funcapi.c

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/*-------------------------------------------------------------------------
 *
 * funcapi.c
 *    Utility and convenience functions for fmgr functions that return
 *    sets and/or composite types, or deal with VARIADIC inputs.
 *
 * Copyright (c) 2002-2023, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/utils/fmgr/funcapi.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/htup_details.h"
#include "access/relation.h"
#include "catalog/namespace.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/regproc.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tuplestore.h"
#include "utils/typcache.h"
 
 
typedef struct polymorphic_actuals
{
    Oid         anyelement_type;    /* anyelement mapping, if known */
    Oid         anyarray_type;  /* anyarray mapping, if known */
    Oid         anyrange_type;  /* anyrange mapping, if known */
    Oid         anymultirange_type; /* anymultirange mapping, if known */
} polymorphic_actuals;
 
static void shutdown_MultiFuncCall(Datum arg);
static TypeFuncClass internal_get_result_type(Oid funcid,
                                              Node *call_expr,
                                              ReturnSetInfo *rsinfo,
                                              Oid *resultTypeId,
                                              TupleDesc *resultTupleDesc);
static void resolve_anyelement_from_others(polymorphic_actuals *actuals);
static void resolve_anyarray_from_others(polymorphic_actuals *actuals);
static void resolve_anyrange_from_others(polymorphic_actuals *actuals);
static void resolve_anymultirange_from_others(polymorphic_actuals *actuals);
static bool resolve_polymorphic_tupdesc(TupleDesc tupdesc,
                                        oidvector *declared_args,
                                        Node *call_expr);
static TypeFuncClass get_type_func_class(Oid typid, Oid *base_typeid);
 
 
/*
 * InitMaterializedSRF
 *
 * Helper function to build the state of a set-returning function used
 * in the context of a single call with materialize mode.  This code
 * includes sanity checks on ReturnSetInfo, creates the Tuplestore and
 * the TupleDesc used with the function and stores them into the
 * function's ReturnSetInfo.
 *
 * "flags" can be set to MAT_SRF_USE_EXPECTED_DESC, to use the tuple
 * descriptor coming from expectedDesc, which is the tuple descriptor
 * expected by the caller.  MAT_SRF_BLESS can be set to complete the
 * information associated to the tuple descriptor, which is necessary
 * in some cases where the tuple descriptor comes from a transient
 * RECORD datatype.
 */
void
InitMaterializedSRF(FunctionCallInfo fcinfo, bits32 flags)
{
    bool        random_access;
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    Tuplestorestate *tupstore;
    MemoryContext old_context,
                per_query_ctx;
    TupleDesc   stored_tupdesc;
 
    /* check to see if caller supports returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize) ||
        ((flags & MAT_SRF_USE_EXPECTED_DESC) != 0 && rsinfo->expectedDesc == NULL))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("materialize mode required, but it is not allowed in this context")));
 
    /*
     * Store the tuplestore and the tuple descriptor in ReturnSetInfo.  This
     * must be done in the per-query memory context.
     */
    per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
    old_context = MemoryContextSwitchTo(per_query_ctx);
 
    /* build a tuple descriptor for our result type */
    if ((flags & MAT_SRF_USE_EXPECTED_DESC) != 0)
        stored_tupdesc = CreateTupleDescCopy(rsinfo->expectedDesc);
    else
    {
        if (get_call_result_type(fcinfo, NULL, &stored_tupdesc) != TYPEFUNC_COMPOSITE)
            elog(ERROR, "return type must be a row type");
    }
 
    /* If requested, bless the tuple descriptor */
    if ((flags & MAT_SRF_BLESS) != 0)
        BlessTupleDesc(stored_tupdesc);
 
    random_access = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
 
    tupstore = tuplestore_begin_heap(random_access, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = stored_tupdesc;
    MemoryContextSwitchTo(old_context);
}
 
 
/*
 * init_MultiFuncCall
 * Create an empty FuncCallContext data structure
 * and do some other basic Multi-function call setup
 * and error checking
 */
FuncCallContext *
init_MultiFuncCall(PG_FUNCTION_ARGS)
{
    FuncCallContext *retval;
 
    /*
     * Bail if we're called in the wrong context
     */
    if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
 
    if (fcinfo->flinfo->fn_extra == NULL)
    {
        /*
         * First call
         */
        ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
        MemoryContext multi_call_ctx;
 
        /*
         * Create a suitably long-lived context to hold cross-call data
         */
        multi_call_ctx = AllocSetContextCreate(fcinfo->flinfo->fn_mcxt,
                                               "SRF multi-call context",
                                               ALLOCSET_SMALL_SIZES);
 
        /*
         * Allocate suitably long-lived space and zero it
         */
        retval = (FuncCallContext *)
            MemoryContextAllocZero(multi_call_ctx,
                                   sizeof(FuncCallContext));
 
        /*
         * initialize the elements
         */
        retval->call_cntr = 0;
        retval->max_calls = 0;
        retval->user_fctx = NULL;
        retval->attinmeta = NULL;
        retval->tuple_desc = NULL;
        retval->multi_call_memory_ctx = multi_call_ctx;
 
        /*
         * save the pointer for cross-call use
         */
        fcinfo->flinfo->fn_extra = retval;
 
        /*
         * Ensure we will get shut down cleanly if the exprcontext is not run
         * to completion.
         */
        RegisterExprContextCallback(rsi->econtext,
                                    shutdown_MultiFuncCall,
                                    PointerGetDatum(fcinfo->flinfo));
    }
    else
    {
        /* second and subsequent calls */
        elog(ERROR, "init_MultiFuncCall cannot be called more than once");
 
        /* never reached, but keep compiler happy */
        retval = NULL;
    }
 
    return retval;
}
 
/*
 * per_MultiFuncCall
 *
 * Do Multi-function per-call setup
 */
FuncCallContext *
per_MultiFuncCall(PG_FUNCTION_ARGS)
{
    FuncCallContext *retval = (FuncCallContext *) fcinfo->flinfo->fn_extra;
 
    return retval;
}
 
/*
 * end_MultiFuncCall
 * Clean up after init_MultiFuncCall
 */
void
end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx)
{
    ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
 
    /* Deregister the shutdown callback */
    UnregisterExprContextCallback(rsi->econtext,
                                  shutdown_MultiFuncCall,
                                  PointerGetDatum(fcinfo->flinfo));
 
    /* But use it to do the real work */
    shutdown_MultiFuncCall(PointerGetDatum(fcinfo->flinfo));
}
 
/*
 * shutdown_MultiFuncCall
 * Shutdown function to clean up after init_MultiFuncCall
 */
static void
shutdown_MultiFuncCall(Datum arg)
{
    FmgrInfo   *flinfo = (FmgrInfo *) DatumGetPointer(arg);
    FuncCallContext *funcctx = (FuncCallContext *) flinfo->fn_extra;
 
    /* unbind from flinfo */
    flinfo->fn_extra = NULL;
 
    /*
     * Delete context that holds all multi-call data, including the
     * FuncCallContext itself
     */
    MemoryContextDelete(funcctx->multi_call_memory_ctx);
}
 
