makefuncs.c

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/*-------------------------------------------------------------------------
 *
 * makefuncs.c
 *    creator functions for various nodes. The functions here are for the
 *    most frequently created nodes.
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/nodes/makefuncs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_class.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "utils/lsyscache.h"


/*
 * makeA_Expr -
 *      makes an A_Expr node
 */
A_Expr *
makeA_Expr(A_Expr_Kind kind, List *name,
           Node *lexpr, Node *rexpr, int location)
{
    A_Expr     *a = makeNode(A_Expr);

    a->kind = kind;
    a->name = name;
    a->lexpr = lexpr;
    a->rexpr = rexpr;
    a->location = location;
    return a;
}

/*
 * makeSimpleA_Expr -
 *      As above, given a simple (unqualified) operator name
 */
A_Expr *
makeSimpleA_Expr(A_Expr_Kind kind, char *name,
                 Node *lexpr, Node *rexpr, int location)
{
    A_Expr     *a = makeNode(A_Expr);

    a->kind = kind;
    a->name = list_make1(makeString((char *) name));
    a->lexpr = lexpr;
    a->rexpr = rexpr;
    a->location = location;
    return a;
}

/*
 * makeVar -
 *    creates a Var node
 */
Var *
makeVar(Index varno,
        AttrNumber varattno,
        Oid vartype,
        int32 vartypmod,
        Oid varcollid,
        Index varlevelsup)
{
    Var        *var = makeNode(Var);

    var->varno = varno;
    var->varattno = varattno;
    var->vartype = vartype;
    var->vartypmod = vartypmod;
    var->varcollid = varcollid;
    var->varlevelsup = varlevelsup;

    /*
     * Only a few callers need to make Var nodes with varnosyn/varattnosyn
     * different from varno/varattno.  We don't provide separate arguments for
     * them, but just initialize them to the given varno/varattno.  This
     * reduces code clutter and chance of error for most callers.
     */
    var->varnosyn = varno;
    var->varattnosyn = varattno;

    /* Likewise, we just set location to "unknown" here */
    var->location = -1;

    return var;
}

/*
 * makeVarFromTargetEntry -
 *      convenience function to create a same-level Var node from a
 *      TargetEntry
 */
Var *
makeVarFromTargetEntry(Index varno,
                       TargetEntry *tle)
{
    return makeVar(varno,
                   tle->resno,
                   exprType((Node *) tle->expr),
                   exprTypmod((Node *) tle->expr),
                   exprCollation((Node *) tle->expr),
                   0);
}

/*
 * makeWholeRowVar -
 *    creates a Var node representing a whole row of the specified RTE
 *
 * A whole-row reference is a Var with varno set to the correct range
 * table entry, and varattno == 0 to signal that it references the whole
 * tuple.  (Use of zero here is unclean, since it could easily be confused
 * with error cases, but it's not worth changing now.)  The vartype indicates
 * a rowtype; either a named composite type, or a domain over a named
 * composite type (only possible if the RTE is a function returning that),
 * or RECORD.  This function encapsulates the logic for determining the
 * correct rowtype OID to use.
 *
 * If allowScalar is true, then for the case where the RTE is a single function
 * returning a non-composite result type, we produce a normal Var referencing
 * the function's result directly, instead of the single-column composite
 * value that the whole-row notation might otherwise suggest.
 */
Var *
makeWholeRowVar(RangeTblEntry *rte,
                Index varno,
                Index varlevelsup,
                bool allowScalar)
{
    Var        *result;
    Oid         toid;
    Node       *fexpr;

    switch (rte->rtekind)
    {
        case RTE_RELATION:
            /* relation: the rowtype is a named composite type */
            toid = get_rel_type_id(rte->relid);
            if (!OidIsValid(toid))
                elog(ERROR, "could not find type OID for relation %u",
                     rte->relid);
            result = makeVar(varno,
                             InvalidAttrNumber,
                             toid,
                             -1,
                             InvalidOid,
                             varlevelsup);
            break;

        case RTE_FUNCTION:

