The Tor Browser: xpcom/string/src/nsTSubstring.cpp@b8a032363ba2 (annotated)

xpcom/string/src/nsTSubstring.cpp@b8a032363ba2 (annotated)

xpcom/string/src/nsTSubstring.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* 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 "mozilla/MemoryReporting.h"
 #include "double-conversion.h"
 using double_conversion::DoubleToStringConverter;
 #ifdef XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE
 nsTSubstring_CharT::nsTSubstring_CharT( char_type *data, size_type length,
                                         uint32_t flags)
   : mData(data),
     mLength(length),
     mFlags(flags)
   {
     if (flags & F_OWNED) {
       STRING_STAT_INCREMENT(Adopt);
 #ifdef NS_BUILD_REFCNT_LOGGING
       NS_LogCtor(mData, "StringAdopt", 1);
 #endif
     }
   }
 #endif /* XPCOM_STRING_CONSTRUCTOR_OUT_OF_LINE */
   /**
    * helper function for down-casting a nsTSubstring to a nsTFixedString.
    */
 inline const nsTFixedString_CharT*
 AsFixedString( const nsTSubstring_CharT* s )
   {
     return static_cast<const nsTFixedString_CharT*>(s);
   }
   /**
    * this function is called to prepare mData for writing.  the given capacity
    * indicates the required minimum storage size for mData, in sizeof(char_type)
    * increments.  this function returns true if the operation succeeds.  it also
    * returns the old data and old flags members if mData is newly allocated.
    * the old data must be released by the caller.
    */
 bool
 nsTSubstring_CharT::MutatePrep( size_type capacity, char_type** oldData, uint32_t* oldFlags )
   {
     // initialize to no old data
     *oldData = nullptr;
     *oldFlags = 0;
     size_type curCapacity = Capacity();
     // If |capacity > kMaxCapacity|, then our doubling algorithm may not be
     // able to allocate it.  Just bail out in cases like that.  We don't want
     // to be allocating 2GB+ strings anyway.
     PR_STATIC_ASSERT((sizeof(nsStringBuffer) & 0x1) == 0);
     const size_type kMaxCapacity =
       (size_type(-1)/2 - sizeof(nsStringBuffer)) / sizeof(char_type) - 2;
     if (capacity > kMaxCapacity) {
       // Also assert for |capacity| equal to |size_type(-1)|, since we used to
       // use that value to flag immutability.
       NS_ASSERTION(capacity != size_type(-1), "Bogus capacity");
       return false;
     }
     // |curCapacity == 0| means that the buffer is immutable or 0-sized, so we
     // need to allocate a new buffer. We cannot use the existing buffer even
     // though it might be large enough.
     if (curCapacity != 0)
       {
         if (capacity <= curCapacity) {
           mFlags &= ~F_VOIDED;  // mutation clears voided flag
           return true;
         }
         // Use doubling algorithm when forced to increase available capacity.
         size_type temp = curCapacity;
         while (temp < capacity)
           temp <<= 1;
         NS_ASSERTION(XPCOM_MIN(temp, kMaxCapacity) >= capacity,
                      "should have hit the early return at the top");
         capacity = XPCOM_MIN(temp, kMaxCapacity);
       }
     //
     // several cases:
     //
     //  (1) we have a shared buffer (mFlags & F_SHARED)
     //  (2) we have an owned buffer (mFlags & F_OWNED)
     //  (3) we have a fixed buffer (mFlags & F_FIXED)
     //  (4) we have a readonly buffer
     //
     // requiring that we in some cases preserve the data before creating
     // a new buffer complicates things just a bit ;-)
     //
     size_type storageSize = (capacity + 1) * sizeof(char_type);
     // case #1
     if (mFlags & F_SHARED)
       {
         nsStringBuffer* hdr = nsStringBuffer::FromData(mData);
         if (!hdr->IsReadonly())
           {
             nsStringBuffer *newHdr = nsStringBuffer::Realloc(hdr, storageSize);
             if (!newHdr)
               return false; // out-of-memory (original header left intact)
             hdr = newHdr;
             mData = (char_type*) hdr->Data();
             mFlags &= ~F_VOIDED;  // mutation clears voided flag
             return true;
           }
       }
     char_type* newData;
     uint32_t newDataFlags;
       // if we have a fixed buffer of sufficient size, then use it.  this helps
       // avoid heap allocations.
