwise.
PRBool EnsureCapacity(size_type capacity, size_type elementSize);
// Resize the storage to the minimum required amount.
// @param elementSize The size of an array element.
void ShrinkCapacity(size_type elementSize);
// This method may be called to resize a "gap" in the array by shifting
// elements around. It updates mLength appropriately. If the resulting
// array has zero elements, then the array's memory is free'd.
// @param start The starting index of the gap.
// @param oldLen The current length of the gap.
// @param newLen The desired length of the gap.
// @param elementSize The size of an array element.
void ShiftData(index_type start, size_type oldLen, size_type newLen,
size_type elementSize);
// This method increments the length member of the array's header.
void IncrementLength(PRUint32 n) {
NS_ASSERTION(mHdr != &sEmptyHdr, "bad data pointer");
mHdr->mLength += n;
}
protected:
// We prefix mData with a structure of this type. This is done to minimize
// the size of the nsTArray object when it is empty.
struct Header {
PRUint32 mLength;
PRUint32 mCapacity;
};
static const Header sEmptyHdr;
// The array's elements (prefixed with a Header). This pointer is never
// null. If the array is empty, then this will point to sEmptyHdr.
Header *mHdr;
};
//
// This class defines convenience functions for element specific operations.
// Specialize this template if necessary.
//
template<class E>
class nsTArrayElementTraits {
public:
// Invoke the default constructor in place.
static inline void Construct(E *e) {
new (NS_STATIC_CAST(void *, e)) E();
}
// Invoke the copy-constructor in place.
template<class A>
static inline void Construct(E *e, const A &arg) {
new (NS_STATIC_CAST(void *, e)) E(arg);
}
// Invoke the destructor in place.
static inline void Destruct(E *e) {
e->~E();
}
};
// This class exists because VC6 cannot handle static template functions.
// Otherwise, the Compare method would be defined directly on nsTArray.
template <class E, class Comparator>
class nsQuickSortComparator {
public:
typedef E elem_type;
// This function is meant to be used with the NS_QuickSort function. It
// maps the callback API expected by NS_QuickSort to the Comparator API
// used by nsTArray. See nsTArray::Sort.
static int Compare(const void* e1, const void* e2, void *data) {
const Comparator* c = NS_REINTERPRET_CAST(const Comparator*, data);
const elem_type* a = NS_STATIC_CAST(const elem_type*, e1);
const elem_type* b = NS_STATIC_CAST(const elem_type*, e2);
return c->LessThan(*a, *b) ? -1 : (c->Equals(*a, *b) ? 0 : 1);
}
};
// The default comparator used by nsTArray
template<class A, class B>
class nsDefaultComparator {
public:
PRBool Equals(const A& a, const B& b) const {
return a == b;
}
PRBool LessThan(const A& a, const B& b) const {
return a < b;
}
};
//
// The templatized array class that dynamically resizes its storage as elements
// are added. This class is designed to behave a bit like std::vector.
//
// The template parameter specifies the type of the elements (elem_type), and
// has the following requirements:
//
// elem_type MUST define a copy-constructor.
// elem_type MAY define operator< for sorting.
// elem_type MAY define operator== for searching.
//
// For methods taking a Comparator instance, the Comparator must be a class
// defining the following methods:
//
// class Comparator {
// public:
// /** @return True if the elements are equals; false otherwise. */
// PRBool Equals(const elem_type& a, const elem_type& b) const;
//
// /** @return True if (a < b); false otherwise. */
// PRBool LessThan(const elem_type& a, const elem_type& b) const;
// };
//
// The Equals method is used for searching, and the LessThan method is used
// for sorting.
//
template<class E>
class nsTArray : public nsTArray_base {
public:
typedef E elem_type;
typedef nsTArray<E> self_type;
typedef nsTArrayElementTraits<E> elem_traits;
//
// Finalization method
//
~nsTArray() { Clear(); }
//
// Initialization methods
//
nsTArray() {}
// Initialize this array and pre-allocate some number of elements.
explicit nsTArray(size_type capacity) {
SetCapacity(capacity);
}
// The array's copy-constructor performs a 'deep' copy of the given array.
