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xpath.c
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xpath.c
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/**
* @file xpath.c
* SQLite extension module to select parts of XML documents
* using libxml2 XPath and SQLite's virtual table mechanism.
*
* 2013 March 15
*
* The author disclaims copyright to this source code.
* In place of a legal notice, here is a blessing:
*
* May you do good and not evil.
* May you find forgiveness for yourself and forgive others.
* May you share freely, never taking more than you give.
*
********************************************************************
*/
#if defined(_WIN32) || defined(_WIN64)
#include <windows.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <libxml/xpath.h>
#ifdef WITH_XSLT
#include <libxslt/xslt.h>
#include <libxslt/transform.h>
#include <libxslt/xsltutils.h>
#endif
#ifdef STANDALONE
#include <sqlite3.h>
#else
#include <sqlite3ext.h>
static SQLITE_EXTENSION_INIT1
#endif
/**
* @typedef XDOC
* @struct XDOC
* Structure to cache XML document.
*/
typedef struct XDOC {
xmlDocPtr doc; /**< XML document. */
int refcnt; /**< Reference counter. */
} XDOC;
/**
* @typedef XMOD
* @struct XMOD
* Structure holding per module/database data.
*/
typedef struct XMOD {
int refcnt; /**< Reference counter. */
sqlite3_mutex *mutex; /**< DOC table mutex. */
int sdoc; /**< Size of docs array. */
int ndoc; /**< Number of used entries in docs array. */
XDOC *docs; /**< Array of modules's DOCs. */
} XMOD;
static int initialized = 0;
static XMOD *xmod = 0;
/**
* @typedef XTAB
* @struct XTAB
* Structure to describe virtual table.
*/
typedef struct XTAB {
sqlite3_vtab vtab; /**< SQLite virtual table. */
sqlite3 *db; /**< Open database. */
XMOD *xm; /**< Module data. */
struct XCSR *xc; /**< Current cursor. */
int sdoc; /**< Size of idocs array. */
int ndoc; /**< Number of used entries in idocs array. */
int *idocs; /**< Indexes in module-wide DOC table. */
} XTAB;
/**
* @typedef XEXP
* @struct XEXP
* Structure to describe XPath expression.
*/
typedef struct XEXP {
struct XEXP *next; /**< Next item. */
struct XEXP *prev; /**< Previous item. */
xmlDocPtr doc; /**< Current XML document. */
xmlXPathContextPtr pctx; /**< Current XPath context. */
xmlXPathObjectPtr pobj; /**< Current XPath objects. */
xmlNodePtr parent; /**< Current parent node or NULL. */
int pos; /**< Position within XPath expr. */
int conv; /**< Conversion: string/boolean/number. */
char expr[1]; /**< XPath expression text. */
} XEXP;
/**
* @typedef XCSR
* @struct XCSR
* Structure to describe virtual table cursor.
*/
typedef struct XCSR {
sqlite3_vtab_cursor cursor; /**< SQLite virtual table cursor */
int pos; /**< Current index. */
int nexpr; /**< Number of XPath expr. */
XEXP *first; /**< First XPath expr. */
XEXP *last; /**< Last XPath expr. */
} XCSR;
/**
* Connect to virtual table.