 
/*
 * get_call_result_type
 *      Given a function's call info record, determine the kind of datatype
 *      it is supposed to return.  If resultTypeId isn't NULL, *resultTypeId
 *      receives the actual datatype OID (this is mainly useful for scalar
 *      result types).  If resultTupleDesc isn't NULL, *resultTupleDesc
 *      receives a pointer to a TupleDesc when the result is of a composite
 *      type, or NULL when it's a scalar result.
 *
 * One hard case that this handles is resolution of actual rowtypes for
 * functions returning RECORD (from either the function's OUT parameter
 * list, or a ReturnSetInfo context node).  TYPEFUNC_RECORD is returned
 * only when we couldn't resolve the actual rowtype for lack of information.
 *
 * The other hard case that this handles is resolution of polymorphism.
 * We will never return polymorphic pseudotypes (ANYELEMENT etc), either
 * as a scalar result type or as a component of a rowtype.
 *
 * This function is relatively expensive --- in a function returning set,
 * try to call it only the first time through.
 */
TypeFuncClass
get_call_result_type(FunctionCallInfo fcinfo,
                     Oid *resultTypeId,
                     TupleDesc *resultTupleDesc)
{
    return internal_get_result_type(fcinfo->flinfo->fn_oid,
                                    fcinfo->flinfo->fn_expr,
                                    (ReturnSetInfo *) fcinfo->resultinfo,
                                    resultTypeId,
                                    resultTupleDesc);
}
 
/*
 * get_expr_result_type
 *      As above, but work from a calling expression node tree
 */
TypeFuncClass
get_expr_result_type(Node *expr,
                     Oid *resultTypeId,
                     TupleDesc *resultTupleDesc)
{
    TypeFuncClass result;
 
    if (expr && IsA(expr, FuncExpr))
        result = internal_get_result_type(((FuncExpr *) expr)->funcid,
                                          expr,
                                          NULL,
                                          resultTypeId,
                                          resultTupleDesc);
    else if (expr && IsA(expr, OpExpr))
        result = internal_get_result_type(get_opcode(((OpExpr *) expr)->opno),
                                          expr,
                                          NULL,
                                          resultTypeId,
                                          resultTupleDesc);
    else if (expr && IsA(expr, RowExpr) &&
             ((RowExpr *) expr)->row_typeid == RECORDOID)
    {
        /* We can resolve the record type by generating the tupdesc directly */
        RowExpr    *rexpr = (RowExpr *) expr;
        TupleDesc   tupdesc;
        AttrNumber  i = 1;
        ListCell   *lcc,
                   *lcn;
 
        tupdesc = CreateTemplateTupleDesc(list_length(rexpr->args));
        Assert(list_length(rexpr->args) == list_length(rexpr->colnames));
        forboth(lcc, rexpr->args, lcn, rexpr->colnames)
        {
            Node       *col = (Node *) lfirst(lcc);
            char       *colname = strVal(lfirst(lcn));
 
            TupleDescInitEntry(tupdesc, i,
                               colname,
                               exprType(col),
                               exprTypmod(col),
                               0);
            TupleDescInitEntryCollation(tupdesc, i,
                                        exprCollation(col));
            i++;
        }
        if (resultTypeId)
            *resultTypeId = rexpr->row_typeid;
        if (resultTupleDesc)
            *resultTupleDesc = BlessTupleDesc(tupdesc);
        return TYPEFUNC_COMPOSITE;
    }
    else if (expr && IsA(expr, Const) &&
             ((Const *) expr)->consttype == RECORDOID &&
             !((Const *) expr)->constisnull)
    {
        /*
         * When EXPLAIN'ing some queries with SEARCH/CYCLE clauses, we may
         * need to resolve field names of a RECORD-type Const.  The datum
         * should contain a typmod that will tell us that.
         */
        HeapTupleHeader rec;
        Oid         tupType;
        int32       tupTypmod;
 
        rec = DatumGetHeapTupleHeader(((Const *) expr)->constvalue);
        tupType = HeapTupleHeaderGetTypeId(rec);
        tupTypmod = HeapTupleHeaderGetTypMod(rec);
        if (resultTypeId)
            *resultTypeId = tupType;
        if (tupType != RECORDOID || tupTypmod >= 0)
        {
            /* Should be able to look it up */
            if (resultTupleDesc)
                *resultTupleDesc = lookup_rowtype_tupdesc_copy(tupType,
                                                               tupTypmod);
            return TYPEFUNC_COMPOSITE;
        }
        else
        {
            /* This shouldn't really happen ... */
            if (resultTupleDesc)
                *resultTupleDesc = NULL;
            return TYPEFUNC_RECORD;
        }
    }
    else
    {
        /* handle as a generic expression; no chance to resolve RECORD */
        Oid         typid = exprType(expr);
        Oid         base_typid;
 
        if (resultTypeId)
            *resultTypeId = typid;
        if (resultTupleDesc)
            *resultTupleDesc = NULL;
        result = get_type_func_class(typid, &base_typid);
        if ((result == TYPEFUNC_COMPOSITE ||
             result == TYPEFUNC_COMPOSITE_DOMAIN) &&
            resultTupleDesc)
            *resultTupleDesc = lookup_rowtype_tupdesc_copy(base_typid, -1);
    }
 
    return result;
}
 
/*
 * get_func_result_type
 *      As above, but work from a function's OID only
 *
 * This will not be able to resolve pure-RECORD results nor polymorphism.
 */
TypeFuncClass
get_func_result_type(Oid functionId,
                     Oid *resultTypeId,
                     TupleDesc *resultTupleDesc)
{
    return internal_get_result_type(functionId,
                                    NULL,
                                    NULL,
                                    resultTypeId,
                                    resultTupleDesc);
}
 
/*
 * internal_get_result_type -- workhorse code implementing all the above
 *
 * funcid must always be supplied.  call_expr and rsinfo can be NULL if not
 * available.  We will return TYPEFUNC_RECORD, and store NULL into
 * *resultTupleDesc, if we cannot deduce the complete result rowtype from
 * the available information.
 */
static TypeFuncClass
internal_get_result_type(Oid funcid,
                         Node *call_expr,
                         ReturnSetInfo *rsinfo,
                         Oid *resultTypeId,
                         TupleDesc *resultTupleDesc)
{
    TypeFuncClass result;
    HeapTuple   tp;
    Form_pg_proc procform;
    Oid         rettype;
    Oid         base_rettype;
    TupleDesc   tupdesc;
 
    /* First fetch the function's pg_proc row to inspect its rettype */
    tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for function %u", funcid);
    procform = (Form_pg_proc) GETSTRUCT(tp);
 
    rettype = procform->prorettype;
 
    /* Check for OUT parameters defining a RECORD result */
    tupdesc = build_function_result_tupdesc_t(tp);
    if (tupdesc)
    {
        /*
         * It has OUT parameters, so it's basically like a regular composite
         * type, except we have to be able to resolve any polymorphic OUT
         * parameters.
         */
        if (resultTypeId)
            *resultTypeId = rettype;
 
        if (resolve_polymorphic_tupdesc(tupdesc,
                                        &procform->proargtypes,
                                        call_expr))
        {
            if (tupdesc->tdtypeid == RECORDOID &&
                tupdesc->tdtypmod < 0)
                assign_record_type_typmod(tupdesc);
            if (resultTupleDesc)
                *resultTupleDesc = tupdesc;
            result = TYPEFUNC_COMPOSITE;
        }
        else
        {
            if (resultTupleDesc)
                *resultTupleDesc = NULL;
            result = TYPEFUNC_RECORD;
        }
 
        ReleaseSysCache(tp);
 
        return result;
    }
 
    /*
     * If scalar polymorphic result, try to resolve it.
     */
    if (IsPolymorphicType(rettype))
    {
        Oid         newrettype = exprType(call_expr);
 
        if (newrettype == InvalidOid)   /* this probably should not happen */
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("could not determine actual result type for function \"%s\" declared to return type %s",
                            NameStr(procform->proname),
                            format_type_be(rettype))));
        rettype = newrettype;
    }
 
    if (resultTypeId)
        *resultTypeId = rettype;
    if (resultTupleDesc)
        *resultTupleDesc = NULL;    /* default result */
 
