Initial commit

Signed-off-by: Mavridis Philippe <mavridisf@gmail.com>

1 files changed, 447 insertions, 0 deletions

diff --git a/src/sqlite/delete.c b/src/sqlite/delete.c
new file mode 100644
index 0000000..2908885
--- /dev/null
+++ b/src/sqlite/delete.c
@@ -0,0 +1,447 @@
+/*
+** 2001 September 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.
+**
+*************************************************************************
+** This file contains C code routines that are called by the parser
+** in order to generate code for DELETE FROM statements.
+**
+** $Id: delete.c,v 1.1.1.1 2006/02/03 20:35:13 hoganrobert Exp $
+*/
+#include "sqliteInt.h"
+
+/*
+** Look up every table that is named in pSrc.  If any table is not found,
+** add an error message to pParse->zErrMsg and return NULL.  If all tables
+** are found, return a pointer to the last table.
+*/
+Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
+  Table *pTab = 0;
+  int i;
+  struct SrcList_item *pItem;
+  for(i=0, pItem=pSrc->a; i<pSrc->nSrc; i++, pItem++){
+    pTab = sqlite3LocateTable(pParse, pItem->zName, pItem->zDatabase);
+    sqlite3DeleteTable(pParse->db, pItem->pTab);
+    pItem->pTab = pTab;
+    if( pTab ){
+      pTab->nRef++;
+    }
+  }
+  return pTab;
+}
+
+/*
+** Check to make sure the given table is writable.  If it is not
+** writable, generate an error message and return 1.  If it is
+** writable return 0;
+*/
+int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
+  if( pTab->readOnly && (pParse->db->flags & SQLITE_WriteSchema)==0
+        && pParse->nested==0 ){
+    sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
+    return 1;
+  }
+#ifndef SQLITE_OMIT_VIEW
+  if( !viewOk && pTab->pSelect ){
+    sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
+    return 1;
+  }
+#endif
+  return 0;
+}
+
+/*
+** Generate code that will open a table for reading.
+*/
+void sqlite3OpenTableForReading(
+  Vdbe *v,        /* Generate code into this VDBE */
+  int iCur,       /* The cursor number of the table */
+  Table *pTab     /* The table to be opened */
+){
+  sqlite3VdbeAddOp(v, OP_Integer, pTab->iDb, 0);
+  sqlite3VdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
+  VdbeComment((v, "# %s", pTab->zName));
+  sqlite3VdbeAddOp(v, OP_SetNumColumns, iCur, pTab->nCol);
+}
+
+
+/*
+** Generate code for a DELETE FROM statement.
+**
+**     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
+**                 \________/       \________________/
+**                  pTabList              pWhere
+*/
+void sqlite3DeleteFrom(
+  Parse *pParse,         /* The parser context */
+  SrcList *pTabList,     /* The table from which we should delete things */
+  Expr *pWhere           /* The WHERE clause.  May be null */
+){
+  Vdbe *v;               /* The virtual database engine */
+  Table *pTab;           /* The table from which records will be deleted */
+  const char *zDb;       /* Name of database holding pTab */
+  int end, addr = 0;     /* A couple addresses of generated code */
+  int i;                 /* Loop counter */
+  WhereInfo *pWInfo;     /* Information about the WHERE clause */
+  Index *pIdx;           /* For looping over indices of the table */
+  int iCur;              /* VDBE Cursor number for pTab */
+  sqlite3 *db;           /* Main database structure */
+  AuthContext sContext;  /* Authorization context */
+  int oldIdx = -1;       /* Cursor for the OLD table of AFTER triggers */
+  NameContext sNC;       /* Name context to resolve expressions in */
+
+#ifndef SQLITE_OMIT_TRIGGER
+  int isView;                  /* True if attempting to delete from a view */
+  int triggers_exist = 0;      /* True if any triggers exist */
+#endif
+
+  sContext.pParse = 0;
+  if( pParse->nErr || sqlite3_malloc_failed ){
+    goto delete_from_cleanup;
+  }
+  db = pParse->db;
+  assert( pTabList->nSrc==1 );
+
+  /* Locate the table which we want to delete.  This table has to be
+  ** put in an SrcList structure because some of the subroutines we
+  ** will be calling are designed to work with multiple tables and expect
+  ** an SrcList* parameter instead of just a Table* parameter.
+  */
+  pTab = sqlite3SrcListLookup(pParse, pTabList);
+  if( pTab==0 )  goto delete_from_cleanup;
+
+  /* Figure out if we have any triggers and if the table being
+  ** deleted from is a view
+  */
+#ifndef SQLITE_OMIT_TRIGGER
+  triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0);
+  isView = pTab->pSelect!=0;
+#else
+# define triggers_exist 0
+# define isView 0
+#endif
+#ifdef SQLITE_OMIT_VIEW
+# undef isView
+# define isView 0
+#endif
+
+  if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){
+    goto delete_from_cleanup;
+  }
+  assert( pTab->iDb<db->nDb );
+  zDb = db->aDb[pTab->iDb].zName;
+  if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
+    goto delete_from_cleanup;
+  }
+
+  /* If pTab is really a view, make sure it has been initialized.
