/src/mozilla-central/dom/base/nsTextFragment.h

Source (jump to first uncovered line)
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

/*
 * A class which represents a fragment of text (eg inside a text
 * node); if only codepoints below 256 are used, the text is stored as
 * a char*; otherwise the text is stored as a char16_t*
 */

#ifndef nsTextFragment_h___
#define nsTextFragment_h___

#include "mozilla/Attributes.h"
#include "mozilla/MemoryReporting.h"

#include "nsString.h"
#include "nsStringBuffer.h"
#include "nsReadableUtils.h"
#include "nsISupportsImpl.h"

// XXX should this normalize the code to keep a \u0000 at the end?

// XXX nsTextFragmentPool?

/**
 * A fragment of text. If mIs2b is 1 then the m2b pointer is valid
 * otherwise the m1b pointer is valid. If m1b is used then each byte
 * of data represents a single ucs2 character with the high byte being
 * zero.
 *
 * This class does not have a virtual destructor therefore it is not
 * meant to be subclassed.
 */
class nsTextFragment final {
public:
  static nsresult Init();
  static void Shutdown();

  /**
   * Default constructor. Initialize the fragment to be empty.
   */
  nsTextFragment()
    : m1b(nullptr), mAllBits(0)
  {
    MOZ_COUNT_CTOR(nsTextFragment);
    NS_ASSERTION(sizeof(FragmentBits) == 4, "Bad field packing!");
  }

  ~nsTextFragment();

  /**
   * Change the contents of this fragment to be a copy of the
   * the argument fragment, or to "" if unable to allocate enough memory.
   */
  nsTextFragment& operator=(const nsTextFragment& aOther);

  /**
   * Return true if this fragment is represented by char16_t data
   */
  bool Is2b() const
  {
    return mState.mIs2b;
  }

  /**
   * Return true if this fragment contains Bidi text
   * For performance reasons this flag is only set if explicitely requested (by
   * setting the aUpdateBidi argument on SetTo or Append to true).
   */
  bool IsBidi() const
  {
    return mState.mIsBidi;
  }

  /**
   * Get a pointer to constant char16_t data.
   */
  const char16_t *Get2b() const
  {
    MOZ_ASSERT(Is2b(), "not 2b text");
    return static_cast<char16_t*>(m2b->Data());
  }

  /**
   * Get a pointer to constant char data.
   */
  const char *Get1b() const
  {
    NS_ASSERTION(!Is2b(), "not 1b text");
    return (const char *)m1b;
  }

  /**
   * Get the length of the fragment. The length is the number of logical
   * characters, not the number of bytes to store the characters.
   */
  uint32_t GetLength() const
  {
    return mState.mLength;
  }

  bool CanGrowBy(size_t n) const
  {
    return n < (1 << 29) && mState.mLength + n < (1 << 29);
  }

  /**
   * Change the contents of this fragment to be a copy of the given
   * buffer. If aUpdateBidi is true, contents of the fragment will be scanned,
   * and mState.mIsBidi will be turned on if it includes any Bidi characters.
   * If aForce2b is true, aBuffer will be stored as char16_t as is.  Then,
   * you can access the value faster but may waste memory if all characters
   * are less than U+0100.
   */
  bool SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi,
             bool aForce2b);

  bool SetTo(const nsString& aString, bool aUpdateBidi, bool aForce2b)
  {
    ReleaseText();
    if (aForce2b && !aUpdateBidi) {
      nsStringBuffer* buffer = nsStringBuffer::FromString(aString);
      if (buffer) {
        NS_ADDREF(m2b = buffer);
        mState.mInHeap = true;
        mState.mIs2b = true;
        mState.mLength = aString.Length();
        return true;
      }
    }

    return SetTo(aString.get(), aString.Length(), aUpdateBidi, aForce2b);
  }

  /**
   * Append aData to the end of this fragment. If aUpdateBidi is true, contents
   * of the fragment will be scanned, and mState.mIsBidi will be turned on if
   * it includes any Bidi characters.
   * If aForce2b is true, the string will be stored as char16_t as is.  Then,
   * you can access the value faster but may waste memory if all characters
   * are less than U+0100.
   */
  bool Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi,
              bool aForce2b);

  /**
   * Append the contents of this string fragment to aString
   */
  void AppendTo(nsAString& aString) const {
    if (!AppendTo(aString, mozilla::fallible)) {
      aString.AllocFailed(aString.Length() + GetLength());
    }
  }