    /* Classify the result type */
    result = get_type_func_class(rettype, &base_rettype);
    switch (result)
    {
        case TYPEFUNC_COMPOSITE:
        case TYPEFUNC_COMPOSITE_DOMAIN:
            if (resultTupleDesc)
                *resultTupleDesc = lookup_rowtype_tupdesc_copy(base_rettype, -1);
            /* Named composite types can't have any polymorphic columns */
            break;
        case TYPEFUNC_SCALAR:
            break;
        case TYPEFUNC_RECORD:
            /* We must get the tupledesc from call context */
            if (rsinfo && IsA(rsinfo, ReturnSetInfo) &&
                rsinfo->expectedDesc != NULL)
            {
                result = TYPEFUNC_COMPOSITE;
                if (resultTupleDesc)
                    *resultTupleDesc = rsinfo->expectedDesc;
                /* Assume no polymorphic columns here, either */
            }
            break;
        default:
            break;
    }
 
    ReleaseSysCache(tp);
 
    return result;
}
 
/*
 * get_expr_result_tupdesc
 *      Get a tupdesc describing the result of a composite-valued expression
 *
 * If expression is not composite or rowtype can't be determined, returns NULL
 * if noError is true, else throws error.
 *
 * This is a simpler version of get_expr_result_type() for use when the caller
 * is only interested in determinate rowtype results.
 */
TupleDesc
get_expr_result_tupdesc(Node *expr, bool noError)
{
    TupleDesc   tupleDesc;
    TypeFuncClass functypclass;
 
    functypclass = get_expr_result_type(expr, NULL, &tupleDesc);
 
    if (functypclass == TYPEFUNC_COMPOSITE ||
        functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
        return tupleDesc;
 
    if (!noError)
    {
        Oid         exprTypeId = exprType(expr);
 
        if (exprTypeId != RECORDOID)
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("type %s is not composite",
                            format_type_be(exprTypeId))));
        else
            ereport(ERROR,
                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                     errmsg("record type has not been registered")));
    }
 
    return NULL;
}
 
/*
 * Resolve actual type of ANYELEMENT from other polymorphic inputs
 *
 * Note: the error cases here and in the sibling functions below are not
 * really user-facing; they could only occur if the function signature is
 * incorrect or the parser failed to enforce consistency of the actual
 * argument types.  Hence, we don't sweat too much over the error messages.
 */
static void
resolve_anyelement_from_others(polymorphic_actuals *actuals)
{
    if (OidIsValid(actuals->anyarray_type))
    {
        /* Use the element type corresponding to actual type */
        Oid         array_base_type = getBaseType(actuals->anyarray_type);
        Oid         array_typelem = get_element_type(array_base_type);
 
        if (!OidIsValid(array_typelem))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("argument declared %s is not an array but type %s",
                            "anyarray",
                            format_type_be(array_base_type))));
        actuals->anyelement_type = array_typelem;
    }
    else if (OidIsValid(actuals->anyrange_type))
    {
        /* Use the element type corresponding to actual type */
        Oid         range_base_type = getBaseType(actuals->anyrange_type);
        Oid         range_typelem = get_range_subtype(range_base_type);
 
        if (!OidIsValid(range_typelem))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("argument declared %s is not a range type but type %s",
                            "anyrange",
                            format_type_be(range_base_type))));
        actuals->anyelement_type = range_typelem;
    }
    else if (OidIsValid(actuals->anymultirange_type))
    {
        /* Use the element type based on the multirange type */
        Oid         multirange_base_type;
        Oid         multirange_typelem;
        Oid         range_base_type;
        Oid         range_typelem;
 
        multirange_base_type = getBaseType(actuals->anymultirange_type);
        multirange_typelem = get_multirange_range(multirange_base_type);
        if (!OidIsValid(multirange_typelem))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("argument declared %s is not a multirange type but type %s",
                            "anymultirange",
                            format_type_be(multirange_base_type))));
 
        range_base_type = getBaseType(multirange_typelem);
        range_typelem = get_range_subtype(range_base_type);
 
        if (!OidIsValid(range_typelem))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("argument declared %s does not contain a range type but type %s",
                            "anymultirange",
                            format_type_be(range_base_type))));
        actuals->anyelement_type = range_typelem;
    }
    else
        elog(ERROR, "could not determine polymorphic type");
}
 
/*
 * Resolve actual type of ANYARRAY from other polymorphic inputs
 */
static void
resolve_anyarray_from_others(polymorphic_actuals *actuals)
{
    /* If we don't know ANYELEMENT, resolve that first */
    if (!OidIsValid(actuals->anyelement_type))
        resolve_anyelement_from_others(actuals);
 
    if (OidIsValid(actuals->anyelement_type))
    {
        /* Use the array type corresponding to actual type */
        Oid         array_typeid = get_array_type(actuals->anyelement_type);
 
        if (!OidIsValid(array_typeid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("could not find array type for data type %s",
                            format_type_be(actuals->anyelement_type))));
        actuals->anyarray_type = array_typeid;
    }
    else
        elog(ERROR, "could not determine polymorphic type");
}
 
/*
 * Resolve actual type of ANYRANGE from other polymorphic inputs
 */
static void
resolve_anyrange_from_others(polymorphic_actuals *actuals)
{
    /*
     * We can't deduce a range type from other polymorphic array or base
     * types, because there may be multiple range types with the same subtype,
     * but we can deduce it from a polymorphic multirange type.
     */
    if (OidIsValid(actuals->anymultirange_type))
    {
        /* Use the element type based on the multirange type */
        Oid         multirange_base_type = getBaseType(actuals->anymultirange_type);
        Oid         multirange_typelem = get_multirange_range(multirange_base_type);
 
        if (!OidIsValid(multirange_typelem))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("argument declared %s is not a multirange type but type %s",
                            "anymultirange",
                            format_type_be(multirange_base_type))));
        actuals->anyrange_type = multirange_typelem;
    }
    else
        elog(ERROR, "could not determine polymorphic type");
}
 
/*
 * Resolve actual type of ANYMULTIRANGE from other polymorphic inputs
 */
static void
resolve_anymultirange_from_others(polymorphic_actuals *actuals)
{
    /*
     * We can't deduce a multirange type from polymorphic array or base types,
     * because there may be multiple range types with the same subtype, but we
     * can deduce it from a polymorphic range type.
     */
    if (OidIsValid(actuals->anyrange_type))
    {
        Oid         range_base_type = getBaseType(actuals->anyrange_type);
        Oid         multirange_typeid = get_range_multirange(range_base_type);
 
        if (!OidIsValid(multirange_typeid))
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("could not find multirange type for data type %s",
                            format_type_be(actuals->anyrange_type))));
        actuals->anymultirange_type = multirange_typeid;
    }
    else
        elog(ERROR, "could not determine polymorphic type");
}
 
/*
 * Given the result tuple descriptor for a function with OUT parameters,
 * replace any polymorphic column types (ANYELEMENT etc) in the tupdesc
 * with concrete data types deduced from the input arguments.
 * declared_args is an oidvector of the function's declared input arg types
 * (showing which are polymorphic), and call_expr is the call expression.
 *
 * Returns true if able to deduce all types, false if necessary information
 * is not provided (call_expr is NULL or arg types aren't identifiable).
 */
static bool
resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
                            Node *call_expr)
{
    int         natts = tupdesc->natts;
    int         nargs = declared_args->dim1;
    bool        have_polymorphic_result = false;
    bool        have_anyelement_result = false;
    bool        have_anyarray_result = false;
    bool        have_anyrange_result = false;
    bool        have_anymultirange_result = false;
    bool        have_anycompatible_result = false;
    bool        have_anycompatible_array_result = false;
    bool        have_anycompatible_range_result = false;
    bool        have_anycompatible_multirange_result = false;
    polymorphic_actuals poly_actuals;
    polymorphic_actuals anyc_actuals;
    Oid         anycollation = InvalidOid;
    Oid         anycompatcollation = InvalidOid;
    int         i;
 