+  */
+  if( isView && sqlite3ViewGetColumnNames(pParse, pTab) ){
+    goto delete_from_cleanup;
+  }
+
+  /* Allocate a cursor used to store the old.* data for a trigger.
+  */
+  if( triggers_exist ){ 
+    oldIdx = pParse->nTab++;
+  }
+
+  /* Resolve the column names in the WHERE clause.
+  */
+  assert( pTabList->nSrc==1 );
+  iCur = pTabList->a[0].iCursor = pParse->nTab++;
+  memset(&sNC, 0, sizeof(sNC));
+  sNC.pParse = pParse;
+  sNC.pSrcList = pTabList;
+  if( sqlite3ExprResolveNames(&sNC, pWhere) ){
+    goto delete_from_cleanup;
+  }
+
+  /* Start the view context
+  */
+  if( isView ){
+    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
+  }
+
+  /* Begin generating code.
+  */
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 ){
+    goto delete_from_cleanup;
+  }
+  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
+  sqlite3BeginWriteOperation(pParse, triggers_exist, pTab->iDb);
+
+  /* If we are trying to delete from a view, construct that view into
+  ** a temporary table.
+  */
+  if( isView ){
+    Select *pView = sqlite3SelectDup(pTab->pSelect);
+    sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0);
+    sqlite3SelectDelete(pView);
+  }
+
+  /* Initialize the counter of the number of rows deleted, if
+  ** we are counting rows.
+  */
+  if( db->flags & SQLITE_CountRows ){
+    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
+  }
+
+  /* Special case: A DELETE without a WHERE clause deletes everything.
+  ** 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 && !triggers_exist ){
+    if( db->flags & SQLITE_CountRows ){
+      /* If counting rows deleted, just count the total number of
+      ** entries in the table. */
+      int endOfLoop = sqlite3VdbeMakeLabel(v);
+      int addr;
+      if( !isView ){
+        sqlite3OpenTableForReading(v, iCur, pTab);
+      }
+      sqlite3VdbeAddOp(v, OP_Rewind, iCur, sqlite3VdbeCurrentAddr(v)+2);
+      addr = sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
+      sqlite3VdbeAddOp(v, OP_Next, iCur, addr);
+      sqlite3VdbeResolveLabel(v, endOfLoop);
+      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
+    }
+    if( !isView ){
+      sqlite3VdbeAddOp(v, OP_Clear, pTab->tnum, pTab->iDb);
+      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+        sqlite3VdbeAddOp(v, OP_Clear, pIdx->tnum, pIdx->iDb);
+      }
+    }
+  }
+
+  /* The usual case: There is a WHERE clause so we have to scan through
+  ** the table and pick which records to delete.
+  */
+  else{
+    /* Ensure all required collation sequences are available. */
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      if( sqlite3CheckIndexCollSeq(pParse, pIdx) ){
+        goto delete_from_cleanup;
+      }
+    }
+
+    /* Begin the database scan
+    */
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
+    if( pWInfo==0 ) goto delete_from_cleanup;
+
+    /* Remember the rowid of every item to be deleted.
+    */
+    sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
+    sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0);
+    if( db->flags & SQLITE_CountRows ){
+      sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
+    }
+
+    /* End the database scan loop.
+    */
+    sqlite3WhereEnd(pWInfo);
+
+    /* Open the pseudo-table used to store OLD if there are triggers.
+    */
+    if( triggers_exist ){
+      sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
+      sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
+    }
+
+    /* Delete every item whose key was written to the list during the
+    ** database scan.  We have to delete items after the scan is complete
+    ** because deleting an item can change the scan order.
+    */
+    sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0);
+    end = sqlite3VdbeMakeLabel(v);
+
+    /* This is the beginning of the delete loop when there are
+    ** row triggers.
+    */
+    if( triggers_exist ){
+      addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end);
+      if( !isView ){
+        sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
+        sqlite3OpenTableForReading(v, iCur, pTab);
+      }
+      sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
+      sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
+      sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
+      sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);
+      if( !isView ){
+        sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
+      }
+
+      (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_BEFORE, pTab,
+          -1, oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
+          addr);
+    }
+
+    if( !isView ){
+      /* 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.