     if ((mFlags & F_CLASS_FIXED) && (capacity < AsFixedString(this)->mFixedCapacity))
       {
         newData = AsFixedString(this)->mFixedBuf;
         newDataFlags = F_TERMINATED | F_FIXED;
       }
     else
       {
         // if we reach here then, we must allocate a new buffer.  we cannot
         // make use of our F_OWNED or F_FIXED buffers because they are not
         // large enough.
         nsStringBuffer* newHdr =
           nsStringBuffer::Alloc(storageSize).take();
         if (!newHdr)
           return false; // we are still in a consistent state
         newData = (char_type*) newHdr->Data();
         newDataFlags = F_TERMINATED | F_SHARED;
       }
     // save old data and flags
     *oldData = mData;
     *oldFlags = mFlags;
     mData = newData;
     SetDataFlags(newDataFlags);
     // mLength does not change
     // though we are not necessarily terminated at the moment, now is probably
     // still the best time to set F_TERMINATED.
     return true;
   }
 void
 nsTSubstring_CharT::Finalize()
   {
     ::ReleaseData(mData, mFlags);
     // mData, mLength, and mFlags are purposefully left dangling
   }
 bool
 nsTSubstring_CharT::ReplacePrepInternal(index_type cutStart, size_type cutLen,
                                         size_type fragLen, size_type newLen)
   {
     char_type* oldData;
     uint32_t oldFlags;
     if (!MutatePrep(newLen, &oldData, &oldFlags))
       return false; // out-of-memory
     if (oldData)
       {
         // determine whether or not we need to copy part of the old string
         // over to the new string.
         if (cutStart > 0)
           {
             // copy prefix from old string
             char_traits::copy(mData, oldData, cutStart);
           }
         if (cutStart + cutLen < mLength)
           {
             // copy suffix from old string to new offset
             size_type from = cutStart + cutLen;
             size_type fromLen = mLength - from;
             uint32_t to = cutStart + fragLen;
             char_traits::copy(mData + to, oldData + from, fromLen);
           }
         ::ReleaseData(oldData, oldFlags);
       }
     else
       {
         // original data remains intact
         // determine whether or not we need to move part of the existing string
         // to make room for the requested hole.
         if (fragLen != cutLen && cutStart + cutLen < mLength)
           {
             uint32_t from = cutStart + cutLen;
             uint32_t fromLen = mLength - from;
             uint32_t to = cutStart + fragLen;
             char_traits::move(mData + to, mData + from, fromLen);
           }
       }
     // add null terminator (mutable mData always has room for the null-
     // terminator).
     mData[newLen] = char_type(0);
     mLength = newLen;
     return true;
   }
 nsTSubstring_CharT::size_type
 nsTSubstring_CharT::Capacity() const
   {
     // return 0 to indicate an immutable or 0-sized buffer
     size_type capacity;
     if (mFlags & F_SHARED)
       {
         // if the string is readonly, then we pretend that it has no capacity.
         nsStringBuffer* hdr = nsStringBuffer::FromData(mData);
         if (hdr->IsReadonly())
           capacity = 0;
         else {
           capacity = (hdr->StorageSize() / sizeof(char_type)) - 1;
         }
       }
     else if (mFlags & F_FIXED)
       {
         capacity = AsFixedString(this)->mFixedCapacity;
       }
     else if (mFlags & F_OWNED)
       {
         // we don't store the capacity of an adopted buffer because that would
         // require an additional member field.  the best we can do is base the
         // capacity on our length.  remains to be seen if this is the right
         // trade-off.
         capacity = mLength;
       }
     else
       {
         capacity = 0;
       }
     return capacity;
   }
 bool
 nsTSubstring_CharT::EnsureMutable( size_type newLen )
   {
     if (newLen == size_type(-1) || newLen == mLength)
       {
         if (mFlags & (F_FIXED | F_OWNED))
           return true;
         if ((mFlags & F_SHARED) && !nsStringBuffer::FromData(mData)->IsReadonly())
           return true;
         newLen = mLength;
       }
     return SetLength(newLen, fallible_t());
   }
 // ---------------------------------------------------------------------------
   // This version of Assign is optimized for single-character assignment.