    /* See if there are any polymorphic outputs; quick out if not */
    for (i = 0; i < natts; i++)
    {
        switch (TupleDescAttr(tupdesc, i)->atttypid)
        {
            case ANYELEMENTOID:
            case ANYNONARRAYOID:
            case ANYENUMOID:
                have_polymorphic_result = true;
                have_anyelement_result = true;
                break;
            case ANYARRAYOID:
                have_polymorphic_result = true;
                have_anyarray_result = true;
                break;
            case ANYRANGEOID:
                have_polymorphic_result = true;
                have_anyrange_result = true;
                break;
            case ANYMULTIRANGEOID:
                have_polymorphic_result = true;
                have_anymultirange_result = true;
                break;
            case ANYCOMPATIBLEOID:
            case ANYCOMPATIBLENONARRAYOID:
                have_polymorphic_result = true;
                have_anycompatible_result = true;
                break;
            case ANYCOMPATIBLEARRAYOID:
                have_polymorphic_result = true;
                have_anycompatible_array_result = true;
                break;
            case ANYCOMPATIBLERANGEOID:
                have_polymorphic_result = true;
                have_anycompatible_range_result = true;
                break;
            case ANYCOMPATIBLEMULTIRANGEOID:
                have_polymorphic_result = true;
                have_anycompatible_multirange_result = true;
                break;
            default:
                break;
        }
    }
    if (!have_polymorphic_result)
        return true;
 
    /*
     * Otherwise, extract actual datatype(s) from input arguments.  (We assume
     * the parser already validated consistency of the arguments.  Also, for
     * the ANYCOMPATIBLE pseudotype family, we expect that all matching
     * arguments were coerced to the selected common supertype, so that it
     * doesn't matter which one's exposed type we look at.)
     */
    if (!call_expr)
        return false;           /* no hope */
 
    memset(&poly_actuals, 0, sizeof(poly_actuals));
    memset(&anyc_actuals, 0, sizeof(anyc_actuals));
 
    for (i = 0; i < nargs; i++)
    {
        switch (declared_args->values[i])
        {
            case ANYELEMENTOID:
            case ANYNONARRAYOID:
            case ANYENUMOID:
                if (!OidIsValid(poly_actuals.anyelement_type))
                {
                    poly_actuals.anyelement_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(poly_actuals.anyelement_type))
                        return false;
                }
                break;
            case ANYARRAYOID:
                if (!OidIsValid(poly_actuals.anyarray_type))
                {
                    poly_actuals.anyarray_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(poly_actuals.anyarray_type))
                        return false;
                }
                break;
            case ANYRANGEOID:
                if (!OidIsValid(poly_actuals.anyrange_type))
                {
                    poly_actuals.anyrange_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(poly_actuals.anyrange_type))
                        return false;
                }
                break;
            case ANYMULTIRANGEOID:
                if (!OidIsValid(poly_actuals.anymultirange_type))
                {
                    poly_actuals.anymultirange_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(poly_actuals.anymultirange_type))
                        return false;
                }
                break;
            case ANYCOMPATIBLEOID:
            case ANYCOMPATIBLENONARRAYOID:
                if (!OidIsValid(anyc_actuals.anyelement_type))
                {
                    anyc_actuals.anyelement_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(anyc_actuals.anyelement_type))
                        return false;
                }
                break;
            case ANYCOMPATIBLEARRAYOID:
                if (!OidIsValid(anyc_actuals.anyarray_type))
                {
                    anyc_actuals.anyarray_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(anyc_actuals.anyarray_type))
                        return false;
                }
                break;
            case ANYCOMPATIBLERANGEOID:
                if (!OidIsValid(anyc_actuals.anyrange_type))
                {
                    anyc_actuals.anyrange_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(anyc_actuals.anyrange_type))
                        return false;
                }
                break;
            case ANYCOMPATIBLEMULTIRANGEOID:
                if (!OidIsValid(anyc_actuals.anymultirange_type))
                {
                    anyc_actuals.anymultirange_type =
                        get_call_expr_argtype(call_expr, i);
                    if (!OidIsValid(anyc_actuals.anymultirange_type))
                        return false;
                }
                break;
            default:
                break;
        }
    }
 
    /* If needed, deduce one polymorphic type from others */
    if (have_anyelement_result && !OidIsValid(poly_actuals.anyelement_type))
        resolve_anyelement_from_others(&poly_actuals);
 
    if (have_anyarray_result && !OidIsValid(poly_actuals.anyarray_type))
        resolve_anyarray_from_others(&poly_actuals);
 
    if (have_anyrange_result && !OidIsValid(poly_actuals.anyrange_type))
        resolve_anyrange_from_others(&poly_actuals);
 
    if (have_anymultirange_result && !OidIsValid(poly_actuals.anymultirange_type))
        resolve_anymultirange_from_others(&poly_actuals);
 
    if (have_anycompatible_result && !OidIsValid(anyc_actuals.anyelement_type))
        resolve_anyelement_from_others(&anyc_actuals);
 
    if (have_anycompatible_array_result && !OidIsValid(anyc_actuals.anyarray_type))
        resolve_anyarray_from_others(&anyc_actuals);
 
    if (have_anycompatible_range_result && !OidIsValid(anyc_actuals.anyrange_type))
        resolve_anyrange_from_others(&anyc_actuals);
 
    if (have_anycompatible_multirange_result && !OidIsValid(anyc_actuals.anymultirange_type))
        resolve_anymultirange_from_others(&anyc_actuals);
 
    /*
     * Identify the collation to use for polymorphic OUT parameters. (It'll
     * necessarily be the same for both anyelement and anyarray, likewise for
     * anycompatible and anycompatiblearray.)  Note that range types are not
     * collatable, so any possible internal collation of a range type is not
     * considered here.
     */
    if (OidIsValid(poly_actuals.anyelement_type))
        anycollation = get_typcollation(poly_actuals.anyelement_type);
    else if (OidIsValid(poly_actuals.anyarray_type))
        anycollation = get_typcollation(poly_actuals.anyarray_type);
 
    if (OidIsValid(anyc_actuals.anyelement_type))
        anycompatcollation = get_typcollation(anyc_actuals.anyelement_type);
    else if (OidIsValid(anyc_actuals.anyarray_type))
        anycompatcollation = get_typcollation(anyc_actuals.anyarray_type);
 
    if (OidIsValid(anycollation) || OidIsValid(anycompatcollation))
    {
        /*
         * The types are collatable, so consider whether to use a nondefault
         * collation.  We do so if we can identify the input collation used
         * for the function.
         */
        Oid         inputcollation = exprInputCollation(call_expr);
 
        if (OidIsValid(inputcollation))
        {
            if (OidIsValid(anycollation))
                anycollation = inputcollation;
            if (OidIsValid(anycompatcollation))
                anycompatcollation = inputcollation;
        }
    }
 
