parse_target.c

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/*-------------------------------------------------------------------------
 *
 * parse_target.c
 *	  handle target lists
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.113 2003/09/25 06:58:01 petere Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "commands/dbcommands.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "parser/parsetree.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
#include "utils/builtins.h"


static void markTargetListOrigin(ParseState *pstate, Resdom *res, Var *var);
static List *ExpandAllTables(ParseState *pstate);
static char *FigureColname(Node *node);
static int	FigureColnameInternal(Node *node, char **name);


/*
 * transformTargetEntry()
 *	Transform any ordinary "expression-type" node into a targetlist entry.
 *	This is exported so that parse_clause.c can generate targetlist entries
 *	for ORDER/GROUP BY items that are not already in the targetlist.
 *
 * node		the (untransformed) parse tree for the value expression.
 * expr		the transformed expression, or NULL if caller didn't do it yet.
 * colname	the column name to be assigned, or NULL if none yet set.
 * resjunk	true if the target should be marked resjunk, ie, it is not
 *			wanted in the final projected tuple.
 */
TargetEntry *
transformTargetEntry(ParseState *pstate,
					 Node *node,
					 Node *expr,
					 char *colname,
					 bool resjunk)
{
	Oid			type_id;
	int32		type_mod;
	Resdom	   *resnode;

	/* Transform the node if caller didn't do it already */
	if (expr == NULL)
		expr = transformExpr(pstate, node);

	if (IsA(expr, RangeVar))
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("relation reference \"%s\" cannot be used as a select-list entry",
						((RangeVar *) expr)->relname),
				 errhint("Write \"%s\".* to denote all the columns of the relation.",
						 ((RangeVar *) expr)->relname)));

	type_id = exprType(expr);
	type_mod = exprTypmod(expr);

	if (colname == NULL && !resjunk)
	{
		/*
		 * Generate a suitable column name for a column without any
		 * explicit 'AS ColumnName' clause.
		 */
		colname = FigureColname(node);
	}

	resnode = makeResdom((AttrNumber) pstate->p_next_resno++,
						 type_id,
						 type_mod,
						 colname,
						 resjunk);

	return makeTargetEntry(resnode, (Expr *) expr);
}


/*
 * transformTargetList()
 * Turns a list of ResTarget's into a list of TargetEntry's.
 *
 * At this point, we don't care whether we are doing SELECT, INSERT,
 * or UPDATE; we just transform the given expressions.
 */
List *
transformTargetList(ParseState *pstate, List *targetlist)
{
	FastList	p_target;
	List	   *o_target;

	FastListInit(&p_target);

	foreach(o_target, targetlist)
	{
		ResTarget  *res = (ResTarget *) lfirst(o_target);

		if (IsA(res->val, ColumnRef))
		{
			ColumnRef  *cref = (ColumnRef *) res->val;
			List	   *fields = cref->fields;

			if (strcmp(strVal(llast(fields)), "*") == 0)
			{
				int		numnames = length(fields);

				if (numnames == 1)
				{
					/*
					 * Target item is a single '*', expand all tables
					 * (e.g., SELECT * FROM emp)
					 */
					FastConc(&p_target,
							 ExpandAllTables(pstate));
				}
				else
				{
					/*
					 * Target item is relation.*, expand that table
					 * (e.g., SELECT emp.*, dname FROM emp, dept)
					 */
					char	   *schemaname;
					char	   *relname;
					RangeTblEntry *rte;
					int			sublevels_up;

					switch (numnames)
					{
						case 2:
							schemaname = NULL;
							relname = strVal(lfirst(fields));
							break;
						case 3:
							schemaname = strVal(lfirst(fields));
							relname = strVal(lsecond(fields));
							break;
						case 4:
						{
							char	   *name1 = strVal(lfirst(fields));

							/*
							 * We check the catalog name and then ignore
							 * it.
							 */
							if (strcmp(name1, get_database_name(MyDatabaseId)) != 0)
								ereport(ERROR,
										(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
										 errmsg("cross-database references are not implemented")));
							schemaname = strVal(lsecond(fields));
							relname = strVal(lthird(fields));
							break;
						}
						default:
							ereport(ERROR,
									(errcode(ERRCODE_SYNTAX_ERROR),
									 errmsg("improper qualified name (too many dotted names): %s",
											NameListToString(fields))));
							schemaname = NULL;		/* keep compiler quiet */
							relname = NULL;
							break;
					}

					rte = refnameRangeTblEntry(pstate, schemaname, relname,
											   &sublevels_up);
					if (rte == NULL)
						rte = addImplicitRTE(pstate, makeRangeVar(schemaname,
																  relname));

