genx - XML writer

`local genx = require'genx'`

A ffi binding of genx, a library for generating well-formed canonical XML documents, written by Tim Bray.

only UTF8 encoding supported
no empty element tags
no <!DOCTYPE> declarations (write it yourself before calling w:start_doc())
no pretty-printing (add linebreaks and indentation yourself with w:text() where needed)

local w = genx.new()
w:start_doc(io.stdout)
w:start_element'root'
w:text'hello'
w:end_element()
w:end_doc()
w:free()

`genx.new() -> w`	Create a new genx writer.
`w:free()`	Free the genx writer.
`w:start_doc(file)`	Start an XML document on a `FILE *` or Lua file object
`w:start_doc(write)`	Start an XML document on a write function to be called as `write([s[, size]])`
`w:end_doc()`	Flush pending updates and release the file handle
`w:ns(uri[, prefix]) -> ns`	Declare a namespace for reuse. The same namespace can be declared multiple times.
`w:element(name[, ns \| uri,prefix]) -> elem`	Declare an element for reuse. The same element can be declared multiple times.
`w:attr(name[, ns \| uri,prefix]) -> attr`	Declare an attribute for reuse. The same attribute can be declared multiple times.
`w:comment(s)`	Add a comment to the current XML stream.
`w:pi(target, text)`	Add a PI to the current XML stream.
`w:start_element(elem \| name [, ns \| uri,prefix])`	Start a new XML element.
`w:end_element()`	End the current element.
`w:add_attr(attr, val[, ns \| uri,prefix])`	Add an attribute to the current element. Attributes are sorted by name in the output stream.
`w:add_ns(ns \| [uri,prefix])`	Add a namespace to the current element.
`w:unset_default_namespace()`	Add a `xmlns=""` declaration to unset the default namespace declaration. This is a no-op if no default namespace is in effect.
`w:text(s[, size])`	Add utf-8 text.
`w:char(char)`	Add an unicode code point.
`w:check_text(s) -> genxStatus`	Check utf-8 text.
`w:scrub_text(s) -> s`	Scrub utf-8 text of invalid characters.

See the genx manual for more info.