Create a standardized expression_tree_mutator support routine
to go along with expression_tree_walker. (_walker is not suitable for routines that need to alter the tree structure significantly.) Other minor cleanups in clauses.c.
This commit is contained in:
Tom Lane
parent
f0b651ac6b
commit
6bc601b648
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.27 1999/07/17 20:17:16 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.28 1999/08/09 00:51:26 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -45,10 +45,9 @@ preprocess_targetlist(List *tlist,
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Index result_relation,
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List *range_table)
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{
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List *expanded_tlist = NIL;
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Oid relid = InvalidOid;
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List *t_list = NIL;
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List *temp = NIL;
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List *expanded_tlist;
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List *t_list;
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if (result_relation >= 1 && command_type != CMD_SELECT)
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relid = getrelid(result_relation, range_table);
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@ -61,14 +60,7 @@ preprocess_targetlist(List *tlist,
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expanded_tlist = expand_targetlist(tlist, relid, command_type, result_relation);
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/* XXX should the fix-opids be this early?? */
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/* was mapCAR */
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foreach(temp, expanded_tlist)
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{
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TargetEntry *tle = lfirst(temp);
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if (tle->expr)
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fix_opid(tle->expr);
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}
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fix_opids(expanded_tlist);
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t_list = copyObject(expanded_tlist);
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/* ------------------
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.43 1999/07/27 03:51:04 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.44 1999/08/09 00:51:24 tgl Exp $
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*
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* HISTORY
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* AUTHOR DATE MAJOR EVENT
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@ -28,7 +28,7 @@
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#include "utils/lsyscache.h"
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static bool fix_opid_walker(Node *node, void *context);
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static bool fix_opids_walker(Node *node, void *context);
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static int is_single_func(Node *node);
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@ -367,7 +367,7 @@ pull_constant_clauses(List *quals, List **constantQual)
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else
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restqual = lcons(lfirst(q), restqual);
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}
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freeList(quals);
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freeList(quals); /* XXX seems a tad risky? */
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*constantQual = constqual;
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return restqual;
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}
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@ -409,6 +409,7 @@ clause_get_relids_vars(Node *clause, Relids *relids, List **vars)
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if (vi == NIL)
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var_list = lappend(var_list, var);
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}
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freeList(clvars);
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*relids = varno_list;
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*vars = var_list;
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@ -426,6 +427,7 @@ NumRelids(Node *clause)
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List *vars = pull_var_clause(clause);
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List *var_list = NIL;
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List *i;
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int result;
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foreach(i, vars)
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{
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@ -435,7 +437,10 @@ NumRelids(Node *clause)
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var_list = lconsi(var->varno, var_list);
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}
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return length(var_list);
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result = length(var_list);
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freeList(vars);
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freeList(var_list);
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return result;
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}
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/*
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@ -506,42 +511,28 @@ qual_clause_p(Node *clause)
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}
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/*
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* fix_opid
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* fix_opids
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* Calculate opid field from opno for each Oper node in given tree.
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* (The given tree can be anything expression_tree_walker handles.)
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*
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* Returns nothing.
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* Returns its argument, which has been modified in-place.
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*/
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void
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fix_opid(Node *clause)
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List *
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fix_opids(List *clauses)
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{
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/* This tree walk requires no special setup, so away we go... */
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fix_opid_walker(clause, NULL);
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fix_opids_walker((Node *) clauses, NULL);
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return clauses;
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}
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static bool
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fix_opid_walker (Node *node, void *context)
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fix_opids_walker (Node *node, void *context)
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{
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if (node == NULL)
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return false;
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if (is_opclause(node))
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replace_opid((Oper *) ((Expr *) node)->oper);
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return expression_tree_walker(node, fix_opid_walker, context);
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}
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/*
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* fix_opids
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* Calculate the opid from the opno for all the clauses...
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*
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* Returns its argument.
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*
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* XXX This could and should be merged with fix_opid.
