C# TriggerStep类代码示例

    /*
    **
    ** 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 the implementation for TRIGGERs
    *************************************************************************
    **  Included in SQLite3 port to C#-SQLite;  2008 Noah B Hart
    **  C#-SQLite is an independent reimplementation of the SQLite software library
    **
    **  SQLITE_SOURCE_ID: 2010-03-09 19:31:43 4ae453ea7be69018d8c16eb8dabe05617397dc4d
    **
    **  $Header: Community.CsharpSqlite/src/trigger_c.cs,v 6604176a7dbe 2010/03/12 23:35:36 Noah $
    *************************************************************************
    */
    //#include "sqliteInt.h"

#if !SQLITE_OMIT_TRIGGER
    /*
** Delete a linked list of TriggerStep structures.
*/
    static void sqlite3DeleteTriggerStep( sqlite3 db, ref TriggerStep pTriggerStep )
    {
      while ( pTriggerStep != null )
      {
        TriggerStep pTmp = pTriggerStep;
        pTriggerStep = pTriggerStep.pNext;

        sqlite3ExprDelete( db, ref pTmp.pWhere );
        sqlite3ExprListDelete( db, ref pTmp.pExprList );
        sqlite3SelectDelete( db, ref pTmp.pSelect );
        sqlite3IdListDelete( db, ref pTmp.pIdList );

        pTriggerStep = null;sqlite3DbFree( db, ref pTmp );
      }
    }

        public static void DeleteTriggerStep(Context ctx, ref TriggerStep triggerStep)
        {
            while (triggerStep != null)
            {
                TriggerStep tmp = triggerStep;
                triggerStep = triggerStep.Next;

                Expr.Delete(ctx, ref tmp.Where);
                Expr.ListDelete(ctx, ref tmp.ExprList);
                Select.Delete(ctx, ref tmp.Select);
                Parse.IdListDelete(ctx, ref tmp.IdList);
                
                C._tagfree(ctx, ref tmp);
                triggerStep = null; //: C#
            }
        }

    /*
    ** Generate VDBE code for the statements inside the body of a single 
    ** trigger.
    */
    static int codeTriggerProgram(
    Parse pParse,            /* The parser context */
    TriggerStep pStepList,   /* List of statements inside the trigger body */
    int orconf               /* Conflict algorithm. (OE_Abort, etc) */
    )
    {
      TriggerStep pStep;
      Vdbe v = pParse.pVdbe;
      sqlite3 db = pParse.db;

      Debug.Assert( pParse.pTriggerTab != null && pParse.pToplevel != null );
      Debug.Assert( pStepList != null );
      Debug.Assert( v != null );
      for ( pStep = pStepList; pStep != null; pStep = pStep.pNext )
      {
        /* Figure out the ON CONFLICT policy that will be used for this step
        ** of the trigger program. If the statement that caused this trigger
        ** to fire had an explicit ON CONFLICT, then use it. Otherwise, use
        ** the ON CONFLICT policy that was specified as part of the trigger
        ** step statement. Example:
        **
        **   CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
        **     INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
        **   END;
        **
        **   INSERT INTO t1 ... ;            -- insert into t2 uses REPLACE policy
        **   INSERT OR IGNORE INTO t1 ... ;  -- insert into t2 uses IGNORE policy
        */
        pParse.eOrconf = ( orconf == OE_Default ) ? pStep.orconf : (u8)orconf;

        switch ( pStep.op )
        {
          case TK_UPDATE:
            {
              sqlite3Update( pParse,
                targetSrcList( pParse, pStep ),
                sqlite3ExprListDup( db, pStep.pExprList, 0 ),
                sqlite3ExprDup( db, pStep.pWhere, 0 ),
                pParse.eOrconf
              );
              break;
            }
          case TK_INSERT:
            {
              sqlite3Insert( pParse,
                targetSrcList( pParse, pStep ),
                sqlite3ExprListDup( db, pStep.pExprList, 0 ),
                sqlite3SelectDup( db, pStep.pSelect, 0 ),
                sqlite3IdListDup( db, pStep.pIdList ),
                pParse.eOrconf
              );
              break;
            }
          case TK_DELETE:
            {
              sqlite3DeleteFrom( pParse,
                targetSrcList( pParse, pStep ),
                sqlite3ExprDup( db, pStep.pWhere, 0 )
              );
              break;
            }
          default:
            Debug.Assert( pStep.op == TK_SELECT );
            {
              SelectDest sDest = new SelectDest();
              Select pSelect = sqlite3SelectDup( db, pStep.pSelect, 0 );
              sqlite3SelectDestInit( sDest, SRT_Discard, 0 );
              sqlite3Select( pParse, pSelect, ref sDest );
              sqlite3SelectDelete( db, ref pSelect );
              break;
            }
        }
        if ( pStep.op != TK_SELECT )
        {
          sqlite3VdbeAddOp0( v, OP_ResetCount );
        }
      }