+      */
+      sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite);
+
+      /* This is the beginning of the delete loop when there are no
+      ** row triggers */
+      if( !triggers_exist ){ 
+        addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end);
+      }
+
+      /* Delete the row */
+      sqlite3GenerateRowDelete(db, v, pTab, iCur, pParse->nested==0);
+    }
+
+    /* If there are row triggers, close all cursors then invoke
+    ** the AFTER triggers
+    */
+    if( triggers_exist ){
+      if( !isView ){
+        for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
+          sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
+        }
+        sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
+      }
+      (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_AFTER, pTab, -1,
+          oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
+          addr);
+    }
+
+    /* End of the delete loop */
+    sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
+    sqlite3VdbeResolveLabel(v, end);
+    sqlite3VdbeAddOp(v, OP_ListReset, 0, 0);
+
+    /* Close the cursors after the loop if there are no row triggers */
+    if( !triggers_exist ){
+      for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
+        sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
+      }
+      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
+    }
+  }
+
+  /*
+  ** Return the number of rows that were deleted. If this routine is 
+  ** generating code because of a call to sqlite3NestedParse(), do not
+  ** invoke the callback function.
+  */
+  if( db->flags & SQLITE_CountRows && pParse->nested==0 && !pParse->trigStack ){
+    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
+    sqlite3VdbeSetNumCols(v, 1);
+    sqlite3VdbeSetColName(v, 0, "rows deleted", P3_STATIC);
+  }
+
+delete_from_cleanup:
+  sqlite3AuthContextPop(&sContext);
+  sqlite3SrcListDelete(pTabList);
+  sqlite3ExprDelete(pWhere);
+  return;
+}
+
+/*
+** This routine generates VDBE code that causes a single row of a
+** single table to be deleted.
+**
+** The VDBE must be in a particular state when this routine is called.
+** These are the requirements:
+**
+**   1.  A read/write cursor pointing to pTab, the table containing the row
+**       to be deleted, must be opened as cursor number "base".
+**
+**   2.  Read/write cursors for all indices of pTab must be open as
+**       cursor number base+i for the i-th index.
+**
+**   3.  The record number of the row to be deleted must be on the top
+**       of the stack.
+**
+** This routine pops the top of the stack to remove the record number
+** and then generates code to remove both the table record and all index
+** entries that point to that record.
+*/
+void sqlite3GenerateRowDelete(
+  sqlite3 *db,       /* The database containing the index */
+  Vdbe *v,           /* Generate code into this VDBE */
+  Table *pTab,       /* Table containing the row to be deleted */
+  int iCur,          /* Cursor number for the table */
+  int count          /* Increment the row change counter */
+){
+  int addr;
+  addr = sqlite3VdbeAddOp(v, OP_NotExists, iCur, 0);
+  sqlite3GenerateRowIndexDelete(db, v, pTab, iCur, 0);
+  sqlite3VdbeAddOp(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
+  sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
+}
+
+/*
+** This routine generates VDBE code that causes the deletion of all
+** index entries associated with a single row of a single table.
+**
+** The VDBE must be in a particular state when this routine is called.
+** These are the requirements:
+**
+**   1.  A read/write cursor pointing to pTab, the table containing the row
+**       to be deleted, must be opened as cursor number "iCur".
+**
+**   2.  Read/write cursors for all indices of pTab must be open as
+**       cursor number iCur+i for the i-th index.
+**
+**   3.  The "iCur" cursor must be pointing to the row that is to be
+**       deleted.
+*/
+void sqlite3GenerateRowIndexDelete(
+  sqlite3 *db,       /* The database containing the index */
+  Vdbe *v,           /* Generate code into this VDBE */
+  Table *pTab,       /* Table containing the row to be deleted */
+  int iCur,          /* Cursor number for the table */
+  char *aIdxUsed     /* Only delete if aIdxUsed!=0 && aIdxUsed[i]!=0 */
+){
+  int i;
+  Index *pIdx;
+
+  for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
+    if( aIdxUsed!=0 && aIdxUsed[i-1]==0 ) continue;
+    sqlite3GenerateIndexKey(v, pIdx, iCur);
+    sqlite3VdbeAddOp(v, OP_IdxDelete, iCur+i, 0);
+  }
+}
+
+/*
+** Generate code that will assemble an index key and put it on the top
+** of the tack.  The key with be for index pIdx which is an index on pTab.
+** iCur is the index of a cursor open on the pTab table and pointing to
+** the entry that needs indexing.
+*/
+void sqlite3GenerateIndexKey(
+  Vdbe *v,           /* Generate code into this VDBE */
+  Index *pIdx,       /* The index for which to generate a key */
+  int iCur           /* Cursor number for the pIdx->pTable table */
+){
+  int j;
+  Table *pTab = pIdx->pTable;
+
+  sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
+  for(j=0; j<pIdx->nColumn; j++){
+    int idx = pIdx->aiColumn[j];
+    if( idx==pTab->iPKey ){
+      sqlite3VdbeAddOp(v, OP_Dup, j, 0);
+    }else{
+      sqlite3VdbeAddOp(v, OP_Column, iCur, idx);
+      sqlite3ColumnDefault(v, pTab, idx);
+    }
+  }
+  sqlite3VdbeAddOp(v, OP_MakeRecord, pIdx->nColumn, (1<<24));
+  sqlite3IndexAffinityStr(v, pIdx);
+}