    /* And finally replace the tuple column types as needed */
    for (i = 0; i < natts; i++)
    {
        Form_pg_attribute att = TupleDescAttr(tupdesc, i);
 
        switch (att->atttypid)
        {
            case ANYELEMENTOID:
            case ANYNONARRAYOID:
            case ANYENUMOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   poly_actuals.anyelement_type,
                                   -1,
                                   0);
                TupleDescInitEntryCollation(tupdesc, i + 1, anycollation);
                break;
            case ANYARRAYOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   poly_actuals.anyarray_type,
                                   -1,
                                   0);
                TupleDescInitEntryCollation(tupdesc, i + 1, anycollation);
                break;
            case ANYRANGEOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   poly_actuals.anyrange_type,
                                   -1,
                                   0);
                /* no collation should be attached to a range type */
                break;
            case ANYMULTIRANGEOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   poly_actuals.anymultirange_type,
                                   -1,
                                   0);
                /* no collation should be attached to a multirange type */
                break;
            case ANYCOMPATIBLEOID:
            case ANYCOMPATIBLENONARRAYOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   anyc_actuals.anyelement_type,
                                   -1,
                                   0);
                TupleDescInitEntryCollation(tupdesc, i + 1, anycompatcollation);
                break;
            case ANYCOMPATIBLEARRAYOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   anyc_actuals.anyarray_type,
                                   -1,
                                   0);
                TupleDescInitEntryCollation(tupdesc, i + 1, anycompatcollation);
                break;
            case ANYCOMPATIBLERANGEOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   anyc_actuals.anyrange_type,
                                   -1,
                                   0);
                /* no collation should be attached to a range type */
                break;
            case ANYCOMPATIBLEMULTIRANGEOID:
                TupleDescInitEntry(tupdesc, i + 1,
                                   NameStr(att->attname),
                                   anyc_actuals.anymultirange_type,
                                   -1,
                                   0);
                /* no collation should be attached to a multirange type */
                break;
            default:
                break;
        }
    }
 
    return true;
}
 
/*
 * Given the declared argument types and modes for a function, replace any
 * polymorphic types (ANYELEMENT etc) in argtypes[] with concrete data types
 * deduced from the input arguments found in call_expr.
 *
 * Returns true if able to deduce all types, false if necessary information
 * is not provided (call_expr is NULL or arg types aren't identifiable).
 *
 * This is the same logic as resolve_polymorphic_tupdesc, but with a different
 * argument representation, and slightly different output responsibilities.
 *
 * argmodes may be NULL, in which case all arguments are assumed to be IN mode.
 */
bool
resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
                             Node *call_expr)
{
    bool        have_polymorphic_result = false;
    bool        have_anyelement_result = false;
    bool        have_anyarray_result = false;
    bool        have_anyrange_result = false;
    bool        have_anymultirange_result = false;
    bool        have_anycompatible_result = false;
    bool        have_anycompatible_array_result = false;
    bool        have_anycompatible_range_result = false;
    bool        have_anycompatible_multirange_result = false;
    polymorphic_actuals poly_actuals;
    polymorphic_actuals anyc_actuals;
    int         inargno;
    int         i;
 
    /*
     * First pass: resolve polymorphic inputs, check for outputs.  As in
     * resolve_polymorphic_tupdesc, we rely on the parser to have enforced
     * type consistency and coerced ANYCOMPATIBLE args to a common supertype.
     */
    memset(&poly_actuals, 0, sizeof(poly_actuals));
    memset(&anyc_actuals, 0, sizeof(anyc_actuals));
    inargno = 0;
    for (i = 0; i < numargs; i++)
    {
        char        argmode = argmodes ? argmodes[i] : PROARGMODE_IN;
 
        switch (argtypes[i])
        {
            case ANYELEMENTOID:
            case ANYNONARRAYOID:
            case ANYENUMOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anyelement_result = true;
                }
                else
                {
                    if (!OidIsValid(poly_actuals.anyelement_type))
                    {
                        poly_actuals.anyelement_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(poly_actuals.anyelement_type))
                            return false;
                    }
                    argtypes[i] = poly_actuals.anyelement_type;
                }
                break;
            case ANYARRAYOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anyarray_result = true;
                }
                else
                {
                    if (!OidIsValid(poly_actuals.anyarray_type))
                    {
                        poly_actuals.anyarray_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(poly_actuals.anyarray_type))
                            return false;
                    }
                    argtypes[i] = poly_actuals.anyarray_type;
                }
                break;
            case ANYRANGEOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anyrange_result = true;
                }
                else
                {
                    if (!OidIsValid(poly_actuals.anyrange_type))
                    {
                        poly_actuals.anyrange_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(poly_actuals.anyrange_type))
                            return false;
                    }
                    argtypes[i] = poly_actuals.anyrange_type;
                }
                break;
            case ANYMULTIRANGEOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anymultirange_result = true;
                }
                else
                {
                    if (!OidIsValid(poly_actuals.anymultirange_type))
                    {
                        poly_actuals.anymultirange_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(poly_actuals.anymultirange_type))
                            return false;
                    }
                    argtypes[i] = poly_actuals.anymultirange_type;
                }
                break;
            case ANYCOMPATIBLEOID:
            case ANYCOMPATIBLENONARRAYOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anycompatible_result = true;
                }
                else
                {
                    if (!OidIsValid(anyc_actuals.anyelement_type))
                    {
                        anyc_actuals.anyelement_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(anyc_actuals.anyelement_type))
                            return false;
                    }
                    argtypes[i] = anyc_actuals.anyelement_type;
                }
                break;
            case ANYCOMPATIBLEARRAYOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anycompatible_array_result = true;
                }
                else
                {
                    if (!OidIsValid(anyc_actuals.anyarray_type))
                    {
                        anyc_actuals.anyarray_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(anyc_actuals.anyarray_type))
                            return false;
                    }
                    argtypes[i] = anyc_actuals.anyarray_type;
                }
                break;
            case ANYCOMPATIBLERANGEOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anycompatible_range_result = true;
                }
                else
                {
                    if (!OidIsValid(anyc_actuals.anyrange_type))
                    {
                        anyc_actuals.anyrange_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(anyc_actuals.anyrange_type))
                            return false;
                    }
                    argtypes[i] = anyc_actuals.anyrange_type;
                }
                break;
            case ANYCOMPATIBLEMULTIRANGEOID:
                if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                {
                    have_polymorphic_result = true;
                    have_anycompatible_multirange_result = true;
                }
                else
                {
                    if (!OidIsValid(anyc_actuals.anymultirange_type))
                    {
                        anyc_actuals.anymultirange_type =
                            get_call_expr_argtype(call_expr, inargno);
                        if (!OidIsValid(anyc_actuals.anymultirange_type))
                            return false;
                    }
                    argtypes[i] = anyc_actuals.anymultirange_type;
                }
                break;
            default:
                break;
        }
        if (argmode != PROARGMODE_OUT && argmode != PROARGMODE_TABLE)
            inargno++;
    }
 
    /* Done? */
    if (!have_polymorphic_result)
        return true;
 
    /* If needed, deduce one polymorphic type from others */
    if (have_anyelement_result && !OidIsValid(poly_actuals.anyelement_type))
        resolve_anyelement_from_others(&poly_actuals);
 
    if (have_anyarray_result && !OidIsValid(poly_actuals.anyarray_type))
        resolve_anyarray_from_others(&poly_actuals);
 
    if (have_anyrange_result && !OidIsValid(poly_actuals.anyrange_type))
        resolve_anyrange_from_others(&poly_actuals);
 
    if (have_anymultirange_result && !OidIsValid(poly_actuals.anymultirange_type))
        resolve_anymultirange_from_others(&poly_actuals);
 
    if (have_anycompatible_result && !OidIsValid(anyc_actuals.anyelement_type))
        resolve_anyelement_from_others(&anyc_actuals);
 
    if (have_anycompatible_array_result && !OidIsValid(anyc_actuals.anyarray_type))
        resolve_anyarray_from_others(&anyc_actuals);
 
    if (have_anycompatible_range_result && !OidIsValid(anyc_actuals.anyrange_type))
        resolve_anyrange_from_others(&anyc_actuals);
 
    if (have_anycompatible_multirange_result && !OidIsValid(anyc_actuals.anymultirange_type))
        resolve_anymultirange_from_others(&anyc_actuals);
 
