Support building on MS-Windows with libxml2.

 src/makefile.w32-in (OBJ2): Add xml.$(O).
 (GLOBAL_SOURCES): Add xml.c.
 ($(BLD)/xml.$(O)): New dependency list.
 src/xml.c (DEF_XML2_FN, LOAD_XML2_FN) [WINDOWSNT]: New macros.
 (fn_htmlReadMemory, fn_xmlReadMemory, fn_xmlDocGetRootElement)
 (fn_xmlFreeDoc, fn_xmlCleanupParser, fn_xmlCheckVersion)
 [!WINDOWSNT]: New macros.
 (init_libxml2_functions, libxml2_loaded_p): New functions.
 (parse_region): Call fn_xmlCheckVersion instead of using the macro
 LIBXML_TEST_VERSION.  Call libxml2 functions via the fn_* macros.
 (xml_cleanup_parser): New function, export for fn_xmlCleanupParser.
 Calls xmlCleanupParser only if libxml2 was loaded (or statically
 linked in).
 (Flibxml_parse_html_region, Flibxml_parse_xml_region): Call
 init_libxml2_functions before calling libxml2 functions.
 (syms_of_xml) <Qlibxml2_dll>: DEFSYM it.
 src/emacs.c: Don't include libxml/parser.h.
 (shut_down_emacs): Call xml_cleanup_parser, instead of calling
 xmlCleanupParser directly.
 src/ lisp.h [HAVE_LIBXML2]: Add prototype for xml_cleanup_parser.

 nt/configure.bat: Support building with libxml2.
 nt/INSTALL:
 nt/README.W32: Add information about libxml2.

 lisp/term/w32-win.el (dynamic-library-alist): Add libxml2 DLLs.

 lib-src/makefile.w32-in (obj): Add xml.o.

5 files changed, 159 insertions, 20 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6bd946c0900..d60379b76b4 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,33 @@
 2012-04-07  Eli Zaretskii  <eliz@gnu.org>
 
+        Support building on MS-Windows with libxml2.
+
+        * makefile.w32-in (OBJ2): Add xml.$(O).
+        (GLOBAL_SOURCES): Add xml.c.
+        ($(BLD)/xml.$(O)): New dependency list.
+
+        * xml.c (DEF_XML2_FN, LOAD_XML2_FN) [WINDOWSNT]: New macros.
+        (fn_htmlReadMemory, fn_xmlReadMemory, fn_xmlDocGetRootElement)
+        (fn_xmlFreeDoc, fn_xmlCleanupParser, fn_xmlCheckVersion)
+        [!WINDOWSNT]: New macros.
+        (init_libxml2_functions, libxml2_loaded_p): New functions.
+        (parse_region): Call fn_xmlCheckVersion instead of using the macro
+        LIBXML_TEST_VERSION.  Call libxml2 functions via the fn_* macros.
+        (xml_cleanup_parser): New function, export for fn_xmlCleanupParser.
+        Calls xmlCleanupParser only if libxml2 was loaded (or statically
+        linked in).
+        (Flibxml_parse_html_region, Flibxml_parse_xml_region): Call
+        init_libxml2_functions before calling libxml2 functions.
+        (syms_of_xml) <Qlibxml2_dll>: DEFSYM it.
+
+        * emacs.c: Don't include libxml/parser.h.
+        (shut_down_emacs): Call xml_cleanup_parser, instead of calling
+        xmlCleanupParser directly.
+
+        * lisp.h [HAVE_LIBXML2]: Add prototype for xml_cleanup_parser.
+
+2012-04-07  Eli Zaretskii  <eliz@gnu.org>
+
         * indent.c (Fvertical_motion): If there is a display string at
         point, use it.vpos to compute how many lines to backtrack after
         move_it_to point.  (Bug#11133)
diff --git a/src/emacs.c b/src/emacs.c
index 0e77223ee00..c36c7df7e45 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -82,10 +82,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <sys/personality.h>
 #endif
 
-#ifdef HAVE_LIBXML2
-#include <libxml/parser.h>
-#endif
-
 #ifndef O_RDWR
 #define O_RDWR 2
 #endif
@@ -2124,7 +2120,7 @@ shut_down_emacs (int sig, int no_x, Lisp_Object stuff)
 #endif
 
 #ifdef HAVE_LIBXML2
-  xmlCleanupParser ();
+  xml_cleanup_parser ();
 #endif
 }
 
diff --git a/src/lisp.h b/src/lisp.h
index bd19da55b2a..62695f15644 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3549,6 +3549,7 @@ EXFUN (Fmsdos_downcase_filename, 1);
 #ifdef HAVE_LIBXML2
 /* Defined in xml.c */
 extern void syms_of_xml (void);
+extern void xml_cleanup_parser (void);
 #endif
 
