Flat string reader

Introduced flat string reader abstraction which reads directly from a
flat string independent of the character width.  Replaced the
stream-based input to the regexp parser with a flat string reader and
dropped the 'next' field; now Next() reads directly from the string.

[Erik Corry, 2008-11-19 09:45:38]

Does it lint.

LGTM.

http://codereview.chromium.org/11231/diff/1/4
File src/jsregexp.cc (right):

http://codereview.chromium.org/11231/diff/1/4#newcode211
Line 211: pattern->Flatten(shape);
Since this shape is only used once I think you should just make it in the
Flatten call.  This also avoids the subtlety around the fact that flattening a
string changes its shape, so the shape can't be reused again anyway.

http://codereview.chromium.org/11231/diff/1/6
File src/objects.cc (right):

http://codereview.chromium.org/11231/diff/1/6#newcode3504
Line 3504: FlatStringReader* FlatStringReader::top_ = NULL;
Some people don't like static initializers.  Perhaps this should be in a
function called from v8::Initialize?

http://codereview.chromium.org/11231/diff/1/7
File src/objects.h (right):

http://codereview.chromium.org/11231/diff/1/7#newcode3595
Line 3595: explicit FlatStringReader(Handle<String> str);
FlatStringReaders can only be stack allocated, right?  So it should be marked as
such.  Also if it is used with some kinds of handles there could be issues
around the lifetime of the handle vs lifetime of the FlatStringReader.  That
deserves a comment.

[Christian Plesner Hansen, 2008-11-19 10:15:26]

Nope, it didn't lint.  Note however that interpreter-re2k.cc doesn't lint
either.

http://codereview.chromium.org/11231/diff/1/6
File src/objects.cc (right):

http://codereview.chromium.org/11231/diff/1/6#newcode3504
Line 3504: FlatStringReader* FlatStringReader::top_ = NULL;
I don't think initialization of pointers to NULL are an issue.