SWIG interface file for LibXML2 tree API

libxml2.i

// use SWIG version >= 1.3.40

%module libxml2

%{
  #include <libxml2/libxml/tree.h>
  #include <stdio.h>
%}

%native(nullNs) int getNullNs (lua_State *L);

%{
  int getNullNs (lua_State *L)
  {
    lua_pushlightuserdata (L, NULL);
    return 1;
  }
%}

%typemap(in) xmlChar* {
  $1 = (xmlChar*) (lua_tostring (L, $input));
}

%typemap(in) xmlNs* {
  $1 = (xmlNs*) (lua_topointer (L, $input));
}

%typemap(out) xmlChar* {
  lua_pushstring (L, (const char*)$1);
  SWIG_arg ++;
}

%typemap(in, numinputs=0) (xmlChar ** mem, int * size) (xmlChar *temp, int templen) {
  $1 = &temp;
  $2 = &templen;
}

%typemap(argout) (xmlChar ** mem, int * size) {
  // Append output value $1 to $result
  lua_pushlstring (L, *$1, *$2);
  SWIG_arg ++;
}


%include </usr/include/libxml2/libxml/xmlexports.h>
%include </usr/include/libxml2/libxml/xmlversion.h>
%include </usr/include/libxml2/libxml/tree.h>

libxml2_test.lua

require "xml"

local doc = xml.NewDoc "1.0"
local root = xml.NewNode (xml.nullNs, "root")
local child = xml.NewNode (xml.nullNs, "child")
xml.AddChild (root, child)
xml.DocSetRootElement (doc, root)

xml.NodeAddContent (child, "text content")
xml.SetProp (child, "attr", "value")

local str = xml.DocDumpMemory (doc)
print (str)

Makefile

libxml2.so: libxml2_wrap.c
        gcc -g -shared -fPIC -I/usr/include/libxml2 -o $@ $< -L/usr/lib/libxml2 -lxml2

libxml2_wrap.c: libxml2.i
        swig -lua -o $@ $<

xml.lua

require "libxml2"

xml = {}
setmetatable (xml, {__index = function (tbl, key) return libxml2["xml" .. key] end})

xml.nullNs = libxml2.nullNs ()