* @param db SQLite database pointer
* @param aux user specific pointer
* @param argc argument count
* @param argv argument vector
* @param vtabp pointer receiving virtual table pointer
* @param errp pointer receiving error messag
* @result SQLite error code
*
* Argument vector contains:
*
* argv[0] - module name<br>
* argv[1] - database name<br>
* argv[2] - table name (virtual table)<br>
*/
static int
xpath_connect(sqlite3* db, void *aux, int argc, const char * const *argv,
sqlite3_vtab **vtabp, char **errp)
{
int rc = SQLITE_ERROR;
XTAB *xt;
xt = sqlite3_malloc(sizeof (XTAB));
if (!xt) {
nomem:
*errp = sqlite3_mprintf("out of memory");
return rc;
}
memset(xt, 0, sizeof (XTAB));
xt->db = db;
xt->xm = (XMOD *) aux;
xt->xc = 0;
xt->sdoc = 128;
xt->ndoc = 0;
xt->idocs = sqlite3_malloc(xt->sdoc * sizeof (int));
if (!xt->idocs) {
sqlite3_free(xt);
goto nomem;
}
rc = sqlite3_declare_vtab(db,
"CREATE TABLE x("
" DOCID INTEGER PRIMARY KEY,"
" XML HIDDEN BLOB,"
" PATH HIDDEN TEXT,"
" OPTIONS HIDDEN INTEGER,"
" ENCODING HIDDEN TEXT,"
" BASEURL HIDDEN TEXT,"
" XMLDUMP HIDDEN TEXT"
")");
if (rc != SQLITE_OK) {
sqlite3_free(xt->idocs);
sqlite3_free(xt);
*errp = sqlite3_mprintf("table definition failed (error %d)", rc);
return rc;
}
*vtabp = &xt->vtab;
*errp = 0;
return SQLITE_OK;
}
/**
* Create virtual table.
* @param db SQLite database pointer
* @param aux user specific pointer
* @param argc argument count
* @param argv argument vector
* @param vtabp pointer receiving virtual table pointer
* @param errp pointer receiving error messag
* @result SQLite error code
*/
static int
xpath_create(sqlite3* db, void *aux, int argc,
const char *const *argv,
sqlite3_vtab **vtabp, char **errp)
{
return xpath_connect(db, aux, argc, argv, vtabp, errp);
}
/**
* Disconnect virtual table.
* @param vtab virtual table pointer
* @result always SQLITE_OK
*/
static int
xpath_disconnect(sqlite3_vtab *vtab)
{
XTAB *xt = (XTAB *) vtab;
XMOD *xm = xt->xm;
int i, n;
if (xm->mutex) {
sqlite3_mutex_enter(xm->mutex);
for (i = 0; xm->docs && (i < xt->ndoc); i++) {
n = xt->idocs[i];
if ((n >= 0) && (n < xm->sdoc)) {
xmlDocPtr doc = xm->docs[n].doc;
if (doc) {
xm->docs[n].refcnt -= 1;
if (xm->docs[n].refcnt <= 0) {
xm->docs[n].doc = 0;
xm->docs[n].refcnt = 0;
xm->ndoc--;
xmlFreeDoc(doc);
}
}
}
}
sqlite3_mutex_leave(xm->mutex);
}
sqlite3_free(xt->idocs);
sqlite3_free(xt);
return SQLITE_OK;
}
/**
* Destroy virtual table.
* @param vtab virtual table pointer
* @result always SQLITE_OK
*/
static int
xpath_destroy(sqlite3_vtab *vtab)
{
return xpath_disconnect(vtab);
}
/**
* Determines information for filter function according to constraints.
* @param vtab virtual table
* @param info index/constraint information
* @result SQLite error code
*/
static int
xpath_bestindex(sqlite3_vtab *vtab, sqlite3_index_info *info)
{
return SQLITE_OK;
}
/**
* Open virtual table and return cursor.
* @param vtab virtual table pointer
* @param cursorp pointer receiving cursor pointer
* @result SQLite error code
*/
static int
xpath_open(sqlite3_vtab *vtab, sqlite3_vtab_cursor **cursorp)
{
XCSR *xc = sqlite3_malloc(sizeof (XCSR));
if (!xc) {
return SQLITE_ERROR;
}
xc->cursor.pVtab = vtab;
xc->pos = -1;
xc->nexpr = 0;
xc->first = xc->last = 0;
*cursorp = &xc->cursor;
return SQLITE_OK;
}
/**
* Close virtual table cursor.