 void
 nsTSubstring_CharT::Assign( char_type c )
   {
     if (!ReplacePrep(0, mLength, 1))
       NS_ABORT_OOM(mLength);
     *mData = c;
   }
 bool
 nsTSubstring_CharT::Assign( char_type c, const fallible_t& )
   {
     if (!ReplacePrep(0, mLength, 1))
       return false;
     *mData = c;
     return true;
   }
 void
 nsTSubstring_CharT::Assign( const char_type* data )
   {
     if (!Assign(data, size_type(-1), fallible_t()))
       NS_ABORT_OOM(char_traits::length(data));
   }
 void
 nsTSubstring_CharT::Assign( const char_type* data, size_type length )
   {
     if (!Assign(data, length, fallible_t()))
       NS_ABORT_OOM(length);
   }
 bool
 nsTSubstring_CharT::Assign( const char_type* data, size_type length, const fallible_t& )
   {
     if (!data || length == 0)
       {
         Truncate();
         return true;
       }
     if (length == size_type(-1))
       length = char_traits::length(data);
     if (IsDependentOn(data, data + length))
       {
         return Assign(string_type(data, length), fallible_t());
       }
     if (!ReplacePrep(0, mLength, length))
       return false;
     char_traits::copy(mData, data, length);
     return true;
   }
 void
 nsTSubstring_CharT::AssignASCII( const char* data, size_type length )
   {
     if (!AssignASCII(data, length, fallible_t()))
       NS_ABORT_OOM(length);
   }
 bool
 nsTSubstring_CharT::AssignASCII( const char* data, size_type length, const fallible_t& )
   {
     // A Unicode string can't depend on an ASCII string buffer,
     // so this dependence check only applies to CStrings.
 #ifdef CharT_is_char
     if (IsDependentOn(data, data + length))
       {
         return Assign(string_type(data, length), fallible_t());
       }
 #endif
     if (!ReplacePrep(0, mLength, length))
       return false;
     char_traits::copyASCII(mData, data, length);
     return true;
   }
 void
 nsTSubstring_CharT::AssignLiteral( const char_type* data, size_type length )
   {
     ::ReleaseData(mData, mFlags);
     mData = const_cast<char_type*>(data);
     mLength = length;
     SetDataFlags(F_TERMINATED | F_LITERAL);
   }
 void
 nsTSubstring_CharT::Assign( const self_type& str )
 {
   if (!Assign(str, fallible_t()))
     NS_ABORT_OOM(str.Length());
 }
 bool
 nsTSubstring_CharT::Assign( const self_type& str, const fallible_t& )
   {
     // |str| could be sharable.  we need to check its flags to know how to
     // deal with it.
     if (&str == this)
       return true;
     if (!str.mLength)
       {
         Truncate();
         mFlags |= str.mFlags & F_VOIDED;
         return true;
       }
     if (str.mFlags & F_SHARED)
       {
         // nice! we can avoid a string copy :-)
         // |str| should be null-terminated
         NS_ASSERTION(str.mFlags & F_TERMINATED, "shared, but not terminated");
         ::ReleaseData(mData, mFlags);
         mData = str.mData;
         mLength = str.mLength;
         SetDataFlags(F_TERMINATED | F_SHARED);
         // get an owning reference to the mData
         nsStringBuffer::FromData(mData)->AddRef();
         return true;
       }
     else if (str.mFlags & F_LITERAL)
       {
         NS_ABORT_IF_FALSE(str.mFlags & F_TERMINATED, "Unterminated literal");
         AssignLiteral(str.mData, str.mLength);
         return true;
       }
     // else, treat this like an ordinary assignment.
     return Assign(str.Data(), str.Length(), fallible_t());
   }
 void
 nsTSubstring_CharT::Assign( const substring_tuple_type& tuple )
   {
     if (!Assign(tuple, fallible_t()))
       NS_ABORT_OOM(tuple.Length());
   }
 bool
 nsTSubstring_CharT::Assign( const substring_tuple_type& tuple, const fallible_t& )
   {
     if (tuple.IsDependentOn(mData, mData + mLength))
       {
         // take advantage of sharing here...