// @param other The array object to copy.
nsTArray(const self_type& other) {
AppendElements(other);
}
// The array's assignment operator performs a 'deep' copy of the given
// array. It is optimized to reuse existing storage if possible.
// @param other The array object to copy.
nsTArray& operator=(const self_type& other) {
ReplaceElementsAt(0, Length(), other.Elements(), other.Length());
return *this;
}
//
// Accessor methods
//
// This method provides direct access to the array elements.
// @return A pointer to the first element of the array. If the array is
// empty, then this pointer must not be dereferenced.
elem_type* Elements() {
return NS_REINTERPRET_CAST(elem_type *, mHdr + 1);
}
// This method provides direct, readonly access to the array elements.
// @return A pointer to the first element of the array. If the array is
// empty, then this pointer must not be dereferenced.
const elem_type* Elements() const {
return NS_REINTERPRET_CAST(const elem_type *, mHdr + 1);
}
// This method provides direct access to the i'th element of the array.
// The given index must be within the array bounds.
// @param i The index of an element in the array.
// @return A reference to the i'th element of the array.
elem_type& ElementAt(index_type i) {
NS_ASSERTION(i < Length(), "invalid array index");
return Elements()[i];
}
// This method provides direct, readonly access to the i'th element of the
// array. The given index must be within the array bounds.
// @param i The index of an element in the array.
// @return A const reference to the i'th element of the array.
const elem_type& ElementAt(index_type i) const {
NS_ASSERTION(i < Length(), "invalid array index");
return Elements()[i];
}
// Shorthand for ElementAt(i)
elem_type& operator[](index_type i) {
return ElementAt(i);
}
// Shorthand for ElementAt(i)
const elem_type& operator[](index_type i) const {
return ElementAt(i);
}
//
// Search methods
//
// This method searches for the offset of the first element in this
// array that is equal to the given element.
// @param item The item to search for.
// @param start The index to start from.
// @param comp The Comparator used to determine element equality.
// @return The index of the found element or NoIndex if not found.
template<class Item, class Comparator>
index_type IndexOf(const Item& item, index_type start,
const Comparator& comp) const {
const elem_type* iter = Elements() + start, *end = iter + Length();
for (; iter != end; ++iter) {
if (comp.Equals(*iter, item))
return iter - Elements();
}
return NoIndex;
}
// This method searches for the offset of the first element in this
// array that is equal to the given element. This method assumes
// that 'operator==' is defined for elem_type.
// @param item The item to search for.
// @param start The index to start from.
// @return The index of the found element or NoIndex if not found.
template<class Item>
index_type IndexOf(const Item& item, index_type start = 0) const {
return IndexOf(item, start, nsDefaultComparator<elem_type, Item>());
}
// This method searches for the offset of the last element in this
// array that is equal to the given element.
// @param item The item to search for.
// @param start The index to start from. If greater than or equal to the
// length of the array, then the entire array is searched.
// @param comp The Comparator used to determine element equality.
// @return The index of the found element or NoIndex if not found.
template<class Item, class Comparator>
index_type LastIndexOf(const Item& item, index_type start,
const Comparator& comp) const {
if (start >= Length())
start = Length() - 1;
const elem_type* end = Elements() - 1, *iter = end + start + 1;
for (; iter != end; --iter) {
if (comp.Equals(*iter, item))
return iter - Elements();
}
return NoIndex;
}
// This method searches for the offset of the last element in this
// array that is equal to the given element. This method assumes
// that 'operator==' is defined for elem_type.
// @param item The item to search for.
// @param start The index to start from. If greater than or equal to the
// length of the array, then the entire array is searched.
// @return The index of the found element or NoIndex if not found.
template<class Item>
index_type LastIndexOf(const Item& item,
index_type start = NoIndex) const {
return LastIndexOf(item, start, nsDefaultComparator<elem_type, Item>());
}
//
// Mutation methods
//
// This method replaces a range of elements in this array.
