ac4878a060
coerce_type, so that the right things happen when coercing a previously- unknown constant to a destination data type.
455 lines
11 KiB
C
455 lines
11 KiB
C
/*-------------------------------------------------------------------------
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*
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* parse_target.c
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* handle target lists
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_target.c,v 1.53 2000/01/17 02:04:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "nodes/makefuncs.h"
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#include "parser/parse_coerce.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_func.h"
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#include "parser/parse_relation.h"
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#include "parser/parse_target.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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static List *ExpandAllTables(ParseState *pstate);
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static char *FigureColname(Node *expr, Node *resval);
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/*
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* transformTargetEntry()
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* Transform any ordinary "expression-type" node into a targetlist entry.
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* This is exported so that parse_clause.c can generate targetlist entries
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* for ORDER/GROUP BY items that are not already in the targetlist.
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*
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* node the (untransformed) parse tree for the value expression.
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* expr the transformed expression, or NULL if caller didn't do it yet.
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* colname the column name to be assigned, or NULL if none yet set.
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* resjunk true if the target should be marked resjunk, ie, it is not
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* wanted in the final projected tuple.
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*/
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TargetEntry *
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transformTargetEntry(ParseState *pstate,
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Node *node,
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Node *expr,
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char *colname,
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bool resjunk)
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{
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Oid type_id;
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int32 type_mod;
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Resdom *resnode;
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/* Transform the node if caller didn't do it already */
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if (expr == NULL)
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expr = transformExpr(pstate, node, EXPR_COLUMN_FIRST);
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type_id = exprType(expr);
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type_mod = exprTypmod(expr);
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if (colname == NULL)
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{
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/* Generate a suitable column name for a column without any
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* explicit 'AS ColumnName' clause.
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*/
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colname = FigureColname(expr, node);
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}
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resnode = makeResdom((AttrNumber) pstate->p_last_resno++,
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type_id,
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type_mod,
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colname,
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(Index) 0,
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(Oid) InvalidOid,
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resjunk);
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return makeTargetEntry(resnode, expr);
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}
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/*
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* transformTargetList()
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* Turns a list of ResTarget's into a list of TargetEntry's.
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*
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* At this point, we don't care whether we are doing SELECT, INSERT,
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* or UPDATE; we just transform the given expressions.
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*/
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List *
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transformTargetList(ParseState *pstate, List *targetlist)
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{
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List *p_target = NIL;
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while (targetlist != NIL)
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{
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ResTarget *res = (ResTarget *) lfirst(targetlist);
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if (IsA(res->val, Attr))
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{
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Attr *att = (Attr *) res->val;
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if (att->relname != NULL && strcmp(att->relname, "*") == 0)
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{
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/*
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* Target item is a single '*', expand all tables
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* (eg. SELECT * FROM emp)
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*/
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p_target = nconc(p_target,
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ExpandAllTables(pstate));
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}
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else if (att->attrs != NIL &&
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strcmp(strVal(lfirst(att->attrs)), "*") == 0)
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{
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/*
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* Target item is relation.*, expand that table
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* (eg. SELECT emp.*, dname FROM emp, dept)
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*/
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p_target = nconc(p_target,
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expandAll(pstate,
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att->relname,
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att->relname,
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&pstate->p_last_resno));
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}
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else
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{
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/* Plain Attr node, treat it as an expression */
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p_target = lappend(p_target,
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transformTargetEntry(pstate,
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res->val,
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NULL,
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res->name,
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false));
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}
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}
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else
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{
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/* Everything else but Attr */
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p_target = lappend(p_target,
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transformTargetEntry(pstate,
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res->val,
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NULL,
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res->name,
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false));
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}
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targetlist = lnext(targetlist);
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}
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return p_target;
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}
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/*
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* updateTargetListEntry()
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* This is used in INSERT and UPDATE statements only. It prepares a
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* TargetEntry for assignment to a column of the target table.
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* This includes coercing the given value to the target column's type
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* (if necessary), and dealing with any subscripts attached to the target
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* column itself.