         return Assign(string_type(tuple), fallible_t());
       }
     size_type length = tuple.Length();
     // don't use ReplacePrep here because it changes the length
     char_type* oldData;
     uint32_t oldFlags;
     if (!MutatePrep(length, &oldData, &oldFlags))
       return false;
     if (oldData)
       ::ReleaseData(oldData, oldFlags);
     tuple.WriteTo(mData, length);
     mData[length] = 0;
     mLength = length;
     return true;
   }
 void
 nsTSubstring_CharT::Adopt( char_type* data, size_type length )
   {
     if (data)
       {
         ::ReleaseData(mData, mFlags);
         if (length == size_type(-1))
           length = char_traits::length(data);
         mData = data;
         mLength = length;
         SetDataFlags(F_TERMINATED | F_OWNED);
         STRING_STAT_INCREMENT(Adopt);
 #ifdef NS_BUILD_REFCNT_LOGGING
         // Treat this as construction of a "StringAdopt" object for leak
         // tracking purposes.
         NS_LogCtor(mData, "StringAdopt", 1);
 #endif // NS_BUILD_REFCNT_LOGGING
       }
     else
       {
         SetIsVoid(true);
       }
   }
   // This version of Replace is optimized for single-character replacement.
 void
 nsTSubstring_CharT::Replace( index_type cutStart, size_type cutLength, char_type c )
   {
     cutStart = XPCOM_MIN(cutStart, Length());
     if (ReplacePrep(cutStart, cutLength, 1))
       mData[cutStart] = c;
   }
 bool
 nsTSubstring_CharT::Replace( index_type cutStart, size_type cutLength, char_type c, const mozilla::fallible_t& )
   {
     cutStart = XPCOM_MIN(cutStart, Length());
     if (!ReplacePrep(cutStart, cutLength, 1))
       return false;
     mData[cutStart] = c;
     return true;
   }
 void
 nsTSubstring_CharT::Replace( index_type cutStart, size_type cutLength, const char_type* data, size_type length )
   {
     if (!Replace(cutStart, cutLength, data, length, mozilla::fallible_t()))
       {
         NS_ABORT_OOM(Length() - cutLength + 1);
       }
   }
 bool
 nsTSubstring_CharT::Replace( index_type cutStart, size_type cutLength, const char_type* data, size_type length, const mozilla::fallible_t& )
   {
       // unfortunately, some callers pass null :-(
     if (!data)
       {
         length = 0;
       }
     else
       {
         if (length == size_type(-1))
           length = char_traits::length(data);
         if (IsDependentOn(data, data + length))
           {
             nsTAutoString_CharT temp(data, length);
             return Replace(cutStart, cutLength, temp, mozilla::fallible_t());
           }
       }
     cutStart = XPCOM_MIN(cutStart, Length());
     bool ok = ReplacePrep(cutStart, cutLength, length);
     if (!ok)
       return false;
     if (length > 0)
       char_traits::copy(mData + cutStart, data, length);
     return true;
   }
 void
 nsTSubstring_CharT::ReplaceASCII( index_type cutStart, size_type cutLength, const char* data, size_type length )
   {
     if (length == size_type(-1))
       length = strlen(data);
     // A Unicode string can't depend on an ASCII string buffer,
     // so this dependence check only applies to CStrings.
 #ifdef CharT_is_char
     if (IsDependentOn(data, data + length))
       {
         nsTAutoString_CharT temp(data, length);
         Replace(cutStart, cutLength, temp);
         return;
       }
 #endif
     cutStart = XPCOM_MIN(cutStart, Length());
     if (ReplacePrep(cutStart, cutLength, length) && length > 0)
       char_traits::copyASCII(mData + cutStart, data, length);
   }
 void
 nsTSubstring_CharT::Replace( index_type cutStart, size_type cutLength, const substring_tuple_type& tuple )
   {
     if (tuple.IsDependentOn(mData, mData + mLength))
       {
         nsTAutoString_CharT temp(tuple);
         Replace(cutStart, cutLength, temp);
         return;
       }
     size_type length = tuple.Length();
     cutStart = XPCOM_MIN(cutStart, Length());
     if (ReplacePrep(cutStart, cutLength, length) && length > 0)
       tuple.WriteTo(mData + cutStart, length);
   }
 void
 nsTSubstring_CharT::ReplaceLiteral( index_type cutStart, size_type cutLength, const char_type* data, size_type length )
   {
     cutStart = XPCOM_MIN(cutStart, Length());
     if (!cutStart && cutLength == Length())
       AssignLiteral(data, length);
     else if (ReplacePrep(cutStart, cutLength, length) && length > 0)
       char_traits::copy(mData + cutStart, data, length);
   }
 void
 nsTSubstring_CharT::SetCapacity( size_type capacity )
   {
     if (!SetCapacity(capacity, fallible_t()))
       NS_ABORT_OOM(capacity);
   }
 bool
 nsTSubstring_CharT::SetCapacity( size_type capacity, const fallible_t& )
   {
     // capacity does not include room for the terminating null char
     // if our capacity is reduced to zero, then free our buffer.
