517943 - Need a way to append the contents of an nsTArray to another without copying

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Henri Sivonen (:hsivonen)]

.Append() on nsTArray copy constucts. The HTML5 parser needs a method that moves stuff over from another nsTArray and empties the other array withou running constructors/destructors. (In order to move around tree operations without leaking or prematurely deleting members that aren't refcounted but deleted when the tree op goes away.)

Comment 1

[Henri Sivonen (:hsivonen)]

Attachment: Add MoveElementsFrom to nsTArray

Comment 2

[Benjamin Smedberg]

Comment on attachment 402066 [details] [diff] [review]
Add MoveElementsFrom to nsTArray

No other parts of nsTArray will assign from another array without copy construction: this seems like an unfortunate design decision.

Comment 3

[Henri Sivonen (:hsivonen)]

SwapElements() kind of assigns from another array without copy construction.

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 402066 [details] [diff] [review]
Add MoveElementsFrom to nsTArray

sr=dbaron (assuming bsmedberg's review+), if you stick an NS_PRECONDITION(&array != this, "argument must be different array"); (or better assertion text) at the beginning

Comment 5

[Benjamin Smedberg]

Comment on attachment 402066 [details] [diff] [review]
Add MoveElementsFrom to nsTArray

Please make the comment

"Move all elements from another array to the end of this array without calling copy constructors or destructors."

Comment 6

[Henri Sivonen (:hsivonen)]

Thank you for the reviews.

Pushed with the changes suggested:
http://hg.mozilla.org/mozilla-central/rev/f2a06414948c