      return 0;
    }

    /*
    ** Convert the pStep.target token into a SrcList and return a pointer
    ** to that SrcList.
    **
    ** This routine adds a specific database name, if needed, to the target when
    ** forming the SrcList.  This prevents a trigger in one database from
    ** referring to a target in another database.  An exception is when the
    ** trigger is in TEMP in which case it can refer to any other database it
    ** wants.
    */
    static SrcList targetSrcList(
    Parse pParse,       /* The parsing context */
    TriggerStep pStep   /* The trigger containing the target token */
    )
    {
      int iDb;             /* Index of the database to use */
      SrcList pSrc;        /* SrcList to be returned */

      pSrc = sqlite3SrcListAppend( pParse.db, 0, pStep.target, 0 );
      //if ( pSrc != null )
      //{
      Debug.Assert( pSrc.nSrc > 0 );
      Debug.Assert( pSrc.a != null );
      iDb = sqlite3SchemaToIndex( pParse.db, pStep.pTrig.pSchema );
      if ( iDb == 0 || iDb >= 2 )
      {
        sqlite3 db = pParse.db;
        Debug.Assert( iDb < pParse.db.nDb );
        pSrc.a[pSrc.nSrc - 1].zDatabase = db.aDb[iDb].zName;// sqlite3DbStrDup( db, db.aDb[iDb].zName );
      }
      //}
      return pSrc;
    }

    /*
    ** Allocate space to hold a new trigger step.  The allocated space
    ** holds both the TriggerStep object and the TriggerStep.target.z string.
    **
    ** If an OOM error occurs, NULL is returned and db.mallocFailed is set.
    */
    static TriggerStep triggerStepAllocate(
    sqlite3 db,                /* Database connection */
    u8 op,                     /* Trigger opcode */
    Token pName                /* The target name */
    )
    {
      TriggerStep pTriggerStep;

      pTriggerStep = new TriggerStep();// sqlite3DbMallocZero( db, sizeof( TriggerStep ) + pName.n );
      //if ( pTriggerStep != null )
      //{
      string z;// = (char*)&pTriggerStep[1];
      z = pName.z;// memcpy( z, pName.z, pName.n );
      pTriggerStep.target.z = z;
      pTriggerStep.target.n = pName.n;
      pTriggerStep.op = op;
      //}
      return pTriggerStep;
    }

    /*
    ** Turn a SELECT statement (that the pSelect parameter points to) into
    ** a trigger step.  Return a pointer to a TriggerStep structure.
    **
    ** The parser calls this routine when it finds a SELECT statement in
    ** body of a TRIGGER.
    */
    static TriggerStep sqlite3TriggerSelectStep( sqlite3 db, Select pSelect )
    {
      TriggerStep pTriggerStep = new TriggerStep();// sqlite3DbMallocZero( db, sizeof(TriggerStep ))
      if ( pTriggerStep == null )
      {
        sqlite3SelectDelete( db, ref pSelect );
        return null;
      }

      pTriggerStep.op = TK_SELECT;
      pTriggerStep.pSelect = pSelect;
      pTriggerStep.orconf = OE_Default;
      return pTriggerStep;
    }

    /*
    ** This routine is called after all of the trigger actions have been parsed
    ** in order to complete the process of building the trigger.
    */
    static 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 */
      string zName;                       /* Name of trigger */

      sqlite3 db = pParse.db;             /* The database */
      DbFixer sFix = new DbFixer();       /* Fixer object */
      int iDb;                            /* Database containing the trigger */
      Token nameToken = new Token();      /* Trigger name for error reporting */

      pParse.pNewTrigger = null;
      if ( NEVER( pParse.nErr != 0 ) || pTrig == null )
        goto triggerfinish_cleanup;
      zName = pTrig.zName;
      iDb = sqlite3SchemaToIndex( pParse.db, pTrig.pSchema );
      pTrig.step_list = pStepList;
      while ( pStepList != null )
      {
        pStepList.pTrig = pTrig;
        pStepList = pStepList.pNext;
      }
      nameToken.z = pTrig.zName;
      nameToken.n = sqlite3Strlen30( nameToken.z );
      if ( sqlite3FixInit( sFix, pParse, iDb, "trigger", nameToken ) != 0
      && sqlite3FixTriggerStep( sFix, pTrig.step_list ) != 0 )
      {
        goto triggerfinish_cleanup;
      }