 #ifdef HAVE_MENUS
diff --git a/src/makefile.w32-in b/src/makefile.w32-in
index d7ca325e223..da831d07a36 100644
--- a/src/makefile.w32-in
+++ b/src/makefile.w32-in
@@ -128,6 +128,7 @@ OBJ2 =  $(BLD)/sysdep.$(O)		\
         $(BLD)/image.$(O)               \
         $(BLD)/terminal.$(O)            \
         $(BLD)/menu.$(O)                \
+        $(BLD)/xml.$(O)                 \
         $(BLD)/w32term.$(O)             \
         $(BLD)/w32xfns.$(O)             \
         $(BLD)/w32fns.$(O)              \
@@ -225,7 +226,7 @@ GLOBAL_SOURCES =   dosfns.c msdos.c \
         process.c callproc.c unexw32.c \
         region-cache.c sound.c atimer.c \
         doprnt.c intervals.c textprop.c composite.c \
-        gnutls.c
+        gnutls.c xml.c
 SOME_MACHINE_OBJECTS = dosfns.o msdos.o \
         xterm.o xfns.o xmenu.o xselect.o xrdb.o xsmfns.o dbusbind.o
 obj = $(GLOBAL_SOURCES:.c=.o)
@@ -940,6 +941,13 @@ $(BLD)/gnutls.$(O) : \
         $(LISP_H) \
         $(PROCESS_H)
 
+$(BLD)/xml.$(O) : \
+        $(SRC)/xml.c \
+        $(SRC)/w32.h \
+        $(CONFIG_H) \
+        $(LISP_H) \
+        $(SRC)/buffer.h
+
 $(BLD)/image.$(O) : \
         $(SRC)/image.c \
         $(SRC)/epaths.h \
diff --git a/src/xml.c b/src/xml.c
index 5c4b6ee35f0..7be8613f74a 100644
--- a/src/xml.c
+++ b/src/xml.c
@@ -28,6 +28,99 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "lisp.h"
 #include "buffer.h"
 
+
+static Lisp_Object Qlibxml2_dll;
+
+#ifdef WINDOWSNT
+
+#include <windows.h>
+#include "w32.h"
+
+/* Macro for defining functions that will be loaded from the libxml2 DLL.  */
+#define DEF_XML2_FN(rettype,func,args) static rettype (FAR CDECL *fn_##func)args
+
+/* Macro for loading libxml2 functions from the library.  */
+#define LOAD_XML2_FN(lib,func) {                                        \
+    fn_##func = (void *) GetProcAddress (lib, #func);                   \
+    if (!fn_##func) goto bad_library;                                   \
+  }
+
+DEF_XML2_FN (htmlDocPtr, htmlReadMemory,
+             (const char *, int, const char *, const char *, int));
+DEF_XML2_FN (xmlDocPtr, xmlReadMemory,
+             (const char *, int, const char *, const char *, int));
+DEF_XML2_FN (xmlNodePtr, xmlDocGetRootElement, (xmlDocPtr));
+DEF_XML2_FN (void, xmlFreeDoc, (xmlDocPtr));
+DEF_XML2_FN (void, xmlCleanupParser, (void));
+DEF_XML2_FN (void, xmlCheckVersion, (int));
+
+static int
+libxml2_loaded_p (void)
+{
+  Lisp_Object found = Fassq (Qlibxml2_dll, Vlibrary_cache);
+
+  if (CONSP (found))
+    return EQ (XCDR (found), Qt) ? 1 : 0;
+  return 0;
+}
+
+#else  /* !WINDOWSNT */
+
+#define fn_htmlReadMemory       htmlReadMemory
+#define fn_xmlReadMemory        xmlReadMemory
+#define fn_xmlDocGetRootElement xmlDocGetRootElement
+#define fn_xmlFreeDoc           xmlFreeDoc
+#define fn_xmlCleanupParser     xmlCleanupParser
+#define fn_xmlCheckVersion      xmlCheckVersion
+
+static inine int
+libxml2_loaded_p (void)
+{
+  return 1;
+}
+
+#endif  /* !WINDOWSNT */
+
+static int
+init_libxml2_functions (Lisp_Object libraries)
+{
+#ifdef WINDOWSNT
+  Lisp_Object found = Fassq (Qlibxml2_dll, Vlibrary_cache);
+
+  if (libxml2_loaded_p ())
+    return 1;
+  else
+    {
+      HMODULE library;
+
+      if (!(library = w32_delayed_load (libraries, Qlibxml2_dll)))
+        {
+          message ("%s", "libxml2 library not found");
+          return 0;
+        }
+
+      /* LOAD_XML2_FN jumps to bad_library if it fails to find the
+         named function.  */
+      LOAD_XML2_FN (library, htmlReadMemory);
+      LOAD_XML2_FN (library, xmlReadMemory);
+      LOAD_XML2_FN (library, xmlDocGetRootElement);
+      LOAD_XML2_FN (library, xmlFreeDoc);
+      LOAD_XML2_FN (library, xmlCleanupParser);
+      LOAD_XML2_FN (library, xmlCheckVersion);
+
+      Vlibrary_cache = Fcons (Fcons (Qlibxml2_dll, Qt), Vlibrary_cache);
+      return 1;
+    }
+
+ bad_library:
+  Vlibrary_cache = Fcons (Fcons (Qlibxml2_dll, Qnil), Vlibrary_cache);
+
+  return 0;
+#else  /* !WINDOWSNT */
+  return 1;
+#endif  /* !WINDOWSNT */
+}
+
 static Lisp_Object
 make_dom (xmlNode *node)
 {
@@ -92,7 +185,7 @@ parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, int html
   EMACS_INT bytes;
   EMACS_INT istart, iend;
 
