Bug 32136 – Add a rope representation to JSString.

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Gavin Barraclough]

Add a rope representation to JSString.  Presently JSString always holds its data in UString form.  Instead, allow the result of a string concatenation to be represented in a tree form - with a variable sized, reference-counted rope node retaining a set of UString::Reps (or other rope nopes).

Strings must still currently be resolved down to a flat UString representation before being used, but by holding the string in a rope representation during construction we can avoid copying data until we know the final size of the string.

[Gavin Barraclough]

Created attachment 44274 [details]
The Patch

[Gavin Barraclough]

Created attachment 44275 [details]
Add back an export accidentally deleted.

[WebKit Review Bot]

Attachment 44275 [details] did not pass style-queue:

Failed to run "WebKitTools/Scripts/check-webkit-style" exit_code: 1
JavaScriptCore/runtime/JSString.h:163:  More than one command on the same line  [whitespace/newline] [4]
JavaScriptCore/runtime/JSString.h:164:  More than one command on the same line  [whitespace/newline] [4]
Total errors found: 2

[Oliver Hunt]

Comment on attachment 44275 [details]
Add back an export accidentally deleted.

r=me

[Gavin Barraclough]

Sending        JavaScriptCore/ChangeLog
Sending        JavaScriptCore/JavaScriptCore.exp
Sending        JavaScriptCore/interpreter/Interpreter.cpp
Sending        JavaScriptCore/jit/JITOpcodes.cpp
Sending        JavaScriptCore/jit/JITStubs.cpp
Sending        JavaScriptCore/runtime/JSString.cpp
Sending        JavaScriptCore/runtime/JSString.h
Sending        JavaScriptCore/runtime/Operations.h
Sending        JavaScriptCore/runtime/StringObject.cpp
Transmitting file data .........
Committed revision 51671.