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xpath.c File Reference

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Detailed Description

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.

Definition in file xpath.c.#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <libxml/xpath.h>
#include <sqlite3ext.h>

Go to the source code of this file.

Data Structures
struct	XCSR
	Structure to describe virtual table cursor. More...
struct	XDOC
	Structure to cache XML document. More...
struct	XEXP
	Structure to describe XPath expression. More...
struct	XMOD
	Structure holding per module/database data. More...
struct	XTAB
	Structure to describe virtual table. More...
Typedefs
typedef XDOC	XDOC
typedef XMOD	XMOD
typedef XTAB	XTAB
typedef XEXP	XEXP
typedef XCSR	XCSR
Functions
int	xpath_connect (sqlite3 *db, void *aux, int argc, const char *const *argv, sqlite3_vtab **vtabp, char **errp)
	Connect to virtual table.
int	xpath_create (sqlite3 *db, void *aux, int argc, const char *const *argv, sqlite3_vtab **vtabp, char **errp)
	Create virtual table.
int	xpath_disconnect (sqlite3_vtab *vtab)
	Disconnect virtual table.
int	xpath_destroy (sqlite3_vtab *vtab)
	Destroy virtual table.
int	xpath_bestindex (sqlite3_vtab *vtab, sqlite3_index_info *info)
	Determines information for filter function according to constraints.
int	xpath_open (sqlite3_vtab *vtab, sqlite3_vtab_cursor **cursorp)
	Open virtual table and return cursor.
int	xpath_close (sqlite3_vtab_cursor *cursor)
	Close virtual table cursor.
int	xpath_next (sqlite3_vtab_cursor *cursor)
	Retrieve next row from virtual table cursor.
int	xpath_filter (sqlite3_vtab_cursor *cursor, int idxNum, const char *idxStr, int argc, sqlite3_value **argv)
	Filter function for virtual table.
int	xpath_eof (sqlite3_vtab_cursor *cursor)
	Return end of table state of virtual table cursor.
int	xpath_column (sqlite3_vtab_cursor *cursor, sqlite3_context *ctx, int n)
	Return column data of virtual table.
int	xpath_rowid (sqlite3_vtab_cursor *cursor, sqlite3_int64 *rowidp)
	Return current rowid of virtual table cursor.
int	xpath_update (sqlite3_vtab *vtab, int argc, sqlite3_value **argv, sqlite3_int64 *rowidp)
	Insert/delete row into/from virtual table.
void	xpath_vfunc_common (sqlite3_context *ctx, int conv, int argc, sqlite3_value **argv)
	Common XPath select function for virtual table.
void	xpath_vfunc_string (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning string value from virtual table.
void	xpath_vfunc_boolean (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning boolean value from virtual table.
void	xpath_vfunc_number (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning number from virtual table.
void	xpath_vfunc_xml (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning XML from virtual table.
int	xpath_findfunc (sqlite3_vtab *vtab, int nargs, const char *name, void(**pfunc)(sqlite3_context *, int, sqlite3_value **), void **parg)
	Find overloaded function on virtual table.
void	xpath_func_common (sqlite3_context *ctx, int conv, int argc, sqlite3_value **argv)
	Common XPath select function.
void	xpath_func_string (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning string value.
void	xpath_func_boolean (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning boolean value.
void	xpath_func_number (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning number.
void	xpath_func_xml (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	XPath select function returning XML.
void	xpath_func_dump (sqlite3_context *ctx, int argc, sqlite3_value **argv)
	Function to dump XML document.
void	xpath_fini (void *aux)
	Module finalizer.
int	xpath_init (sqlite3 *db)
	Module initializer creating SQLite module and functions.
int	sqlite3_extension_init (sqlite3 *db, char **errmsg, const sqlite3_api_routines *api)
	Initializer for SQLite extension load mechanism.
Variables
int	initialized = 0
XMOD *	xmod = 0
sqlite3_module	xpath_mod
	SQLite module descriptor.