            /*
             * If there's more than one function, or ordinality is requested,
             * force a RECORD result, since there's certainly more than one
             * column involved and it can't be a known named type.
             */
            if (rte->funcordinality || list_length(rte->functions) != 1)
            {
                /* always produces an anonymous RECORD result */
                result = makeVar(varno,
                                 InvalidAttrNumber,
                                 RECORDOID,
                                 -1,
                                 InvalidOid,
                                 varlevelsup);
                break;
            }

            fexpr = ((RangeTblFunction *) linitial(rte->functions))->funcexpr;
            toid = exprType(fexpr);
            if (type_is_rowtype(toid))
            {
                /* func returns composite; same as relation case */
                result = makeVar(varno,
                                 InvalidAttrNumber,
                                 toid,
                                 -1,
                                 InvalidOid,
                                 varlevelsup);
            }
            else if (allowScalar)
            {
                /* func returns scalar; just return its output as-is */
                result = makeVar(varno,
                                 1,
                                 toid,
                                 -1,
                                 exprCollation(fexpr),
                                 varlevelsup);
            }
            else
            {
                /* func returns scalar, but we want a composite result */
                result = makeVar(varno,
                                 InvalidAttrNumber,
                                 RECORDOID,
                                 -1,
                                 InvalidOid,
                                 varlevelsup);
            }
            break;

        default:

            /*
             * RTE is a join, subselect, tablefunc, or VALUES.  We represent
             * this as a whole-row Var of RECORD type. (Note that in most
             * cases the Var will be expanded to a RowExpr during planning,
             * but that is not our concern here.)
             */
            result = makeVar(varno,
                             InvalidAttrNumber,
                             RECORDOID,
                             -1,
                             InvalidOid,
                             varlevelsup);
            break;
    }

    return result;
}

/*
 * makeTargetEntry -
 *    creates a TargetEntry node
 */
TargetEntry *
makeTargetEntry(Expr *expr,
                AttrNumber resno,
                char *resname,
                bool resjunk)
{
    TargetEntry *tle = makeNode(TargetEntry);

    tle->expr = expr;
    tle->resno = resno;
    tle->resname = resname;

    /*
     * We always set these fields to 0. If the caller wants to change them he
     * must do so explicitly.  Few callers do that, so omitting these
     * arguments reduces the chance of error.
     */
    tle->ressortgroupref = 0;
    tle->resorigtbl = InvalidOid;
    tle->resorigcol = 0;

    tle->resjunk = resjunk;

    return tle;
}

/*
 * flatCopyTargetEntry -
 *    duplicate a TargetEntry, but don't copy substructure
 *
 * This is commonly used when we just want to modify the resno or substitute
 * a new expression.
 */
TargetEntry *
flatCopyTargetEntry(TargetEntry *src_tle)
{
    TargetEntry *tle = makeNode(TargetEntry);

    Assert(IsA(src_tle, TargetEntry));
    memcpy(tle, src_tle, sizeof(TargetEntry));
    return tle;
}

/*
 * makeFromExpr -
 *    creates a FromExpr node
 */
FromExpr *
makeFromExpr(List *fromlist, Node *quals)
{
    FromExpr   *f = makeNode(FromExpr);

    f->fromlist = fromlist;
    f->quals = quals;
    return f;
}

/*
 * makeConst -
 *    creates a Const node
 */
Const *
makeConst(Oid consttype,
          int32 consttypmod,
          Oid constcollid,
          int constlen,
          Datum constvalue,
          bool constisnull,
          bool constbyval)
{
    Const      *cnst = makeNode(Const);

    /*
     * If it's a varlena value, force it to be in non-expanded (non-toasted)
     * format; this avoids any possible dependency on external values and
     * improves consistency of representation, which is important for equal().
     */
    if (!constisnull && constlen == -1)
        constvalue = PointerGetDatum(PG_DETOAST_DATUM(constvalue));

    cnst->consttype = consttype;
    cnst->consttypmod = consttypmod;
    cnst->constcollid = constcollid;
    cnst->constlen = constlen;
    cnst->constvalue = constvalue;
    cnst->constisnull = constisnull;
    cnst->constbyval = constbyval;
    cnst->location = -1;        /* "unknown" */

    return cnst;
}

/*
 * makeNullConst -
 *    creates a Const node representing a NULL of the specified type/typmod
 *
 * This is a convenience routine that just saves a lookup of the type's
 * storage properties.
 */
Const *
makeNullConst(Oid consttype, int32 consttypmod, Oid constcollid)
{
    int16       typLen;
    bool        typByVal;

    get_typlenbyval(consttype, &typLen, &typByVal);
    return makeConst(consttype,
                     consttypmod,
                     constcollid,
                     (int) typLen,
                     (Datum) 0,
                     true,
                     typByVal);
}