    /* And finally replace the output column types as needed */
    for (i = 0; i < numargs; i++)
    {
        switch (argtypes[i])
        {
            case ANYELEMENTOID:
            case ANYNONARRAYOID:
            case ANYENUMOID:
                argtypes[i] = poly_actuals.anyelement_type;
                break;
            case ANYARRAYOID:
                argtypes[i] = poly_actuals.anyarray_type;
                break;
            case ANYRANGEOID:
                argtypes[i] = poly_actuals.anyrange_type;
                break;
            case ANYMULTIRANGEOID:
                argtypes[i] = poly_actuals.anymultirange_type;
                break;
            case ANYCOMPATIBLEOID:
            case ANYCOMPATIBLENONARRAYOID:
                argtypes[i] = anyc_actuals.anyelement_type;
                break;
            case ANYCOMPATIBLEARRAYOID:
                argtypes[i] = anyc_actuals.anyarray_type;
                break;
            case ANYCOMPATIBLERANGEOID:
                argtypes[i] = anyc_actuals.anyrange_type;
                break;
            case ANYCOMPATIBLEMULTIRANGEOID:
                argtypes[i] = anyc_actuals.anymultirange_type;
                break;
            default:
                break;
        }
    }
 
    return true;
}
 
/*
 * get_type_func_class
 *      Given the type OID, obtain its TYPEFUNC classification.
 *      Also, if it's a domain, return the base type OID.
 *
 * This is intended to centralize a bunch of formerly ad-hoc code for
 * classifying types.  The categories used here are useful for deciding
 * how to handle functions returning the datatype.
 */
static TypeFuncClass
get_type_func_class(Oid typid, Oid *base_typeid)
{
    *base_typeid = typid;
 
    switch (get_typtype(typid))
    {
        case TYPTYPE_COMPOSITE:
            return TYPEFUNC_COMPOSITE;
        case TYPTYPE_BASE:
        case TYPTYPE_ENUM:
        case TYPTYPE_RANGE:
        case TYPTYPE_MULTIRANGE:
            return TYPEFUNC_SCALAR;
        case TYPTYPE_DOMAIN:
            *base_typeid = typid = getBaseType(typid);
            if (get_typtype(typid) == TYPTYPE_COMPOSITE)
                return TYPEFUNC_COMPOSITE_DOMAIN;
            else                /* domain base type can't be a pseudotype */
                return TYPEFUNC_SCALAR;
        case TYPTYPE_PSEUDO:
            if (typid == RECORDOID)
                return TYPEFUNC_RECORD;
 
            /*
             * We treat VOID and CSTRING as legitimate scalar datatypes,
             * mostly for the convenience of the JDBC driver (which wants to
             * be able to do "SELECT * FROM foo()" for all legitimately
             * user-callable functions).
             */
            if (typid == VOIDOID || typid == CSTRINGOID)
                return TYPEFUNC_SCALAR;
            return TYPEFUNC_OTHER;
    }
    /* shouldn't get here, probably */
    return TYPEFUNC_OTHER;
}
 
 
/*
 * get_func_arg_info
 *
 * Fetch info about the argument types, names, and IN/OUT modes from the
 * pg_proc tuple.  Return value is the total number of arguments.
 * Other results are palloc'd.  *p_argtypes is always filled in, but
 * *p_argnames and *p_argmodes will be set NULL in the default cases
 * (no names, and all IN arguments, respectively).
 *
 * Note that this function simply fetches what is in the pg_proc tuple;
 * it doesn't do any interpretation of polymorphic types.
 */
int
get_func_arg_info(HeapTuple procTup,
                  Oid **p_argtypes, char ***p_argnames, char **p_argmodes)
{
    Form_pg_proc procStruct = (Form_pg_proc) GETSTRUCT(procTup);
    Datum       proallargtypes;
    Datum       proargmodes;
    Datum       proargnames;
    bool        isNull;
    ArrayType  *arr;
    int         numargs;
    Datum      *elems;
    int         nelems;
    int         i;
 
    /* First discover the total number of parameters and get their types */
    proallargtypes = SysCacheGetAttr(PROCOID, procTup,
                                     Anum_pg_proc_proallargtypes,
                                     &isNull);
    if (!isNull)
    {
        /*
         * We expect the arrays to be 1-D arrays of the right types; verify
         * that.  For the OID and char arrays, we don't need to use
         * deconstruct_array() since the array data is just going to look like
         * a C array of values.
         */
        arr = DatumGetArrayTypeP(proallargtypes);   /* ensure not toasted */
        numargs = ARR_DIMS(arr)[0];
        if (ARR_NDIM(arr) != 1 ||
            numargs < 0 ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != OIDOID)
            elog(ERROR, "proallargtypes is not a 1-D Oid array or it contains nulls");
        Assert(numargs >= procStruct->pronargs);
        *p_argtypes = (Oid *) palloc(numargs * sizeof(Oid));
        memcpy(*p_argtypes, ARR_DATA_PTR(arr),
               numargs * sizeof(Oid));
    }
    else
    {
        /* If no proallargtypes, use proargtypes */
        numargs = procStruct->proargtypes.dim1;
        Assert(numargs == procStruct->pronargs);
        *p_argtypes = (Oid *) palloc(numargs * sizeof(Oid));
        memcpy(*p_argtypes, procStruct->proargtypes.values,
               numargs * sizeof(Oid));
    }
 
    /* Get argument names, if available */
    proargnames = SysCacheGetAttr(PROCOID, procTup,
                                  Anum_pg_proc_proargnames,
                                  &isNull);
    if (isNull)
        *p_argnames = NULL;
    else
    {
        deconstruct_array_builtin(DatumGetArrayTypeP(proargnames), TEXTOID,
                                  &elems, NULL, &nelems);
        if (nelems != numargs)  /* should not happen */
            elog(ERROR, "proargnames must have the same number of elements as the function has arguments");
        *p_argnames = (char **) palloc(sizeof(char *) * numargs);
        for (i = 0; i < numargs; i++)
            (*p_argnames)[i] = TextDatumGetCString(elems[i]);
    }
 
    /* Get argument modes, if available */
    proargmodes = SysCacheGetAttr(PROCOID, procTup,
                                  Anum_pg_proc_proargmodes,
                                  &isNull);
    if (isNull)
        *p_argmodes = NULL;
    else
    {
        arr = DatumGetArrayTypeP(proargmodes);  /* ensure not toasted */
        if (ARR_NDIM(arr) != 1 ||
            ARR_DIMS(arr)[0] != numargs ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != CHAROID)
            elog(ERROR, "proargmodes is not a 1-D char array of length %d or it contains nulls",
                 numargs);
        *p_argmodes = (char *) palloc(numargs * sizeof(char));
        memcpy(*p_argmodes, ARR_DATA_PTR(arr),
               numargs * sizeof(char));
    }
 
    return numargs;
}
 
/*
 * get_func_trftypes
 *
 * Returns the number of transformed types used by the function.
 * If there are any, a palloc'd array of the type OIDs is returned
 * into *p_trftypes.
 */
int
get_func_trftypes(HeapTuple procTup,
                  Oid **p_trftypes)
{
    Datum       protrftypes;
    ArrayType  *arr;
    int         nelems;
    bool        isNull;
 
    protrftypes = SysCacheGetAttr(PROCOID, procTup,
                                  Anum_pg_proc_protrftypes,
                                  &isNull);
    if (!isNull)
    {
        /*
         * We expect the arrays to be 1-D arrays of the right types; verify
         * that.  For the OID and char arrays, we don't need to use
         * deconstruct_array() since the array data is just going to look like
         * a C array of values.
         */
        arr = DatumGetArrayTypeP(protrftypes);  /* ensure not toasted */
        nelems = ARR_DIMS(arr)[0];
        if (ARR_NDIM(arr) != 1 ||
            nelems < 0 ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != OIDOID)
            elog(ERROR, "protrftypes is not a 1-D Oid array or it contains nulls");
        *p_trftypes = (Oid *) palloc(nelems * sizeof(Oid));
        memcpy(*p_trftypes, ARR_DATA_PTR(arr),
               nelems * sizeof(Oid));
 
        return nelems;
    }
    else
        return 0;
}
 
/*
 * get_func_input_arg_names
 *
 * Extract the names of input arguments only, given a function's
 * proargnames and proargmodes entries in Datum form.
 *
 * Returns the number of input arguments, which is the length of the
 * palloc'd array returned to *arg_names.  Entries for unnamed args
 * are set to NULL.  You don't get anything if proargnames is NULL.
 */
int
get_func_input_arg_names(Datum proargnames, Datum proargmodes,
                         char ***arg_names)
{
    ArrayType  *arr;
    int         numargs;
    Datum      *argnames;
    char       *argmodes;
    char      **inargnames;
    int         numinargs;
    int         i;
 