* @param cursor cursor pointer
* @result SQLite error code
*/
static int
xpath_close(sqlite3_vtab_cursor *cursor)
{
XCSR *xc = (XCSR *) cursor;
XEXP *xp = xc->first, *next;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
while (xp) {
next = xp->next;
if (xp->pobj) {
xmlXPathFreeObject(xp->pobj);
}
if (xp->pctx) {
xmlXPathFreeContext(xp->pctx);
}
sqlite3_free(xp);
xp = next;
}
if (xt->xc == xc) {
xt->xc = 0;
}
sqlite3_free(xc);
return SQLITE_OK;
}
/**
* Retrieve next row from virtual table cursor.
* @param cursor virtual table cursor
* @result SQLite error code
*/
static int
xpath_next(sqlite3_vtab_cursor *cursor)
{
XCSR *xc = (XCSR *) cursor;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
XEXP *xp;
if (xc->pos < xt->ndoc) {
int ninc = 0;
if ((xc->pos >= 0) && xc->nexpr) {
int newpos;
xmlNodePtr node, parent = 0;
xp = xc->first;
while (xp) {
if (xp->pobj) {
if (xp == xc->first) {
parent = xp->parent;
} else if (parent != xp->parent) {
break;
}
}
xp = xp->next;
}
if (parent && !xp) {
int pchg = 0;
xp = xc->first;
while (xp) {
if (xp->pobj && (xp->pobj->type == XPATH_NODESET) &&
xp->pobj->nodesetval) {
newpos = xp->pos + 1;
if (newpos < xp->pobj->nodesetval->nodeNr) {
node = xp->pobj->nodesetval->nodeTab[newpos];
if (node->parent != xp->parent) {
pchg++;
}
} else {
pchg++;
}
}
xp = xp->next;
}
if ((pchg != 0) && (pchg != xc->nexpr)) {
xp = xc->first;
while (xp) {
if (xp->pobj && (xp->pobj->type == XPATH_NODESET) &&
xp->pobj->nodesetval) {
newpos = xp->pos + 1;
if (newpos < xp->pobj->nodesetval->nodeNr) {
node = xp->pobj->nodesetval->nodeTab[newpos];
if (node->parent == xp->parent) {
xp->pos = newpos;
ninc++;
}
} else {
xp->pos = xp->pobj->nodesetval->nodeNr;
ninc++;
}
}
xp = xp->next;
}
}
}
if (!ninc) {
xp = xc->first;
while (xp) {
if (xp->pobj && (xp->pobj->type == XPATH_NODESET) &&
xp->pobj->nodesetval) {
newpos = xp->pos + 1;
if (newpos < xp->pobj->nodesetval->nodeNr) {
xp->pos = newpos;
ninc++;
} else {
xp->pos = xp->pobj->nodesetval->nodeNr;
}
}
xp = xp->next;
}
}
}
if (!ninc) {
xc->pos++;
xp = xc->first;
while (xp) {
xp->pos = -1;
xp->parent = 0;
xp = xp->next;
}
}
}
return SQLITE_OK;
}
/**
* Filter function for virtual table.
* @param cursor virtual table cursor
* @param idxNum not used
* @param idxStr nod used
* @param argc number arguments (not used)
* @param argv argument (nothing or RHS of filter expression, not used)
* @result SQLite error code
*/
static int
xpath_filter(sqlite3_vtab_cursor *cursor, int idxNum,
const char *idxStr, int argc, sqlite3_value **argv)
{
XCSR *xc = (XCSR *) cursor;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
xc->pos = -1;
xt->xc = xc;
return xpath_next(cursor);
}
/**
* Return end of table state of virtual table cursor.
* @param cursor virtual table cursor
* @result true/false
*/
static int
xpath_eof(sqlite3_vtab_cursor *cursor)
{
XCSR *xc = (XCSR *) cursor;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
return xc->pos >= xt->ndoc;
}
/**
* Return column data of virtual table.