/*
 * makeBoolConst -
 *    creates a Const node representing a boolean value (can be NULL too)
 */
Node *
makeBoolConst(bool value, bool isnull)
{
    /* note that pg_type.h hardwires size of bool as 1 ... duplicate it */
    return (Node *) makeConst(BOOLOID, -1, InvalidOid, 1,
                              BoolGetDatum(value), isnull, true);
}

/*
 * makeBoolExpr -
 *    creates a BoolExpr node
 */
Expr *
makeBoolExpr(BoolExprType boolop, List *args, int location)
{
    BoolExpr   *b = makeNode(BoolExpr);

    b->boolop = boolop;
    b->args = args;
    b->location = location;

    return (Expr *) b;
}

/*
 * makeAlias -
 *    creates an Alias node
 *
 * NOTE: the given name is copied, but the colnames list (if any) isn't.
 */
Alias *
makeAlias(const char *aliasname, List *colnames)
{
    Alias      *a = makeNode(Alias);

    a->aliasname = pstrdup(aliasname);
    a->colnames = colnames;

    return a;
}

/*
 * makeRelabelType -
 *    creates a RelabelType node
 */
RelabelType *
makeRelabelType(Expr *arg, Oid rtype, int32 rtypmod, Oid rcollid,
                CoercionForm rformat)
{
    RelabelType *r = makeNode(RelabelType);

    r->arg = arg;
    r->resulttype = rtype;
    r->resulttypmod = rtypmod;
    r->resultcollid = rcollid;
    r->relabelformat = rformat;
    r->location = -1;

    return r;
}

/*
 * makeRangeVar -
 *    creates a RangeVar node (rather oversimplified case)
 */
RangeVar *
makeRangeVar(char *schemaname, char *relname, int location)
{
    RangeVar   *r = makeNode(RangeVar);

    r->catalogname = NULL;
    r->schemaname = schemaname;
    r->relname = relname;
    r->inh = true;
    r->relpersistence = RELPERSISTENCE_PERMANENT;
    r->alias = NULL;
    r->location = location;

    return r;
}

/*
 * makeTypeName -
 *  build a TypeName node for an unqualified name.
 *
 * typmod is defaulted, but can be changed later by caller.
 */
TypeName *
makeTypeName(char *typnam)
{
    return makeTypeNameFromNameList(list_make1(makeString(typnam)));
}

/*
 * makeTypeNameFromNameList -
 *  build a TypeName node for a String list representing a qualified name.
 *
 * typmod is defaulted, but can be changed later by caller.
 */
TypeName *
makeTypeNameFromNameList(List *names)
{
    TypeName   *n = makeNode(TypeName);

    n->names = names;
    n->typmods = NIL;
    n->typemod = -1;
    n->location = -1;
    return n;
}

/*
 * makeTypeNameFromOid -
 *  build a TypeName node to represent a type already known by OID/typmod.
 */
TypeName *
makeTypeNameFromOid(Oid typeOid, int32 typmod)
{
    TypeName   *n = makeNode(TypeName);

    n->typeOid = typeOid;
    n->typemod = typmod;
    n->location = -1;
    return n;
}

/*
 * makeColumnDef -
 *  build a ColumnDef node to represent a simple column definition.
 *
 * Type and collation are specified by OID.
 * Other properties are all basic to start with.
 */
ColumnDef *
makeColumnDef(const char *colname, Oid typeOid, int32 typmod, Oid collOid)
{
    ColumnDef  *n = makeNode(ColumnDef);

    n->colname = pstrdup(colname);
    n->typeName = makeTypeNameFromOid(typeOid, typmod);
    n->inhcount = 0;
    n->is_local = true;
    n->is_not_null = false;
    n->is_from_type = false;
    n->storage = 0;
    n->raw_default = NULL;
    n->cooked_default = NULL;
    n->collClause = NULL;
    n->collOid = collOid;
    n->constraints = NIL;
    n->fdwoptions = NIL;
    n->location = -1;