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*
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*/
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List *
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fix_opids(List *clauses)
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{
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fix_opid((Node *) clauses);
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return clauses;
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return expression_tree_walker(node, fix_opids_walker, context);
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}
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/*
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@ -658,12 +649,17 @@ static int is_single_func(Node *node)
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if (vars != NIL)
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{
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int funcvarno = ((Var *) lfirst(vars))->varno;
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List *v;
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/* need to check that all args of func are same relation */
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while ((vars = lnext(vars)) != NIL)
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foreach(v, lnext(vars))
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{
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if (((Var *) lfirst(vars))->varno != funcvarno)
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return 0;
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if (((Var *) lfirst(v))->varno != funcvarno)
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{
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funcvarno = 0;
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break;
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}
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}
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freeList(vars);
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return funcvarno;
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}
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}
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@ -730,6 +726,8 @@ get_rels_atts(Node *clause,
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/*--------------------
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* CommuteClause: commute a binary operator clause
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*
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* XXX the clause is destructively modified!
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*--------------------
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*/
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void
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@ -768,7 +766,7 @@ CommuteClause(Node *clause)
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}
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/*--------------------
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/*
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* Standard expression-tree walking support
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*
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* We used to have near-duplicate code in many different routines that
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@ -778,12 +776,15 @@ CommuteClause(Node *clause)
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* these routines only actually care about certain node types, and don't
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* care about other types except insofar as they have to recurse through
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* non-primitive node types. Therefore, we now provide generic tree-walking
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* logic to consolidate the redundant "boilerplate" code.
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*
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* logic to consolidate the redundant "boilerplate" code. There are
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* two versions: expression_tree_walker() and expression_tree_mutator().
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*/
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/*--------------------
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* expression_tree_walker() is designed to support routines that traverse
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* a tree in a read-only fashion (although it will also work for routines
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* that modify nodes in-place but never add or delete nodes). A walker
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* routine should look like this:
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* that modify nodes in-place but never add/delete/replace nodes).
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* A walker routine should look like this:
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*
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* bool my_walker (Node *node, my_struct *context)
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* {
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@ -803,8 +804,8 @@ CommuteClause(Node *clause)
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* }
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*
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* The "context" argument points to a struct that holds whatever context
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* information the walker routine needs (it can be used to return data
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* gathered by the walker, too). This argument is not touched by
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* information the walker routine needs --- it can be used to return data
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* gathered by the walker, too. This argument is not touched by
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* expression_tree_walker, but it is passed down to recursive sub-invocations
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* of my_walker. The tree walk is started from a setup routine that
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* fills in the appropriate context struct, calls my_walker with the top-level
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@ -930,7 +931,7 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context)
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break;
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case T_SubLink:
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/* A "bare" SubLink (note we will not come here if we found
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* a SUBPLAN_EXPR node above). Examine the lefthand side,
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* a SUBPLAN_EXPR node above it). Examine the lefthand side,
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* but not the oper list nor the subquery.
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*/
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return walker(((SubLink *) node)->lefthand, context);
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@ -950,3 +951,238 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context)
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}
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return false;
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}
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/*--------------------
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* expression_tree_mutator() is designed to support routines that make a
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* modified copy of an expression tree, with some nodes being added,
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* removed, or replaced by new subtrees. The original tree is (normally)
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* not changed. Each recursion level is responsible for returning a copy of
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* (or appropriately modified substitute for) the subtree it is handed.
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* A mutator routine should look like this:
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*
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* Node * my_mutator (Node *node, my_struct *context)
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* {
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* if (node == NULL)
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* return NULL;
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* // check for nodes that special work is required for, eg:
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* if (IsA(node, Var))
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* {
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* ... create and return modified copy of Var node
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* }
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* else if (IsA(node, ...))
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* {
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* ... do special transformations of other node types
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* }
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* // for any node type not specially processed, do:
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* return expression_tree_mutator(node, my_mutator, (void *) context);
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* }
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*
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* The "context" argument points to a struct that holds whatever context
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* information the mutator routine needs --- it can be used to return extra
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* data gathered by the mutator, too. This argument is not touched by
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* expression_tree_mutator, but it is passed down to recursive sub-invocations
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* of my_mutator. The tree walk is started from a setup routine that
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* fills in the appropriate context struct, calls my_mutator with the
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* top-level node of the tree, and does any required post-processing.