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Typedef Documentation

typedef struct XCSR XCSR

typedef struct XDOC XDOC

typedef struct XEXP XEXP

typedef struct XMOD XMOD

typedef struct XTAB XTAB

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Function Documentation

int sqlite3_extension_init (  sqlite3 *    db, char **    errmsg, const sqlite3_api_routines *    api )

Initializer for SQLite extension load mechanism. Parameters: db  SQLite database pointer errmsg  pointer receiving error message api  SQLite API routines Returns: SQLite error code Definition at line 1658 of file xpath.c. References xpath_init(). Referenced by impexp_init().

int xpath_bestindex (  sqlite3_vtab *    vtab, sqlite3_index_info *    info )  [static]

Determines information for filter function according to constraints. Parameters: vtab  virtual table info  index/constraint information Returns: SQLite error code Definition at line 255 of file xpath.c.

int xpath_close (  sqlite3_vtab_cursor *    cursor )  [static]

Close virtual table cursor. Parameters: cursor  cursor pointer Returns: SQLite error code Definition at line 290 of file xpath.c. References XCSR::cursor, XCSR::first, XEXP::next, XEXP::pctx, XEXP::pobj, and XTAB::xc.

int xpath_column (  sqlite3_vtab_cursor *    cursor, sqlite3_context *    ctx, int    n )  [static]

Return column data of virtual table. Parameters: cursor  virtual table cursor ctx  SQLite function context n  column index Returns: SQLite error code Definition at line 461 of file xpath.c. References XCSR::cursor, XDOC::doc, XMOD::docs, XTAB::idocs, XTAB::ndoc, XCSR::pos, and XTAB::xm.

int xpath_connect (  sqlite3 *    db, void *    aux, int    argc, const char *const *    argv, sqlite3_vtab **    vtabp, char **    errp )  [static]

Connect to virtual table. Parameters: db  SQLite database pointer aux  user specific pointer argc  argument count argv  argument vector vtabp  pointer receiving virtual table pointer errp  pointer receiving error messag Returns: SQLite error code Argument vector contains: argv[0] - module name argv[1] - database name argv[2] - table name (virtual table) Definition at line 135 of file xpath.c. References XTAB::db, XTAB::idocs, XTAB::ndoc, XTAB::sdoc, XTAB::vtab, XTAB::xc, and XTAB::xm. Referenced by xpath_create().

int xpath_create (  sqlite3 *    db, void *    aux, int    argc, const char *const *    argv, sqlite3_vtab **    vtabp, char **    errp )  [static]

Create virtual table. Parameters: db  SQLite database pointer aux  user specific pointer argc  argument count argv  argument vector vtabp  pointer receiving virtual table pointer errp  pointer receiving error messag Returns: SQLite error code Definition at line 191 of file xpath.c. References xpath_connect().

int xpath_destroy (  sqlite3_vtab *    vtab )  [static]

Destroy virtual table. Parameters: vtab  virtual table pointer Returns: always SQLITE_OK Definition at line 242 of file xpath.c. References xpath_disconnect().

int xpath_disconnect (  sqlite3_vtab *    vtab )  [static]

Disconnect virtual table. Parameters: vtab  virtual table pointer Returns: always SQLITE_OK Definition at line 205 of file xpath.c. References XDOC::doc, XMOD::docs, XTAB::idocs, XMOD::mutex, XMOD::ndoc, XTAB::ndoc, XDOC::refcnt, XMOD::sdoc, and XTAB::xm. Referenced by xpath_destroy().

int xpath_eof (  sqlite3_vtab_cursor *    cursor )  [static]

Return end of table state of virtual table cursor. Parameters: cursor  virtual table cursor Returns: true/false Definition at line 444 of file xpath.c. References XCSR::cursor, XTAB::ndoc, and XCSR::pos.

int xpath_filter (  sqlite3_vtab_cursor *    cursor, int    idxNum, const char *    idxStr, int    argc, sqlite3_value **    argv )  [static]

Filter function for virtual table. Parameters: cursor  virtual table cursor idxNum  not used idxStr  nod used argc  number arguments (not used) argv  argument (nothing or RHS of filter expression, not used) Returns: SQLite error code Definition at line 426 of file xpath.c. References XCSR::cursor, XCSR::pos, XTAB::xc, and xpath_next().

int xpath_findfunc (  sqlite3_vtab *    vtab, int    nargs, const char *    name, void(**    pfunc)(sqlite3_context *, int, sqlite3_value **), void **    parg )  [static]