    /* Do nothing if null proargnames */
    if (proargnames == PointerGetDatum(NULL))
    {
        *arg_names = NULL;
        return 0;
    }
 
    /*
     * We expect the arrays to be 1-D arrays of the right types; verify that.
     * For proargmodes, we don't need to use deconstruct_array() since the
     * array data is just going to look like a C array of values.
     */
    arr = DatumGetArrayTypeP(proargnames);  /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != TEXTOID)
        elog(ERROR, "proargnames is not a 1-D text array or it contains nulls");
    deconstruct_array_builtin(arr, TEXTOID, &argnames, NULL, &numargs);
    if (proargmodes != PointerGetDatum(NULL))
    {
        arr = DatumGetArrayTypeP(proargmodes);  /* ensure not toasted */
        if (ARR_NDIM(arr) != 1 ||
            ARR_DIMS(arr)[0] != numargs ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != CHAROID)
            elog(ERROR, "proargmodes is not a 1-D char array of length %d or it contains nulls",
                 numargs);
        argmodes = (char *) ARR_DATA_PTR(arr);
    }
    else
        argmodes = NULL;
 
    /* zero elements probably shouldn't happen, but handle it gracefully */
    if (numargs <= 0)
    {
        *arg_names = NULL;
        return 0;
    }
 
    /* extract input-argument names */
    inargnames = (char **) palloc(numargs * sizeof(char *));
    numinargs = 0;
    for (i = 0; i < numargs; i++)
    {
        if (argmodes == NULL ||
            argmodes[i] == PROARGMODE_IN ||
            argmodes[i] == PROARGMODE_INOUT ||
            argmodes[i] == PROARGMODE_VARIADIC)
        {
            char       *pname = TextDatumGetCString(argnames[i]);
 
            if (pname[0] != '\0')
                inargnames[numinargs] = pname;
            else
                inargnames[numinargs] = NULL;
            numinargs++;
        }
    }
 
    *arg_names = inargnames;
    return numinargs;
}
 
 
/*
 * get_func_result_name
 *
 * If the function has exactly one output parameter, and that parameter
 * is named, return the name (as a palloc'd string).  Else return NULL.
 *
 * This is used to determine the default output column name for functions
 * returning scalar types.
 */
char *
get_func_result_name(Oid functionId)
{
    char       *result;
    HeapTuple   procTuple;
    Datum       proargmodes;
    Datum       proargnames;
    ArrayType  *arr;
    int         numargs;
    char       *argmodes;
    Datum      *argnames;
    int         numoutargs;
    int         nargnames;
    int         i;
 
    /* First fetch the function's pg_proc row */
    procTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(functionId));
    if (!HeapTupleIsValid(procTuple))
        elog(ERROR, "cache lookup failed for function %u", functionId);
 
    /* If there are no named OUT parameters, return NULL */
    if (heap_attisnull(procTuple, Anum_pg_proc_proargmodes, NULL) ||
        heap_attisnull(procTuple, Anum_pg_proc_proargnames, NULL))
        result = NULL;
    else
    {
        /* Get the data out of the tuple */
        proargmodes = SysCacheGetAttrNotNull(PROCOID, procTuple,
                                             Anum_pg_proc_proargmodes);
        proargnames = SysCacheGetAttrNotNull(PROCOID, procTuple,
                                             Anum_pg_proc_proargnames);
 
        /*
         * We expect the arrays to be 1-D arrays of the right types; verify
         * that.  For the char array, we don't need to use deconstruct_array()
         * since the array data is just going to look like a C array of
         * values.
         */
        arr = DatumGetArrayTypeP(proargmodes);  /* ensure not toasted */
        numargs = ARR_DIMS(arr)[0];
        if (ARR_NDIM(arr) != 1 ||
            numargs < 0 ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != CHAROID)
            elog(ERROR, "proargmodes is not a 1-D char array or it contains nulls");
        argmodes = (char *) ARR_DATA_PTR(arr);
        arr = DatumGetArrayTypeP(proargnames);  /* ensure not toasted */
        if (ARR_NDIM(arr) != 1 ||
            ARR_DIMS(arr)[0] != numargs ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != TEXTOID)
            elog(ERROR, "proargnames is not a 1-D text array of length %d or it contains nulls",
                 numargs);
        deconstruct_array_builtin(arr, TEXTOID, &argnames, NULL, &nargnames);
        Assert(nargnames == numargs);
 
        /* scan for output argument(s) */
        result = NULL;
        numoutargs = 0;
        for (i = 0; i < numargs; i++)
        {
            if (argmodes[i] == PROARGMODE_IN ||
                argmodes[i] == PROARGMODE_VARIADIC)
                continue;
            Assert(argmodes[i] == PROARGMODE_OUT ||
                   argmodes[i] == PROARGMODE_INOUT ||
                   argmodes[i] == PROARGMODE_TABLE);
            if (++numoutargs > 1)
            {
                /* multiple out args, so forget it */
                result = NULL;
                break;
            }
            result = TextDatumGetCString(argnames[i]);
            if (result == NULL || result[0] == '\0')
            {
                /* Parameter is not named, so forget it */
                result = NULL;
                break;
            }
        }
    }
 
    ReleaseSysCache(procTuple);
 
    return result;
}
 
 
/*
 * build_function_result_tupdesc_t
 *
 * Given a pg_proc row for a function, return a tuple descriptor for the
 * result rowtype, or NULL if the function does not have OUT parameters.
 *
 * Note that this does not handle resolution of polymorphic types;
 * that is deliberate.
 */
TupleDesc
build_function_result_tupdesc_t(HeapTuple procTuple)
{
    Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(procTuple);
    Datum       proallargtypes;
    Datum       proargmodes;
    Datum       proargnames;
    bool        isnull;
 
    /* Return NULL if the function isn't declared to return RECORD */
    if (procform->prorettype != RECORDOID)
        return NULL;
 
    /* If there are no OUT parameters, return NULL */
    if (heap_attisnull(procTuple, Anum_pg_proc_proallargtypes, NULL) ||
        heap_attisnull(procTuple, Anum_pg_proc_proargmodes, NULL))
        return NULL;
 
    /* Get the data out of the tuple */
    proallargtypes = SysCacheGetAttrNotNull(PROCOID, procTuple,
                                            Anum_pg_proc_proallargtypes);
    proargmodes = SysCacheGetAttrNotNull(PROCOID, procTuple,
                                         Anum_pg_proc_proargmodes);
    proargnames = SysCacheGetAttr(PROCOID, procTuple,
                                  Anum_pg_proc_proargnames,
                                  &isnull);
    if (isnull)
        proargnames = PointerGetDatum(NULL);    /* just to be sure */
 
    return build_function_result_tupdesc_d(procform->prokind,
                                           proallargtypes,
                                           proargmodes,
                                           proargnames);
}
 