// @param start The starting index of the elements to replace.
// @param count The number of elements to replace. This may be zero to
// insert elements without removing any existing elements.
// @param array The values to copy into this array. Must be non-null,
// and these elements must not already exist in the array
// being modified.
// @param arrayLen The number of values to copy into this array.
// @return A pointer to the new elements in the array, or null if
// the operation failed due to insufficient memory.
template<class Item>
elem_type *ReplaceElementsAt(index_type start, size_type count,
const Item* array, size_type arrayLen) {
// Adjust memory allocation up-front to catch errors.
if (!EnsureCapacity(Length() + arrayLen - count, sizeof(elem_type)))
return nsnull;
DestructRange(start, count);
ShiftData(start, count, arrayLen, sizeof(elem_type));
AssignRange(start, arrayLen, array);
return Elements() + start;
}
// A variation on the ReplaceElementsAt method defined above.
template<class Item>
elem_type *ReplaceElementsAt(index_type start, size_type count,
const nsTArray<Item>& array) {
return ReplaceElementsAt(start, count, array.Elements(), array.Length());
}
// A variation on the ReplaceElementsAt method defined above.
template<class Item>
elem_type *ReplaceElementsAt(index_type start, size_type count,
const Item& item) {
return ReplaceElementsAt(start, count, &item, 1);
}
// A variation on the ReplaceElementsAt method defined above.
template<class Item>
elem_type *InsertElementsAt(index_type index, const Item* array,
size_type arrayLen) {
return ReplaceElementsAt(index, 0, array, arrayLen);
}
// A variation on the ReplaceElementsAt method defined above.
template<class Item>
elem_type *InsertElementsAt(index_type index, const nsTArray<Item>& array) {
return ReplaceElementsAt(index, 0, array.Elements(), array.Length());
}
// A variation on the ReplaceElementsAt method defined above.
template<class Item>
elem_type *InsertElementAt(index_type index, const Item& item) {
return ReplaceElementsAt(index, 0, &item, 1);
}
// Insert a new element without copy-constructing. This is useful to avoid
// temporaries.
// @return A pointer to the newly inserted element, or null on OOM.
elem_type* InsertElementAt(index_type index) {
if (!EnsureCapacity(Length() + 1, sizeof(elem_type)))
return nsnull;
ShiftData(index, 0, 1, sizeof(elem_type));
elem_type *elem = Elements() + index;
elem_traits::Construct(elem);
return elem;
}
// This method appends elements to the end of this array.
// @param array The elements to append to this array.
// @param arrayLen The number of elements to append to this array.
// @return A pointer to the new elements in the array, or null if
// the operation failed due to insufficient memory.
template<class Item>
elem_type *AppendElements(const Item* array, size_type arrayLen) {
if (!EnsureCapacity(Length() + arrayLen, sizeof(elem_type)))
return nsnull;
index_type len = Length();
AssignRange(len, arrayLen, array);
IncrementLength(arrayLen);
return Elements() + len;
}
// A variation on the AppendElements method defined above.
template<class Item>
elem_type *AppendElements(const nsTArray<Item>& array) {
return AppendElements(array.Elements(), array.Length());
}
// A variation on the AppendElements method defined above.
template<class Item>
elem_type *AppendElement(const Item& item) {
return AppendElements(&item, 1);
}
// Append a new element without copy-constructing. This is useful to avoid
// temporaries.
// @return A pointer to the newly appended element, or null on OOM.
elem_type *AppendElement() {
if (!EnsureCapacity(Length() + 1, sizeof(elem_type)))
return nsnull;
elem_type *elem = Elements() + Length();
elem_traits::Construct(elem);
IncrementLength(1);
return elem;
}
// This method removes a range of elements from this array.
// @param start The starting index of the elements to remove.