      /* if we are not initializing,
      ** build the sqlite_master entry
      */
      if ( 0 == db.init.busy )
      {
        Vdbe v;
        string z;

        /* Make an entry in the sqlite_master table */
        v = sqlite3GetVdbe( pParse );
        if ( v == null )
          goto triggerfinish_cleanup;
        sqlite3BeginWriteOperation( pParse, 0, iDb );
        z = pAll.z.Substring( 0, pAll.n );//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, ref z );
        sqlite3ChangeCookie( pParse, iDb );
        sqlite3VdbeAddParseSchemaOp( v, iDb,
            sqlite3MPrintf( db, "type='trigger' AND name='%q'", zName ) );
      }

      if ( db.init.busy != 0 )
      {
        Trigger pLink = pTrig;
        Hash pHash = db.aDb[iDb].pSchema.trigHash;
        Debug.Assert( sqlite3SchemaMutexHeld( db, iDb, null ) );
        pTrig = sqlite3HashInsert( ref pHash, zName, sqlite3Strlen30( zName ), pTrig );
        if ( pTrig != null )
        {
          //db.mallocFailed = 1;
        }
        else if ( pLink.pSchema == pLink.pTabSchema )
        {
          Table pTab;
          int n = sqlite3Strlen30( pLink.table );
          pTab = sqlite3HashFind( pLink.pTabSchema.tblHash, pLink.table, n, (Table)null );
          Debug.Assert( pTab != null );
          pLink.pNext = pTab.pTrigger;
          pTab.pTrigger = pLink;
        }
      }

triggerfinish_cleanup:
      sqlite3DeleteTrigger( db, ref pTrig );
      Debug.Assert( pParse.pNewTrigger == null );
      sqlite3DeleteTriggerStep( db, ref pStepList );
    }

static int sqlite3FixTriggerStep(
DbFixer pFix,     /* Context of the fixation */
TriggerStep pStep /* The trigger step be fixed to one database */
)
{
  while ( pStep != null )
  {
    if ( sqlite3FixSelect( pFix, pStep.pSelect ) != 0 )
    {
      return 1;
    }
    if ( sqlite3FixExpr( pFix, pStep.pWhere ) != 0 )
    {
      return 1;
    }
    if ( sqlite3FixExprList( pFix, pStep.pExprList ) != 0 )
    {
      return 1;
    }
    pStep = pStep.pNext;
  }
  return 0;
}

        static int CodeTriggerProgram(Parse parse, TriggerStep stepList, OE orconf)
        {
            Vdbe v = parse.V;
            Context ctx = parse.Ctx;
            Debug.Assert(parse.TriggerTab != null && parse.Toplevel != null);
            Debug.Assert(stepList != null);
            Debug.Assert(v != null);
            for (TriggerStep step = stepList; step != null; step = step.Next)
            {
                // Figure out the ON CONFLICT policy that will be used for this step of the trigger program. If the statement that caused this trigger
                // to fire had an explicit ON CONFLICT, then use it. Otherwise, use the ON CONFLICT policy that was specified as part of the trigger
                // step statement. Example:
                //
                //   CREATE TRIGGER AFTER INSERT ON t1 BEGIN;
                //     INSERT OR REPLACE INTO t2 VALUES(new.a, new.b);
                //   END;
                //
                //   INSERT INTO t1 ... ;            -- insert into t2 uses REPLACE policy
                //   INSERT OR IGNORE INTO t1 ... ;  -- insert into t2 uses IGNORE policy
                parse.Orconf = (orconf == OE.Default ? step.Orconf : orconf);