* @param cursor virtual table cursor
* @param ctx SQLite function context
* @param n column index
* @result SQLite error code
*/
static int
xpath_column(sqlite3_vtab_cursor *cursor, sqlite3_context *ctx, int n)
{
XCSR *xc = (XCSR *) cursor;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
XMOD *xm = (XMOD *) xt->xm;
if ((xc->pos < 0) || (xc->pos >= xt->ndoc)) {
sqlite3_result_error(ctx, "column out of bounds", -1);
return SQLITE_ERROR;
}
if (n == 0) {
n = xt->idocs[xc->pos];
if (xm->docs[n].doc) {
sqlite3_result_int(ctx, n + 1);
return SQLITE_OK;
}
} else if (n == 6) {
n = xt->idocs[xc->pos];
if (xm->docs[n].doc) {
xmlChar *dump = 0;
int dump_len = 0;
xmlDocDumpFormatMemoryEnc(xm->docs[n].doc, &dump,
&dump_len, "utf-8", 1);
if (dump) {
sqlite3_result_text(ctx, (char *) dump, dump_len,
SQLITE_TRANSIENT);
xmlFree(dump);
return SQLITE_OK;
}
}
}
sqlite3_result_null(ctx);
return SQLITE_OK;
}
/**
* Return current rowid of virtual table cursor.
* @param cursor virtual table cursor
* @param rowidp value buffer to receive current rowid
* @result SQLite error code
*/
static int
xpath_rowid(sqlite3_vtab_cursor *cursor, sqlite3_int64 *rowidp)
{
XCSR *xc = (XCSR *) cursor;
XTAB *xt = (XTAB *) xc->cursor.pVtab;
XMOD *xm = (XMOD *) xt->xm;
int n = xt->idocs[xc->pos];
if (xm->docs[n].doc) {
*rowidp = (sqlite3_int64) (n + 1);
return SQLITE_OK;
}
return SQLITE_ERROR;
}
/**
* Insert/delete row into/from virtual table.
* @param vtab virtual table pointer
* @param argc number of arguments
* @param argv argument vector
* @param rowidp value buffer to receive rowid
* @result SQLite error code
*
* Examples:
*
* CREATE VIRTUAL TABLE X USING xpath();<br>
* INSERT INTO X(XML) VALUES('xml-string ...');<br>
* INSERT INTO X(PATH,OPTIONS) VALUES(<url>,0);<br>
* DELETE FROM X WHERE DOCID=<docid>;<br>
*
* Virtual table columns:
*
* DOCID - document identifier and ROWID<br>
* XML - XML string<br>
* PATH - pathname or URL<br>
* OPTIONS - parser options, see libxml's XML_PARSE_* defines<br>
* ENCODING - optional document encoding, default UTF-8<br>
* BASEURL - optional base URL when XML string given<br>
* XMLDUMP - output column, XML dump of document tree<br>
*
* All columns except DOCID are hidden. UPDATE on the virtual table
* is not supported. Default parser options are XML_PARSE_NOERROR,
* XML_PARSE_NOWARNING, and XML_PARSE_NONET.
*/
static int
xpath_update(sqlite3_vtab *vtab, int argc, sqlite3_value **argv,
sqlite3_int64 *rowidp)
{
int n = -1, rc = SQLITE_ERROR;
XTAB *xt = (XTAB *) vtab;
XMOD *xm = (XMOD *) xt->xm;
xmlDocPtr doc = 0, docToFree = 0;
if (argc == 1) {
/* DELETE */
int i, k = -1;
n = sqlite3_value_int(argv[0]);
for (i = 0; i < xt->ndoc; i++) {
if ((n - 1) == xt->idocs[i]) {
k = xt->idocs[i];
memmove(xt->idocs + i, xt->idocs + i + 1,
(xt->ndoc - (i + 1)) * sizeof (int));
xt->ndoc--;
break;
}
}
if ((k >= 0) && xm->mutex) {
n = k;
doc = xm->docs[n].doc;
}
rc = SQLITE_OK;
} else if ((argc > 1) && (sqlite3_value_type(argv[0]) == SQLITE_NULL)) {
/* INSERT */
int i, docid;
int opts = (XML_PARSE_NOERROR | XML_PARSE_NOWARNING | XML_PARSE_NONET);
char *enc = 0;
if (sqlite3_value_type(argv[1]) != SQLITE_NULL) {
