[Cython] constant Py_UNICODE arrays

[Aaron DeVore]

I'm working with serializing an XML tree. To make it as fast as
possible I am using a raw array of Py_UNICODE characters instead of
"".join(l) or something of the sort. One problem I am running into is
that I need to append certain strings many times (e.g. '<', '</',
'>'). That incurs significant overhead in calls to the Python API.
Here is a basic idea of what is happening right now (the real code is
more complex):

cdef void append(UnicodeBuffer *ubuffer, unicode un):
----Py_UNICODE *string = PyUnicode_AsUnicode(un)
----... append string to buffer ...

cdef void render(UnicodeBuffer *ubuffer, Tag tag):
----append(buffer, u"<")
----append(buffer, tag.name)
----...render attributes with more append calls...
----append(buffer, u">")

I'm trying to find something where I could also append with a function
like this one:

cdef void appendArray(UnicodeBuffer *ubuffer, Py_UNICODE *string, int length):
----...append string to buffer...

One possibility is having several arrays of commonly used unicode
strings sitting around. In that case render() from above might look
like this:

cdef void render(UnicodeBuffer *ubuffer, Tag tag):
----appendArray(buffer, ustring_lt, 1)
----append(buffer, tag.name)
----...render attributes with more append calls...
----append(buffer, ustring_gt, 1)

What would be the best way to go about this?

-Aaron DeVore