/*
** Generate code to drop and reload the internal representation of table
** pTab from the database, including triggers and temporary triggers.
** Argument zName is the name of the table in the database schema at
** the time the generated code is executed. This can be different from
** pTab->zName if this function is being called to code part of an
** "ALTER TABLE RENAME TO" statement.
生成代码删除和重新加载从数据库表pTab的内部表达示,
包括触发器和临时触发器。
参数zName在数据库模式中的表的名称生成的代码执行。
这可以不同于pTab - > zName如果这个函数被调用的代码的一部分“ALTER TABLE RENAME TO”声明。
*/
static void reloadTableSchema(Parse *pParse, Table *pTab, const char *zName){
Vdbe *v;
char *zWhere;
int iDb; /* Index of database containing pTab 包含pTab数据库索引*/
#ifndef SQLITE_OMIT_TRIGGER
Trigger *pTrig;
#endif
v = sqlite3GetVdbe(pParse);
if( NEVER(v==0) ) return;
assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
assert( iDb>=0 );
#ifndef SQLITE_OMIT_TRIGGER
/* Drop any table triggers from the internal schema. 降低任何表触发器内部模式。*/
for(pTrig=sqlite3TriggerList(pParse, pTab); pTrig; pTrig=pTrig->pNext){
int iTrigDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
assert( iTrigDb==iDb || iTrigDb==1 );
sqlite3VdbeAddOp4(v, OP_DropTrigger, iTrigDb, 0, 0, pTrig->zName, 0);
}
#endif
/* Drop the table and index from the internal schema. 从内部模式中降低表和索引*/
sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);
/* Reload the table, index and permanent trigger schemas. 重载表、索引和不变的触发器模式*/
zWhere = sqlite3MPrintf(pParse->db, "tbl_name=%Q", zName);
if( !zWhere ) return;
sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);
#ifndef SQLITE_OMIT_TRIGGER
/* Now, if the table is not stored in the temp database, reload any temp
** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined.
现在，如果表没有在临时数据库中存储，那么重载任何临时触发器。
不要用IN(...)在 SQLITE_OMIT_SUBQUERY被默认的情况下。
*/
if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
sqlite3VdbeAddParseSchemaOp(v, 1, zWhere);
}
#endif
}
/*
** The parser calls this routine after the CREATE VIRTUAL TABLE statement
** has been completely parsed.
*/
void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){
Table *pTab = pParse->pNewTable; /* The table being constructed */
sqlite3 *db = pParse->db; /* The database connection */
if( pTab==0 ) return;
addArgumentToVtab(pParse);
pParse->sArg.z = 0;
if( pTab->nModuleArg<1 ) return;
/* If the CREATE VIRTUAL TABLE statement is being entered for the
** first time (in other words if the virtual table is actually being
** created now instead of just being read out of sqlite_master) then
** do additional initialization work and store the statement text
** in the sqlite_master table.
*/
if( !db->init.busy ){
char *zStmt;
char *zWhere;
int iDb;
int iReg;
Vdbe *v;
/* Compute the complete text of the CREATE VIRTUAL TABLE statement */
if( pEnd ){
pParse->sNameToken.n = (int)(pEnd->z - pParse->sNameToken.z) + pEnd->n;
}
zStmt = sqlite3MPrintf(db, "CREATE VIRTUAL TABLE %T", &pParse->sNameToken);
/* A slot for the record has already been allocated in the
** SQLITE_MASTER table. We just need to update that slot with all
** the information we've collected.
**
** The VM register number pParse->regRowid holds the rowid of an
** entry in the sqlite_master table tht was created for this vtab
** by sqlite3StartTable().
*/
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
sqlite3NestedParse(pParse,
"UPDATE %Q.%s "
"SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q "
"WHERE rowid=#%d",
db->aDb[iDb].zDbSName, MASTER_NAME,
pTab->zName,
pTab->zName,
zStmt,
pParse->regRowid
);
sqlite3DbFree(db, zStmt);
v = sqlite3GetVdbe(pParse);
sqlite3ChangeCookie(pParse, iDb);
sqlite3VdbeAddOp0(v, OP_Expire);
zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName);
sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);
iReg = ++pParse->nMem;
sqlite3VdbeLoadString(v, iReg, pTab->zName);
sqlite3VdbeAddOp2(v, OP_VCreate, iDb, iReg);
}
/* If we are rereading the sqlite_master table create the in-memory
** record of the table. The xConnect() method is not called until
** the first time the virtual table is used in an SQL statement. This
** allows a schema that contains virtual tables to be loaded before
** the required virtual table implementations are registered. */
else {
Table *pOld;
Schema *pSchema = pTab->pSchema;
const char *zName = pTab->zName;
assert( sqlite3SchemaMutexHeld(db, 0, pSchema) );
pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab);
if( pOld ){
sqlite3OomFault(db);
assert( pTab==pOld ); /* Malloc must have failed inside HashInsert() */
return;
}
pParse->pNewTable = 0;
}
}
/*
** This routine is called after all of the trigger actions have been parsed
** in order to complete the process of building the trigger.
*/
SQLITE_PRIVATE void sqlite3FinishTrigger(
Parse *pParse, /* Parser context */
TriggerStep *pStepList, /* The triggered program */
Token *pAll /* Token that describes the complete CREATE TRIGGER */
){
Trigger *pTrig = pParse->pNewTrigger; /* Trigger being finished */
char *zName; /* Name of trigger */
sqlite3 *db = pParse->db; /* The database */
DbFixer sFix; /* Fixer object */
int iDb; /* Database containing the trigger */
Token nameToken; /* Trigger name for error reporting */
pParse->pNewTrigger = 0;
if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
zName = pTrig->zName;
iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
pTrig->step_list = pStepList;
while( pStepList ){
pStepList->pTrig = pTrig;
pStepList = pStepList->pNext;
}
nameToken.z = pTrig->zName;
nameToken.n = sqlite3Strlen30(nameToken.z);
sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken);
if( sqlite3FixTriggerStep(&sFix, pTrig->step_list)
|| sqlite3FixExpr(&sFix, pTrig->pWhen)
){
goto triggerfinish_cleanup;
}
/* if we are not initializing,
** build the sqlite_master entry
*/
if( !db->init.busy ){
Vdbe *v;
char *z;
/* Make an entry in the sqlite_master table */
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto triggerfinish_cleanup;
sqlite3BeginWriteOperation(pParse, 0, iDb);
z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
sqlite3NestedParse(pParse,
"INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
db->aDb[iDb].zName, SCHEMA_TABLE(iDb), zName,
pTrig->table, z);
sqlite3DbFree(db, z);
sqlite3ChangeCookie(pParse, iDb);
sqlite3VdbeAddParseSchemaOp(v, iDb,
sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));
}
if( db->init.busy ){
Trigger *pLink = pTrig;
Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig);
if( pTrig ){
db->mallocFailed = 1;
}else if( pLink->pSchema==pLink->pTabSchema ){
Table *pTab;
int n = sqlite3Strlen30(pLink->table);
pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table, n);
assert( pTab!=0 );
pLink->pNext = pTab->pTrigger;
pTab->pTrigger = pLink;
}
}
triggerfinish_cleanup:
sqlite3DeleteTrigger(db, pTrig);
assert( !pParse->pNewTrigger );
sqlite3DeleteTriggerStep(db, pStepList);
}