     if (capacity == 0)
       {
         ::ReleaseData(mData, mFlags);
         mData = char_traits::sEmptyBuffer;
         mLength = 0;
         SetDataFlags(F_TERMINATED);
         return true;
       }
     char_type* oldData;
     uint32_t oldFlags;
     if (!MutatePrep(capacity, &oldData, &oldFlags))
       return false; // out-of-memory
     // compute new string length
     size_type newLen = XPCOM_MIN(mLength, capacity);
     if (oldData)
       {
         // preserve old data
         if (mLength > 0)
           char_traits::copy(mData, oldData, newLen);
         ::ReleaseData(oldData, oldFlags);
       }
     // adjust mLength if our buffer shrunk down in size
     if (newLen < mLength)
       mLength = newLen;
     // always null-terminate here, even if the buffer got longer.  this is
     // for backwards compat with the old string implementation.
     mData[capacity] = char_type(0);
     return true;
   }
 void
 nsTSubstring_CharT::SetLength( size_type length )
   {
     SetCapacity(length);
     mLength = length;
   }
 bool
 nsTSubstring_CharT::SetLength( size_type length, const fallible_t& )
   {
     if (!SetCapacity(length, fallible_t()))
       return false;
     mLength = length;
     return true;
   }
 void
 nsTSubstring_CharT::SetIsVoid( bool val )
   {
     if (val)
       {
         Truncate();
         mFlags |= F_VOIDED;
       }
     else
       {
         mFlags &= ~F_VOIDED;
       }
   }
 bool
 nsTSubstring_CharT::Equals( const self_type& str ) const
   {
     return mLength == str.mLength && char_traits::compare(mData, str.mData, mLength) == 0;
   }
 bool
 nsTSubstring_CharT::Equals( const self_type& str, const comparator_type& comp ) const
   {
     return mLength == str.mLength && comp(mData, str.mData, mLength, str.mLength) == 0;
   }
 bool
 nsTSubstring_CharT::Equals( const char_type* data ) const
   {
     // unfortunately, some callers pass null :-(
     if (!data)
       {
         NS_NOTREACHED("null data pointer");
         return mLength == 0;
       }
     // XXX avoid length calculation?
     size_type length = char_traits::length(data);
     return mLength == length && char_traits::compare(mData, data, mLength) == 0;
   }
 bool
 nsTSubstring_CharT::Equals( const char_type* data, const comparator_type& comp ) const
   {
     // unfortunately, some callers pass null :-(
     if (!data)
       {
         NS_NOTREACHED("null data pointer");
         return mLength == 0;
       }
     // XXX avoid length calculation?
     size_type length = char_traits::length(data);
     return mLength == length && comp(mData, data, mLength, length) == 0;
   }
 bool
 nsTSubstring_CharT::EqualsASCII( const char* data, size_type len ) const
   {
     return mLength == len && char_traits::compareASCII(mData, data, len) == 0;
   }
 bool
 nsTSubstring_CharT::EqualsASCII( const char* data ) const
   {
     return char_traits::compareASCIINullTerminated(mData, mLength, data) == 0;
   }
 bool
 nsTSubstring_CharT::LowerCaseEqualsASCII( const char* data, size_type len ) const
   {
     return mLength == len && char_traits::compareLowerCaseToASCII(mData, data, len) == 0;
   }
 bool
 nsTSubstring_CharT::LowerCaseEqualsASCII( const char* data ) const
   {
     return char_traits::compareLowerCaseToASCIINullTerminated(mData, mLength, data) == 0;
   }
 nsTSubstring_CharT::size_type
 nsTSubstring_CharT::CountChar( char_type c ) const
   {
     const char_type *start = mData;
     const char_type *end   = mData + mLength;
     return NS_COUNT(start, end, c);
   }
 int32_t
 nsTSubstring_CharT::FindChar( char_type c, index_type offset ) const
   {
     if (offset < mLength)
       {
         const char_type* result = char_traits::find(mData + offset, mLength - offset, c);
         if (result)
           return result - mData;
       }
     return -1;
   }
 void
 nsTSubstring_CharT::StripChar( char_type aChar, int32_t aOffset )
   {
     if (mLength == 0 || aOffset >= int32_t(mLength))
       return;
     if (!EnsureMutable()) // XXX do this lazily?
