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postgres/src/backend/parser/parse_expr.c
Tom Lane 455891bf96 Code review for UPDATE tab SET col = DEFAULT patch ... whack it around 
so it has some chance of working in rules ...
2003-07-03 16:34:26 +00:00

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/*-------------------------------------------------------------------------
*
* parse_expr.c
* handle expressions in parser
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.155 2003/07/03 16:34:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "commands/dbcommands.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/params.h"
#include "nodes/plannodes.h"
#include "parser/analyze.h"
#include "parser/gramparse.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
int max_expr_depth = DEFAULT_MAX_EXPR_DEPTH;
static int expr_depth_counter = 0;
bool Transform_null_equals = false;
static Node *typecast_expression(ParseState *pstate, Node *expr,
TypeName *typename);
static Node *transformColumnRef(ParseState *pstate, ColumnRef *cref);
static Node *transformIndirection(ParseState *pstate, Node *basenode,
List *indirection);
/*
* Initialize for parsing a new query.
*
* We reset the expression depth counter here, in case it was left nonzero
* due to elog()'ing out of the last parsing operation.
*/
void
parse_expr_init(void)
{
expr_depth_counter = 0;
}
/*
* transformExpr -
* Analyze and transform expressions. Type checking and type casting is
* done here. The optimizer and the executor cannot handle the original
* (raw) expressions collected by the parse tree. Hence the transformation
* here.
*
* NOTE: there are various cases in which this routine will get applied to
* an already-transformed expression. Some examples:
* 1. At least one construct (BETWEEN/AND) puts the same nodes
* into two branches of the parse tree; hence, some nodes
* are transformed twice.
* 2. Another way it can happen is that coercion of an operator or
* function argument to the required type (via coerce_type())
* can apply transformExpr to an already-transformed subexpression.
* An example here is "SELECT count(*) + 1.0 FROM table".
* While it might be possible to eliminate these cases, the path of
* least resistance so far has been to ensure that transformExpr() does
* no damage if applied to an already-transformed tree. This is pretty
* easy for cases where the transformation replaces one node type with
* another, such as A_Const => Const; we just do nothing when handed
* a Const. More care is needed for node types that are used as both
* input and output of transformExpr; see SubLink for example.
*/
Node *
transformExpr(ParseState *pstate, Node *expr)
{
Node *result = NULL;
if (expr == NULL)
return NULL;
/*
* Guard against an overly complex expression leading to coredump due
* to stack overflow here, or in later recursive routines that
* traverse expression trees. Note that this is very unlikely to
* happen except with pathological queries; but we don't want someone
* to be able to crash the backend quite that easily...
*/
if (++expr_depth_counter > max_expr_depth)
elog(ERROR, "Expression too complex: nesting depth exceeds max_expr_depth = %d",
max_expr_depth);
switch (nodeTag(expr))
{
case T_ColumnRef:
{
result = transformColumnRef(pstate, (ColumnRef *) expr);
break;
}
case T_ParamRef:
{
ParamRef *pref = (ParamRef *) expr;
int paramno = pref->number;
ParseState *toppstate;
Param *param;
List *fields;
/*
* Find topmost ParseState, which is where paramtype info
* lives.
