Additional code cleanup resulting from a review of the new trigger code. (CVS 572)

FossilOrigin-Name: 37dbdd551e88440933066133ec9cc1e10b03fc1a

src/delete.c

@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle DELETE FROM statements.
 **
-** $Id: delete.c,v 1.33 2002/05/19 23:43:14 danielk1977 Exp $
+** $Id: delete.c,v 1.34 2002/05/21 11:38:11 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -75,6 +75,7 @@ void sqliteDeleteFrom(
 ){
   Vdbe *v;               /* The virtual database engine */
   Table *pTab;           /* The table from which records will be deleted */
+  char *zTab;            /* Name of the table from which we are deleting */
   IdList *pTabList;      /* An ID list holding pTab and nothing else */
   int end, addr;         /* A couple addresses of generated code */
   int i;                 /* Loop counter */
@@ -96,32 +97,28 @@ void sqliteDeleteFrom(
   /* Check for the special case of a VIEW with one or more ON DELETE triggers 
   ** defined 
   */
-  {
-    Table *pTab;
-    char *zTab = sqliteTableNameFromToken(pTableName);
-
-    if( zTab != 0 ){
-      pTab = sqliteFindTable(pParse->db, zTab);
-      if( pTab ){
-        row_triggers_exist = 
-          sqliteTriggersExist(pParse, pTab->pTrigger, 
-              TK_DELETE, TK_BEFORE, TK_ROW, 0) ||
-          sqliteTriggersExist(pParse, pTab->pTrigger, 
-              TK_DELETE, TK_AFTER, TK_ROW, 0);
-      }
-      sqliteFree(zTab);
-      if( row_triggers_exist &&  pTab->pSelect ){
-        /* Just fire VIEW triggers */
-        sqliteViewTriggers(pParse, pTab, pWhere, OE_Replace, 0);
-        return;
-      }
+  zTab = sqliteTableNameFromToken(pTableName);
+  if( zTab != 0 ){
+    pTab = sqliteFindTable(pParse->db, zTab);
+    if( pTab ){
+      row_triggers_exist = 
+        sqliteTriggersExist(pParse, pTab->pTrigger, 
+            TK_DELETE, TK_BEFORE, TK_ROW, 0) ||
+        sqliteTriggersExist(pParse, pTab->pTrigger, 
+            TK_DELETE, TK_AFTER, TK_ROW, 0);
+    }
+    sqliteFree(zTab);
+    if( row_triggers_exist &&  pTab->pSelect ){
+      /* Just fire VIEW triggers */
+      sqliteViewTriggers(pParse, pTab, pWhere, OE_Replace, 0);
+      return;
     }
   }
 
   /* Locate the table which we want to delete.  This table has to be
   ** put in an IdList structure because some of the subroutines we
   ** will be calling are designed to work with multiple tables and expect
-  ** an IdList* parameter instead of just a Table* parameger.
+  ** an IdList* parameter instead of just a Table* parameter.
   */
   pTabList = sqliteTableTokenToIdList(pParse, pTableName);
   if( pTabList==0 ) goto delete_from_cleanup;
@@ -129,6 +126,8 @@ void sqliteDeleteFrom(
   pTab = pTabList->a[0].pTab;
   assert( pTab->pSelect==0 );  /* This table is not a view */
 
+  /* Allocate a cursor used to store the old.* data for a trigger.
+  */
   if( row_triggers_exist ){ 
     oldIdx = pParse->nTab++;
   }
@@ -151,11 +150,7 @@ void sqliteDeleteFrom(
   if( v==0 ){
     goto delete_from_cleanup;
   }
-  if( row_triggers_exist ){ 
-    sqliteBeginMultiWriteOperation(pParse);
-  } else {
-    sqliteBeginWriteOperation(pParse);
-  }
+  sqliteBeginWriteOperation(pParse, row_triggers_exist);
 
   /* Initialize the counter of the number of rows deleted, if
   ** we are counting rows.
@@ -165,7 +160,8 @@ void sqliteDeleteFrom(
   }
 
   /* Special case: A DELETE without a WHERE clause deletes everything.
-  ** It is easier just to erase the whole table.
+  ** It is easier just to erase the whole table.  Note, however, that
+  ** this means that the row change count will be incorrect.
   */
   if( pWhere==0 && !row_triggers_exist ){
     if( db->flags & SQLITE_CountRows ){
@@ -215,8 +211,10 @@ void sqliteDeleteFrom(
     sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
     end = sqliteVdbeMakeLabel(v);
 
+    /* This is the beginning of the delete loop when there are
+    ** row triggers.
+    */
     if( row_triggers_exist ){
-      int ii;
       addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
       sqliteVdbeAddOp(v, OP_Dup, 0, 0);
 
@@ -226,11 +224,11 @@ void sqliteDeleteFrom(
       sqliteVdbeAddOp(v, OP_OpenTemp, oldIdx, 0);
 
       sqliteVdbeAddOp(v, OP_Integer, 13, 0);
-      for(ii = 0; ii<pTab->nCol; ii++){
-        if( ii==pTab->iPKey ){ 
+      for(i = 0; i<pTab->nCol; i++){
+        if( i==pTab->iPKey ){ 
           sqliteVdbeAddOp(v, OP_Recno, base, 0);
 	} else {
-          sqliteVdbeAddOp(v, OP_Column, base, ii);
+          sqliteVdbeAddOp(v, OP_Column, base, i);
 	}
       }
       sqliteVdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
@@ -242,6 +240,12 @@ void sqliteDeleteFrom(
           oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default);
     }
 
+    /* Open cursors for the table we are deleting from and all its
+    ** indices.  If there are row triggers, this happens inside the
+    ** OP_ListRead loop because the cursor have to all be closed
+    ** before the trigger fires.  If there are no row triggers, the
+    ** cursors are opened only once on the outside the loop.
+    */
     pParse->nTab = base + 1;
     openOp = pTab->isTemp ? OP_OpenWrAux : OP_OpenWrite;
     sqliteVdbeAddOp(v, openOp, base, pTab->tnum);
@@ -249,12 +253,18 @@ void sqliteDeleteFrom(
       sqliteVdbeAddOp(v, openOp, pParse->nTab++, pIdx->tnum);
     }
 
+    /* This is the beginning of the delete loop when there are no
+    ** row triggers */
     if( !row_triggers_exist ){ 
       addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
     }
 
-    sqliteGenerateRowDelete(v, pTab, base, pParse->trigStack?0:1);
+    /* Delete the row */
+    sqliteGenerateRowDelete(v, pTab, base, pParse->trigStack==0);
 
+    /* If there are row triggers, close all cursors then invoke
+    ** the AFTER triggers
+    */
     if( row_triggers_exist ){
       for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
         sqliteVdbeAddOp(v, OP_Close, base + i, pIdx->tnum);
@@ -264,10 +274,12 @@ void sqliteDeleteFrom(
           oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default);
     }
 
+    /* End of the delete loop */
     sqliteVdbeAddOp(v, OP_Goto, 0, addr);
     sqliteVdbeResolveLabel(v, end);
     sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
 
+    /* Close the cursors after the loop if there are no row triggers */
     if( !row_triggers_exist ){
       for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
         sqliteVdbeAddOp(v, OP_Close, base + i, pIdx->tnum);