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*
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* pstate parse state
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* tle target list entry to be modified
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* colname target column name (ie, name of attribute to be assigned to)
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* attrno target attribute number
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* indirection subscripts for target column, if any
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*/
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void
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updateTargetListEntry(ParseState *pstate,
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TargetEntry *tle,
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char *colname,
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int attrno,
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List *indirection)
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{
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Oid type_id = exprType(tle->expr); /* type of value provided */
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Oid attrtype; /* type of target column */
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int32 attrtypmod;
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Resdom *resnode = tle->resdom;
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Relation rd = pstate->p_target_relation;
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Assert(rd != NULL);
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if (attrno <= 0)
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elog(ERROR, "Cannot assign to system attribute '%s'", colname);
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attrtype = attnumTypeId(rd, attrno);
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attrtypmod = rd->rd_att->attrs[attrno - 1]->atttypmod;
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/*
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* If there are subscripts on the target column, prepare an
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* array assignment expression. This will generate an array value
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* that the source value has been inserted into, which can then
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* be placed in the new tuple constructed by INSERT or UPDATE.
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* Note that transformArraySubscripts takes care of type coercion.
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*/
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if (indirection)
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{
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Attr *att = makeNode(Attr);
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Node *arrayBase;
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ArrayRef *aref;
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att->relname = pstrdup(RelationGetRelationName(rd));
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att->attrs = lcons(makeString(colname), NIL);
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arrayBase = ParseNestedFuncOrColumn(pstate, att,
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&pstate->p_last_resno,
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EXPR_COLUMN_FIRST);
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aref = transformArraySubscripts(pstate, arrayBase,
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indirection,
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pstate->p_is_insert,
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tle->expr);
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if (pstate->p_is_insert)
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{
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/*
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* The command is INSERT INTO table (arraycol[subscripts]) ...
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* so there is not really a source array value to work with.
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* Let the executor do something reasonable, if it can.
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* Notice that we forced transformArraySubscripts to treat
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* the subscripting op as an array-slice op above, so the
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* source data will have been coerced to array type.
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*/
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aref->refexpr = NULL; /* signal there is no source array */
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}
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tle->expr = (Node *) aref;
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}
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else
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{
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/*
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* For normal non-subscripted target column, do type checking
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* and coercion. But accept InvalidOid, which indicates the
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* source is a NULL constant.
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*/
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if (type_id != InvalidOid)
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{
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if (type_id != attrtype)
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{
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tle->expr = CoerceTargetExpr(pstate, tle->expr, type_id,
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attrtype, attrtypmod);
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if (tle->expr == NULL)
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elog(ERROR, "Attribute '%s' is of type '%s'"
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" but expression is of type '%s'"
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"\n\tYou will need to rewrite or cast the expression",
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colname,
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typeidTypeName(attrtype),
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typeidTypeName(type_id));
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}
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/*
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* If the target is a fixed-length type, it may need a length
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* coercion as well as a type coercion.
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*/
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tle->expr = coerce_type_typmod(pstate, tle->expr,
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attrtype, attrtypmod);
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}
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}
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/*
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* The result of the target expression should now match the destination
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* column's type. Also, reset the resname and resno to identify
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* the destination column --- rewriter and planner depend on that!
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*/
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resnode->restype = attrtype;
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resnode->restypmod = attrtypmod;
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resnode->resname = colname;
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resnode->resno = (AttrNumber) attrno;
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}
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Node *
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CoerceTargetExpr(ParseState *pstate,
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Node *expr,
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Oid type_id,
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Oid attrtype,
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int32 attrtypmod)
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{
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if (can_coerce_type(1, &type_id, &attrtype))
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expr = coerce_type(pstate, expr, type_id, attrtype, attrtypmod);
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#ifndef DISABLE_STRING_HACKS
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/*
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* string hacks to get transparent conversions w/o explicit
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* conversions
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*/
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else if ((attrtype == BPCHAROID) || (attrtype == VARCHAROID))
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{
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Oid text_id = TEXTOID;
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if (type_id == TEXTOID)
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{
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}
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else if (can_coerce_type(1, &type_id, &text_id))
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expr = coerce_type(pstate, expr, type_id, text_id, attrtypmod);
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else
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expr = NULL;
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}
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#endif
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else
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expr = NULL;
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return expr;
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}
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/*
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* checkInsertTargets -
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* generate a list of column names if not supplied or
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* test supplied column names to make sure they are in target table.