                switch (step.OP)
                {
                    case TK.UPDATE:
                        Update(parse,
                          TargetSrcList(parse, step),
                          Expr.ListDup(ctx, step.ExprList, 0),
                          Expr.Dup(ctx, step.Where, 0),
                          parse.Orconf);
                        break;
                    case TK.INSERT:
                        Insert(parse,
                          TargetSrcList(parse, step),
                          Expr.ListDup(ctx, step.ExprList, 0),
                          Select.Dup(ctx, step.Select, 0),
                          Expr.IdListDup(ctx, step.IdList),
                          parse.Orconf);
                        break;
                    case TK.DELETE:
                        DeleteFrom(parse,
                          TargetSrcList(parse, step),
                          Expr.Dup(ctx, step.Where, 0));
                        break;
                    default:
                        Debug.Assert(step.OP == TK.SELECT);
                        SelectDest sDest = new SelectDest();
                        Select select = Expr.SelectDup(ctx, step.Select, 0);
                        Select.DestInit(sDest, SRT.Discard, 0);
                        Select.Select_(parse, select, ref sDest);
                        Select.Delete(ctx, ref select);
                        break;
                }
                if (step.OP != TK.SELECT)
                    v.AddOp0(OP.ResetCount);
            }
            return 0;
        }

 static SrcList TargetSrcList(Parse parse, TriggerStep step)
 {
     Context ctx = parse.Ctx;
     SrcList src = Parse.SrcListAppend(parse.Ctx, null, step.Target, null); // SrcList to be returned
     if (src != null)
     {
         Debug.Assert(src.Srcs > 0);
         Debug.Assert(src.Ids != null);
         int db = Prepare.SchemaToIndex(ctx, step.Trig.Schema); // Index of the database to use
         if (db == 0 || db >= 2)
         {
             Debug.Assert(db < ctx.DBs.length);
             src.Ids[src.Srcs - 1].Database = ctx.DBs[db].Name; //: _tagstrdup(ctx, ctx->DBs[db].Name);
         }
     }
     return src;
 }

 static TriggerStep TriggerStepAllocate(Context ctx, TK op, Token name)
 {
     TriggerStep triggerStep = new TriggerStep(); //: _tagalloc(ctx, sizeof(TriggerStep) + name->length, true);
     if (triggerStep != null)
     {
         string z = name.data;
         triggerStep.Target.data = z;
         triggerStep.Target.length = name.length;
         triggerStep.OP = op;
     }
     return triggerStep;
 }

 public static TriggerStep SelectStep(Context ctx, Select select)
 {
     TriggerStep triggerStep = new TriggerStep(); //: _tagalloc(ctx, sizeof(TriggerStep), true);
     if (triggerStep == null)
     {
         Select.Delete(ctx, ref select);
         return null;
     }
     triggerStep.OP = TK.SELECT;
     triggerStep.Select = select;
     triggerStep.Orconf = OE.Default;
     return triggerStep;
 }

        public static void FinishTrigger(Parse parse, TriggerStep stepList, Token all)
        {
            Trigger trig = parse.NewTrigger; // Trigger being finished
            Context ctx = parse.Ctx; // The database
            Token nameToken = new Token(); // Trigger name for error reporting

            parse.NewTrigger = null;
            if (C._NEVER(parse.Errs != 0) || trig == null) goto triggerfinish_cleanup;
            string name = trig.Name; // Name of trigger
            int db = Prepare.SchemaToIndex(parse.Ctx, trig.Schema); // Database containing the trigger
            trig.StepList = stepList;
            while (stepList != null)
            {
                stepList.Trig = trig;
                stepList = stepList.Next;
            }
            nameToken.data = trig.Name;
            nameToken.length = (uint)nameToken.data.Length;
            DbFixer sFix = new DbFixer(); // Fixer object
            if (sFix.FixInit(parse, db, "trigger", nameToken) && sFix.FixTriggerStep(trig.StepList))
                goto triggerfinish_cleanup;

            // if we are not initializing, build the sqlite_master entry
            if (ctx.Init.Busy)
            {
                // Make an entry in the sqlite_master table
                Vdbe v = parse.GetVdbe();
                if (v == null) goto triggerfinish_cleanup;
                parse.BeginWriteOperation(0, db);
                string z = all.data.Substring(0, (int)all.length); //: _tagstrndup(ctx, (char *)all->data, all->length);
                parse.NestedParse("INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')", ctx.DBs[db].Name, E.SCHEMA_TABLE(db), name, trig.Table, z);
                C._tagfree(ctx, ref z);
                parse.ChangeCookie(db);
                v.AddParseSchemaOp(db, C._mtagprintf(ctx, "type='trigger' AND name='%q'", name));
            }

