Thanks to the generous support of Torchbox (http://www.torchbox.com), I

have been able to significantly improve the contrib/xml XPath
integration code.

New features:

* XPath set-returning function allows multiple results from an several
XPath queries to be used as a virtual table.
* Using libxslt, XSLT transformations (with and without parameters) are
supported. (Caution: This support allows generic URL fetching from
within the backend as well).

I've removed the old code so that it is all libxml based. Rather than
attach as a patch, I've put the tar.gz (10k!) at
http://www.azuli.co.uk/pgxml-1.0.tar.gz
(all files in archive are xml/....).

I think this is worth replacing the contrib version with, even though
the function names have changed (though the same functionality is
there), because it includes a SRF and some SPI usage, in addition to
linking to an external library. And it isn't a big module! Obviously, I
understand that people might prefer to move it elsewhere, or might have
reservations about replacing an existing contrib module with an
incompatible one. I'm open to suggestions.

John Gray

1 files changed, 184 insertions, 0 deletions

diff --git a/contrib/xml/xslt_proc.c b/contrib/xml/xslt_proc.c
new file mode 100644
index 0000000000..64f9736622
--- /dev/null
+++ b/contrib/xml/xslt_proc.c
@@ -0,0 +1,184 @@
+/* XSLT processing functions (requiring libxslt) */
+/* John Gray, for Torchbox 2003-04-01 */
+
+#include "postgres.h"
+#include "fmgr.h"
+#include "executor/spi.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+
+/* libxml includes */
+
+#include <libxml/xpath.h>
+#include <libxml/tree.h>
+#include <libxml/xmlmemory.h>
+
+/* libxslt includes */
+
+#include <libxslt/xslt.h>
+#include <libxslt/xsltInternals.h>
+#include <libxslt/transform.h>
+#include <libxslt/xsltutils.h>
+
+
+/* declarations to come from xpath.c */
+
+extern void elog_error(int level, char *explain, int force);
+extern void pgxml_parser_init();
+extern xmlChar *pgxml_texttoxmlchar(text *textstring);
+
+#define GET_STR(textp) DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(textp)))
+
+/* local defs */
+static void parse_params(const char **params, text *paramstr);
+
+Datum xslt_process(PG_FUNCTION_ARGS);
+
+
+#define MAXPARAMS 20
+
+PG_FUNCTION_INFO_V1(xslt_process);
+
+Datum xslt_process(PG_FUNCTION_ARGS) {
+
+
+  const char *params[MAXPARAMS + 1]; /* +1 for the terminator */
+  xsltStylesheetPtr stylesheet = NULL;
+  xmlDocPtr doctree;
+  xmlDocPtr restree;
+  xmlDocPtr ssdoc = NULL;
+  xmlChar *resstr;
+  int resstat;
+  int reslen;
+
+  text *doct  = PG_GETARG_TEXT_P(0);
+  text *ssheet  = PG_GETARG_TEXT_P(1);
+  text *paramstr;
+  text *tres;
+
+
+  if (fcinfo->nargs == 3)
+    {
+      paramstr = PG_GETARG_TEXT_P(2);
+      parse_params(params,paramstr);
+    }
+  else /* No parameters */
+    {
+      params[0] = NULL;
+    }
+
+  /* Setup parser */
+  pgxml_parser_init();
+
+  /* Check to see if document is a file or a literal */
+
+  if (VARDATA(doct)[0] == '<')
+    {
+      doctree = xmlParseMemory((char *) VARDATA(doct), VARSIZE(doct)-VARHDRSZ);
+    } 
+  else 
+    {
+      doctree = xmlParseFile(GET_STR(doct));
+    }
+
+  if (doctree == NULL)
+    {
+      xmlCleanupParser();
+      elog_error(ERROR,"Error parsing XML document",0);
+
+      PG_RETURN_NULL();
+    }
+
+  /* Same for stylesheet */
+  if (VARDATA(ssheet)[0] == '<')
+    {
+      ssdoc = xmlParseMemory((char *) VARDATA(ssheet),
+					    VARSIZE(ssheet)-VARHDRSZ);
+      if (ssdoc == NULL) 
+	{
+	  xmlFreeDoc(doctree);
+	  xmlCleanupParser();
+	  elog_error(ERROR,"Error parsing stylesheet as XML document",0);	  
+	  PG_RETURN_NULL();
+	}
+
+      stylesheet = xsltParseStylesheetDoc(ssdoc);
+    }
+  else 
+   {
+      stylesheet = xsltParseStylesheetFile(GET_STR(ssheet));
+    }
+
+
+  if (stylesheet == NULL)
+    {
+      xmlFreeDoc(doctree);
+      xsltCleanupGlobals();
+      xmlCleanupParser();
+      elog_error(ERROR,"Failed to parse stylesheet",0);
+      PG_RETURN_NULL();
+    }
+
+  restree = xsltApplyStylesheet(stylesheet, doctree, params);
+  resstat = xsltSaveResultToString(&resstr, &reslen, restree, stylesheet);
+
+  xsltFreeStylesheet(stylesheet);
+  xmlFreeDoc(restree);
+  xmlFreeDoc(doctree);
+  
+  xsltCleanupGlobals();
+  xmlCleanupParser();
+  
+  if (resstat < 0) {
+    PG_RETURN_NULL();
+  }
+  
+  tres = palloc(reslen + VARHDRSZ);
+  memcpy(VARDATA(tres),resstr,reslen);
+  VARATT_SIZEP(tres) = reslen + VARHDRSZ;
+  
+  PG_RETURN_TEXT_P(tres);
+}
+
+
+void parse_params(const char **params, text *paramstr)
+{
+  char *pos;
+  char *pstr;
+
+  int i;
+  char *nvsep="=";
+  char *itsep=",";
+
+  pstr = GET_STR(paramstr);
+
+  pos=pstr;
+  
+  for (i=0; i < MAXPARAMS; i++) 
+    {
+      params[i] = pos;
+      pos = strstr(pos,nvsep);
+      if (pos != NULL) {
+	*pos = '\0';
+	pos++;
+      } else {
+	params[i]=NULL;
+	break;
+      }
+      /* Value */
+      i++;
+      params[i]=pos;
+      pos = strstr(pos,itsep);
+      if (pos != NULL) {
+	*pos = '\0';
+	pos++;
+      } else {
+	break;
+      }
+
+    }
+  if (i < MAXPARAMS) 
+    {
+      params[i+1]=NULL;
+    }
+}