*/
toppstate = pstate;
while (toppstate->parentParseState != NULL)
toppstate = toppstate->parentParseState;
/* Check parameter number is in range */
if (paramno <= 0) /* probably can't happen? */
elog(ERROR, "Parameter '$%d' is out of range",
paramno);
if (paramno > toppstate->p_numparams)
{
if (!toppstate->p_variableparams)
elog(ERROR, "Parameter '$%d' is out of range",
paramno);
/* Okay to enlarge param array */
if (toppstate->p_paramtypes)
toppstate->p_paramtypes =
(Oid *) repalloc(toppstate->p_paramtypes,
paramno * sizeof(Oid));
else
toppstate->p_paramtypes =
(Oid *) palloc(paramno * sizeof(Oid));
/* Zero out the previously-unreferenced slots */
MemSet(toppstate->p_paramtypes + toppstate->p_numparams,
0,
(paramno - toppstate->p_numparams) * sizeof(Oid));
toppstate->p_numparams = paramno;
}
if (toppstate->p_variableparams)
{
/* If not seen before, initialize to UNKNOWN type */
if (toppstate->p_paramtypes[paramno-1] == InvalidOid)
toppstate->p_paramtypes[paramno-1] = UNKNOWNOID;
}
param = makeNode(Param);
param->paramkind = PARAM_NUM;
param->paramid = (AttrNumber) paramno;
param->paramtype = toppstate->p_paramtypes[paramno-1];
result = (Node *) param;
/* handle qualification, if any */
foreach(fields, pref->fields)
{
result = ParseFuncOrColumn(pstate,
makeList1(lfirst(fields)),
makeList1(result),
false, false, true);
}
/* handle subscripts, if any */
result = transformIndirection(pstate, result,
pref->indirection);
break;
}
case T_A_Const:
{
A_Const *con = (A_Const *) expr;
Value *val = &con->val;
result = (Node *) make_const(val);
if (con->typename != NULL)
result = typecast_expression(pstate, result,
con->typename);
break;
}
case T_ExprFieldSelect:
{
ExprFieldSelect *efs = (ExprFieldSelect *) expr;
List *fields;
result = transformExpr(pstate, efs->arg);
/* handle qualification, if any */
foreach(fields, efs->fields)
{
result = ParseFuncOrColumn(pstate,
makeList1(lfirst(fields)),
makeList1(result),
false, false, true);
}
/* handle subscripts, if any */
result = transformIndirection(pstate, result,
efs->indirection);
break;
}
case T_TypeCast:
{
TypeCast *tc = (TypeCast *) expr;
Node *arg = transformExpr(pstate, tc->arg);
result = typecast_expression(pstate, arg, tc->typename);
break;
}
case T_A_Expr:
{
A_Expr *a = (A_Expr *) expr;
switch (a->kind)
{
case AEXPR_OP:
{
/*
* Special-case "foo = NULL" and "NULL = foo"
* for compatibility with standards-broken
* products (like Microsoft's). Turn these
* into IS NULL exprs.
*/
if (Transform_null_equals &&
length(a->name) == 1 &&
strcmp(strVal(lfirst(a->name)), "=") == 0 &&
(exprIsNullConstant(a->lexpr) ||
exprIsNullConstant(a->rexpr)))
{
NullTest *n = makeNode(NullTest);
n->nulltesttype = IS_NULL;
if (exprIsNullConstant(a->lexpr))
n->arg = (Expr *) a->rexpr;
else
n->arg = (Expr *) a->lexpr;
result = transformExpr(pstate,
(Node *) n);
}
else
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
result = (Node *) make_op(pstate,
a->name,
lexpr,
rexpr);
}
}
break;
case AEXPR_AND:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
lexpr = coerce_to_boolean(pstate, lexpr, "AND");
rexpr = coerce_to_boolean(pstate, rexpr, "AND");
result = (Node *) makeBoolExpr(AND_EXPR,
makeList2(lexpr,
rexpr));
}
break;
case AEXPR_OR:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
lexpr = coerce_to_boolean(pstate, lexpr, "OR");
rexpr = coerce_to_boolean(pstate, rexpr, "OR");
result = (Node *) makeBoolExpr(OR_EXPR,
makeList2(lexpr,
rexpr));
}
break;
case AEXPR_NOT:
{
Node *rexpr = transformExpr(pstate,
a->rexpr);
rexpr = coerce_to_boolean(pstate, rexpr, "NOT");
result = (Node *) makeBoolExpr(NOT_EXPR,
makeList1(rexpr));
}
break;
case AEXPR_OP_ANY:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
result = (Node *) make_scalar_array_op(pstate,
a->name,
true,
lexpr,
rexpr);
}
break;
case AEXPR_OP_ALL:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
result = (Node *) make_scalar_array_op(pstate,
a->name,
false,
lexpr,
rexpr);
}
break;
case AEXPR_DISTINCT:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
result = (Node *) make_op(pstate,
a->name,
lexpr,
rexpr);
if (((OpExpr *) result)->opresulttype != BOOLOID)
elog(ERROR, "IS DISTINCT FROM requires = operator to yield boolean");
/*
* We rely on DistinctExpr and OpExpr being same struct
*/
NodeSetTag(result, T_DistinctExpr);
}
break;
case AEXPR_NULLIF:
{
Node *lexpr = transformExpr(pstate,
a->lexpr);
Node *rexpr = transformExpr(pstate,
a->rexpr);
result = (Node *) make_op(pstate,
a->name,
lexpr,
rexpr);
if (((OpExpr *) result)->opresulttype != BOOLOID)
elog(ERROR, "NULLIF requires = operator to yield boolean");
/*
* We rely on NullIfExpr and OpExpr being same struct
*/
NodeSetTag(result, T_NullIfExpr);
}
break;
case AEXPR_OF:
{
/*
* Checking an expression for match to type.