  /**
   * Append the contents of this string fragment to aString
   * @return false if an out of memory condition is detected, true otherwise
   */
  MOZ_MUST_USE
  bool AppendTo(nsAString& aString,
                const mozilla::fallible_t& aFallible) const {
    if (mState.mIs2b) {
      if (aString.IsEmpty()) {
        m2b->ToString(mState.mLength, aString);
        return true;
      }
      bool ok = aString.Append(Get2b(), mState.mLength, aFallible);
      if (!ok) {
        return false;
      }

      return true;
    } else {
      return AppendASCIItoUTF16(Substring(m1b, mState.mLength), aString,
                                aFallible);
    }
  }

  /**
   * Append a substring of the contents of this string fragment to aString.
   * @param aOffset where to start the substring in this text fragment
   * @param aLength the length of the substring
   */
  void AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength) const {
    if (!AppendTo(aString, aOffset, aLength, mozilla::fallible)) {
      aString.AllocFailed(aString.Length() + aLength);
    }
  }

  /**
   * Append a substring of the contents of this string fragment to aString.
   * @param aString the string in which to append
   * @param aOffset where to start the substring in this text fragment
   * @param aLength the length of the substring
   * @return false if an out of memory condition is detected, true otherwise
   */
  MOZ_MUST_USE
  bool AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength,
                const mozilla::fallible_t& aFallible) const
  {
    if (mState.mIs2b) {
      bool ok = aString.Append(Get2b() + aOffset, aLength, aFallible);
      if (!ok) {
        return false;
      }

      return true;
    } else {
      return AppendASCIItoUTF16(Substring(m1b + aOffset, aLength), aString,
                                aFallible);
    }
  }

  /**
   * Make a copy of the fragments contents starting at offset for
   * count characters. The offset and count will be adjusted to
   * lie within the fragments data. The fragments data is converted if
   * necessary.
   */
  void CopyTo(char16_t *aDest, int32_t aOffset, int32_t aCount);

  /**
   * Return the character in the text-fragment at the given
   * index. This always returns a char16_t.
   */
  char16_t CharAt(int32_t aIndex) const
  {
    MOZ_ASSERT(uint32_t(aIndex) < mState.mLength, "bad index");
    return mState.mIs2b ? Get2b()[aIndex] : static_cast<unsigned char>(m1b[aIndex]);
  }

  void SetBidi(bool aBidi)
  {
    mState.mIsBidi = aBidi;
  }

  struct FragmentBits {
    // uint32_t to ensure that the values are unsigned, because we
    // want 0/1, not 0/-1!
    // Making these bool causes Windows to not actually pack them,
    // which causes crashes because we assume this structure is no more than
    // 32 bits!
    uint32_t mInHeap : 1;
    uint32_t mIs2b : 1;
    uint32_t mIsBidi : 1;
    // Note that when you change the bits of mLength, you also need to change
    // NS_MAX_TEXT_FRAGMENT_LENGTH.
    uint32_t mLength : 29;
  };

#define NS_MAX_TEXT_FRAGMENT_LENGTH (static_cast<uint32_t>(0x1FFFFFFF))

  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

private:
  void ReleaseText();

  /**
   * Scan the contents of the fragment and turn on mState.mIsBidi if it
   * includes any Bidi characters.
   */
  void UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength);

  union {
    nsStringBuffer* m2b;
    const char* m1b; // This is const since it can point to shared data
  };

  union {
    uint32_t mAllBits;
    FragmentBits mState;
  };
};

