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259 lines
6.0 KiB
C
259 lines
6.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* tlist.c
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* Target list manipulation routines
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.50 2001/03/22 03:59:40 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/tlist.h"
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#include "optimizer/var.h"
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/*****************************************************************************
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* ---------- RELATION node target list routines ----------
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*****************************************************************************/
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/*
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* tlistentry_member
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* Finds the (first) member of the given tlist whose expression is
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* equal() to the given expression. Result is NULL if no such member.
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*/
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TargetEntry *
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tlistentry_member(Node *node, List *targetlist)
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{
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List *temp;
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foreach(temp, targetlist)
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{
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TargetEntry *tlentry = (TargetEntry *) lfirst(temp);
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if (equal(node, tlentry->expr))
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return tlentry;
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}
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return NULL;
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}
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#ifdef NOT_USED
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/*
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* matching_tlist_expr
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* Same as tlistentry_member(), except returns the tlist expression
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* rather than its parent TargetEntry node.
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*/
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Node *
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matching_tlist_expr(Node *node, List *targetlist)
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{
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TargetEntry *tlentry;
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tlentry = tlistentry_member(node, targetlist);
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if (tlentry)
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return tlentry->expr;
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return (Node *) NULL;
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}
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#endif
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/*
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* tlist_member
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* Same as tlistentry_member(), except returns the Resdom node
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* rather than its parent TargetEntry node.
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*/
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Resdom *
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tlist_member(Node *node, List *targetlist)
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{
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TargetEntry *tlentry;
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tlentry = tlistentry_member(node, targetlist);
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if (tlentry)
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return tlentry->resdom;
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return (Resdom *) NULL;
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}
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/*
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* add_var_to_tlist
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* Creates a targetlist entry corresponding to the supplied var node
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* 'var' and adds the new targetlist entry to the targetlist field of
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* 'rel'. No entry is created if 'var' is already in the tlist.
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*/
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void
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add_var_to_tlist(RelOptInfo *rel, Var *var)
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{
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if (!tlistentry_member((Node *) var, rel->targetlist))
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{
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/* XXX is copyObject necessary here? */
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rel->targetlist = lappend(rel->targetlist,
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create_tl_element((Var *) copyObject(var),
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length(rel->targetlist) + 1));
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}
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}
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/*
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* create_tl_element
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* Creates a target list entry node and its associated (resdom var) pair
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* with its resdom number equal to 'resdomno'.
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*/
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TargetEntry *
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create_tl_element(Var *var, int resdomno)
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{
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return makeTargetEntry(makeResdom(resdomno,
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var->vartype,
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var->vartypmod,
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NULL,
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false),
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(Node *) var);
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}
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/*****************************************************************************
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* ---------- GENERAL target list routines ----------
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*****************************************************************************/
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/*
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* new_unsorted_tlist
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* Creates a copy of a target list by creating new resdom nodes
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* without sort information.
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*
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* 'targetlist' is the target list to be copied.
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*
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* Returns the resulting target list.
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*
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*/
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List *
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new_unsorted_tlist(List *targetlist)
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{
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List *new_targetlist = (List *) copyObject((Node *) targetlist);
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List *x;
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foreach(x, new_targetlist)
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{
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TargetEntry *tle = (TargetEntry *) lfirst(x);
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tle->resdom->reskey = 0;
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tle->resdom->reskeyop = (Oid) 0;
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}
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return new_targetlist;
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}
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/*
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* flatten_tlist
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* Create a target list that only contains unique variables.
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*
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* Note that Vars with varlevelsup > 0 are not included in the output
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* tlist. We expect that those will eventually be replaced with Params,
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* but that probably has not happened at the time this routine is called.
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*
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* 'tlist' is the current target list
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*
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* Returns the "flattened" new target list.
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*
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* The result is entirely new structure sharing no nodes with the original.
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* Copying the Var nodes is probably overkill, but be safe for now.
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*/
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List *
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flatten_tlist(List *tlist)
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{
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List *vlist = pull_var_clause((Node *) tlist, false);
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List *new_tlist;
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new_tlist = add_to_flat_tlist(NIL, vlist);
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freeList(vlist);
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return new_tlist;
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}
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/*
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* add_to_flat_tlist
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* Add more vars to a flattened tlist (if they're not already in it)
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*
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* 'tlist' is the flattened tlist
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* 'vars' is a list of var nodes
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*
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* Returns the extended tlist.
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*/
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List *
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add_to_flat_tlist(List *tlist, List *vars)
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{
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int next_resdomno = length(tlist) + 1;
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List *v;
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foreach(v, vars)
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{
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Var *var = lfirst(v);
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if (!tlistentry_member((Node *) var, tlist))
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{
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Resdom *r;
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r = makeResdom(next_resdomno++,
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var->vartype,
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var->vartypmod,
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NULL,
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false);
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tlist = lappend(tlist,
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makeTargetEntry(r, copyObject(var)));
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}
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}
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return tlist;
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}
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Var *
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get_expr(TargetEntry *tle)
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{
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Assert(tle != NULL);
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Assert(tle->expr != NULL);
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return (Var *) tle->expr;
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}
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/*
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* get_sortgroupclause_tle
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* Find the targetlist entry matching the given SortClause
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* (or GroupClause) by ressortgroupref, and return it.
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*
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* Because GroupClause is typedef'd as SortClause, either kind of
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* node can be passed without casting.
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*/
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TargetEntry *
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get_sortgroupclause_tle(SortClause *sortClause,
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List *targetList)
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{
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Index refnumber = sortClause->tleSortGroupRef;
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List *l;
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foreach(l, targetList)
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{
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TargetEntry *tle = (TargetEntry *) lfirst(l);
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if (tle->resdom->ressortgroupref == refnumber)
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return tle;
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}
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elog(ERROR, "get_sortgroupclause_tle: ORDER/GROUP BY expression not found in targetlist");
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return NULL; /* keep compiler quiet */
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}
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/*
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* get_sortgroupclause_expr
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* Find the targetlist entry matching the given SortClause
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* (or GroupClause) by ressortgroupref, and return its expression.
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*
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* Because GroupClause is typedef'd as SortClause, either kind of
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* node can be passed without casting.
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*/
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Node *
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get_sortgroupclause_expr(SortClause *sortClause, List *targetList)
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{
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TargetEntry *tle = get_sortgroupclause_tle(sortClause, targetList);
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return tle->expr;
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}
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