       NS_ABORT_OOM(mLength);
     // XXX(darin): this code should defer writing until necessary.
     char_type* to   = mData + aOffset;
     char_type* from = mData + aOffset;
     char_type* end  = mData + mLength;
     while (from < end)
       {
         char_type theChar = *from++;
         if (aChar != theChar)
           *to++ = theChar;
       }
     *to = char_type(0); // add the null
     mLength = to - mData;
   }
 void
 nsTSubstring_CharT::StripChars( const char_type* aChars, uint32_t aOffset )
   {
     if (aOffset >= uint32_t(mLength))
       return;
     if (!EnsureMutable()) // XXX do this lazily?
       NS_ABORT_OOM(mLength);
     // XXX(darin): this code should defer writing until necessary.
     char_type* to   = mData + aOffset;
     char_type* from = mData + aOffset;
     char_type* end  = mData + mLength;
     while (from < end)
       {
         char_type theChar = *from++;
         const char_type* test = aChars;
         for (; *test && *test != theChar; ++test);
         if (!*test) {
           // Not stripped, copy this char.
           *to++ = theChar;
         }
       }
     *to = char_type(0); // add the null
     mLength = to - mData;
   }
 int
 nsTSubstring_CharT::AppendFunc(void* arg, const char* s, uint32_t len)
   {
     self_type* self = static_cast<self_type*>(arg);
     // NSPR sends us the final null terminator even though we don't want it
     if (len && s[len - 1] == '\0') {
       --len;
     }
     self->AppendASCII(s, len);
     return len;
   }
 void nsTSubstring_CharT::AppendPrintf( const char* format, ...)
   {
     va_list ap;
     va_start(ap, format);
     uint32_t r = PR_vsxprintf(AppendFunc, this, format, ap);
     if (r == (uint32_t) -1)
       NS_RUNTIMEABORT("Allocation or other failure in PR_vsxprintf");
     va_end(ap);
   }
 void nsTSubstring_CharT::AppendPrintf( const char* format, va_list ap )
   {
     uint32_t r = PR_vsxprintf(AppendFunc, this, format, ap);
     if (r == (uint32_t) -1)
       NS_RUNTIMEABORT("Allocation or other failure in PR_vsxprintf");
   }
 /* hack to make sure we define FormatWithoutTrailingZeros only once */
 #ifdef CharT_is_PRUnichar
 // Returns the length of the formatted aDouble in buf.
 static int
 FormatWithoutTrailingZeros(char (& buf)[40], double aDouble,
                            int precision)
 {
   static const DoubleToStringConverter converter(DoubleToStringConverter::UNIQUE_ZERO |
                                                  DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN,
                                                  "Infinity",
                                                  "NaN",
                                                  'e',
                                                  -6, 21,
 , 1);
   double_conversion::StringBuilder builder(buf, sizeof(buf));
   bool exponential_notation = false;
   converter.ToPrecision(aDouble, precision, &exponential_notation, &builder);
   int length = builder.position();
   char* formattedDouble = builder.Finalize();
   // If we have a shorter string than precision, it means we have a special
   // value (NaN or Infinity).  All other numbers will be formatted with at
   // least precision digits.
   if (length <= precision) {
     return length;
   }
   char* end = formattedDouble + length;
   char* decimalPoint = strchr(buf, '.');
   // No trailing zeros to remove.
   if (decimalPoint == nullptr) {
     return length;
   }
   if (MOZ_UNLIKELY(exponential_notation)) {
     // We need to check for cases like 1.00000e-10 (yes, this is
     // disgusting).