#endif /* nsTextFragment_h___ */


Coverage Report

Created: 2018-09-25 14:53

Line	Count	Source (jump to first uncovered line)
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		/*
8		* A class which represents a fragment of text (eg inside a text
9		* node); if only codepoints below 256 are used, the text is stored as
10		* a char; otherwise the text is stored as a char16_t
11		*/
12
13		#ifndef nsTextFragment_h___
14		#define nsTextFragment_h___
15
16		#include "mozilla/Attributes.h"
17		#include "mozilla/MemoryReporting.h"
18
19		#include "nsString.h"
20		#include "nsStringBuffer.h"
21		#include "nsReadableUtils.h"
22		#include "nsISupportsImpl.h"
23
24		// XXX should this normalize the code to keep a \u0000 at the end?
25
26		// XXX nsTextFragmentPool?
27
28		/**
29		* A fragment of text. If mIs2b is 1 then the m2b pointer is valid
30		* otherwise the m1b pointer is valid. If m1b is used then each byte
31		* of data represents a single ucs2 character with the high byte being
32		* zero.
33		*
34		* This class does not have a virtual destructor therefore it is not
35		* meant to be subclassed.
36		*/
37		class nsTextFragment final {
38		public:
39		static nsresult Init();
40		static void Shutdown();
41
42		/**
43		* Default constructor. Initialize the fragment to be empty.
44		*/
45		nsTextFragment()
46		: m1b(nullptr), mAllBits(0)
47	0	{
48	0	MOZ_COUNT_CTOR(nsTextFragment);
49	0	NS_ASSERTION(sizeof(FragmentBits) == 4, "Bad field packing!");
50	0	}
51
52		~nsTextFragment();
53
54		/**
55		* Change the contents of this fragment to be a copy of the
56		* the argument fragment, or to "" if unable to allocate enough memory.
57		*/
58		nsTextFragment& operator=(const nsTextFragment& aOther);
59
60		/**
61		* Return true if this fragment is represented by char16_t data
62		*/
63		bool Is2b() const
64	0	{
65	0	return mState.mIs2b;
66	0	}
67
68		/**
69		* Return true if this fragment contains Bidi text
70		* For performance reasons this flag is only set if explicitely requested (by
71		* setting the aUpdateBidi argument on SetTo or Append to true).
72		*/
73		bool IsBidi() const
74	0	{
75	0	return mState.mIsBidi;
76	0	}
77
78		/**
79		* Get a pointer to constant char16_t data.
80		*/
81		const char16_t *Get2b() const
82	0	{
83	0	MOZ_ASSERT(Is2b(), "not 2b text");
84	0	return static_cast<char16_t*>(m2b->Data());
85	0	}
86
87		/**
88		* Get a pointer to constant char data.
89		*/
90		const char *Get1b() const
91	0	{
92	0	NS_ASSERTION(!Is2b(), "not 1b text");
93	0	return (const char *)m1b;
94	0	}
95
96		/**
97		* Get the length of the fragment. The length is the number of logical
98		* characters, not the number of bytes to store the characters.
99		*/
100		uint32_t GetLength() const
101	0	{
102	0	return mState.mLength;
103	0	}
104
105		bool CanGrowBy(size_t n) const
106	0	{
107	0	return n < (1 << 29) && mState.mLength + n < (1 << 29);
108	0	}
109
110		/**
111		* Change the contents of this fragment to be a copy of the given
112		* buffer. If aUpdateBidi is true, contents of the fragment will be scanned,
113		* and mState.mIsBidi will be turned on if it includes any Bidi characters.
114		* If aForce2b is true, aBuffer will be stored as char16_t as is. Then,
115		* you can access the value faster but may waste memory if all characters
116		* are less than U+0100.
117		*/
118		bool SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi,
119		bool aForce2b);
120
121		bool SetTo(const nsString& aString, bool aUpdateBidi, bool aForce2b)
122	0	{
123	0	ReleaseText();
124	0	if (aForce2b && !aUpdateBidi) {
125	0	nsStringBuffer* buffer = nsStringBuffer::FromString(aString);
126	0	if (buffer) {
127	0	NS_ADDREF(m2b = buffer);
128	0	mState.mInHeap = true;
129	0	mState.mIs2b = true;
130	0	mState.mLength = aString.Length();
131	0	return true;
132	0	}
133	0	}
134	0
135	0	return SetTo(aString.get(), aString.Length(), aUpdateBidi, aForce2b);
136	0	}
137
138		/**
139		* Append aData to the end of this fragment. If aUpdateBidi is true, contents
140		* of the fragment will be scanned, and mState.mIsBidi will be turned on if
141		* it includes any Bidi characters.
142		* If aForce2b is true, the string will be stored as char16_t as is. Then,