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* Also return an integer list of the columns' attribute numbers.
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* (used exclusively for inserts)
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*/
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List *
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checkInsertTargets(ParseState *pstate, List *cols, List **attrnos)
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{
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*attrnos = NIL;
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if (cols == NIL)
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{
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/*
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* Generate default column list for INSERT.
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*/
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Form_pg_attribute *attr = pstate->p_target_relation->rd_att->attrs;
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int numcol = pstate->p_target_relation->rd_rel->relnatts;
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int i;
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for (i = 0; i < numcol; i++)
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{
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Ident *id = makeNode(Ident);
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id->name = palloc(NAMEDATALEN);
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StrNCpy(id->name, NameStr(attr[i]->attname), NAMEDATALEN);
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id->indirection = NIL;
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id->isRel = false;
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cols = lappend(cols, id);
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*attrnos = lappendi(*attrnos, i+1);
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}
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}
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else
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{
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/*
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* Do initial validation of user-supplied INSERT column list.
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*/
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List *tl;
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foreach(tl, cols)
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{
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char *name = ((Ident *) lfirst(tl))->name;
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int attrno;
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/* Lookup column name, elog on failure */
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attrno = attnameAttNum(pstate->p_target_relation, name);
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/* Check for duplicates */
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if (intMember(attrno, *attrnos))
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elog(ERROR, "Attribute '%s' specified more than once", name);
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*attrnos = lappendi(*attrnos, attrno);
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}
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}
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return cols;
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}
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/*
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* ExpandAllTables -
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* turns '*' (in the target list) into a list of attributes
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* (of all relations in the range table)
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*/
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static List *
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ExpandAllTables(ParseState *pstate)
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{
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List *target = NIL;
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List *rt,
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*rtable;
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rtable = pstate->p_rtable;
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if (pstate->p_is_rule)
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{
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/*
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* skip first two entries, "*new*" and "*current*"
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*/
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rtable = lnext(lnext(rtable));
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}
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/* SELECT *; */
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if (rtable == NIL)
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elog(ERROR, "Wildcard with no tables specified.");
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foreach(rt, rtable)
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{
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RangeTblEntry *rte = lfirst(rt);
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/*
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* we only expand those listed in the from clause. (This will
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* also prevent us from using the wrong table in inserts: eg.
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* tenk2 in "insert into tenk2 select * from tenk1;")
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*/
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if (!rte->inFromCl)
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continue;
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target = nconc(target,
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expandAll(pstate, rte->relname, rte->refname,
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&pstate->p_last_resno));
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}
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return target;
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}
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/*
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* FigureColname -
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* if the name of the resulting column is not specified in the target
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* list, we have to guess a suitable name. The SQL spec provides some
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* guidance, but not much...
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*
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*/
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static char *
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FigureColname(Node *expr, Node *resval)
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{
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/* Some of these are easiest to do with the untransformed node */
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switch (nodeTag(resval))
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{
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case T_Ident:
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return ((Ident *) resval)->name;
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case T_Attr:
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{
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List *attrs = ((Attr *) resval)->attrs;
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if (attrs)
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{
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while (lnext(attrs) != NIL)
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attrs = lnext(attrs);
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return strVal(lfirst(attrs));
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}
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}
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break;
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default:
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break;
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}
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/* Otherwise, work with the transformed node */
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switch (nodeTag(expr))
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{
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case T_Expr:
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if (((Expr *) expr)->opType == FUNC_EXPR && IsA(resval, FuncCall))
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return ((FuncCall *) resval)->funcname;
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break;
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case T_Aggref:
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return ((Aggref *) expr)->aggname;
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case T_CaseExpr:
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{
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char *name;
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name = FigureColname(((CaseExpr *) expr)->defresult, resval);
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if (strcmp(name, "?column?") == 0)
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name = "case";
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return name;
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}
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break;
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default:
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break;
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}
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return "?column?";
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}
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