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*
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* Each level of recursion must return an appropriately modified Node.
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* If expression_tree_mutator() is called, it will make an exact copy
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* of the given Node, but invoke my_mutator() to copy the sub-node(s)
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* of that Node. In this way, my_mutator() has full control over the
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* copying process but need not directly deal with expression trees
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* that it has no interest in.
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*
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* Just as for expression_tree_walker, the node types handled by
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* expression_tree_mutator include all those normally found in target lists
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* and qualifier clauses during the planning stage.
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*
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* expression_tree_mutator will handle a SUBPLAN_EXPR node by recursing into
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* the args and slink->oper lists (which belong to the outer plan), but it
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* will simply copy the link to the inner plan, since that's typically what
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* expression tree mutators want. A mutator that wants to modify the subplan
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* can force appropriate behavior by recognizing subplan nodes and doing the
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* right thing.
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*
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* Bare SubLink nodes (without a SUBPLAN_EXPR) are handled by recursing into
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* the "lefthand" argument list only. (A bare SubLink should be seen only if
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* the tree has not yet been processed by subselect.c.) Again, this can be
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* overridden by the mutator, but it seems to be the most useful default
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* behavior.
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*--------------------
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*/
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Node *
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expression_tree_mutator(Node *node, Node * (*mutator) (), void *context)
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{
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/*
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* The mutator has already decided not to modify the current node,
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* but we must call the mutator for any sub-nodes.
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*/
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#define FLATCOPY(newnode, node, nodetype) \
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( (newnode) = makeNode(nodetype), \
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memcpy((newnode), (node), sizeof(nodetype)) )
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#define CHECKFLATCOPY(newnode, node, nodetype) \
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( AssertMacro(IsA((node), nodetype)), \
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(newnode) = makeNode(nodetype), \
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memcpy((newnode), (node), sizeof(nodetype)) )
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#define MUTATE(newfield, oldfield, fieldtype) \
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( (newfield) = (fieldtype) mutator((Node *) (oldfield), context) )
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if (node == NULL)
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return NULL;
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switch (nodeTag(node))
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{
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case T_Ident:
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case T_Const:
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case T_Var:
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case T_Param:
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/* primitive node types with no subnodes */
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return (Node *) copyObject(node);
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case T_Expr:
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{
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Expr *expr = (Expr *) node;
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Expr *newnode;
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FLATCOPY(newnode, expr, Expr);
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if (expr->opType == SUBPLAN_EXPR)
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{
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SubLink *oldsublink = ((SubPlan *) expr->oper)->sublink;
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SubPlan *newsubplan;
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/* flat-copy the oper node, which is a SubPlan */
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CHECKFLATCOPY(newsubplan, expr->oper, SubPlan);
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newnode->oper = (Node *) newsubplan;
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/* likewise its SubLink node */
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CHECKFLATCOPY(newsubplan->sublink, oldsublink, SubLink);
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/* transform args list (params to be passed to subplan) */
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MUTATE(newnode->args, expr->args, List *);
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/* transform sublink's oper list as well */
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MUTATE(newsubplan->sublink->oper, oldsublink->oper, List*);
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/* but not the subplan itself, which is referenced as-is */
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}
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else
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{
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/* for other Expr node types, just transform args list,
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* linking to original oper node (OK?)