					FastConc(&p_target,
							 expandRelAttrs(pstate, rte));
				}
			}
			else
			{
				/* Plain ColumnRef node, treat it as an expression */
				FastAppend(&p_target,
						   transformTargetEntry(pstate,
												res->val,
												NULL,
												res->name,
												false));
			}
		}
		else
		{
			/* Everything else but ColumnRef */
			FastAppend(&p_target,
					   transformTargetEntry(pstate,
											res->val,
											NULL,
											res->name,
											false));
		}
	}

	return FastListValue(&p_target);
}


/*
 * markTargetListOrigins()
 *		Mark targetlist columns that are simple Vars with the source
 *		table's OID and column number.
 *
 * Currently, this is done only for SELECT targetlists, since we only
 * need the info if we are going to send it to the frontend.
 */
void
markTargetListOrigins(ParseState *pstate, List *targetlist)
{
	List	   *l;

	foreach(l, targetlist)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		markTargetListOrigin(pstate, tle->resdom, (Var *) tle->expr);
	}
}

/*
 * markTargetListOrigin()
 *		If 'var' is a Var of a plain relation, mark 'res' with its origin
 *
 * This is split out so it can recurse for join references.  Note that we
 * do not drill down into views, but report the view as the column owner.
 */
static void
markTargetListOrigin(ParseState *pstate, Resdom *res, Var *var)
{
	Index		levelsup;
	RangeTblEntry *rte;
	AttrNumber	attnum;

	if (var == NULL || !IsA(var, Var))
		return;
	levelsup = var->varlevelsup;
	while (levelsup-- > 0)
	{
		pstate = pstate->parentParseState;
		Assert(pstate != NULL);
	}
	Assert(var->varno > 0 &&
		   (int) var->varno <= length(pstate->p_rtable));
	rte = rt_fetch(var->varno, pstate->p_rtable);
	attnum = var->varattno;

	switch (rte->rtekind)
	{
		case RTE_RELATION:
			/* It's a table or view, report it */
			res->resorigtbl = rte->relid;
			res->resorigcol = attnum;
			break;
		case RTE_SUBQUERY:
			{
				/* Subselect-in-FROM: copy up from the subselect */
				TargetEntry *te = get_tle_by_resno(rte->subquery->targetList,
												   attnum);

				if (te == NULL || te->resdom->resjunk)
					elog(ERROR, "subquery %s does not have attribute %d",
						 rte->eref->aliasname, attnum);
				res->resorigtbl = te->resdom->resorigtbl;
				res->resorigcol = te->resdom->resorigcol;
			}
			break;
		case RTE_JOIN:
			{
				/* Join RTE --- recursively inspect the alias variable */
				Var		   *aliasvar;

				Assert(attnum > 0 && attnum <= length(rte->joinaliasvars));
				aliasvar = (Var *) nth(attnum - 1, rte->joinaliasvars);
				markTargetListOrigin(pstate, res, aliasvar);
			}
			break;
		case RTE_SPECIAL:
		case RTE_FUNCTION:
			/* not a simple relation, leave it unmarked */
			break;
	}
}


/*
 * updateTargetListEntry()
 *	This is used in INSERT and UPDATE statements only.	It prepares a
 *	TargetEntry for assignment to a column of the target table.
 *	This includes coercing the given value to the target column's type
 *	(if necessary), and dealing with any subscripts attached to the target
 *	column itself.
 *
 * pstate		parse state
 * tle			target list entry to be modified
 * colname		target column name (ie, name of attribute to be assigned to)
 * attrno		target attribute number
 * indirection	subscripts for target column, if any
 */
void
updateTargetListEntry(ParseState *pstate,
					  TargetEntry *tle,
					  char *colname,
					  int attrno,
					  List *indirection)
{
	Oid			type_id;		/* type of value provided */
	Oid			attrtype;		/* type of target column */
	int32		attrtypmod;
	Resdom	   *resnode = tle->resdom;
	Relation	rd = pstate->p_target_relation;

	Assert(rd != NULL);
	if (attrno <= 0)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot assign to system column \"%s\"",
						colname)));
	attrtype = attnumTypeId(rd, attrno);
	attrtypmod = rd->rd_att->attrs[attrno - 1]->atttypmod;

	/*