Add the sqlite3_overload_function() API - part of the virtual table
interface. (CVS 3426) FossilOrigin-Name: aa7728f9f5b80dbb1b3db124f84b9166bf72bdd3
This commit is contained in:
drh
+2
-15
@@ -16,7 +16,7 @@
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** sqliteRegisterBuildinFunctions() found at the bottom of the file.
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** All other code has file scope.
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**
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** $Id: func.c,v 1.133 2006/08/19 11:34:01 drh Exp $
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** $Id: func.c,v 1.134 2006/09/16 21:45:14 drh Exp $
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*/
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#include "sqliteInt.h"
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#include <ctype.h>
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@@ -548,19 +548,6 @@ static void versionFunc(
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sqlite3_result_text(context, sqlite3_version, -1, SQLITE_STATIC);
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}
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/*
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** The MATCH() function is unimplemented. If anybody tries to use it,
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** return an error.
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*/
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static void matchStub(
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sqlite3_context *context,
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int argc,
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sqlite3_value **argv
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){
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static const char zErr[] = "MATCH is not implemented";
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sqlite3_result_error(context, zErr, sizeof(zErr)-1);
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}
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/*
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** EXPERIMENTAL - This is not an official function. The interface may
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@@ -1043,7 +1030,6 @@ void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
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{ "last_insert_rowid", 0, 1, SQLITE_UTF8, 0, last_insert_rowid },
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{ "changes", 0, 1, SQLITE_UTF8, 0, changes },
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{ "total_changes", 0, 1, SQLITE_UTF8, 0, total_changes },
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{ "match", 2, 0, SQLITE_UTF8, 0, matchStub },
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#ifdef SQLITE_SOUNDEX
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{ "soundex", 1, 0, SQLITE_UTF8, 0, soundexFunc},
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#endif
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@@ -1116,6 +1102,7 @@ void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
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}
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}
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sqlite3RegisterDateTimeFunctions(db);
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sqlite3_overload_function(db, "MATCH", 2);
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#ifdef SQLITE_SSE
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(void)sqlite3SseFunctions(db);
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#endif
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+28
-2
@@ -14,7 +14,7 @@
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** other files are for internal use by SQLite and should not be
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** accessed by users of the library.
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**
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** $Id: main.c,v 1.357 2006/09/15 07:28:50 drh Exp $
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** $Id: main.c,v 1.358 2006/09/16 21:45:14 drh Exp $
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*/
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#include "sqliteInt.h"
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#include "os.h"
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@@ -541,6 +541,32 @@ int sqlite3_create_function16(
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}
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#endif
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/*
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** Declare that a function has been overloaded by a virtual table.
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**
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** If the function already exists as a regular global function, then
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** this routine is a no-op. If the function does not exist, then create
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** a new one that always throws a run-time error.
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**
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** When virtual tables intend to provide an overloaded function, they
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** should call this routine to make sure the global function exists.
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** A global function must exist in order for name resolution to work
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** properly.
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*/
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int sqlite3_overload_function(
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sqlite3 *db,
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const char *zName,
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int nArg
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){
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int nName = strlen(zName);
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if( sqlite3FindFunction(db, zName, nName, nArg, SQLITE_UTF8, 0)==0 ){
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sqlite3CreateFunc(db, zName, nArg, SQLITE_UTF8,
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0, sqlite3InvalidFunction, 0, 0);
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}
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return sqlite3ApiExit(db, SQLITE_OK);
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}
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#ifndef SQLITE_OMIT_TRACE
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/*
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** Register a trace function. The pArg from the previously registered trace
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@@ -908,8 +934,8 @@ static int openDatabase(
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** is accessed.
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*/
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if( !sqlite3MallocFailed() ){
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sqlite3RegisterBuiltinFunctions(db);
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sqlite3Error(db, SQLITE_OK, 0);
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sqlite3RegisterBuiltinFunctions(db);
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}
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db->magic = SQLITE_MAGIC_OPEN;
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+19
-1
@@ -12,7 +12,7 @@
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** This header file defines the interface that the SQLite library
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** presents to client programs.
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**
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** @(#) $Id: sqlite.h.in,v 1.193 2006/09/15 07:28:50 drh Exp $
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** @(#) $Id: sqlite.h.in,v 1.194 2006/09/16 21:45:14 drh Exp $
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*/
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#ifndef _SQLITE3_H_
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#define _SQLITE3_H_
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@@ -1782,6 +1782,24 @@ struct sqlite3_vtab_cursor {
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*/
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int sqlite3_declare_vtab(sqlite3*, const char *zCreateTable);
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/*
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** Virtual tables can provide alternative implementations of functions
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** using the xFindFunction method. But global versions of those functions
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** must exist in order to be overloaded.
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**
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** This API makes sure a global version of a function with a particular
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** name and number of parameters exists. If no such function exists
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** before this API is called, a new function is created. The implementation
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** of the new function always causes an exception to be thrown. So
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** the new function is not good for anything by itself. Its only
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** purpose is to be a place-holder function that can be overloaded
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** by virtual tables.
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**
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** This API should be considered part of the virtual table interface,
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** which is experimental and subject to change.
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*/
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int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
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/*
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** The interface to the virtual-table mechanism defined above (back up
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** to a comment remarkably similar to this one) is currently considered
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+2
-1
@@ -11,7 +11,7 @@
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*************************************************************************
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** Internal interface definitions for SQLite.
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**
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** @(#) $Id: sqliteInt.h,v 1.527 2006/09/15 07:28:50 drh Exp $
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** @(#) $Id: sqliteInt.h,v 1.528 2006/09/16 21:45:14 drh Exp $
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*/
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#ifndef _SQLITEINT_H_
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#define _SQLITEINT_H_
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@@ -1874,6 +1874,7 @@ int sqlite3VtabCallConnect(Parse*, Table*);
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int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
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int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
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FuncDef *sqlite3VtabOverloadFunction(FuncDef*, int nArg, Expr*);
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void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
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#ifdef SQLITE_SSE
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#include "sseInt.h"
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@@ -267,6 +267,27 @@ void *sqlite3_user_data(sqlite3_context *p){
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return p->pFunc->pUserData;
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}
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/*
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** The following is the implementation of an SQL function that always
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** fails with an error message stating that the function is used in the
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** wrong context. The sqlite3_overload_function() API might construct
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** SQL function that use this routine so that the functions will exist
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** for name resolution but are actually overloaded by the xFindFunction
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** method of virtual tables.
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*/
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void sqlite3InvalidFunction(
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sqlite3_context *context, /* The function calling context */
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int argc, /* Number of arguments to the function */
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sqlite3_value **argv /* Value of each argument */
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){
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const char *zName = context->pFunc->zName;
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char *zErr;
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zErr = sqlite3MPrintf(
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"unable to use function %s in the requested context", zName);
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sqlite3_result_error(context, zErr, -1);
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sqliteFree(zErr);
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}
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/*
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** Allocate or return the aggregate context for a user function. A new
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** context is allocated on the first call. Subsequent calls return the
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