            if (!ctx.Init.Busy)
            {
                Trigger link = trig;
                Debug.Assert(Btree.SchemaMutexHeld(ctx, db, null));
                trig = ctx.DBs[db].Schema.TriggerHash.Insert(name, name.Length, trig);
                if (trig != null)
                    ctx.MallocFailed = true;
                else if (link.Schema == link.TabSchema)
                {
                    int tableLength = link.Table.Length;
                    Table table = (Table)link.TabSchema.TableHash.Find(link.Table, tableLength, (Table)null);
                    Debug.Assert(table != null);
                    link.Next = table.Triggers;
                    table.Triggers = link;
                }
            }

        triggerfinish_cleanup:
            DeleteTrigger(ctx, ref trig);
            Debug.Assert(parse.NewTrigger == null);
            DeleteTriggerStep(ctx, ref stepList);
        }

 public bool FixTriggerStep(TriggerStep step)
 {
     while (step != null)
     {
         if (FixSelect(step.Select) || FixExpr(step.Where) || FixExprList(step.ExprList))
             return true;
         step = step.Next;
     }
     return false;
 }

    /*
    ** Generate VDBE code for zero or more statements inside the body of a
    ** trigger.
    */
    static int codeTriggerProgram(
    Parse pParse,            /* The parser context */
    TriggerStep pStepList,   /* List of statements inside the trigger body */
    int orconfin              /* Conflict algorithm. (OE_Abort, etc) */
    )
    {
      TriggerStep pTriggerStep = pStepList;
      int orconf;
      Vdbe v = pParse.pVdbe;
      sqlite3 db = pParse.db;

      Debug.Assert( pTriggerStep != null );
      Debug.Assert( v != null );
      sqlite3VdbeAddOp2( v, OP_ContextPush, 0, 0 );
#if SQLITE_DEBUG
      VdbeComment( v, "begin trigger %s", pStepList.pTrig.name );
#endif
      while ( pTriggerStep != null )
      {
        sqlite3ExprCacheClear( pParse );
        orconf = ( orconfin == OE_Default ) ? pTriggerStep.orconf : orconfin;
        pParse.trigStack.orconf = orconf;
        switch ( pTriggerStep.op )
        {
          case TK_UPDATE:
            {
              SrcList pSrc;
              pSrc = targetSrcList( pParse, pTriggerStep );
              sqlite3VdbeAddOp2( v, OP_ResetCount, 0, 0 );
              sqlite3Update( pParse, pSrc,
              sqlite3ExprListDup( db, pTriggerStep.pExprList, 0 ),
              sqlite3ExprDup( db, pTriggerStep.pWhere, 0 ), orconf );
              sqlite3VdbeAddOp2( v, OP_ResetCount, 1, 0 );
              break;
            }
          case TK_INSERT:
            {
              SrcList pSrc;
              pSrc = targetSrcList( pParse, pTriggerStep );
              sqlite3VdbeAddOp2( v, OP_ResetCount, 0, 0 );
              sqlite3Insert( pParse, pSrc,
              sqlite3ExprListDup( db, pTriggerStep.pExprList, 0 ),
              sqlite3SelectDup( db, pTriggerStep.pSelect, 0 ),
              sqlite3IdListDup( db, pTriggerStep.pIdList ), orconf );
              sqlite3VdbeAddOp2( v, OP_ResetCount, 1, 0 );
              break;
            }
          case TK_DELETE:
            {
              SrcList pSrc;
              sqlite3VdbeAddOp2( v, OP_ResetCount, 0, 0 );
              pSrc = targetSrcList( pParse, pTriggerStep );
              sqlite3DeleteFrom( pParse, pSrc,
              sqlite3ExprDup( db, pTriggerStep.pWhere, 0 ) );
              sqlite3VdbeAddOp2( v, OP_ResetCount, 1, 0 );
              break;
            }
          default: Debug.Assert( pTriggerStep.op == TK_SELECT );
            {
              Select ss = sqlite3SelectDup( db, pTriggerStep.pSelect, 0 );
              if ( ss != null )
              {
                SelectDest dest = new SelectDest();

                sqlite3SelectDestInit( dest, SRT_Discard, 0 );
                sqlite3Select( pParse, ss, ref dest );
                sqlite3SelectDelete( db, ref ss );
              }
              break;
            }
        }
        pTriggerStep = pTriggerStep.pNext;
      }
      sqlite3VdbeAddOp2( v, OP_ContextPop, 0, 0 );
#if SQLITE_DEBUG
      VdbeComment( v, "end trigger %s", pStepList.pTrig.name );
#endif
      return 0;
    }