Find overloaded function on virtual table. Parameters: vtab  virtual table nargs  number arguments name  function name pfunc  pointer to function (value return) parg  pointer to function's argument (value return) Returns: 0 or 1 Definition at line 1008 of file xpath.c. References xpath_vfunc_boolean(), xpath_vfunc_number(), xpath_vfunc_string(), and xpath_vfunc_xml().

void xpath_fini (  void *    aux )  [static]

Module finalizer. Parameters: aux  pointer to module data Returns: SQLite error code Definition at line 1518 of file xpath.c. References XDOC::doc, XMOD::docs, initialized, XMOD::mutex, XMOD::ndoc, XDOC::refcnt, XMOD::refcnt, and XMOD::sdoc. Referenced by xpath_init().

void xpath_func_boolean (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning boolean value. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 1259 of file xpath.c. References xpath_func_common(). Referenced by xpath_init().

void xpath_func_common (  sqlite3_context *    ctx, int    conv, int    argc, sqlite3_value **    argv )  [static]

Common XPath select function. Parameters: ctx  SQLite function context conv  conversion (0=string, 1=boolean, 2=number) argc  number of arguments argv  argument vector Examples: SELECT xpath_string(<docid>, '//book/title'); SELECT xpath_number(<xml-string>, '//book/price', <options;&gt, <encoding>, <base-url>); The <docid> argument is the DOCID value of a row in a virtual table. Otherwise a string containing an XML document is expected. The optional arguments are <options> - parser options, see libxml's XML_PARSE_* defines <encoding> - encoding of the XML document <base-url> - base URL of the XML document Definition at line 1106 of file xpath.c. References XDOC::doc, XMOD::docs, XMOD::mutex, XDOC::refcnt, and XMOD::sdoc. Referenced by xpath_func_boolean(), xpath_func_number(), xpath_func_string(), and xpath_func_xml().

void xpath_func_dump (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

Function to dump XML document. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Examples: SELECT xml_dump(<docid>, <encoding> <fmt>) The <docid> argument is the DOCID value of a row in a virtual table. The <encoding> argument is the optional encoding (default UTF-8). The <fmt> argument is the optional formatting flag for the xmlDocDumpFormatMemoryEnc() libxml2 function. Definition at line 1308 of file xpath.c. References XDOC::doc, XMOD::docs, XMOD::mutex, and XMOD::sdoc. Referenced by xpath_init().

void xpath_func_number (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning number. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 1272 of file xpath.c. References xpath_func_common(). Referenced by xpath_init().

void xpath_func_string (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning string value. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 1246 of file xpath.c. References xpath_func_common(). Referenced by xpath_init().

void xpath_func_xml (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning XML. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 1285 of file xpath.c. References xpath_func_common(). Referenced by xpath_init().

int xpath_init (  sqlite3 *    db )  [static]

Module initializer creating SQLite module and functions. Parameters: db  database pointer Returns: SQLite error code Definition at line 1571 of file xpath.c. References XMOD::docs, initialized, XMOD::mutex, XMOD::ndoc, XMOD::refcnt, XMOD::sdoc, xpath_fini(), xpath_func_boolean(), xpath_func_dump(), xpath_func_number(), xpath_func_string(), xpath_func_xml(), and xpath_mod. Referenced by sqlite3_extension_init().

int xpath_next (  sqlite3_vtab_cursor *    cursor )  [static]

Retrieve next row from virtual table cursor. Parameters: cursor  virtual table cursor Returns: SQLite error code Definition at line 321 of file xpath.c. References XCSR::cursor, XCSR::first, XTAB::ndoc, XCSR::nexpr, XEXP::next, XEXP::parent, XEXP::pobj, XEXP::pos, and XCSR::pos. Referenced by xpath_filter().

int xpath_open (  sqlite3_vtab *    vtab, sqlite3_vtab_cursor **    cursorp )  [static]

Open virtual table and return cursor. Parameters: vtab  virtual table pointer cursorp  pointer receiving cursor pointer Returns: SQLite error code Definition at line 268 of file xpath.c. References XCSR::cursor, XCSR::first, XCSR::last, XCSR::nexpr, and XCSR::pos.

int xpath_rowid (  sqlite3_vtab_cursor *    cursor, sqlite3_int64 *    rowidp )  [static]

