diff options
Diffstat (limited to 'src/backend/nodes/nodeFuncs.c')
| -rw-r--r-- | src/backend/nodes/nodeFuncs.c | 1717 |
1 files changed, 1684 insertions, 33 deletions
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c index c72332a6112..7944936ba6e 100644 --- a/src/backend/nodes/nodeFuncs.c +++ b/src/backend/nodes/nodeFuncs.c @@ -1,74 +1,1725 @@ /*------------------------------------------------------------------------- * * nodeFuncs.c - * All node routines more complicated than simple access/modification + * Various general-purpose manipulations of Node trees * * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/nodes/nodeFuncs.c,v 1.29 2008/01/01 19:45:50 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/nodes/nodeFuncs.c,v 1.30 2008/08/25 22:42:32 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" +#include "catalog/pg_type.h" +#include "miscadmin.h" #include "nodes/nodeFuncs.h" +#include "nodes/relation.h" +#include "utils/builtins.h" +#include "utils/lsyscache.h" -static bool var_is_inner(Var *var); +static bool expression_returns_set_walker(Node *node, void *context); /* - * single_node - - * Returns t if node corresponds to a single-noded expression + * exprType - + * returns the Oid of the type of the expression. (Used for typechecking.) + */ +Oid +exprType(Node *expr) +{ + Oid type; + + if (!expr) + return InvalidOid; + + switch (nodeTag(expr)) + { + case T_Var: + type = ((Var *) expr)->vartype; + break; + case T_Const: + type = ((Const *) expr)->consttype; + break; + case T_Param: + type = ((Param *) expr)->paramtype; + break; + case T_Aggref: + type = ((Aggref *) expr)->aggtype; + break; + case T_ArrayRef: + { + ArrayRef *arrayref = (ArrayRef *) expr; + + /* slice and/or store operations yield the array type */ + if (arrayref->reflowerindexpr || arrayref->refassgnexpr) + type = arrayref->refarraytype; + else + type = arrayref->refelemtype; + } + break; + case T_FuncExpr: + type = ((FuncExpr *) expr)->funcresulttype; + break; + case T_OpExpr: + type = ((OpExpr *) expr)->opresulttype; + break; + case T_DistinctExpr: + type = ((DistinctExpr *) expr)->opresulttype; + break; + case T_ScalarArrayOpExpr: + type = BOOLOID; + break; + case T_BoolExpr: + type = BOOLOID; + break; + case T_SubLink: + { + SubLink *sublink = (SubLink *) expr; + + if (sublink->subLinkType == EXPR_SUBLINK || + sublink->subLinkType == ARRAY_SUBLINK) + { + /* get the type of the subselect's first target column */ + Query *qtree = (Query *) sublink->subselect; + TargetEntry *tent; + + if (!qtree || !IsA(qtree, Query)) + elog(ERROR, "cannot get type for untransformed sublink"); + tent = (TargetEntry *) linitial(qtree->targetList); + Assert(IsA(tent, TargetEntry)); + Assert(!tent->resjunk); + type = exprType((Node *) tent->expr); + if (sublink->subLinkType == ARRAY_SUBLINK) + { + type = get_array_type(type); + if (!OidIsValid(type)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("could not find array type for data type %s", + format_type_be(exprType((Node *) tent->expr))))); + } + } + else + { + /* for all other sublink types, result is boolean */ + type = BOOLOID; + } + } + break; + case T_SubPlan: + { + /* + * Although the parser does not ever deal with already-planned + * expression trees, we support SubPlan nodes in this routine + * for the convenience of ruleutils.c. + */ + SubPlan *subplan = (SubPlan *) expr; + + if (subplan->subLinkType == EXPR_SUBLINK || + subplan->subLinkType == ARRAY_SUBLINK) + { + /* get the type of the subselect's first target column */ + type = subplan->firstColType; + if (subplan->subLinkType == ARRAY_SUBLINK) + { + type = get_array_type(type); + if (!OidIsValid(type)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("could not find array type for data type %s", + format_type_be(subplan->firstColType)))); + } + } + else + { + /* for all other subplan types, result is boolean */ + type = BOOLOID; + } + } + break; + case T_AlternativeSubPlan: + { + /* As above, supported for the convenience of ruleutils.c */ + AlternativeSubPlan *asplan = (AlternativeSubPlan *) expr; + + /* subplans should all return the same thing */ + type = exprType((Node *) linitial(asplan->subplans)); + } + break; + case T_FieldSelect: + type = ((FieldSelect *) expr)->resulttype; + break; + case T_FieldStore: + type = ((FieldStore *) expr)->resulttype; + break; + case T_RelabelType: + type = ((RelabelType *) expr)->resulttype; + break; + case T_CoerceViaIO: + type = ((CoerceViaIO *) expr)->resulttype; + break; + case T_ArrayCoerceExpr: + type = ((ArrayCoerceExpr *) expr)->resulttype; + break; + case T_ConvertRowtypeExpr: + type = ((ConvertRowtypeExpr *) expr)->resulttype; + break; + case T_CaseExpr: + type = ((CaseExpr *) expr)->casetype; + break; + case T_CaseTestExpr: + type = ((CaseTestExpr *) expr)->typeId; + break; + case T_ArrayExpr: + type = ((ArrayExpr *) expr)->array_typeid; + break; + case T_RowExpr: + type = ((RowExpr *) expr)->row_typeid; + break; + case T_RowCompareExpr: + type = BOOLOID; + break; + case T_CoalesceExpr: + type = ((CoalesceExpr *) expr)->coalescetype; + break; + case T_MinMaxExpr: + type = ((MinMaxExpr *) expr)->minmaxtype; + break; + case T_XmlExpr: + if (((XmlExpr *) expr)->op == IS_DOCUMENT) + type = BOOLOID; + else if (((XmlExpr *) expr)->op == IS_XMLSERIALIZE) + type = TEXTOID; + else + type = XMLOID; + break; + case T_NullIfExpr: + type = exprType((Node *) linitial(((NullIfExpr *) expr)->args)); + break; + case T_NullTest: + type = BOOLOID; + break; + case T_BooleanTest: + type = BOOLOID; + break; + case T_CoerceToDomain: + type = ((CoerceToDomain *) expr)->resulttype; + break; + case T_CoerceToDomainValue: + type = ((CoerceToDomainValue *) expr)->typeId; + break; + case T_SetToDefault: + type = ((SetToDefault *) expr)->typeId; + break; + case T_CurrentOfExpr: + type = BOOLOID; + break; + default: + elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr)); + type = InvalidOid; /* keep compiler quiet */ + break; + } + return type; +} + +/* + * exprTypmod - + * returns the type-specific attrmod of the expression, if it can be + * determined. In most cases, it can't and we return -1. + */ +int32 +exprTypmod(Node *expr) +{ + if (!expr) + return -1; + + switch (nodeTag(expr)) + { + case T_Var: + return ((Var *) expr)->vartypmod; + case T_Const: + return ((Const *) expr)->consttypmod; + case T_Param: + return ((Param *) expr)->paramtypmod; + case T_ArrayRef: + /* typmod is the same for array or element */ + return ((ArrayRef *) expr)->reftypmod; + case T_FuncExpr: + { + int32 coercedTypmod; + + /* Be smart about length-coercion functions... */ + if (exprIsLengthCoercion(expr, &coercedTypmod)) + return coercedTypmod; + } + break; + case T_SubLink: + { + SubLink *sublink = (SubLink *) expr; + + if (sublink->subLinkType == EXPR_SUBLINK || + sublink->subLinkType == ARRAY_SUBLINK) + { + /* get the typmod of the subselect's first target column */ + Query *qtree = (Query *) sublink->subselect; + TargetEntry *tent; + + if (!qtree || !IsA(qtree, Query)) + elog(ERROR, "cannot get type for untransformed sublink"); + tent = (TargetEntry *) linitial(qtree->targetList); + Assert(IsA(tent, TargetEntry)); + Assert(!tent->resjunk); + return exprTypmod((Node *) tent->expr); + /* note we don't need to care if it's an array */ + } + } + break; + case T_FieldSelect: + return ((FieldSelect *) expr)->resulttypmod; + case T_RelabelType: + return ((RelabelType *) expr)->resulttypmod; + case T_ArrayCoerceExpr: + return ((ArrayCoerceExpr *) expr)->resulttypmod; + case T_CaseExpr: + { + /* + * If all the alternatives agree on type/typmod, return that + * typmod, else use -1 + */ + CaseExpr *cexpr = (CaseExpr *) expr; + Oid casetype = cexpr->casetype; + int32 typmod; + ListCell *arg; + + if (!cexpr->defresult) + return -1; + if (exprType((Node *) cexpr->defresult) != casetype) + return -1; + typmod = exprTypmod((Node *) cexpr->defresult); + if (typmod < 0) + return -1; /* no point in trying harder */ + foreach(arg, cexpr->args) + { + CaseWhen *w = (CaseWhen *) lfirst(arg); + + Assert(IsA(w, CaseWhen)); + if (exprType((Node *) w->result) != casetype) + return -1; + if (exprTypmod((Node *) w->result) != typmod) + return -1; + } + return typmod; + } + break; + case T_CaseTestExpr: + return ((CaseTestExpr *) expr)->typeMod; + case T_ArrayExpr: + { + /* + * If all the elements agree on type/typmod, return that + * typmod, else use -1 + */ + ArrayExpr *arrayexpr = (ArrayExpr *) expr; + Oid commontype; + int32 typmod; + ListCell *elem; + + if (arrayexpr->elements == NIL) + return -1; + typmod = exprTypmod((Node *) linitial(arrayexpr->elements)); + if (typmod < 0) + return -1; /* no point in trying harder */ + if (arrayexpr->multidims) + commontype = arrayexpr->array_typeid; + else + commontype = arrayexpr->element_typeid; + foreach(elem, arrayexpr->elements) + { + Node *e = (Node *) lfirst(elem); + + if (exprType(e) != commontype) + return -1; + if (exprTypmod(e) != typmod) + return -1; + } + return typmod; + } + break; + case T_CoalesceExpr: + { + /* + * If all the alternatives agree on type/typmod, return that + * typmod, else use -1 + */ + CoalesceExpr *cexpr = (CoalesceExpr *) expr; + Oid coalescetype = cexpr->coalescetype; + int32 typmod; + ListCell *arg; + + if (exprType((Node *) linitial(cexpr->args)) != coalescetype) + return -1; + typmod = exprTypmod((Node *) linitial(cexpr->args)); + if (typmod < 0) + return -1; /* no point in trying harder */ + for_each_cell(arg, lnext(list_head(cexpr->args))) + { + Node *e = (Node *) lfirst(arg); + + if (exprType(e) != coalescetype) + return -1; + if (exprTypmod(e) != typmod) + return -1; + } + return typmod; + } + break; + case T_MinMaxExpr: + { + /* + * If all the alternatives agree on type/typmod, return that + * typmod, else use -1 + */ + MinMaxExpr *mexpr = (MinMaxExpr *) expr; + Oid minmaxtype = mexpr->minmaxtype; + int32 typmod; + ListCell *arg; + + if (exprType((Node *) linitial(mexpr->args)) != minmaxtype) + return -1; + typmod = exprTypmod((Node *) linitial(mexpr->args)); + if (typmod < 0) + return -1; /* no point in trying harder */ + for_each_cell(arg, lnext(list_head(mexpr->args))) + { + Node *e = (Node *) lfirst(arg); + + if (exprType(e) != minmaxtype) + return -1; + if (exprTypmod(e) != typmod) + return -1; + } + return typmod; + } + break; + case T_NullIfExpr: + { + NullIfExpr *nexpr = (NullIfExpr *) expr; + + return exprTypmod((Node *) linitial(nexpr->args)); + } + break; + case T_CoerceToDomain: + return ((CoerceToDomain *) expr)->resulttypmod; + case T_CoerceToDomainValue: + return ((CoerceToDomainValue *) expr)->typeMod; + case T_SetToDefault: + return ((SetToDefault *) expr)->typeMod; + default: + break; + } + return -1; +} + +/* + * exprIsLengthCoercion + * Detect whether an expression tree is an application of a datatype's + * typmod-coercion function. Optionally extract the result's typmod. + * + * If coercedTypmod is not NULL, the typmod is stored there if the expression + * is a length-coercion function, else -1 is stored there. + * + * Note that a combined type-and-length coercion will be treated as a + * length coercion by this routine. */ bool -single_node(Node *node) +exprIsLengthCoercion(Node *expr, int32 *coercedTypmod) { - if (IsA(node, Const) || - IsA(node, Var) || - IsA(node, Param)) + if (coercedTypmod != NULL) + *coercedTypmod = -1; /* default result on failure */ + + /* + * Scalar-type length coercions are FuncExprs, array-type length coercions + * are ArrayCoerceExprs + */ + if (expr && IsA(expr, FuncExpr)) + { + FuncExpr *func = (FuncExpr *) expr; + int nargs; + Const *second_arg; + + /* + * If it didn't come from a coercion context, reject. + */ + if (func->funcformat != COERCE_EXPLICIT_CAST && + func->funcformat != COERCE_IMPLICIT_CAST) + return