Cleanup the usage of ScanDirection: use the symbolic names for the

possible ScanDirection alternatives rather than magic numbers
(-1, 0, 1).  Also, use the ScanDirection macros in a few places
rather than directly checking whether `dir == ForwardScanDirection'
and the like. Per patch from James William Pye. His patch also
changed ScanDirection to be a "char" rather than an enum, which
I haven't applied.

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 4ba8e8fc6d9dad69fd194050facf924861434d1d..35911039f7958e6dd4a1b944ecd3c1d6a39cbe70 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.206 2006/01/11 08:43:11 neilc Exp $
+ *   $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.207 2006/02/21 23:01:53 neilc Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -172,7 +172,8 @@ heapgetpage(HeapScanDesc scan, BlockNumber page)
  *     tuple as indicated by "dir"; return the next tuple in scan->rs_ctup,
  *     or set scan->rs_ctup.t_data = NULL if no more tuples.
  *
- * dir == 0 means "re-fetch the tuple indicated by scan->rs_ctup".
+ * dir == NoMovementScanDirection means "re-fetch the tuple indicated
+ * by scan->rs_ctup".
  *
  * Note: the reason nkeys/key are passed separately, even though they are
  * kept in the scan descriptor, is that the caller may not want us to check
@@ -189,12 +190,13 @@ heapgetpage(HeapScanDesc scan, BlockNumber page)
  */
 static void
 heapgettup(HeapScanDesc scan,
-          int dir,
+          ScanDirection dir,
           int nkeys,
           ScanKey key)
 {
    HeapTuple   tuple = &(scan->rs_ctup);
    Snapshot    snapshot = scan->rs_snapshot;
+   bool        backward = ScanDirectionIsBackward(dir);
    BlockNumber page;
    Page        dp;
    int         lines;
@@ -205,11 +207,8 @@ heapgettup(HeapScanDesc scan,
    /*
     * calculate next starting lineoff, given scan direction
     */
-   if (dir > 0)
+   if (ScanDirectionIsForward(dir))
    {
-       /*
-        * forward scan direction
-        */
        if (!scan->rs_inited)
        {
            /*
@@ -242,11 +241,8 @@ heapgettup(HeapScanDesc scan,
 
        linesleft = lines - lineoff + 1;
    }
-   else if (dir < 0)
+   else if (backward)
    {
-       /*
-        * reverse scan direction
-        */
        if (!scan->rs_inited)
        {
            /*
@@ -352,7 +348,7 @@ heapgettup(HeapScanDesc scan,
             * otherwise move to the next item on the page
             */
            --linesleft;
-           if (dir < 0)
+           if (backward)
            {
                --lpp;          /* move back in this page's ItemId array */
                --lineoff;
@@ -373,7 +369,7 @@ heapgettup(HeapScanDesc scan,
        /*
         * return NULL if we've exhausted all the pages
         */
-       if ((dir < 0) ? (page == 0) : (page + 1 >= scan->rs_nblocks))
+       if (backward ? (page == 0) : (page + 1 >= scan->rs_nblocks))
        {
            if (BufferIsValid(scan->rs_cbuf))
                ReleaseBuffer(scan->rs_cbuf);
@@ -384,7 +380,7 @@ heapgettup(HeapScanDesc scan,
            return;
        }
 
-       page = (dir < 0) ? (page - 1) : (page + 1);
+       page = backward ? (page - 1) : (page + 1);
 
        heapgetpage(scan, page);
 
@@ -393,7 +389,7 @@ heapgettup(HeapScanDesc scan,
        dp = (Page) BufferGetPage(scan->rs_cbuf);
        lines = PageGetMaxOffsetNumber((Page) dp);
        linesleft = lines;
-       if (dir < 0)
+       if (backward)
        {
            lineoff = lines;
            lpp = PageGetItemId(dp, lines);
@@ -421,11 +417,12 @@ heapgettup(HeapScanDesc scan,
  */
 static void
 heapgettup_pagemode(HeapScanDesc scan,
-                   int dir,
+                   ScanDirection dir,
                    int nkeys,
                    ScanKey key)
 {
    HeapTuple   tuple = &(scan->rs_ctup);
+   bool        backward = ScanDirectionIsBackward(dir);
    BlockNumber page;
    Page        dp;
    int         lines;
@@ -437,11 +434,8 @@ heapgettup_pagemode(HeapScanDesc scan,
    /*
     * calculate next starting lineindex, given scan direction
     */
-   if (dir > 0)
+   if (ScanDirectionIsForward(dir))
    {
-       /*
-        * forward scan direction
-        */
        if (!scan->rs_inited)
        {
            /*
@@ -471,11 +465,8 @@ heapgettup_pagemode(HeapScanDesc scan,
 
        linesleft = lines - lineindex;
    }
-   else if (dir < 0)
+   else if (backward)
    {
-       /*
-        * reverse scan direction
-        */
        if (!scan->rs_inited)
        {
            /*
@@ -584,14 +575,10 @@ heapgettup_pagemode(HeapScanDesc scan,
             * otherwise move to the next item on the page
             */
            --linesleft;
-           if (dir < 0)
-           {
+           if (backward)
                --lineindex;
-           }
            else
-           {
                ++lineindex;
-           }
        }
 