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("ROWID must be NULL");
rc = SQLITE_CONSTRAINT;
goto done;
}
if (sqlite3_value_type(argv[2]) != SQLITE_NULL) {
docid = sqlite3_value_int(argv[2]);
if ((sqlite3_value_type(argv[3]) != SQLITE_NULL) ||
(sqlite3_value_type(argv[4]) != SQLITE_NULL)) {
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("XML and PATH must be NULL");
rc = SQLITE_CONSTRAINT;
goto done;
}
sqlite3_mutex_enter(xm->mutex);
for (i = 0; xm->docs && (i < xt->ndoc); i++) {
if ((docid - 1) == xt->idocs[i]) {
sqlite3_mutex_leave(xm->mutex);
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("constraint violation");
rc = SQLITE_CONSTRAINT;
goto done;
}
}
if ((docid > 0) && (docid <= xm->sdoc)) {
doc = xm->docs[docid - 1].doc;
if (doc) {
xm->docs[docid - 1].refcnt++;
}
}
sqlite3_mutex_leave(xm->mutex);
if (!doc) {
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("invalid DOCID");
goto done;
}
goto havedoc;
}
if (((sqlite3_value_type(argv[3]) == SQLITE_NULL) &&
(sqlite3_value_type(argv[4]) == SQLITE_NULL)) ||
((sqlite3_value_type(argv[3]) != SQLITE_NULL) &&
(sqlite3_value_type(argv[4]) != SQLITE_NULL))) {
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("specify one of XML or PATH");
rc = SQLITE_CONSTRAINT;
goto done;
}
if (sqlite3_value_type(argv[5]) != SQLITE_NULL) {
opts = sqlite3_value_int(argv[5]);
}
if (sqlite3_value_type(argv[6]) != SQLITE_NULL) {
enc = (char *) sqlite3_value_text(argv[6]);
}
if (sqlite3_value_type(argv[4]) != SQLITE_NULL) {
doc = xmlReadFile((char *) sqlite3_value_text(argv[4]), enc, opts);
} else {
char *url = 0;
if (sqlite3_value_type(argv[7]) != SQLITE_NULL) {
url = (char *) sqlite3_value_text(argv[7]);
}
doc = xmlReadMemory(sqlite3_value_blob(argv[3]),
sqlite3_value_bytes(argv[3]),
url ? url : "", enc, opts);
}
if (!doc) {
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("read error");
goto done;
}
docToFree = doc;
havedoc:
if (xt->ndoc >= xt->sdoc) {
int *idocs = sqlite3_realloc(xt->idocs, xt->sdoc +
128 * sizeof (int));
if (!idocs) {
goto nomem;
}
xt->idocs = idocs;
xt->sdoc += 128;
}
if (!xm->mutex) {
goto nomem;
}
sqlite3_mutex_enter(xm->mutex);
if (xm->ndoc >= xt->sdoc) {
XDOC *docs = sqlite3_realloc(xm->docs, xt->sdoc +
128 * sizeof (XDOC));
if (!docs) {
sqlite3_mutex_leave(xm->mutex);
goto nomem;
}
xm->docs = docs;
docs += xt->sdoc;
memset(docs, 0, 128 * sizeof (XDOC));
xt->sdoc += 128;
}
for (i = 0; i < xm->sdoc; i++) {
if (!xm->docs[i].doc) {
xm->docs[i].doc = doc;
xm->docs[i].refcnt = 1;
xm->ndoc++;
xt->idocs[xt->ndoc++] = i;
*rowidp = (sqlite3_int64) (i + 1);
doc = docToFree = 0;
rc = SQLITE_OK;
break;
}
}
} else {
/* UPDATE */
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("UPDATE not supported");
}
done:
if (docToFree) {
xmlFreeDoc(docToFree);
} else if (doc && (n >= 0)) {
sqlite3_mutex_enter(xm->mutex);
xm->docs[n].refcnt -= 1;
if (xm->docs[n].refcnt <= 0) {
xm->docs[n].doc = 0;
xm->docs[n].refcnt = 0;
xm->ndoc--;
xmlFreeDoc(doc);
}
sqlite3_mutex_leave(xm->mutex);
}
return rc;
nomem:
if (vtab->zErrMsg) {
sqlite3_free(vtab->zErrMsg);
}
vtab->zErrMsg = sqlite3_mprintf("out of memory");
rc = SQLITE_NOMEM;
goto done;
}
/**
* Common XPath select function for virtual table.