* Will result in a boolean constant node.
*/
List *telem;
A_Const *n;
Oid ltype,
rtype;
bool matched = FALSE;
Node *lexpr = transformExpr(pstate,
a->lexpr);
ltype = exprType(lexpr);
foreach(telem, (List *) a->rexpr)
{
rtype = LookupTypeName(lfirst(telem));
matched = (rtype == ltype);
if (matched)
break;
}
/*
* Expect two forms: equals or not equals.
* Flip the sense of the result for not
* equals.
*/
if (strcmp(strVal(lfirst(a->name)), "!=") == 0)
matched = (!matched);
n = makeNode(A_Const);
n->val.type = T_String;
n->val.val.str = (matched ? "t" : "f");
n->typename = SystemTypeName("bool");
result = transformExpr(pstate, (Node *) n);
}
break;
}
break;
}
case T_FuncCall:
{
FuncCall *fn = (FuncCall *) expr;
List *targs;
List *args;
/*
* Transform the list of arguments. We use a shallow
* list copy and then transform-in-place to avoid O(N^2)
* behavior from repeated lappend's.
*/
targs = listCopy(fn->args);
foreach(args, targs)
{
lfirst(args) = transformExpr(pstate,
(Node *) lfirst(args));
}
result = ParseFuncOrColumn(pstate,
fn->funcname,
targs,
fn->agg_star,
fn->agg_distinct,
false);
break;
}
case T_SubLink:
{
SubLink *sublink = (SubLink *) expr;
List *qtrees;
Query *qtree;
/* If we already transformed this node, do nothing */
if (IsA(sublink->subselect, Query))
{
result = expr;
break;
}
pstate->p_hasSubLinks = true;
qtrees = parse_sub_analyze(sublink->subselect, pstate);
if (length(qtrees) != 1)
elog(ERROR, "Bad query in subselect");
qtree = (Query *) lfirst(qtrees);
if (qtree->commandType != CMD_SELECT ||
qtree->resultRelation != 0)
elog(ERROR, "Bad query in subselect");
sublink->subselect = (Node *) qtree;
if (sublink->subLinkType == EXISTS_SUBLINK)
{
/*
* EXISTS needs no lefthand or combining operator.
* These fields should be NIL already, but make sure.
*/
sublink->lefthand = NIL;
sublink->operName = NIL;
sublink->operOids = NIL;
sublink->useOr = FALSE;
}
else if (sublink->subLinkType == EXPR_SUBLINK ||
sublink->subLinkType == ARRAY_SUBLINK)
{
List *tlist = qtree->targetList;
/*
* Make sure the subselect delivers a single column
* (ignoring resjunk targets).
*/
if (tlist == NIL ||
((TargetEntry *) lfirst(tlist))->resdom->resjunk)
elog(ERROR, "Subselect must have a field");
while ((tlist = lnext(tlist)) != NIL)
{
if (!((TargetEntry *) lfirst(tlist))->resdom->resjunk)
elog(ERROR, "Subselect must have only one field");
}
/*
* EXPR and ARRAY need no lefthand or combining operator.
* These fields should be NIL already, but make sure.
*/
sublink->lefthand = NIL;
sublink->operName = NIL;
sublink->operOids = NIL;
sublink->useOr = FALSE;
}
else
{
/* ALL, ANY, or MULTIEXPR: generate operator list */
List *left_list = sublink->lefthand;
List *right_list = qtree->targetList;
int row_length = length(left_list);
bool needNot = false;
List *op = sublink->operName;
char *opname = strVal(llast(op));
List *elist;
/* transform lefthand expressions */
foreach(elist, left_list)
lfirst(elist) = transformExpr(pstate, lfirst(elist));
/*
* If the expression is "<> ALL" (with unqualified opname)
* then convert it to "NOT IN". This is a hack to improve
* efficiency of expressions output by pre-7.4 Postgres.