143		* you can access the value faster but may waste memory if all characters
144		* are less than U+0100.
145		*/
146		bool Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi,
147		bool aForce2b);
148
149		/**
150		* Append the contents of this string fragment to aString
151		*/
152	0	void AppendTo(nsAString& aString) const {
153	0	if (!AppendTo(aString, mozilla::fallible)) {
154	0	aString.AllocFailed(aString.Length() + GetLength());
155	0	}
156	0	}
157
158		/**
159		* Append the contents of this string fragment to aString
160		* @return false if an out of memory condition is detected, true otherwise
161		*/
162		MOZ_MUST_USE
163		bool AppendTo(nsAString& aString,
164	0	const mozilla::fallible_t& aFallible) const {
165	0	if (mState.mIs2b) {
166	0	if (aString.IsEmpty()) {
167	0	m2b->ToString(mState.mLength, aString);
168	0	return true;
169	0	}
170	0	bool ok = aString.Append(Get2b(), mState.mLength, aFallible);
171	0	if (!ok) {
172	0	return false;
173	0	}
174	0
175	0	return true;
176	0	} else {
177	0	return AppendASCIItoUTF16(Substring(m1b, mState.mLength), aString,
178	0	aFallible);
179	0	}
180	0	}
181
182		/**
183		* Append a substring of the contents of this string fragment to aString.
184		* @param aOffset where to start the substring in this text fragment
185		* @param aLength the length of the substring
186		*/
187	0	void AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength) const {
188	0	if (!AppendTo(aString, aOffset, aLength, mozilla::fallible)) {
189	0	aString.AllocFailed(aString.Length() + aLength);
190	0	}
191	0	}
192
193		/**
194		* Append a substring of the contents of this string fragment to aString.
195		* @param aString the string in which to append
196		* @param aOffset where to start the substring in this text fragment
197		* @param aLength the length of the substring
198		* @return false if an out of memory condition is detected, true otherwise
199		*/
200		MOZ_MUST_USE
201		bool AppendTo(nsAString& aString, int32_t aOffset, int32_t aLength,
202		const mozilla::fallible_t& aFallible) const
203	0	{
204	0	if (mState.mIs2b) {
205	0	bool ok = aString.Append(Get2b() + aOffset, aLength, aFallible);
206	0	if (!ok) {
207	0	return false;
208	0	}
209	0
210	0	return true;
211	0	} else {
212	0	return AppendASCIItoUTF16(Substring(m1b + aOffset, aLength), aString,
213	0	aFallible);
214	0	}
215	0	}
216
217		/**
218		* Make a copy of the fragments contents starting at offset for
219		* count characters. The offset and count will be adjusted to
220		* lie within the fragments data. The fragments data is converted if
221		* necessary.
222		*/
223		void CopyTo(char16_t *aDest, int32_t aOffset, int32_t aCount);
224
225		/**
226		* Return the character in the text-fragment at the given
227		* index. This always returns a char16_t.
228		*/
229		char16_t CharAt(int32_t aIndex) const
230	0	{
231	0	MOZ_ASSERT(uint32_t(aIndex) < mState.mLength, "bad index");
232	0	return mState.mIs2b ? Get2b()[aIndex] : static_cast<unsigned char>(m1b[aIndex]);
233	0	}
234
235		void SetBidi(bool aBidi)
236	0	{
237	0	mState.mIsBidi = aBidi;
238	0	}
239
240		struct FragmentBits {
241		// uint32_t to ensure that the values are unsigned, because we
242		// want 0/1, not 0/-1!
243		// Making these bool causes Windows to not actually pack them,
244		// which causes crashes because we assume this structure is no more than
245		// 32 bits!
246		uint32_t mInHeap : 1;
247		uint32_t mIs2b : 1;
248		uint32_t mIsBidi : 1;
249		// Note that when you change the bits of mLength, you also need to change
250		// NS_MAX_TEXT_FRAGMENT_LENGTH.
251		uint32_t mLength : 29;
252		};
253
254	0	#define NS_MAX_TEXT_FRAGMENT_LENGTH (static_cast<uint32_t>(0x1FFFFFFF))
255
256		size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
257
258		private:
259		void ReleaseText();
260
261		/**
262		* Scan the contents of the fragment and turn on mState.mIsBidi if it
263		* includes any Bidi characters.
264		*/
265		void UpdateBidiFlag(const char16_t* aBuffer, uint32_t aLength);
266
267		union {
268		nsStringBuffer* m2b;
269		const char* m1b; // This is const since it can point to shared data
270		};
271
272		union {
273		uint32_t mAllBits;
274		FragmentBits mState;
275		};
276		};
277
278		#endif /* nsTextFragment_h___ */
279