false; + + /* + * If it's not a two-argument or three-argument function with the + * second argument being an int4 constant, it can't have been created + * from a length coercion (it must be a type coercion, instead). + */ + nargs = list_length(func->args); + if (nargs < 2 || nargs > 3) + return false; + + second_arg = (Const *) lsecond(func->args); + if (!IsA(second_arg, Const) || + second_arg->consttype != INT4OID || + second_arg->constisnull) + return false; + + /* + * OK, it is indeed a length-coercion function. + */ + if (coercedTypmod != NULL) + *coercedTypmod = DatumGetInt32(second_arg->constvalue); + return true; - else + } + + if (expr && IsA(expr, ArrayCoerceExpr)) + { + ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) expr; + + /* It's not a length coercion unless there's a nondefault typmod */ + if (acoerce->resulttypmod < 0) + return false; + + /* + * OK, it is indeed a length-coercion expression. + */ + if (coercedTypmod != NULL) + *coercedTypmod = acoerce->resulttypmod; + + return true; + } + + return false; +} + +/* + * expression_returns_set + * Test whether an expression returns a set result. + * + * Because we use expression_tree_walker(), this can also be applied to + * whole targetlists; it'll produce TRUE if any one of the tlist items + * returns a set. + */ +bool +expression_returns_set(Node *clause) +{ + return expression_returns_set_walker(clause, NULL); +} + +static bool +expression_returns_set_walker(Node *node, void *context) +{ + if (node == NULL) return false; + if (IsA(node, FuncExpr)) + { + FuncExpr *expr = (FuncExpr *) node; + + if (expr->funcretset) + return true; + /* else fall through to check args */ + } + if (IsA(node, OpExpr)) + { + OpExpr *expr = (OpExpr *) node; + + if (expr->opretset) + return true; + /* else fall through to check args */ + } + + /* Avoid recursion for some cases that can't return a set */ + if (IsA(node, Aggref)) + return false; + if (IsA(node, DistinctExpr)) + return false; + if (IsA(node, ScalarArrayOpExpr)) + return false; + if (IsA(node, BoolExpr)) + return false; + if (IsA(node, SubLink)) + return false; + if (IsA(node, SubPlan)) + return false; + if (IsA(node, AlternativeSubPlan)) + return false; + if (IsA(node, ArrayExpr)) + return false; + if (IsA(node, RowExpr)) + return false; + if (IsA(node, RowCompareExpr)) + return false; + if (IsA(node, CoalesceExpr)) + return false; + if (IsA(node, MinMaxExpr)) + return false; + if (IsA(node, XmlExpr)) + return false; + if (IsA(node, NullIfExpr)) + return false; + + return expression_tree_walker(node, expression_returns_set_walker, + context); } -/***************************************************************************** - * VAR nodes - *****************************************************************************/ /* - * var_is_outer - * var_is_inner - * var_is_mat - * var_is_rel - * - * Returns t iff the var node corresponds to (respectively): - * the outer relation in a join - * the inner relation of a join - * a materialized relation - * a base relation (i.e., not an attribute reference, a variable from - * some lower join level, or a sort result) - * var node is an array reference + * Standard expression-tree walking support + * + * We used to have near-duplicate code in many different routines that + * understood how to recurse through an expression node tree. That was + * a pain to maintain, and we frequently had bugs due to some particular + * routine neglecting to support a particular node type. In most cases, + * these routines only actually care about certain node types, and don't + * care about other types except insofar as they have to recurse through + * non-primitive node types. Therefore, we now provide generic tree-walking + * logic to consolidate the redundant "boilerplate" code. There are + * two versions: expression_tree_walker() and expression_tree_mutator(). + */ + +/* + * expression_tree_walker() is designed to support routines that traverse + * a tree in a read-only fashion (although it will also work for routines + * that modify nodes in-place but never add/delete/replace nodes). + * A walker routine should look like this: + * + * bool my_walker (Node *node, my_struct *context) + * { + * if (node == NULL) + * return false; + * // check for nodes that special work is required for, eg: + * if (IsA(node, Var)) + * { + * ... do special actions for Var nodes + * } + * else if (IsA(node, ...)) + * { + * ... do special actions for other node types + * } + * // for any node type not specially processed, do: + * return expression_tree_walker(node, my_walker, (void *) context); + * } + * + * The "context" argument points to a struct that holds whatever context + * information the walker routine needs --- it can be used to return data + * gathered by the walker, too. This argument is not touched by + * expression_tree_walker, but it is passed down to recursive sub-invocations + * of my_walker. The tree walk is started from a setup routine that + * fills in the appropriate context struct, calls my_walker with the top-level + * node of the tree, and then examines the results. + * + * The walker routine should return "false" to continue the tree walk, or + * "true" to abort the walk and immediately return "true" to the top-level + * caller. This can be used to short-circuit the traversal if the walker + * has found what it came for. "false" is returned to the top-level caller + * iff no invocation of the walker returned "true". + * + * The node types handled by expression_tree_walker include all those + * normally found in target lists and qualifier clauses during the planning + * stage. In particular, it handles List nodes since a cnf-ified qual clause + * will have List structure at the top level, and it handles TargetEntry nodes + * so that a scan of a target list can be handled without additional code. + * Also, RangeTblRef, FromExpr, JoinExpr, and