Return current rowid of virtual table cursor. Parameters: cursor  virtual table cursor rowidp  value buffer to receive current rowid Returns: SQLite error code Definition at line 505 of file xpath.c. References XCSR::cursor, XDOC::doc, XMOD::docs, XTAB::idocs, XCSR::pos, and XTAB::xm.

int xpath_update (  sqlite3_vtab *    vtab, int    argc, sqlite3_value **    argv, sqlite3_int64 *    rowidp )  [static]

Insert/delete row into/from virtual table. Parameters: vtab  virtual table pointer argc  number of arguments argv  argument vector rowidp  value buffer to receive rowid Returns: SQLite error code Examples: CREATE VIRTUAL TABLE X USING xpath(); INSERT INTO X(XML) VALUES('xml-string ...'); INSERT INTO X(PATH,OPTIONS) VALUES(<url>,0); DELETE FROM X WHERE DOCID=<docid>; Virtual table columns: DOCID - document identifier and ROWID XML - XML string PATH - pathname or URL OPTIONS - parser options, see libxml's XML_PARSE_* defines ENCODING - optional document encoding, default UTF-8 BASEURL - optional base URL when XML string given XMLDUMP - output column, XML dump of document tree 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. Definition at line 550 of file xpath.c. References XDOC::doc, XMOD::docs, XTAB::idocs, XMOD::mutex, XMOD::ndoc, XTAB::ndoc, XDOC::refcnt, XTAB::sdoc, XMOD::sdoc, and XTAB::xm.

void xpath_vfunc_boolean (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning boolean value from virtual table. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 966 of file xpath.c. References xpath_vfunc_common(). Referenced by xpath_findfunc().

void xpath_vfunc_common (  sqlite3_context *    ctx, int    conv, int    argc, sqlite3_value **    argv )  [static]

Common XPath select function for virtual table. Parameters: ctx  SQLite function context conv  conversion (0=string, 1=boolean, 2=number) argc  number of arguments argv  argument vector Examples: CREATE VIRTUAL TABLE X USING xpath(); INSERT INTO X(XML) VALUES('xml-string ...'); SELECT xpath_string(docid, '//book/title') FROM X; SELECT xpath_number(docid, '//book/price') FROM X; The RHS of the xpath_* functions should be a constant string. Definition at line 757 of file xpath.c. References XEXP::conv, XEXP::doc, XDOC::doc, XMOD::docs, XEXP::expr, XCSR::first, XTAB::idocs, XCSR::last, XTAB::ndoc, XCSR::nexpr, XEXP::next, XEXP::parent, XEXP::pctx, XEXP::pobj, XEXP::pos, XCSR::pos, XEXP::prev, XTAB::xc, and XTAB::xm. Referenced by xpath_vfunc_boolean(), xpath_vfunc_number(), xpath_vfunc_string(), and xpath_vfunc_xml().

void xpath_vfunc_number (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning number from virtual table. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 979 of file xpath.c. References xpath_vfunc_common(). Referenced by xpath_findfunc().

void xpath_vfunc_string (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning string value from virtual table. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 953 of file xpath.c. References xpath_vfunc_common(). Referenced by xpath_findfunc().

void xpath_vfunc_xml (  sqlite3_context *    ctx, int    argc, sqlite3_value **    argv )  [static]

XPath select function returning XML from virtual table. Parameters: ctx  SQLite function context argc  number of arguments argv  argument vector Definition at line 992 of file xpath.c. References xpath_vfunc_common(). Referenced by xpath_findfunc().

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Variable Documentation

int initialized = 0 [static]

Definition at line 66 of file xpath.c. Referenced by xpath_fini(), and xpath_init().

XMOD* xmod = 0 [static]

Definition at line 67 of file xpath.c.

sqlite3_module xpath_mod [static]

Initial value: { 1, xpath_create, xpath_connect, xpath_bestindex, xpath_disconnect, xpath_destroy, xpath_open, xpath_close, xpath_filter, xpath_next, xpath_eof, xpath_column, xpath_rowid, xpath_update, 0, 0, 0, 0, xpath_findfunc, } SQLite module descriptor. Definition at line 1058 of file xpath.c. Referenced by xpath_init().

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