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COALESCE() and NULLIF() are now first-class expressions, not macros

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that turn into CASE expressions.  They evaluate their arguments at most
once.  Patch by Kris Jurka, review and (very light) editorializing by me.
This commit is contained in:
Tom Lane
2003-02-16 02:30:39 +00:00
parent de25638d2f
commit 51972a9d5d
22 changed files with 644 additions and 107 deletions
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47
src/backend/nodes/readfuncs.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.148 2003/02/09 06:56:27 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.149 2003/02/16 02:30:37 tgl Exp $
*
* NOTES
* Path and Plan nodes do not have any readfuncs support, because we
@ -606,6 +606,47 @@ _readCaseWhen(void)
READ_DONE();
}
/*
* _readCoalesceExpr
*/
static CoalesceExpr *
_readCoalesceExpr(void)
{
READ_LOCALS(CoalesceExpr);
READ_OID_FIELD(coalescetype);
READ_NODE_FIELD(args);
READ_DONE();
}
/*
* _readNullIfExpr
*/
static NullIfExpr *
_readNullIfExpr(void)
{
READ_LOCALS(NullIfExpr);
READ_OID_FIELD(opno);
READ_OID_FIELD(opfuncid);
/*
* The opfuncid is stored in the textual format primarily for debugging
* and documentation reasons. We want to always read it as zero to force
* it to be re-looked-up in the pg_operator entry. This ensures that
* stored rules don't have hidden dependencies on operators' functions.
* (We don't currently support an ALTER OPERATOR command, but might
* someday.)
*/
local_node->opfuncid = InvalidOid;
READ_OID_FIELD(opresulttype);
READ_BOOL_FIELD(opretset);
READ_NODE_FIELD(args);
READ_DONE();
}
/*
* _readNullTest
*/
@ -895,6 +936,10 @@ parseNodeString(void)
return_value = _readCaseExpr();
else if (MATCH("WHEN", 4))
return_value = _readCaseWhen();
else if (MATCH("COALESCE", 8))
return_value = _readCoalesceExpr();
else if (MATCH("NULLIFEXPR", 10))
return_value = _readNullIfExpr();
else if (MATCH("NULLTEST", 8))
return_value = _readNullTest();
else if (MATCH("BOOLEANTEST", 11))