     char* exponent = end - 1;
     for ( ; ; --exponent) {
       if (*exponent == 'e') {
         break;
       }
     }
     char* zerosBeforeExponent = exponent - 1;
     for ( ; zerosBeforeExponent != decimalPoint; --zerosBeforeExponent) {
       if (*zerosBeforeExponent != '0') {
         break;
       }
     }
     if (zerosBeforeExponent == decimalPoint) {
       --zerosBeforeExponent;
     }
     // Slide the exponent to the left over the trailing zeros.  Don't
     // worry about copying the trailing NUL character.
     size_t exponentSize = end - exponent;
     memmove(zerosBeforeExponent + 1, exponent, exponentSize);
     length -= exponent - (zerosBeforeExponent + 1);
   } else {
     char* trailingZeros = end - 1;
     for ( ; trailingZeros != decimalPoint; --trailingZeros) {
       if (*trailingZeros != '0') {
         break;
       }
     }
     if (trailingZeros == decimalPoint) {
       --trailingZeros;
     }
     length -= end - (trailingZeros + 1);
   }
   return length;
 }
 #endif /* CharT_is_PRUnichar */
 void
 nsTSubstring_CharT::AppendFloat( float aFloat )
 {
   char buf[40];
   int length = FormatWithoutTrailingZeros(buf, aFloat, 6);
   AppendASCII(buf, length);
 }
 void
 nsTSubstring_CharT::AppendFloat( double aFloat )
 {
   char buf[40];
   int length = FormatWithoutTrailingZeros(buf, aFloat, 15);
   AppendASCII(buf, length);
 }
 size_t
 nsTSubstring_CharT::SizeOfExcludingThisMustBeUnshared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   if (mFlags & F_SHARED) {
     return nsStringBuffer::FromData(mData)->
              SizeOfIncludingThisMustBeUnshared(mallocSizeOf);
   }
   if (mFlags & F_OWNED) {
     return mallocSizeOf(mData);
   }
   // If we reach here, exactly one of the following must be true:
   // - F_VOIDED is set, and mData points to sEmptyBuffer;
   // - F_FIXED is set, and mData points to a buffer within a string
   //   object (e.g. nsAutoString);
   // - None of F_SHARED, F_OWNED, F_FIXED is set, and mData points to a buffer
   //   owned by something else.
   //
   // In all three cases, we don't measure it.
   return 0;
 }
 size_t
 nsTSubstring_CharT::SizeOfExcludingThisIfUnshared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   // This is identical to SizeOfExcludingThisMustBeUnshared except for the
   // F_SHARED case.
   if (mFlags & F_SHARED) {
     return nsStringBuffer::FromData(mData)->
              SizeOfIncludingThisIfUnshared(mallocSizeOf);
   }
   if (mFlags & F_OWNED) {
     return mallocSizeOf(mData);
   }
   return 0;
 }
 size_t
 nsTSubstring_CharT::SizeOfExcludingThisEvenIfShared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   // This is identical to SizeOfExcludingThisMustBeUnshared except for the
   // F_SHARED case.
   if (mFlags & F_SHARED) {
     return nsStringBuffer::FromData(mData)->
              SizeOfIncludingThisEvenIfShared(mallocSizeOf);
   }
   if (mFlags & F_OWNED) {
     return mallocSizeOf(mData);
   }
   return 0;
 }
 size_t
 nsTSubstring_CharT::SizeOfIncludingThisMustBeUnshared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   return mallocSizeOf(this) + SizeOfExcludingThisMustBeUnshared(mallocSizeOf);
 }
 size_t
 nsTSubstring_CharT::SizeOfIncludingThisIfUnshared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   return mallocSizeOf(this) + SizeOfExcludingThisIfUnshared(mallocSizeOf);
 }
 size_t
 nsTSubstring_CharT::SizeOfIncludingThisEvenIfShared(
     mozilla::MallocSizeOf mallocSizeOf) const
 {
   return mallocSizeOf(this) + SizeOfExcludingThisEvenIfShared(mallocSizeOf);
 }

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xpcom/string/src/nsTSubstring.cpp@b8a032363ba2 (annotated)

xpcom/string/src/nsTSubstring.cpp