postgresql/contrib/xml/xslt_proc.c

/* 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;
    }
}