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-rw-r--r--dom/base/nsTextFragment.h242
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diff --git a/dom/base/nsTextFragment.h b/dom/base/nsTextFragment.h
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+/* -*- 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 "nsReadableUtils.h"
+#include "nsISupportsImpl.h"
+
+class nsString;
+
+// 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
+ {
+ NS_ASSERTION(Is2b(), "not 2b text");
+ return m2b;
+ }
+
+ /**
+ * 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.
+ */
+ bool SetTo(const char16_t* aBuffer, int32_t aLength, bool aUpdateBidi);
+
+ /**
+ * 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.
+ */
+ bool Append(const char16_t* aBuffer, uint32_t aLength, bool aUpdateBidi);
+
+ /**
+ * 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) {
+ bool ok = aString.Append(m2b, 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(m2b + 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
+ {
+ NS_ASSERTION(uint32_t(aIndex) < mState.mLength, "bad index");
+ return mState.mIs2b ? m2b[aIndex] : static_cast<unsigned char>(m1b[aIndex]);
+ }
+
+ 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;
+ uint32_t mLength : 29;
+ };
+
+ 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 {
+ char16_t *m2b;
+ const char *m1b; // This is const since it can point to shared data
+ };
+
+ union {
+ uint32_t mAllBits;
+ FragmentBits mState;
+ };
+};
+
+#endif /* nsTextFragment_h___ */
+