// @param count The number of elements to remove.
void RemoveElementsAt(index_type start, size_type count) {
DestructRange(start, count);
ShiftData(start, count, 0, sizeof(elem_type));
}
// A variation on the RemoveElementsAt method defined above.
void RemoveElementAt(index_type index) {
RemoveElementsAt(index, 1);
}
// A variation on the RemoveElementsAt method defined above.
void Clear() {
RemoveElementsAt(0, Length());
}
// This helper function combines IndexOf with RemoveElementAt to "search
// and destroy" the first element that is equal to the given element.
// @param item The item to search for.
// @param comp The Comparator used to determine element equality.
// @return PR_TRUE if the element was found
template<class Item, class Comparator>
PRBool RemoveElement(const Item& item, const Comparator& comp) {
index_type i = IndexOf(item, 0, comp);
if (i == NoIndex)
return PR_FALSE;
RemoveElementAt(i);
return PR_TRUE;
}
// A variation on the RemoveElement method defined above that assumes
// that 'operator==' is defined for elem_type.
template<class Item>
PRBool RemoveElement(const Item& item) {
return RemoveElement(item, nsDefaultComparator<elem_type, Item>());
}
// This method causes the elements contained in this array and the given
// array to be swapped.
void SwapElements(self_type& other) {
Header *h = other.mHdr;
other.mHdr = mHdr;
mHdr = h;
}
//
// Allocation
//
// This method may increase the capacity of this array object by the
// specified amount. This method may be called in advance of several
// AppendElement operations to minimize heap re-allocations. This method
// will not reduce the number of elements in this array.
// @param capacity The desired capacity of this array.
void SetCapacity(size_type capacity) {
EnsureCapacity(capacity, sizeof(elem_type));
}
// This method modifies the length of the array. If the new length is
// larger than the existing length of the array, then new elements will be
// constructed using elem_type's default constructor. Otherwise, this call
// removes elements from the array (see also RemoveElementsAt).
// @param newLen The desired length of this array.
// @return True if the operation succeeded; false otherwise.
PRBool SetLength(size_type newLen) {
size_type oldLen = Length();
if (newLen > oldLen) {
SetCapacity(newLen);
// Check for out of memory conditions
if (Capacity() < newLen)
return PR_FALSE;
// Initialize the extra array elements
elem_type *iter = Elements() + oldLen, *end = Elements() + newLen;
for (; iter != end; ++iter) {
elem_traits::Construct(iter);
}
IncrementLength(newLen - oldLen);
} else {
RemoveElementsAt(newLen, oldLen - newLen);
}
return PR_TRUE;
}
// This method may be called to minimize the memory used by this array.
void Compact() {
ShrinkCapacity(sizeof(elem_type));
}
//
// Sorting
//
// This method sorts the elements of the array. It uses the LessThan
// method defined on the given Comparator object to collate elements.
// @param c The Comparator to used to collate elements.
template<class Comparator>
void Sort(const Comparator& comp) {
NS_QuickSort(Elements(), Length(), sizeof(elem_type),
nsQuickSortComparator<elem_type, Comparator>::Compare,
NS_CONST_CAST(Comparator*, &comp));
}
// A variation on the Sort method defined above that assumes that
// 'operator<' is defined for elem_type.
void Sort() {
Sort(nsDefaultComparator<elem_type, elem_type>());
}
protected:
// This method invokes elem_type's destructor on a range of elements.
// @param start The index of the first element to destroy.
// @param count The number of elements to destroy.
void DestructRange(index_type start, size_type count) {
elem_type *iter = Elements() + start, *end = iter + count;
for (; iter != end; ++iter) {
elem_traits::Destruct(iter);
}
}
// This method invokes elem_type's copy-constructor on a range of elements.
// @param start The index of the first element to construct.
// @param count The number of elements to construct.
// @param values The array of elements to copy.
template<class Item>
void AssignRange(index_type start, size_type count,
const Item *values) {
elem_type *iter = Elements() + start, *end = iter + count;
for (; iter != end; ++iter, ++values) {
elem_traits::Construct(iter, *values);
}
}
};
#endif // nsTArray_h__