    return n;
}

/*
 * makeFuncExpr -
 *  build an expression tree representing a function call.
 *
 * The argument expressions must have been transformed already.
 */
FuncExpr *
makeFuncExpr(Oid funcid, Oid rettype, List *args,
             Oid funccollid, Oid inputcollid, CoercionForm fformat)
{
    FuncExpr   *funcexpr;

    funcexpr = makeNode(FuncExpr);
    funcexpr->funcid = funcid;
    funcexpr->funcresulttype = rettype;
    funcexpr->funcretset = false;   /* only allowed case here */
    funcexpr->funcvariadic = false; /* only allowed case here */
    funcexpr->funcformat = fformat;
    funcexpr->funccollid = funccollid;
    funcexpr->inputcollid = inputcollid;
    funcexpr->args = args;
    funcexpr->location = -1;

    return funcexpr;
}

/*
 * makeDefElem -
 *  build a DefElem node
 *
 * This is sufficient for the "typical" case with an unqualified option name
 * and no special action.
 */
DefElem *
makeDefElem(char *name, Node *arg, int location)
{
    DefElem    *res = makeNode(DefElem);

    res->defnamespace = NULL;
    res->defname = name;
    res->arg = arg;
    res->defaction = DEFELEM_UNSPEC;
    res->location = location;

    return res;
}

/*
 * makeDefElemExtended -
 *  build a DefElem node with all fields available to be specified
 */
DefElem *
makeDefElemExtended(char *nameSpace, char *name, Node *arg,
                    DefElemAction defaction, int location)
{
    DefElem    *res = makeNode(DefElem);

    res->defnamespace = nameSpace;
    res->defname = name;
    res->arg = arg;
    res->defaction = defaction;
    res->location = location;

    return res;
}

/*
 * makeFuncCall -
 *
 * Initialize a FuncCall struct with the information every caller must
 * supply.  Any non-default parameters have to be inserted by the caller.
 */
FuncCall *
makeFuncCall(List *name, List *args, int location)
{
    FuncCall   *n = makeNode(FuncCall);

    n->funcname = name;
    n->args = args;
    n->agg_order = NIL;
    n->agg_filter = NULL;
    n->agg_within_group = false;
    n->agg_star = false;
    n->agg_distinct = false;
    n->func_variadic = false;
    n->over = NULL;
    n->location = location;
    return n;
}

/*
 * make_opclause
 *    Creates an operator clause given its operator info, left operand
 *    and right operand (pass NULL to create single-operand clause),
 *    and collation info.
 */
Expr *
make_opclause(Oid opno, Oid opresulttype, bool opretset,
              Expr *leftop, Expr *rightop,
              Oid opcollid, Oid inputcollid)
{
    OpExpr     *expr = makeNode(OpExpr);

    expr->opno = opno;
    expr->opfuncid = InvalidOid;
    expr->opresulttype = opresulttype;
    expr->opretset = opretset;
    expr->opcollid = opcollid;
    expr->inputcollid = inputcollid;
    if (rightop)
        expr->args = list_make2(leftop, rightop);
    else
        expr->args = list_make1(leftop);
    expr->location = -1;
    return (Expr *) expr;
}

/*
 * make_andclause
 *
 * Creates an 'and' clause given a list of its subclauses.
 */
Expr *
make_andclause(List *andclauses)
{
    BoolExpr   *expr = makeNode(BoolExpr);

    expr->boolop = AND_EXPR;
    expr->args = andclauses;
    expr->location = -1;
    return (Expr *) expr;
}

/*
 * make_orclause
 *
 * Creates an 'or' clause given a list of its subclauses.
 */
Expr *
make_orclause(List *orclauses)
{
    BoolExpr   *expr = makeNode(BoolExpr);

    expr->boolop = OR_EXPR;
    expr->args = orclauses;
    expr->location = -1;
    return (Expr *) expr;
}

/*
 * make_notclause
 *
 * Create a 'not' clause given the expression to be negated.
 */
Expr *
make_notclause(Expr *notclause)
{
    BoolExpr   *expr = makeNode(BoolExpr);

    expr->boolop = NOT_EXPR;
    expr->args = list_make1(notclause);
    expr->location = -1;
    return (Expr *) expr;
}