*/
if (sublink->subLinkType == ALL_SUBLINK &&
length(op) == 1 && strcmp(opname, "<>") == 0)
{
sublink->subLinkType = ANY_SUBLINK;
opname = pstrdup("=");
op = makeList1(makeString(opname));
sublink->operName = op;
needNot = true;
}
/* Set useOr if op is "<>" (possibly qualified) */
if (strcmp(opname, "<>") == 0)
sublink->useOr = TRUE;
else
sublink->useOr = FALSE;
/* Combining operators other than =/<> is dubious... */
if (row_length != 1 &&
strcmp(opname, "=") != 0 &&
strcmp(opname, "<>") != 0)
elog(ERROR, "Row comparison cannot use operator %s",
opname);
/*
* To build the list of combining operator OIDs, we must
* scan subquery's targetlist to find values that will
* be matched against lefthand values. We need to
* ignore resjunk targets, so doing the outer
* iteration over right_list is easier than doing it
* over left_list.
*/
sublink->operOids = NIL;
while (right_list != NIL)
{
TargetEntry *tent = (TargetEntry *) lfirst(right_list);
Node *lexpr;
Operator optup;
Form_pg_operator opform;
right_list = lnext(right_list);
if (tent->resdom->resjunk)
continue;
if (left_list == NIL)
elog(ERROR, "Subselect has too many fields");
lexpr = lfirst(left_list);
left_list = lnext(left_list);
/*
* It's OK to use oper() not compatible_oper()
* here, because make_subplan() will insert type
* coercion calls if needed.
*/
optup = oper(op,
exprType(lexpr),
exprType((Node *) tent->expr),
false);
opform = (Form_pg_operator) GETSTRUCT(optup);
if (opform->oprresult != BOOLOID)
elog(ERROR, "%s has result type of %s, but must return %s"
" to be used with quantified predicate subquery",
opname, format_type_be(opform->oprresult),
format_type_be(BOOLOID));
if (get_func_retset(opform->oprcode))
elog(ERROR, "%s must not return a set"
" to be used with quantified predicate subquery",
opname);
sublink->operOids = lappendo(sublink->operOids,
oprid(optup));
ReleaseSysCache(optup);
}
if (left_list != NIL)
elog(ERROR, "Subselect has too few fields");
if (needNot)
{
expr = coerce_to_boolean(pstate, expr, "NOT");
expr = (Node *) makeBoolExpr(NOT_EXPR,
makeList1(expr));
}
}
result = (Node *) expr;
break;
}
case T_CaseExpr:
{
CaseExpr *c = (CaseExpr *) expr;
CaseExpr *newc = makeNode(CaseExpr);
List *newargs = NIL;
List *typeids = NIL;
List *args;
Node *defresult;
Oid ptype;
/* transform the list of arguments */
foreach(args, c->args)
{
CaseWhen *w = (CaseWhen *) lfirst(args);
CaseWhen *neww = makeNode(CaseWhen);
Node *warg;
Assert(IsA(w, CaseWhen));
warg = (Node *) w->expr;
if (c->arg != NULL)
{
/* shorthand form was specified, so expand... */
warg = (Node *) makeSimpleA_Expr(AEXPR_OP, "=",
(Node *) c->arg,
warg);
}
neww->expr = (Expr *) transformExpr(pstate, warg);
neww->expr = (Expr *) coerce_to_boolean(pstate,
(Node *) neww->expr,
"CASE/WHEN");
/*
* result is NULL for NULLIF() construct - thomas
* 1998-11-11
*/
warg = (Node *) w->result;
if (warg == NULL)
{
A_Const *n = makeNode(A_Const);
n->val.type = T_Null;
warg = (Node *) n;
}
neww->result = (Expr *) transformExpr(pstate, warg);
newargs = lappend(newargs, neww);
typeids = lappendo(typeids, exprType((Node *) neww->result));
}
newc->args = newargs;
/*
* It's not shorthand anymore, so drop the implicit
* argument. This is necessary to keep any re-application
* of transformExpr from doing the wrong thing.