-  LIBXML_TEST_VERSION;
+  fn_xmlCheckVersion (LIBXML_VERSION);
 
   validate_region (&start, &end);
 
@@ -111,16 +204,16 @@ parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, int html
   bytes = CHAR_TO_BYTE (iend) - CHAR_TO_BYTE (istart);
 
   if (htmlp)
-    doc = htmlReadMemory ((char *) BYTE_POS_ADDR (CHAR_TO_BYTE (istart)),
-                          bytes, burl, "utf-8",
-                          HTML_PARSE_RECOVER|HTML_PARSE_NONET|
-                          HTML_PARSE_NOWARNING|HTML_PARSE_NOERROR|
-                          HTML_PARSE_NOBLANKS);
+    doc = fn_htmlReadMemory ((char *) BYTE_POS_ADDR (CHAR_TO_BYTE (istart)),
+                             bytes, burl, "utf-8",
+                             HTML_PARSE_RECOVER|HTML_PARSE_NONET|
+                             HTML_PARSE_NOWARNING|HTML_PARSE_NOERROR|
+                             HTML_PARSE_NOBLANKS);
   else
-    doc = xmlReadMemory ((char *) BYTE_POS_ADDR (CHAR_TO_BYTE (istart)),
-                         bytes, burl, "utf-8",
-                         XML_PARSE_NONET|XML_PARSE_NOWARNING|
-                         XML_PARSE_NOBLANKS |XML_PARSE_NOERROR);
+    doc = fn_xmlReadMemory ((char *) BYTE_POS_ADDR (CHAR_TO_BYTE (istart)),
+                            bytes, burl, "utf-8",
+                            XML_PARSE_NONET|XML_PARSE_NOWARNING|
+                            XML_PARSE_NOBLANKS |XML_PARSE_NOERROR);
 
   if (doc != NULL)
     {
@@ -139,19 +232,26 @@ parse_region (Lisp_Object start, Lisp_Object end, Lisp_Object base_url, int html
       if (NILP (result)) {
         /* The document isn't just comments, so get the tree the
            proper way. */
-        xmlNode *node = xmlDocGetRootElement (doc);
+        xmlNode *node = fn_xmlDocGetRootElement (doc);
         if (node != NULL)
           result = make_dom (node);
       } else
         result = Fcons (intern ("top"),
                         Fcons (Qnil, Fnreverse (Fcons (r, result))));
 
-      xmlFreeDoc (doc);
+      fn_xmlFreeDoc (doc);
     }
 
   return result;
 }
 
+void
+xml_cleanup_parser (void)
+{
+  if (libxml2_loaded_p ())
+    fn_xmlCleanupParser ();
+}
+
 DEFUN ("libxml-parse-html-region", Flibxml_parse_html_region,
        Slibxml_parse_html_region,
        2, 3, 0,
@@ -159,7 +259,9 @@ DEFUN ("libxml-parse-html-region", Flibxml_parse_html_region,
 If BASE-URL is non-nil, it is used to expand relative URLs.  */)
   (Lisp_Object start, Lisp_Object end, Lisp_Object base_url)
 {
-  return parse_region (start, end, base_url, 1);
+  if (init_libxml2_functions (Vdynamic_library_alist))
+    return parse_region (start, end, base_url, 1);
+  return Qnil;
 }
 
 DEFUN ("libxml-parse-xml-region", Flibxml_parse_xml_region,
@@ -169,7 +271,9 @@ DEFUN ("libxml-parse-xml-region", Flibxml_parse_xml_region,
 If BASE-URL is non-nil, it is used to expand relative URLs.  */)
   (Lisp_Object start, Lisp_Object end, Lisp_Object base_url)
 {
-  return parse_region (start, end, base_url, 0);
+  if (init_libxml2_functions (Vdynamic_library_alist))
+    return parse_region (start, end, base_url, 0);
+  return Qnil;
 }
 
 
@@ -181,6 +285,8 @@ syms_of_xml (void)
 {
   defsubr (&Slibxml_parse_html_region);
   defsubr (&Slibxml_parse_xml_region);
+
+  DEFSYM (Qlibxml2_dll, "libxml2");
 }
 
 #endif /* HAVE_LIBXML2 */