        /*
@@ -602,7 +589,7 @@ heapgettup_pagemode(HeapScanDesc scan,
        /*
         * return NULL if we've exhausted all the pages
         */
-       if ((dir < 0) ? (page == 0) : (page + 1 >= scan->rs_nblocks))
+       if (backward ? (page == 0) : (page + 1 >= scan->rs_nblocks))
        {
            if (BufferIsValid(scan->rs_cbuf))
                ReleaseBuffer(scan->rs_cbuf);
@@ -613,14 +600,13 @@ heapgettup_pagemode(HeapScanDesc scan,
            return;
        }
 
-       page = (dir < 0) ? (page - 1) : (page + 1);
-
+       page = backward ? (page - 1) : (page + 1);
        heapgetpage(scan, page);
 
        dp = (Page) BufferGetPage(scan->rs_cbuf);
        lines = scan->rs_ntuples;
        linesleft = lines;
-       if (dir < 0)
+       if (backward)
            lineindex = lines - 1;
        else
            lineindex = 0;
@@ -1008,15 +994,11 @@ heap_getnext(HeapScanDesc scan, ScanDirection direction)
 
    HEAPDEBUG_1;                /* heap_getnext( info ) */
 
-   /*
-    * Note: we depend here on the -1/0/1 encoding of ScanDirection.
-    */
    if (scan->rs_pageatatime)
-       heapgettup_pagemode(scan, (int) direction,
+       heapgettup_pagemode(scan, direction,
                            scan->rs_nkeys, scan->rs_key);
    else
-       heapgettup(scan, (int) direction,
-                  scan->rs_nkeys, scan->rs_key);
+       heapgettup(scan, direction, scan->rs_nkeys, scan->rs_key);
 
    if (scan->rs_ctup.t_data == NULL)
    {
@@ -2745,13 +2727,13 @@ heap_restrpos(HeapScanDesc scan)
        {
            scan->rs_cindex = scan->rs_mindex;
            heapgettup_pagemode(scan,
-                               0,          /* "no movement" */
+                               NoMovementScanDirection,
                                0,          /* needn't recheck scan keys */
                                NULL);
        }
        else
            heapgettup(scan,
-                      0,                   /* "no movement" */
+                      NoMovementScanDirection,
                       0,                   /* needn't recheck scan keys */
                       NULL);
    }

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 99c3bca0a9a8202342472d9585963acbc37cff45..57570a5cc0c7a4c85e1a13a497472b878b7a7028 100644 (file)
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.266 2006/02/19 00:04:26 neilc Exp $
+ *   $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.267 2006/02/21 23:01:54 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -218,7 +218,7 @@ ExecutorRun(QueryDesc *queryDesc,
    /*
     * run plan
     */
-   if (direction == NoMovementScanDirection)
+   if (ScanDirectionIsNoMovement(direction))
        result = NULL;
    else
        result = ExecutePlan(estate,

diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 09919dbbc5a287e6b17c9d56b4770b745360136d..001be06521ba763449b3c28410f261d868fa458c 100644 (file)
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.98 2005/11/22 18:17:21 momjian Exp $
+ *   $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.99 2006/02/21 23:01:54 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -795,7 +795,7 @@ PortalRunSelect(Portal portal,
            nprocessed = queryDesc->estate->es_processed;
        }
 
-       if (direction != NoMovementScanDirection)
+       if (!ScanDirectionIsNoMovement(direction))
        {
            long        oldPos;
 
@@ -837,7 +837,7 @@ PortalRunSelect(Portal portal,
            nprocessed = queryDesc->estate->es_processed;
        }
 
-       if (direction != NoMovementScanDirection)
+       if (!ScanDirectionIsNoMovement(direction))
        {
            if (nprocessed > 0 && portal->atEnd)
            {
@@ -890,13 +890,13 @@ RunFromStore(Portal portal, ScanDirection direction, long count,
 
    (*dest->rStartup) (dest, CMD_SELECT, portal->tupDesc);
 
-   if (direction == NoMovementScanDirection)
+   if (ScanDirectionIsNoMovement(direction))
    {
        /* do nothing except start/stop the destination */
    }
    else
    {
-       bool        forward = (direction == ForwardScanDirection);
+       bool        forward = ScanDirectionIsForward(direction);
 
        for (;;)
        {