*/
newc->arg = NULL;
/* transform the default clause */
defresult = (Node *) c->defresult;
if (defresult == NULL)
{
A_Const *n = makeNode(A_Const);
n->val.type = T_Null;
defresult = (Node *) n;
}
newc->defresult = (Expr *) transformExpr(pstate, defresult);
/*
* Note: default result is considered the most significant
* type in determining preferred type. This is how the
* code worked before, but it seems a little bogus to me
* --- tgl
*/
typeids = lconso(exprType((Node *) newc->defresult), typeids);
ptype = select_common_type(typeids, "CASE");
newc->casetype = ptype;
/* Convert default result clause, if necessary */
newc->defresult = (Expr *)
coerce_to_common_type(pstate,
(Node *) newc->defresult,
ptype,
"CASE/ELSE");
/* Convert when-clause results, if necessary */
foreach(args, newc->args)
{
CaseWhen *w = (CaseWhen *) lfirst(args);
w->result = (Expr *)
coerce_to_common_type(pstate,
(Node *) w->result,
ptype,
"CASE/WHEN");
}
result = (Node *) newc;
break;
}
case T_ArrayExpr:
{
ArrayExpr *a = (ArrayExpr *) expr;
ArrayExpr *newa = makeNode(ArrayExpr);
List *newelems = NIL;
List *newcoercedelems = NIL;
List *typeids = NIL;
List *element;
Oid array_type;
Oid element_type;
int ndims;
/* Transform the element expressions */
foreach(element, a->elements)
{
Node *e = (Node *) lfirst(element);
Node *newe;
newe = transformExpr(pstate, e);
newelems = lappend(newelems, newe);
typeids = lappendo(typeids, exprType(newe));
}
/* Select a common type for the elements */
element_type = select_common_type(typeids, "ARRAY");
/* Coerce arguments to common type if necessary */
foreach(element, newelems)
{
Node *e = (Node *) lfirst(element);
Node *newe;
newe = coerce_to_common_type(pstate, e,
element_type,
"ARRAY");
newcoercedelems = lappend(newcoercedelems, newe);
}
/* Do we have an array type to use? */
array_type = get_array_type(element_type);
if (array_type != InvalidOid)
{
/* Elements are presumably of scalar type */
ndims = 1;
}
else
{
/* Must be nested array expressions */
array_type = element_type;
element_type = get_element_type(array_type);
if (!OidIsValid(element_type))
elog(ERROR, "Cannot find array type for datatype %s",
format_type_be(array_type));
/*
* make sure the element expressions all have the same
* number of dimensions
*/
ndims = 0;
foreach(element, newcoercedelems)
{
ArrayExpr *e = (ArrayExpr *) lfirst(element);
if (!IsA(e, ArrayExpr))
elog(ERROR, "Multidimensional ARRAY[] must be built from nested array expressions");
if (ndims == 0)
ndims = e->ndims;
else if (e->ndims != ndims)
elog(ERROR, "Nested array expressions must have "
"common number of dimensions");
if (e->element_typeid != element_type)
elog(ERROR, "Nested array expressions must have "
"common element type");
}
/* increment the number of dimensions */
ndims++;
/* make sure we don't have too many dimensions now */
if (ndims > MAXDIM)
elog(ERROR, "Number of array dimensions, %d, "
"exceeds the maximum allowed %d",
ndims, MAXDIM);
}
newa->array_typeid = array_type;
newa->element_typeid = element_type;
newa->elements = newcoercedelems;
newa->ndims = ndims;
result = (Node *) newa;
break;
}
case T_CoalesceExpr:
{
CoalesceExpr *c = (CoalesceExpr *) expr;
CoalesceExpr *newc = makeNode(CoalesceExpr);
List *newargs = NIL;
List *newcoercedargs = NIL;
List *typeids = NIL;
List *args;
foreach(args, c->args)
{
Node *e = (Node *) lfirst(args);
Node *newe;
newe = transformExpr(pstate, e);
newargs = lappend(newargs, newe);
typeids = lappendo(typeids, exprType(newe));
}
newc->coalescetype = select_common_type(typeids, "COALESCE");
/* Convert arguments if necessary */
foreach(args, newargs)
{
Node *e = (Node *) lfirst(args);
Node *newe;
newe = coerce_to_common_type(pstate, e,
newc->coalescetype,
"COALESCE");
newcoercedargs = lappend(newcoercedargs, newe);
}
newc->args = newcoercedargs;
result = (Node *) newc;
break;
}