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*/
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MUTATE(newnode->args, expr->args, List *);
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}
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return (Node *) newnode;
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}
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break;
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case T_Aggref:
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{
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Aggref *aggref = (Aggref *) node;
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Aggref *newnode;
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FLATCOPY(newnode, aggref, Aggref);
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MUTATE(newnode->target, aggref->target, Node *);
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return (Node *) newnode;
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}
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break;
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case T_Iter:
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{
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Iter *iter = (Iter *) node;
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Iter *newnode;
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FLATCOPY(newnode, iter, Iter);
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MUTATE(newnode->iterexpr, iter->iterexpr, Node *);
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return (Node *) newnode;
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}
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break;
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case T_ArrayRef:
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{
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ArrayRef *arrayref = (ArrayRef *) node;
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ArrayRef *newnode;
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FLATCOPY(newnode, arrayref, ArrayRef);
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MUTATE(newnode->refupperindexpr, arrayref->refupperindexpr,
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List *);
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MUTATE(newnode->reflowerindexpr, arrayref->reflowerindexpr,
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List *);
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MUTATE(newnode->refexpr, arrayref->refexpr,
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Node *);
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MUTATE(newnode->refassgnexpr, arrayref->refassgnexpr,
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Node *);
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return (Node *) newnode;
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}
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break;
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case T_CaseExpr:
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{
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CaseExpr *caseexpr = (CaseExpr *) node;
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CaseExpr *newnode;
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FLATCOPY(newnode, caseexpr, CaseExpr);
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MUTATE(newnode->args, caseexpr->args, List *);
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/* caseexpr->arg should be null, but we'll check it anyway */
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MUTATE(newnode->arg, caseexpr->arg, Node *);
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MUTATE(newnode->defresult, caseexpr->defresult, Node *);
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return (Node *) newnode;
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}
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break;
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case T_CaseWhen:
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{
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CaseWhen *casewhen = (CaseWhen *) node;
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CaseWhen *newnode;
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FLATCOPY(newnode, casewhen, CaseWhen);
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MUTATE(newnode->expr, casewhen->expr, Node *);
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MUTATE(newnode->result, casewhen->result, Node *);
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return (Node *) newnode;
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}
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break;
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case T_SubLink:
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{
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/* A "bare" SubLink (note we will not come here if we found
|
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* a SUBPLAN_EXPR node above it). Transform the lefthand side,
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* but not the oper list nor the subquery.
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*/
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SubLink *sublink = (SubLink *) node;
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SubLink *newnode;
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FLATCOPY(newnode, sublink, SubLink);
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MUTATE(newnode->lefthand, sublink->lefthand, List *);
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return (Node *) newnode;
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}
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break;
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case T_List:
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{
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/* We assume the mutator isn't interested in the list nodes
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* per se, so just invoke it on each list element.
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* NOTE: this would fail badly on a list with integer elements!
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*/
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List *resultlist = NIL;
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List *temp;
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foreach(temp, (List *) node)
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{
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resultlist = lappend(resultlist,
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mutator((Node *) lfirst(temp),
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context));
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}
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return (Node *) resultlist;
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}
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break;
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case T_TargetEntry:
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{
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/* We mutate the expression, but not the resdom, by default. */
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TargetEntry *targetentry = (TargetEntry *) node;
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TargetEntry *newnode;
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FLATCOPY(newnode, targetentry, TargetEntry);
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MUTATE(newnode->expr, targetentry->expr, Node *);
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return (Node *) newnode;
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}
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break;
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default:
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elog(ERROR, "expression_tree_mutator: Unexpected node type %d",
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nodeTag(node));
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break;
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}
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/* can't get here, but keep compiler happy */
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||||
return NULL;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -6,7 +6,7 @@
|
|||
*
|
||||
* Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $Id: clauses.h,v 1.24 1999/07/27 03:51:00 tgl Exp $
|
||||
* $Id: clauses.h,v 1.25 1999/08/09 00:51:23 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -44,7 +44,6 @@ extern void clause_get_relids_vars(Node *clause, Relids *relids, List **vars);
|
|||
extern int NumRelids(Node *clause);
|
||||
extern bool is_joinable(Node *clause);
|
||||
extern bool qual_clause_p(Node *clause);
|
||||
extern void fix_opid(Node *clause);
|
||||
extern List *fix_opids(List *clauses);
|
||||
extern void get_relattval(Node *clause, int targetrelid,
|
||||
int *relid, AttrNumber *attno,
|
||||
|
|
@ -55,6 +54,8 @@ extern void CommuteClause(Node *clause);
|
|||
|
||||
extern bool expression_tree_walker(Node *node, bool (*walker) (),
|
||||
void *context);
|
||||
extern Node *expression_tree_mutator(Node *node, Node * (*mutator) (),
|
||||
void *context);
|
||||
|
||||
#define is_subplan(clause) ((Node*) (clause) != NULL && \
|
||||
nodeTag((Node*) (clause)) == T_Expr && \
|
||||
|
|
|
|||
Loading…
Reference in New Issue