/*
 * make_and_qual
 *
 * Variant of make_andclause for ANDing two qual conditions together.
 * Qual conditions have the property that a NULL nodetree is interpreted
 * as 'true'.
 *
 * NB: this makes no attempt to preserve AND/OR flatness; so it should not
 * be used on a qual that has already been run through prepqual.c.
 */
Node *
make_and_qual(Node *qual1, Node *qual2)
{
    if (qual1 == NULL)
        return qual2;
    if (qual2 == NULL)
        return qual1;
    return (Node *) make_andclause(list_make2(qual1, qual2));
}

/*
 * The planner and executor usually represent qualification expressions
 * as lists of boolean expressions with implicit AND semantics.
 *
 * These functions convert between an AND-semantics expression list and the
 * ordinary representation of a boolean expression.
 *
 * Note that an empty list is considered equivalent to TRUE.
 */
Expr *
make_ands_explicit(List *andclauses)
{
    if (andclauses == NIL)
        return (Expr *) makeBoolConst(true, false);
    else if (list_length(andclauses) == 1)
        return (Expr *) linitial(andclauses);
    else
        return make_andclause(andclauses);
}

List *
make_ands_implicit(Expr *clause)
{
    /*
     * NB: because the parser sets the qual field to NULL in a query that has
     * no WHERE clause, we must consider a NULL input clause as TRUE, even
     * though one might more reasonably think it FALSE.
     */
    if (clause == NULL)
        return NIL;             /* NULL -> NIL list == TRUE */
    else if (is_andclause(clause))
        return ((BoolExpr *) clause)->args;
    else if (IsA(clause, Const) &&
             !((Const *) clause)->constisnull &&
             DatumGetBool(((Const *) clause)->constvalue))
        return NIL;             /* constant TRUE input -> NIL list */
    else
        return list_make1(clause);
}

/*
 * makeIndexInfo
 *    create an IndexInfo node
 */
IndexInfo *
makeIndexInfo(int numattrs, int numkeyattrs, Oid amoid, List *expressions,
              List *predicates, bool unique, bool isready, bool concurrent)
{
    IndexInfo  *n = makeNode(IndexInfo);

    n->ii_NumIndexAttrs = numattrs;
    n->ii_NumIndexKeyAttrs = numkeyattrs;
    Assert(n->ii_NumIndexKeyAttrs != 0);
    Assert(n->ii_NumIndexKeyAttrs <= n->ii_NumIndexAttrs);
    n->ii_Unique = unique;
    n->ii_ReadyForInserts = isready;
    n->ii_Concurrent = concurrent;

    /* expressions */
    n->ii_Expressions = expressions;
    n->ii_ExpressionsState = NIL;

    /* predicates  */
    n->ii_Predicate = predicates;
    n->ii_PredicateState = NULL;

    /* exclusion constraints */
    n->ii_ExclusionOps = NULL;
    n->ii_ExclusionProcs = NULL;
    n->ii_ExclusionStrats = NULL;

    /* speculative inserts */
    n->ii_UniqueOps = NULL;
    n->ii_UniqueProcs = NULL;
    n->ii_UniqueStrats = NULL;

    /* initialize index-build state to default */
    n->ii_BrokenHotChain = false;
    n->ii_ParallelWorkers = 0;

    /* set up for possible use by index AM */
    n->ii_Am = amoid;
    n->ii_AmCache = NULL;
    n->ii_Context = CurrentMemoryContext;

    return n;
}

/*
 * makeGroupingSet
 *
 */
GroupingSet *
makeGroupingSet(GroupingSetKind kind, List *content, int location)
{
    GroupingSet *n = makeNode(GroupingSet);

    n->kind = kind;
    n->content = content;
    n->location = location;
    return n;
}

/*
 * makeVacuumRelation -
 *    create a VacuumRelation node
 */
VacuumRelation *
makeVacuumRelation(RangeVar *relation, Oid oid, List *va_cols)
{
    VacuumRelation *v = makeNode(VacuumRelation);

    v->relation = relation;
    v->oid = oid;
    v->va_cols = va_cols;
    return v;
}