case T_NullTest:
{
NullTest *n = (NullTest *) expr;
n->arg = (Expr *) transformExpr(pstate, (Node *) n->arg);
/* the argument can be any type, so don't coerce it */
result = expr;
break;
}
case T_BooleanTest:
{
BooleanTest *b = (BooleanTest *) expr;
const char *clausename;
switch (b->booltesttype)
{
case IS_TRUE:
clausename = "IS TRUE";
break;
case IS_NOT_TRUE:
clausename = "IS NOT TRUE";
break;
case IS_FALSE:
clausename = "IS FALSE";
break;
case IS_NOT_FALSE:
clausename = "IS NOT FALSE";
break;
case IS_UNKNOWN:
clausename = "IS UNKNOWN";
break;
case IS_NOT_UNKNOWN:
clausename = "IS NOT UNKNOWN";
break;
default:
elog(ERROR, "transformExpr: unexpected booltesttype %d",
(int) b->booltesttype);
clausename = NULL; /* keep compiler quiet */
}
b->arg = (Expr *) transformExpr(pstate, (Node *) b->arg);
b->arg = (Expr *) coerce_to_boolean(pstate,
(Node *) b->arg,
clausename);
result = expr;
break;
}
/*********************************************
* Quietly accept node types that may be presented when we are
* called on an already-transformed tree.
*
* Do any other node types need to be accepted? For now we are
* taking a conservative approach, and only accepting node
* types that are demonstrably necessary to accept.
*********************************************/
case T_Var:
case T_Const:
case T_Param:
case T_Aggref:
case T_ArrayRef:
case T_FuncExpr:
case T_OpExpr:
case T_DistinctExpr:
case T_ScalarArrayOpExpr:
case T_NullIfExpr:
case T_BoolExpr:
case T_FieldSelect:
case T_RelabelType:
case T_CoerceToDomain:
case T_CoerceToDomainValue:
case T_SetToDefault:
{
result = (Node *) expr;
break;
}
default:
/* should not reach here */
elog(ERROR, "transformExpr: does not know how to transform node %d"
" (internal error)", nodeTag(expr));
break;
}
expr_depth_counter--;
return result;
}
static Node *
transformIndirection(ParseState *pstate, Node *basenode, List *indirection)
{
if (indirection == NIL)
return basenode;
return (Node *) transformArraySubscripts(pstate,
basenode,
exprType(basenode),
exprTypmod(basenode),
indirection,
false,
NULL);
}
static Node *
transformColumnRef(ParseState *pstate, ColumnRef *cref)
{
int numnames = length(cref->fields);
Node *node;
RangeVar *rv;
int levels_up;
/*----------
* The allowed syntaxes are:
*
* A First try to resolve as unqualified column name;
* if no luck, try to resolve as unqual. table name (A.*).
* A.B A is an unqual. table name; B is either a
* column or function name (trying column name first).
* A.B.C schema A, table B, col or func name C.
* A.B.C.D catalog A, schema B, table C, col or func D.
* A.* A is an unqual. table name; means whole-row value.
* A.B.* whole-row value of table B in schema A.
* A.B.C.* whole-row value of table C in schema B in catalog A.
*
* We do not need to cope with bare "*"; that will only be accepted by
* the grammar at the top level of a SELECT list, and transformTargetList
* will take care of it before it ever gets here.
*
* Currently, if a catalog name is given then it must equal the current
* database name; we check it here and then discard it.
*
* For whole-row references, the result is an untransformed RangeVar,
* which will work as the argument to a function call, but not in any
* other context at present. (We could instead coerce to a whole-row Var,
* but that will fail for subselect and join RTEs, because there is no
* pg_type entry for their rowtypes.)
*----------
*/
switch (numnames)
{
case 1:
{
char *name = strVal(lfirst(cref->fields));
/* Try to identify as an unqualified column */
node = colnameToVar(pstate, name);
if (node == NULL)
{
/*
* Not known as a column of any range-table entry.
*
* Consider the possibility that it's VALUE in a domain
* check expression. (We handle VALUE as a name, not a
* keyword, to avoid breaking a lot of applications that
* have used VALUE as a column name in the past.)