SetOperationStmt nodes are + * handled, so that query jointrees and setOperation trees can be processed + * without additional code. + * + * expression_tree_walker will handle SubLink nodes by recursing normally + * into the "testexpr" subtree (which is an expression belonging to the outer + * plan). It will also call the walker on the sub-Query node; however, when + * expression_tree_walker itself is called on a Query node, it does nothing + * and returns "false". The net effect is that unless the walker does + * something special at a Query node, sub-selects will not be visited during + * an expression tree walk. This is exactly the behavior wanted in many cases + * --- and for those walkers that do want to recurse into sub-selects, special + * behavior is typically needed anyway at the entry to a sub-select (such as + * incrementing a depth counter). A walker that wants to examine sub-selects + * should include code along the lines of: + * + * if (IsA(node, Query)) + * { + * adjust context for subquery; + * result = query_tree_walker((Query *) node, my_walker, context, + * 0); // adjust flags as needed + * restore context if needed; + * return result; + * } + * + * query_tree_walker is a convenience routine (see below) that calls the + * walker on all the expression subtrees of the given Query node. + * + * expression_tree_walker will handle SubPlan nodes by recursing normally + * into the "testexpr" and the "args" list (which are expressions belonging to + * the outer plan). It will not touch the completed subplan, however. Since + * there is no link to the original Query, it is not possible to recurse into + * subselects of an already-planned expression tree. This is OK for current + * uses, but may need to be revisited in future. + */ + +bool +expression_tree_walker(Node *node, + bool (*walker) (), + void *context) +{ + ListCell *temp; + + /* + * The walker has already visited the current node, and so we need only + * recurse into any sub-nodes it has. + * + * We assume that the walker is not interested in List nodes per se, so + * when we expect a List we just recurse directly to self without + * bothering to call the walker. + */ + if (node == NULL) + return false; + + /* Guard against stack overflow due to overly complex expressions */ + check_stack_depth(); + + switch (nodeTag(node)) + { + case T_Var: + case T_Const: + case T_Param: + case T_CoerceToDomainValue: + case T_CaseTestExpr: + case T_SetToDefault: + case T_CurrentOfExpr: + case T_RangeTblRef: + /* primitive node types with no expression subnodes */ + break; + case T_Aggref: + { + Aggref *expr = (Aggref *) node; + + /* recurse directly on List */ + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_ArrayRef: + { + ArrayRef *aref = (ArrayRef *) node; + + /* recurse directly for upper/lower array index lists */ + if (expression_tree_walker((Node *) aref->refupperindexpr, + walker, context)) + return true; + if (expression_tree_walker((Node *) aref->reflowerindexpr, + walker, context)) + return true; + /* walker must see the refexpr and refassgnexpr, however */ + if (walker(aref->refexpr, context)) + return true; + if (walker(aref->refassgnexpr, context)) + return true; + } + break; + case T_FuncExpr: + { + FuncExpr *expr = (FuncExpr *) node; + + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_OpExpr: + { + OpExpr *expr = (OpExpr *) node; + + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_DistinctExpr: + { + DistinctExpr *expr = (DistinctExpr *) node; + + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_ScalarArrayOpExpr: + { + ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node; + + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_BoolExpr: + { + BoolExpr *expr = (BoolExpr *) node; + + if (expression_tree_walker((Node *) expr->args, + walker, context)) + return true; + } + break; + case T_SubLink: + { + SubLink *sublink = (SubLink *) node; + + if (walker(sublink->testexpr, context)) + return true; + + /* + * Also invoke the walker on the sublink's Query node, so it + * can recurse into the sub-query if it wants to. + */ + return walker(sublink->subselect, context); + } + break; + case T_SubPlan: + { + SubPlan *subplan = (SubPlan *) node; + + /* recurse into the testexpr, but not into the Plan */ + if (walker(subplan->testexpr, context)) + return true; + /* also examine args list */ + if (expression_tree_walker((Node *) subplan->args, + walker, context)) + return true; + } + break; + case T_AlternativeSubPlan: + return walker(((AlternativeSubPlan *) node)->subplans, context); + case T_FieldSelect: + return walker(((FieldSelect *) node)->arg, context); + case T_FieldStore: + { + FieldStore *fstore = (FieldStore *) node; + + if (walker(fstore->arg, context)) + return true; + if (walker(fstore->newvals, context)) + return true; + } + break; + case T_RelabelType: + return walker(((RelabelType *) node)->arg, context); + case T_CoerceViaIO: + return walker(((CoerceViaIO *) node)->arg, context); + case T_ArrayCoerceExpr: + return walker(((ArrayCoerceExpr *) node)->arg, context); + case T_ConvertRowtypeExpr: + return walker(((ConvertRowtypeExpr *) node)->arg, context); + case T_CaseExpr: + { + CaseExpr *caseexpr = (CaseExpr *) node; + + if (walker(caseexpr->arg, context)) + return true; + /* we assume walker doesn't care about CaseWhens, either */ + foreach(temp, caseexpr->args) + { + CaseWhen *when = (CaseWhen *) lfirst(temp); + + Assert(IsA(when, CaseWhen)); + if (walker(when->expr, context)) + return true; + if (walker(when->result, context)) + return true; + } + if (walker(caseexpr->defresult, context)) + return true; + } + break; + case T_ArrayExpr: + return walker(((ArrayExpr *) node)->elements, context); + case T_RowExpr: + return walker(((RowExpr *) node)->args, context); + case T_RowCompareExpr: + { + RowCompareExpr *rcexpr = (RowCompareExpr *) node; + + if (walker(rcexpr->largs, context)) + return true; + if (walker(rcexpr->rargs, context)) + return true; + } + break; + case T_CoalesceExpr: + return walker(((CoalesceExpr *) node)->args, context); + case T_MinMaxExpr: + return walker(((MinMaxExpr *) node)->args, context); + case T_XmlExpr: + { + XmlExpr *xexpr = (XmlExpr *) node; + + if (walker(xexpr->named_args, context)) + return true; + /* we assume walker doesn't care about arg_names */ + if (walker(xexpr->args, context)) + return true; + } + break; + case T_NullIfExpr: + return walker(((NullIfExpr *) node)->args, context); + case T_NullTest: + return walker(((NullTest *) node)->arg, context); + case T_BooleanTest: + return walker(((BooleanTest *) node)->arg, context); + case T_CoerceToDomain: + return walker(((CoerceToDomain *) node)->arg, context); + case T_TargetEntry: + return walker(((TargetEntry *) node)->expr, context); + case T_Query: + /* Do nothing with a sub-Query, per discussion above */ + break; + case T_List: + foreach(temp, (List *) node) + { + if (walker((Node *) lfirst(temp), context)) + return true; + } + break; + case T_FromExpr: + { + FromExpr *from = (FromExpr *) node; + + if (walker(from->fromlist, context)) + return true; + if (walker(from->quals, context)) + return true; + } + break; + case T_JoinExpr: + { + JoinExpr *join = (JoinExpr *) node; + + if (walker(join->larg, context)) + return true; + if (walker(join->rarg, context)) + return true; + if (walker(join->quals, context)) + return true; + + /* + * alias clause, using list are deemed uninteresting. + */ + } + break; + case T_SetOperationStmt: + { + SetOperationStmt *setop = (SetOperationStmt *) node; + + if (walker(setop->larg, context)) + return true; + if (walker(setop->rarg, context)) + return true; + + /* groupClauses are deemed uninteresting */ + } + break; + case T_FlattenedSubLink: + { + FlattenedSubLink *fslink = (FlattenedSubLink *) node; + + if (expression_tree_walker((Node *) fslink->quals, + walker, context)) + return true; + } + break; + case T_AppendRelInfo: + { + AppendRelInfo *appinfo = (AppendRelInfo *) node; + + if (expression_tree_walker((Node *) appinfo->translated_vars, + walker, context)) + return true; + } + break; + default: + elog(ERROR, "unrecognized node type: %d", + (int) nodeTag(node)); + break; + } + return false; +} + +/* + * query_tree_walker --- initiate a walk of a Query's expressions + * + * This routine exists just to reduce the number of places that need to know + * where all the expression subtrees of a Query are. Note it can be used + * for starting a walk at top level of a Query regardless of whether the + * walker intends to descend into subqueries. It is also useful for + * descending into subqueries within a walker. * + * Some callers want to suppress visitation of certain items in the sub-Query, + * typically because they need to process them specially, or don't actually + * want to recurse into subqueries. This is supported by the flags argument, + * which is the bitwise OR of flag values to suppress visitation of + * indicated items. (More flag bits may be added as needed.) */ bool -var_is_outer(Var *var) +query_tree_walker(Query *query, + bool (*walker) (), + void *context, + int flags) { - return (bool) (var->varno == OUTER); + Assert(query != NULL && IsA(query, Query)); + + if (walker((Node *) query->targetList, context)) + return true; + if (walker((Node *) query->returningList, context)) + return true; + if (walker((Node *) query->jointree, context)) + return true; + if (walker(query->setOperations, context)) + return true; + if (walker(query->havingQual, context)) + return true; + if (walker(query->limitOffset, context)) + return true; + if (walker(query->limitCount, context)) + return true; + if (range_table_walker(query->rtable, walker, context, flags)) + return true; + return false; } -static bool -var_is_inner(Var *var) +/* + * range_table_walker is just the part of query_tree_walker that scans + * a query's rangetable. This is split out since it can be useful on + * its own. + */ +bool +range_table_walker(List *rtable, + bool (*walker) (), + void *context, + int flags) { - return (bool) (var->varno == INNER); + ListCell *rt; + + foreach(rt, rtable) + { + RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt); + + switch (rte->rtekind) + { + case RTE_RELATION: + case RTE_SPECIAL: + /* nothing to do */ + break; + case RTE_SUBQUERY: + if (!(flags & QTW_IGNORE_RT_SUBQUERIES)) + if (walker(rte->subquery, context)) + return true; + break; + case RTE_JOIN: + if (!(flags & QTW_IGNORE_JOINALIASES)) + if (walker(rte->joinaliasvars, context)) + return true; + break; + case RTE_FUNCTION: + if (walker(rte->funcexpr, context)) + return true; + break; + case RTE_VALUES: + if (walker(rte->values_lists, context)) + return true; + break; + } + } + return false; } + +/* + * expression_tree_mutator() is designed to support routines that make a + * modified copy of an expression tree, with some nodes being added, + * removed, or replaced by new subtrees. The original tree is (normally) + * not changed. Each recursion level is responsible for returning a copy of + * (or appropriately modified substitute for) the subtree it is handed. + * A mutator routine should look like this: + * + * Node * my_mutator (Node *node, my_struct *context) + * { + * if (node == NULL) + * return NULL; + * // check for nodes that special work is required for, eg: + * if (IsA(node, Var)) + * { + * ... create and return modified copy of Var node + * } + * else if (IsA(node, ...)) + * { + * ... do special transformations of other node types + * } + * // for any node type not specially processed, do: + * return expression_tree_mutator(node, my_mutator, (void *) context); + * } + * + * The "context" argument points to a struct that holds whatever context + * information the mutator routine needs --- it can be used to