* @param ctx SQLite function context
* @param conv conversion (0=string, 1=boolean, 2=number)
* @param argc number of arguments
* @param argv argument vector
*
* Examples:
*
* CREATE VIRTUAL TABLE X USING xpath();<br>
* INSERT INTO X(XML) VALUES('xml-string ...');<br>
* SELECT xpath_string(docid, '//book/title') FROM X;<br>
* SELECT xpath_number(docid, '//book/price') FROM X;<br>
*
* The RHS of the xpath_* functions should be a constant string.
*/
static void
xpath_vfunc_common(sqlite3_context *ctx, int conv, int argc,
sqlite3_value **argv)
{
XTAB *xt = (XTAB *) sqlite3_user_data(ctx);
XMOD *xm = xt->xm;
XCSR *xc = xt->xc;
XEXP *xp;
xmlXPathContextPtr pctx = 0;
xmlXPathObjectPtr pobj = 0;
int n;
char *p;
if ((argc < 2) || !sqlite3_value_text(argv[1])) {
sqlite3_result_error(ctx, "wrong arguments", -1);
goto done;
}
if (!xc) {
sqlite3_result_error(ctx, "not in virtual table context", -1);
goto done;
}
if ((xc->pos < 0) || (xc->pos >= xt->ndoc)) {
sqlite3_result_error(ctx, "cursor out of bounds", -1);
goto done;
}
n = xt->idocs[xc->pos];
if (!xm->docs[n].doc) {
sqlite3_result_error(ctx, "no docid", -1);
goto done;
}
p = (char *) sqlite3_value_text(argv[1]);
if (!p || !p[0]) {
sqlite3_result_error(ctx, "no or empty XPath expression", -1);
goto done;
}
xp = xc->first;
while (xp) {
if (!strcmp(p, xp->expr)) {
break;
}
xp = xp->next;
}
if (!xp) {
xp = sqlite3_malloc(sizeof (XEXP) + strlen(p));
if (!xp) {
sqlite3_result_error(ctx, "out of memory", -1);
goto done;
}
xp->next = xp->prev = 0;
strcpy(xp->expr, p);
pctx = xmlXPathNewContext(xm->docs[n].doc);
if (!pctx) {
sqlite3_free(xp);
sqlite3_result_error(ctx, "out of memory", -1);
goto done;
}
pobj = xmlXPathEvalExpression((xmlChar *) xp->expr, pctx);
if (!pobj) {
sqlite3_free(xp);
sqlite3_result_error(ctx, "bad XPath expression", -1);
goto done;
}
xp->doc = xm->docs[n].doc;
xp->pctx = pctx;
xp->pobj = pobj;
xp->parent = 0;
xp->pos = -1;
xp->conv = conv;
pctx = 0;
pobj = 0;
xc->nexpr++;
if (xc->first) {
xc->last->next = xp;
xp->prev = xc->last;
xc->last = xp;
} else {
xc->first = xc->last = xp;
}
} else if (xm->docs[n].doc != xp->doc) {
if (xp->pobj) {
xmlXPathFreeObject(xp->pobj);
xp->pobj = 0;
}
if (xp->pctx) {
xmlXPathFreeContext(xp->pctx);
xp->pctx = 0;
}
xp->doc = xm->docs[n].doc;
xp->parent = 0;
xp->pos = -1;
if (xp->doc) {
pctx = xmlXPathNewContext(xm->docs[n].doc);
if (!pctx) {
sqlite3_result_error(ctx, "out of memory", -1);
goto done;
}
pobj = xmlXPathEvalExpression((xmlChar *) xp->expr, pctx);
if (!pobj) {
sqlite3_result_error(ctx, "bad XPath expression", -1);
goto done;
}
xp->pctx = pctx;
xp->pobj = pobj;
pctx = 0;
pobj = 0;
}
}
if (xp->pos < 0) {
xp->pos = 0;
}
if (!xp->pobj) {
xp->parent = 0;
sqlite3_result_null(ctx);
goto done;
}