*/
if (pstate->p_value_substitute != NULL &&
strcmp(name, "value") == 0)
{
node = (Node *) copyObject(pstate->p_value_substitute);
break;
}
/*
* Try to find the name as a relation ... but not if
* subscripts appear. Note also that only relations
* already entered into the rangetable will be
* recognized.
*
* This is a hack for backwards compatibility with
* PostQUEL-inspired syntax. The preferred form now
* is "rel.*".
*/
if (cref->indirection == NIL &&
refnameRangeTblEntry(pstate, NULL, name,
&levels_up) != NULL)
{
rv = makeNode(RangeVar);
rv->relname = name;
rv->inhOpt = INH_DEFAULT;
node = (Node *) rv;
}
else
elog(ERROR, "Attribute \"%s\" not found", name);
}
break;
}
case 2:
{
char *name1 = strVal(lfirst(cref->fields));
char *name2 = strVal(lsecond(cref->fields));
/* Whole-row reference? */
if (strcmp(name2, "*") == 0)
{
rv = makeNode(RangeVar);
rv->relname = name1;
rv->inhOpt = INH_DEFAULT;
node = (Node *) rv;
break;
}
/* Try to identify as a once-qualified column */
node = qualifiedNameToVar(pstate, NULL, name1, name2, true);
if (node == NULL)
{
/*
* Not known as a column of any range-table entry, so
* try it as a function call. Here, we will create an
* implicit RTE for tables not already entered.
*/
rv = makeNode(RangeVar);
rv->relname = name1;
rv->inhOpt = INH_DEFAULT;
node = ParseFuncOrColumn(pstate,
makeList1(makeString(name2)),
makeList1(rv),
false, false, true);
}
break;
}
case 3:
{
char *name1 = strVal(lfirst(cref->fields));
char *name2 = strVal(lsecond(cref->fields));
char *name3 = strVal(lthird(cref->fields));
/* Whole-row reference? */
if (strcmp(name3, "*") == 0)
{
rv = makeNode(RangeVar);
rv->schemaname = name1;
rv->relname = name2;
rv->inhOpt = INH_DEFAULT;
node = (Node *) rv;
break;
}
/* Try to identify as a twice-qualified column */
node = qualifiedNameToVar(pstate, name1, name2, name3, true);
if (node == NULL)
{
/* Try it as a function call */
rv = makeNode(RangeVar);
rv->schemaname = name1;
rv->relname = name2;
rv->inhOpt = INH_DEFAULT;
node = ParseFuncOrColumn(pstate,
makeList1(makeString(name3)),
makeList1(rv),
false, false, true);
}
break;
}
case 4:
{
char *name1 = strVal(lfirst(cref->fields));
char *name2 = strVal(lsecond(cref->fields));
char *name3 = strVal(lthird(cref->fields));
char *name4 = strVal(lfourth(cref->fields));
/*
* We check the catalog name and then ignore it.
*/
if (strcmp(name1, get_database_name(MyDatabaseId)) != 0)
elog(ERROR, "Cross-database references are not implemented");
/* Whole-row reference? */
if (strcmp(name4, "*") == 0)
{
rv = makeNode(RangeVar);
rv->schemaname = name2;
rv->relname = name3;
rv->inhOpt = INH_DEFAULT;
node = (Node *) rv;
break;
}
/* Try to identify as a twice-qualified column */
node = qualifiedNameToVar(pstate, name2, name3, name4, true);
if (node == NULL)
{
/* Try it as a function call */
rv = makeNode(RangeVar);
rv->schemaname = name2;
rv->relname = name3;
rv->inhOpt = INH_DEFAULT;
node = ParseFuncOrColumn(pstate,
makeList1(makeString(name4)),
makeList1(rv),
false, false, true);
}
break;
}
default:
elog(ERROR, "Invalid qualified name syntax (too many names)");
node = NULL; /* keep compiler quiet */
break;
}
return transformIndirection(pstate, node, cref->indirection);
}
/*
* 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:
type = ((ArrayRef *) expr)->refrestype;
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, "exprType: Cannot get type for untransformed sublink");
tent = (TargetEntry *) lfirst(qtree->targetList);
Assert(IsA(tent, TargetEntry));
Assert(!tent->resdom->resjunk);
if (sublink->subLinkType == EXPR_SUBLINK)
type = tent->resdom->restype;
else /* ARRAY_SUBLINK */
{
type = get_array_type(tent->resdom->restype);
if (!OidIsValid(type))
elog(ERROR, "Cannot find array type for datatype %s",
format_type_be(tent->resdom->restype));