return extra + * data gathered by the mutator, too. This argument is not touched by + * expression_tree_mutator, but it is passed down to recursive sub-invocations + * of my_mutator. The tree walk is started from a setup routine that + * fills in the appropriate context struct, calls my_mutator with the + * top-level node of the tree, and does any required post-processing. + * + * Each level of recursion must return an appropriately modified Node. + * If expression_tree_mutator() is called, it will make an exact copy + * of the given Node, but invoke my_mutator() to copy the sub-node(s) + * of that Node. In this way, my_mutator() has full control over the + * copying process but need not directly deal with expression trees + * that it has no interest in. + * + * Just as for expression_tree_walker, the node types handled by + * expression_tree_mutator include all those normally found in target lists + * and qualifier clauses during the planning stage. + * + * expression_tree_mutator will handle SubLink nodes by recursing normally + * into the "testexpr" subtree (which is an expression belonging to the outer + * plan). It will also call the mutator on the sub-Query node; however, when + * expression_tree_mutator itself is called on a Query node, it does nothing + * and returns the unmodified Query node. The net effect is that unless the + * mutator does something special at a Query node, sub-selects will not be + * visited or modified; the original sub-select will be linked to by the new + * SubLink node. Mutators that want to descend into sub-selects will usually + * do so by recognizing Query nodes and calling query_tree_mutator (below). + * + * expression_tree_mutator will handle a SubPlan node by recursing into the + * "testexpr" and the "args" list (which belong to the outer plan), but it + * will simply copy the link to the inner plan, since that's typically what + * expression tree mutators want. A mutator that wants to modify the subplan + * can force appropriate behavior by recognizing SubPlan expression nodes + * and doing the right thing. + */ + +Node * +expression_tree_mutator(Node *node, + Node *(*mutator) (), + void *context) +{ + /* + * The mutator has already decided not to modify the current node, but we + * must call the mutator for any sub-nodes. + */ + +#define FLATCOPY(newnode, node, nodetype) \ + ( (newnode) = (nodetype *) palloc(sizeof(nodetype)), \ + memcpy((newnode), (node), sizeof(nodetype)) ) + +#define CHECKFLATCOPY(newnode, node, nodetype) \ + ( AssertMacro(IsA((node), nodetype)), \ + (newnode) = (nodetype *) palloc(sizeof(nodetype)), \ + memcpy((newnode), (node), sizeof(nodetype)) ) + +#define MUTATE(newfield, oldfield, fieldtype) \ + ( (newfield) = (fieldtype) mutator((Node *) (oldfield), context) ) + + if (node == NULL) + return NULL; + + /* Guard against stack overflow due to overly complex expressions */ + check_stack_depth(); + + switch (nodeTag(node)) + { + /* + * Primitive node types with no expression subnodes. Var and + * Const are frequent enough to deserve special cases, the others + * we just use copyObject for. + */ + case T_Var: + { + Var *var = (Var *) node; + Var *newnode; + + FLATCOPY(newnode, var, Var); + return (Node *) newnode; + } + break; + case T_Const: + { + Const *oldnode = (Const *) node; + Const *newnode; + + FLATCOPY(newnode, oldnode, Const); + /* XXX we don't bother with datumCopy; should we? */ + return (Node *) newnode; + } + break; + case T_Param: + case T_CoerceToDomainValue: + case T_CaseTestExpr: + case T_SetToDefault: + case T_CurrentOfExpr: + case T_RangeTblRef: + return (Node *) copyObject(node); + case T_Aggref: + { + Aggref *aggref = (Aggref *) node; + Aggref *newnode; + + FLATCOPY(newnode, aggref, Aggref); + MUTATE(newnode->args, aggref->args, List *); + return (Node *) newnode; + } + break; + case T_ArrayRef: + { + ArrayRef *arrayref = (ArrayRef *) node; + ArrayRef *newnode; + + FLATCOPY(newnode, arrayref, ArrayRef); + MUTATE(newnode->refupperindexpr, arrayref->refupperindexpr, + List *); + MUTATE(newnode->reflowerindexpr, arrayref->reflowerindexpr, + List *); + MUTATE(newnode->refexpr, arrayref->refexpr, + Expr *); + MUTATE(newnode->refassgnexpr, arrayref->refassgnexpr, + Expr *); + return (Node *) newnode; + } + break; + case T_FuncExpr: + { + FuncExpr *expr = (FuncExpr *) node; + FuncExpr *newnode; + + FLATCOPY(newnode, expr, FuncExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_OpExpr: + { + OpExpr *expr = (OpExpr *) node; + OpExpr *newnode; + + FLATCOPY(newnode, expr, OpExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_DistinctExpr: + { + DistinctExpr *expr = (DistinctExpr *) node; + DistinctExpr *newnode; + + FLATCOPY(newnode, expr, DistinctExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_ScalarArrayOpExpr: + { + ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node; + ScalarArrayOpExpr *newnode; + + FLATCOPY(newnode, expr, ScalarArrayOpExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_BoolExpr: + { + BoolExpr *expr = (BoolExpr *) node; + BoolExpr *newnode; + + FLATCOPY(newnode, expr, BoolExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_SubLink: + { + SubLink *sublink = (SubLink *) node; + SubLink *newnode; + + FLATCOPY(newnode, sublink, SubLink); + MUTATE(newnode->testexpr, sublink->testexpr, Node *); + + /* + * Also invoke the mutator on the sublink's Query node, so it + * can recurse into the sub-query if it wants to. + */ + MUTATE(newnode->subselect, sublink->subselect, Node *); + return (Node *) newnode; + } + break; + case T_SubPlan: + { + SubPlan *subplan = (SubPlan *) node; + SubPlan *newnode; + + FLATCOPY(newnode, subplan, SubPlan); + /* transform testexpr */ + MUTATE(newnode->testexpr, subplan->testexpr, Node *); + /* transform args list (params to be passed to subplan) */ + MUTATE(newnode->args, subplan->args, List *); + /* but not the sub-Plan