if ((xp->pobj->type == XPATH_NODESET) && xp->pobj->nodesetval) {
if ((xp->pos < 0) || (xp->pos >= xp->pobj->nodesetval->nodeNr)) {
xp->parent = 0;
sqlite3_result_null(ctx);
} else {
xmlNodePtr node = xp->pobj->nodesetval->nodeTab[xp->pos];
xmlBufferPtr buf = 0;
xp->parent = node->parent;
if (node) {
switch (xp->conv) {
case 1:
p = (char *) xmlXPathCastNodeToString(node);
n = xmlXPathCastStringToBoolean((xmlChar *) p);
sqlite3_result_int(ctx, n);
if (p) {
xmlFree(p);
}
break;
case 2:
sqlite3_result_double(ctx,
xmlXPathCastNodeToNumber(node));
break;
case 3:
buf = xmlBufferCreate();
if (!buf) {
sqlite3_result_error(ctx, "out of memory", -1);
goto done;
}
xmlNodeDump(buf, xp->doc, node, 0, 0);
sqlite3_result_text(ctx, (char *) xmlBufferContent(buf),
xmlBufferLength(buf),
SQLITE_TRANSIENT);
xmlBufferFree(buf);
break;
default:
p = (char *) xmlXPathCastNodeToString(node);
sqlite3_result_text(ctx, p, -1, SQLITE_TRANSIENT);
if (p) {
xmlFree(p);
}
break;
}
} else {
sqlite3_result_null(ctx);
}
}
} else {
xp->parent = 0;
switch (xp->conv) {
case 1:
sqlite3_result_int(ctx, xmlXPathCastToBoolean(xp->pobj));
break;
case 2:
sqlite3_result_double(ctx, xmlXPathCastToNumber(xp->pobj));
break;
default:
p = (char *) xmlXPathCastToString(xp->pobj);
sqlite3_result_text(ctx, p, -1, SQLITE_TRANSIENT);
if (p) {
xmlFree(p);
}
break;
}
}
done:
if (pobj) {
xmlXPathFreeObject(pobj);
}
if (pctx) {
xmlXPathFreeContext(pctx);
}
}
/**
* XPath select function returning string value from virtual table.
* @param ctx SQLite function context
* @param argc number of arguments
* @param argv argument vector
*/
static void
xpath_vfunc_string(sqlite3_context *ctx, int argc, sqlite3_value **argv)
{
return xpath_vfunc_common(ctx, 0, argc, argv);
}
/**
* XPath select function returning boolean value from virtual table.
* @param ctx SQLite function context
* @param argc number of arguments
* @param argv argument vector
*/
static void
xpath_vfunc_boolean(sqlite3_context *ctx, int argc, sqlite3_value **argv)
{
return xpath_vfunc_common(ctx, 1, argc, argv);
}
/**
* XPath select function returning number from virtual table.
* @param ctx SQLite function context
* @param argc number of arguments
* @param argv argument vector
*/
static void
xpath_vfunc_number(sqlite3_context *ctx, int argc, sqlite3_value **argv)
{
return xpath_vfunc_common(ctx, 2, argc, argv);
}
/**
* XPath select function returning XML from virtual table.
* @param ctx SQLite function context
* @param argc number of arguments
* @param argv argument vector
*/
static void
xpath_vfunc_xml(sqlite3_context *ctx, int argc, sqlite3_value **argv)
{
return xpath_vfunc_common(ctx, 3, argc, argv);
}
/**
* Find overloaded function on virtual table.
* @param vtab virtual table
* @param nargs number arguments
* @param name function name