}
}
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 */
TargetEntry *tent;
tent = (TargetEntry *) lfirst(subplan->plan->targetlist);
Assert(IsA(tent, TargetEntry));
Assert(!tent->resdom->resjunk);
if (subplan->subLinkType == EXPR_SUBLINK)
type = tent->resdom->restype;
else /* ARRAY_SUBLINK */
{
type = get_array_type(tent->resdom->restype);
if (!OidIsValid(type))
elog(ERROR, "Cannot find array type for datatype %s",
format_type_be(tent->resdom->restype));
}
}
else
{
/* for all other subplan types, result is boolean */
type = BOOLOID;
}
}
break;
case T_FieldSelect:
type = ((FieldSelect *) expr)->resulttype;
break;
case T_RelabelType:
type = ((RelabelType *) expr)->resulttype;
break;
case T_CaseExpr:
type = ((CaseExpr *) expr)->casetype;
break;
case T_CaseWhen:
type = exprType((Node *) ((CaseWhen *) expr)->result);
break;
case T_ArrayExpr:
type = ((ArrayExpr *) expr)->array_typeid;
break;
case T_CoalesceExpr:
type = ((CoalesceExpr *) expr)->coalescetype;
break;
case T_NullIfExpr:
type = exprType((Node *) lfirst(((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_RangeVar:
/*
* If someone uses a bare relation name in an expression,
* we will likely first notice a problem here (see comments in
* transformColumnRef()). Issue an appropriate error message.
*/
elog(ERROR, "Relation reference \"%s\" cannot be used in an expression",
((RangeVar *) expr)->relname);
type = InvalidOid; /* keep compiler quiet */
break;
default:
elog(ERROR, "exprType: Do not know how to get type for %d node",
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:
{
/* Be smart about string constants... */
Const *con = (Const *) expr;
switch (con->consttype)
{
case BPCHAROID:
if (!con->constisnull)
return VARSIZE(DatumGetPointer(con->constvalue));
break;
default:
break;
}
}
break;
case T_FuncExpr:
{
int32 coercedTypmod;
/* Be smart about length-coercion functions... */
if (exprIsLengthCoercion(expr, &coercedTypmod))
return coercedTypmod;
}
break;
case T_FieldSelect:
return ((FieldSelect *) expr)->resulttypmod;
case T_RelabelType:
return ((RelabelType *) 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;
List *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_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;
List *arg;
typmod = exprTypmod((Node *) lfirst(cexpr->args));
foreach(arg, cexpr->args)
{
Node *e = (Node *) lfirst(arg);
if (exprType(e) != coalescetype)
return -1;
if (exprTypmod(e) != typmod)
return -1;
}
return typmod;
}
break;
case T_NullIfExpr:
{
NullIfExpr *nexpr = (NullIfExpr *) expr;
return exprTypmod((Node *) lfirst(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.
*/
bool
exprIsLengthCoercion(Node *expr, int32 *coercedTypmod)
{
FuncExpr *func;
int nargs;
Const *second_arg;
if (coercedTypmod != NULL)
*coercedTypmod = -1; /* default result on failure */
/* Is it a function-call at all? */
if (expr == NULL || !IsA(expr, FuncExpr))
return false;
func = (FuncExpr *) expr;
/*
* 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 = 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;
}
/*
* Handle an explicit CAST construct.
*
* The given expr has already been transformed, but we need to lookup
* the type name and then apply any necessary coercion function(s).
*/
static Node *
typecast_expression(ParseState *pstate, Node *expr, TypeName *typename)
{
Oid inputType = exprType(expr);
Oid targetType;
targetType = typenameTypeId(typename);
if (inputType == InvalidOid)
return expr; /* do nothing if NULL input */
expr = coerce_to_target_type(pstate, expr, inputType,
targetType, typename->typmod,
COERCION_EXPLICIT,
COERCE_EXPLICIT_CAST);
if (expr == NULL)
elog(ERROR, "Cannot cast type %s to %s",
format_type_be(inputType),
format_type_be(targetType));
return expr;
}
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