itself, which is referenced as-is */ + return (Node *) newnode; + } + break; + case T_AlternativeSubPlan: + { + AlternativeSubPlan *asplan = (AlternativeSubPlan *) node; + AlternativeSubPlan *newnode; + + FLATCOPY(newnode, asplan, AlternativeSubPlan); + MUTATE(newnode->subplans, asplan->subplans, List *); + return (Node *) newnode; + } + break; + case T_FieldSelect: + { + FieldSelect *fselect = (FieldSelect *) node; + FieldSelect *newnode; + + FLATCOPY(newnode, fselect, FieldSelect); + MUTATE(newnode->arg, fselect->arg, Expr *); + return (Node *) newnode; + } + break; + case T_FieldStore: + { + FieldStore *fstore = (FieldStore *) node; + FieldStore *newnode; + + FLATCOPY(newnode, fstore, FieldStore); + MUTATE(newnode->arg, fstore->arg, Expr *); + MUTATE(newnode->newvals, fstore->newvals, List *); + newnode->fieldnums = list_copy(fstore->fieldnums); + return (Node *) newnode; + } + break; + case T_RelabelType: + { + RelabelType *relabel = (RelabelType *) node; + RelabelType *newnode; + + FLATCOPY(newnode, relabel, RelabelType); + MUTATE(newnode->arg, relabel->arg, Expr *); + return (Node *) newnode; + } + break; + case T_CoerceViaIO: + { + CoerceViaIO *iocoerce = (CoerceViaIO *) node; + CoerceViaIO *newnode; + + FLATCOPY(newnode, iocoerce, CoerceViaIO); + MUTATE(newnode->arg, iocoerce->arg, Expr *); + return (Node *) newnode; + } + break; + case T_ArrayCoerceExpr: + { + ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node; + ArrayCoerceExpr *newnode; + + FLATCOPY(newnode, acoerce, ArrayCoerceExpr); + MUTATE(newnode->arg, acoerce->arg, Expr *); + return (Node *) newnode; + } + break; + case T_ConvertRowtypeExpr: + { + ConvertRowtypeExpr *convexpr = (ConvertRowtypeExpr *) node; + ConvertRowtypeExpr *newnode; + + FLATCOPY(newnode, convexpr, ConvertRowtypeExpr); + MUTATE(newnode->arg, convexpr->arg, Expr *); + return (Node *) newnode; + } + break; + case T_CaseExpr: + { + CaseExpr *caseexpr = (CaseExpr *) node; + CaseExpr *newnode; + + FLATCOPY(newnode, caseexpr, CaseExpr); + MUTATE(newnode->arg, caseexpr->arg, Expr *); + MUTATE(newnode->args, caseexpr->args, List *); + MUTATE(newnode->defresult, caseexpr->defresult, Expr *); + return (Node *) newnode; + } + break; + case T_CaseWhen: + { + CaseWhen *casewhen = (CaseWhen *) node; + CaseWhen *newnode; + + FLATCOPY(newnode, casewhen, CaseWhen); + MUTATE(newnode->expr, casewhen->expr, Expr *); + MUTATE(newnode->result, casewhen->result, Expr *); + return (Node *) newnode; + } + break; + case T_ArrayExpr: + { + ArrayExpr *arrayexpr = (ArrayExpr *) node; + ArrayExpr *newnode; + + FLATCOPY(newnode, arrayexpr, ArrayExpr); + MUTATE(newnode->elements, arrayexpr->elements, List *); + return (Node *) newnode; + } + break; + case T_RowExpr: + { + RowExpr *rowexpr = (RowExpr *) node; + RowExpr *newnode; + + FLATCOPY(newnode, rowexpr, RowExpr); + MUTATE(newnode->args, rowexpr->args, List *); + return (Node *) newnode; + } + break; + case T_RowCompareExpr: + { + RowCompareExpr *rcexpr = (RowCompareExpr *) node; + RowCompareExpr *newnode; + + FLATCOPY(newnode, rcexpr, RowCompareExpr); + MUTATE(newnode->largs, rcexpr->largs, List *); + MUTATE(newnode->rargs, rcexpr->rargs, List *); + return (Node *) newnode; + } + break; + case T_CoalesceExpr: + { + CoalesceExpr *coalesceexpr = (CoalesceExpr *) node; + CoalesceExpr *newnode; + + FLATCOPY(newnode, coalesceexpr, CoalesceExpr); + MUTATE(newnode->args, coalesceexpr->args, List *); + return (Node *) newnode; + } + break; + case T_MinMaxExpr: + { + MinMaxExpr *minmaxexpr = (MinMaxExpr *) node; + MinMaxExpr *newnode; + + FLATCOPY(newnode, minmaxexpr, MinMaxExpr); + MUTATE(newnode->args, minmaxexpr->args, List *); + return (Node *) newnode; + } + break; + case T_XmlExpr: + { + XmlExpr *xexpr = (XmlExpr *) node; + XmlExpr *newnode; + + FLATCOPY(newnode, xexpr, XmlExpr); + MUTATE(newnode->named_args, xexpr->named_args, List *); + /* assume mutator does not care about arg_names */ + MUTATE(newnode->args, xexpr->args, List *); + return (Node *) newnode; + } + break; + case T_NullIfExpr: + { + NullIfExpr *expr = (NullIfExpr *) node; + NullIfExpr *newnode; + + FLATCOPY(newnode, expr, NullIfExpr); + MUTATE(newnode->args, expr->args, List *); + return (Node *) newnode; + } + break; + case T_NullTest: + { + NullTest *ntest = (NullTest *) node; + NullTest *newnode; + + FLATCOPY(newnode, ntest, NullTest); + MUTATE(newnode->arg, ntest->arg, Expr *); + return (Node *) newnode; + } + break; + case T_BooleanTest: + { + BooleanTest *btest = (BooleanTest *) node; + BooleanTest *newnode; + + FLATCOPY(newnode, btest, BooleanTest); + MUTATE(newnode->arg, btest->arg, Expr *); + return (Node *) newnode; + } + break; + case T_CoerceToDomain: + { + CoerceToDomain *ctest = (CoerceToDomain *) node; + CoerceToDomain *newnode; + + FLATCOPY(newnode, ctest, CoerceToDomain); + MUTATE(newnode->arg, ctest->arg, Expr *); + return (Node *) newnode; + } + break; + case T_TargetEntry: + { + TargetEntry *targetentry = (TargetEntry *) node; + TargetEntry *newnode; + + FLATCOPY(newnode, targetentry, TargetEntry); + MUTATE(newnode->expr, targetentry->expr, Expr *); + return (Node *) newnode; + } + break; + case T_Query: + /* Do nothing with a sub-Query, per discussion above */ + return node; + case T_List: + { + /* + * We assume the mutator isn't interested in the list nodes + * per se, so just invoke it on each list element. NOTE: this + * would fail badly on a list with integer elements! + */ + List *resultlist; + ListCell *temp; + + resultlist = NIL; + foreach(temp, (List *) node) + { + resultlist = lappend(resultlist, + mutator((Node *) lfirst(temp), + context)); + } + return (Node *) resultlist; + } + break; + case T_FromExpr: + { + FromExpr *from = (FromExpr *) node; + FromExpr *newnode; + + FLATCOPY(newnode, from, FromExpr); + MUTATE(newnode->fromlist, from->fromlist, List *); + MUTATE(newnode->quals, from->quals, Node *); + return (Node *) newnode; + } + break; + case T_JoinExpr: + { + JoinExpr *join = (JoinExpr *) node; + JoinExpr *newnode; + + FLATCOPY(newnode, join, JoinExpr); + MUTATE(newnode->larg, join->larg, Node *); + MUTATE(newnode->rarg, join->rarg, Node *); + MUTATE(newnode->quals, join->quals, Node *); + /* We do not mutate alias or using by default */ + return (Node *) newnode; + } + break; + case T_SetOperationStmt: + { + SetOperationStmt *setop = (SetOperationStmt *) node; + SetOperationStmt *newnode; + + FLATCOPY(newnode, setop, SetOperationStmt); + MUTATE(newnode->larg, setop->larg, Node *); + MUTATE(newnode->rarg, setop->rarg, Node *); + /* We do not mutate groupClauses by default */ + return (Node *) newnode; + } + break; + case T_FlattenedSubLink: + { + FlattenedSubLink *fslink = (FlattenedSubLink *) node; + FlattenedSubLink *newnode; + + FLATCOPY(newnode, fslink, FlattenedSubLink); + /* Assume we need not copy the relids bitmapsets */ + MUTATE(newnode->quals, fslink->quals, Expr *); + return (Node *) newnode; + } + break; + case T_AppendRelInfo: + { + AppendRelInfo *appinfo = (AppendRelInfo *) node; + AppendRelInfo *newnode; + + FLATCOPY(newnode, appinfo, AppendRelInfo); + MUTATE(newnode->translated_vars, appinfo->translated_vars, List *); + return (Node *) newnode; + } + break; + default: + elog(ERROR, "unrecognized node type: %d", + (int) nodeTag(node)); + break; + } + /* can't get here, but keep compiler happy */ + return NULL; +} + + +/* + * query_tree_mutator --- initiate modification of a Query's expressions + * + * This routine exists just to reduce the number of places that need to know + * where all the expression subtrees of a Query are. Note it can be used + * for starting a walk at top level of a Query regardless of whether the + * mutator intends to descend into subqueries. It is also useful for + * descending into subqueries within a mutator. + * + * Some callers want to suppress mutating of certain items in the Query, + * typically because they need to process them specially, or don't actually + * want to recurse into subqueries. This is supported by the flags argument, + * which is the bitwise OR of flag values to suppress mutating of + * indicated items. (More flag bits may be added as needed.) + * + * Normally the Query node itself is copied, but some callers want it to be + * modified in-place; they must pass QTW_DONT_COPY_QUERY in flags. All + * modified substructure is safely copied in any case. + */ +Query * +query_tree_mutator(Query *query, + Node *(*mutator) (), + void *context, + int flags) +{ + Assert(query != NULL && IsA(query, Query)); + + if (!(flags & QTW_DONT_COPY_QUERY)) + { + Query *newquery; + + FLATCOPY(newquery, query, Query); + query = newquery; + } + + MUTATE(query->targetList, query->targetList, List *); + MUTATE(query->returningList, query->returningList, List *); + MUTATE(query->jointree, query->jointree, FromExpr *); + MUTATE(query->setOperations, query->setOperations, Node *); + MUTATE(query->havingQual, query->havingQual, Node *); + MUTATE(query->limitOffset, query->limitOffset, Node *); + MUTATE(query->limitCount, query->limitCount, Node *); + query->rtable = range_table_mutator(query->rtable, + mutator, context, flags); + return query; +} + +/* + * range_table_mutator is just the part of query_tree_mutator that processes + * a query's rangetable. This is split out since it can be useful on + * its own. + */ +List * +range_table_mutator(List *rtable, + Node *(*mutator) (), + void *context, + int flags) +{ + List *newrt = NIL; + ListCell *rt; + + foreach(rt, rtable) + { + RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt); + RangeTblEntry *newrte; + + FLATCOPY(newrte, rte, RangeTblEntry); + switch (rte->rtekind) + { + case RTE_RELATION: + case RTE_SPECIAL: + /* we don't bother to copy eref, aliases, etc; OK? */ + break; + case RTE_SUBQUERY: + if (!(flags & QTW_IGNORE_RT_SUBQUERIES)) + { + CHECKFLATCOPY(newrte->subquery, rte->subquery, Query); + MUTATE(newrte->subquery, newrte->subquery, Query *); + } + else + { + /* else, copy RT subqueries as-is */ + newrte->subquery = copyObject(rte->subquery); + } + break; + case RTE_JOIN: + if (!(flags & QTW_IGNORE_JOINALIASES)) + MUTATE(newrte->joinaliasvars, rte->joinaliasvars, List *); + else + { + /* else, copy join aliases as-is */ + newrte->joinaliasvars = copyObject(rte->joinaliasvars); + } + break; + case RTE_FUNCTION: + MUTATE(newrte->funcexpr, rte->funcexpr, Node *); + break; + case RTE_VALUES: + MUTATE(newrte->values_lists, rte->values_lists, List *); + break; + } + newrt = lappend(newrt, newrte); + } + return newrt; +} + +/* + * query_or_expression_tree_walker --- hybrid form + * + * This routine will invoke query_tree_walker if called on a Query node, + * else will invoke the walker directly. This is a useful way of starting + * the recursion when the walker's normal change of state is not appropriate + * for the outermost Query node. + */ bool -var_is_rel(Var *var) +query_or_expression_tree_walker(Node *node, + bool (*walker) (), + void *context, + int flags) { - return (bool) - !(var_is_inner(var) || var_is_outer(var)); + if (node && IsA(node, Query)) + return query_tree_walker((Query *) node, + walker, + context, + flags); + else + return walker(node, context); +} + +/* + * query_or_expression_tree_mutator --- hybrid form + * + * This routine will invoke query_tree_mutator if called on a Query node, + * else will invoke the mutator directly. This is a useful way of starting + * the recursion when the mutator's normal change of state is not appropriate + * for the outermost Query node. + */ +Node * +query_or_expression_tree_mutator(Node *node, + Node *(*mutator) (), + void *context, + int flags) +{ + if (node && IsA(node, Query)) + return (Node *) query_tree_mutator((Query *) node, + mutator, + context, + flags); + else + return mutator(node, context); } |