/*
 * build_function_result_tupdesc_d
 *
 * Build a RECORD function's tupledesc from the pg_proc proallargtypes,
 * proargmodes, and proargnames arrays.  This is split out for the
 * convenience of ProcedureCreate, which needs to be able to compute the
 * tupledesc before actually creating the function.
 *
 * For functions (but not for procedures), returns NULL if there are not at
 * least two OUT or INOUT arguments.
 */
TupleDesc
build_function_result_tupdesc_d(char prokind,
                                Datum proallargtypes,
                                Datum proargmodes,
                                Datum proargnames)
{
    TupleDesc   desc;
    ArrayType  *arr;
    int         numargs;
    Oid        *argtypes;
    char       *argmodes;
    Datum      *argnames = NULL;
    Oid        *outargtypes;
    char      **outargnames;
    int         numoutargs;
    int         nargnames;
    int         i;
 
    /* Can't have output args if columns are null */
    if (proallargtypes == PointerGetDatum(NULL) ||
        proargmodes == PointerGetDatum(NULL))
        return NULL;
 
    /*
     * We expect the arrays to be 1-D arrays of the right types; verify that.
     * For the OID and char arrays, we don't need to use deconstruct_array()
     * since the array data is just going to look like a C array of values.
     */
    arr = DatumGetArrayTypeP(proallargtypes);   /* ensure not toasted */
    numargs = ARR_DIMS(arr)[0];
    if (ARR_NDIM(arr) != 1 ||
        numargs < 0 ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != OIDOID)
        elog(ERROR, "proallargtypes is not a 1-D Oid array or it contains nulls");
    argtypes = (Oid *) ARR_DATA_PTR(arr);
    arr = DatumGetArrayTypeP(proargmodes);  /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_DIMS(arr)[0] != numargs ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != CHAROID)
        elog(ERROR, "proargmodes is not a 1-D char array of length %d or it contains nulls",
             numargs);
    argmodes = (char *) ARR_DATA_PTR(arr);
    if (proargnames != PointerGetDatum(NULL))
    {
        arr = DatumGetArrayTypeP(proargnames);  /* ensure not toasted */
        if (ARR_NDIM(arr) != 1 ||
            ARR_DIMS(arr)[0] != numargs ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != TEXTOID)
            elog(ERROR, "proargnames is not a 1-D text array of length %d or it contains nulls",
                 numargs);
        deconstruct_array_builtin(arr, TEXTOID, &argnames, NULL, &nargnames);
        Assert(nargnames == numargs);
    }
 
    /* zero elements probably shouldn't happen, but handle it gracefully */
    if (numargs <= 0)
        return NULL;
 
    /* extract output-argument types and names */
    outargtypes = (Oid *) palloc(numargs * sizeof(Oid));
    outargnames = (char **) palloc(numargs * sizeof(char *));
    numoutargs = 0;
    for (i = 0; i < numargs; i++)
    {
        char       *pname;
 
        if (argmodes[i] == PROARGMODE_IN ||
            argmodes[i] == PROARGMODE_VARIADIC)
            continue;
        Assert(argmodes[i] == PROARGMODE_OUT ||
               argmodes[i] == PROARGMODE_INOUT ||
               argmodes[i] == PROARGMODE_TABLE);
        outargtypes[numoutargs] = argtypes[i];
        if (argnames)
            pname = TextDatumGetCString(argnames[i]);
        else
            pname = NULL;
        if (pname == NULL || pname[0] == '\0')
        {
            /* Parameter is not named, so gin up a column name */
            pname = psprintf("column%d", numoutargs + 1);
        }
        outargnames[numoutargs] = pname;
        numoutargs++;
    }
 
    /*
     * If there is no output argument, or only one, the function does not
     * return tuples.
     */
    if (numoutargs < 2 && prokind != PROKIND_PROCEDURE)
        return NULL;
 
    desc = CreateTemplateTupleDesc(numoutargs);
    for (i = 0; i < numoutargs; i++)
    {
        TupleDescInitEntry(desc, i + 1,
                           outargnames[i],
                           outargtypes[i],
                           -1,
                           0);
    }
 
    return desc;
}
 
 
/*
 * RelationNameGetTupleDesc
 *
 * Given a (possibly qualified) relation name, build a TupleDesc.
 *
 * Note: while this works as advertised, it's seldom the best way to
 * build a tupdesc for a function's result type.  It's kept around
 * only for backwards compatibility with existing user-written code.
 */
TupleDesc
RelationNameGetTupleDesc(const char *relname)
{
    RangeVar   *relvar;
    Relation    rel;
    TupleDesc   tupdesc;
    List       *relname_list;
 
    /* Open relation and copy the tuple description */
    relname_list = stringToQualifiedNameList(relname, NULL);
    relvar = makeRangeVarFromNameList(relname_list);
    rel = relation_openrv(relvar, AccessShareLock);
    tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
    relation_close(rel, AccessShareLock);
 
    return tupdesc;
}
 
/*
 * TypeGetTupleDesc
 *
 * Given a type Oid, build a TupleDesc.  (In most cases you should be
 * using get_call_result_type or one of its siblings instead of this
 * routine, so that you can handle OUT parameters, RECORD result type,
 * and polymorphic results.)
 *
 * If the type is composite, *and* a colaliases List is provided, *and*
 * the List is of natts length, use the aliases instead of the relation
 * attnames.  (NB: this usage is deprecated since it may result in
 * creation of unnecessary transient record types.)
 *
 * If the type is a base type, a single item alias List is required.
 */
TupleDesc
TypeGetTupleDesc(Oid typeoid, List *colaliases)
{
    Oid         base_typeoid;
    TypeFuncClass functypclass = get_type_func_class(typeoid, &base_typeoid);
    TupleDesc   tupdesc = NULL;
 
    /*
     * Build a suitable tupledesc representing the output rows.  We
     * intentionally do not support TYPEFUNC_COMPOSITE_DOMAIN here, as it's
     * unlikely that legacy callers of this obsolete function would be
     * prepared to apply domain constraints.
     */
    if (functypclass == TYPEFUNC_COMPOSITE)
    {
        /* Composite data type, e.g. a table's row type */
        tupdesc = lookup_rowtype_tupdesc_copy(base_typeoid, -1);
 
        if (colaliases != NIL)
        {
            int         natts = tupdesc->natts;
            int         varattno;
 
            /* does the list length match the number of attributes? */
            if (list_length(colaliases) != natts)
                ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("number of aliases does not match number of columns")));
 
            /* OK, use the aliases instead */
            for (varattno = 0; varattno < natts; varattno++)
            {
                char       *label = strVal(list_nth(colaliases, varattno));
                Form_pg_attribute attr = TupleDescAttr(tupdesc, varattno);
 
                if (label != NULL)
                    namestrcpy(&(attr->attname), label);
            }
 
            /* The tuple type is now an anonymous record type */
            tupdesc->tdtypeid = RECORDOID;
            tupdesc->tdtypmod = -1;
        }
    }
    else if (functypclass == TYPEFUNC_SCALAR)
    {
        /* Base data type, i.e. scalar */
        char       *attname;
 
        /* the alias list is required for base types */
        if (colaliases == NIL)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("no column alias was provided")));
 
        /* the alias list length must be 1 */
        if (list_length(colaliases) != 1)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("number of aliases does not match number of columns")));
 
        /* OK, get the column alias */
        attname = strVal(linitial(colaliases));
 
        tupdesc = CreateTemplateTupleDesc(1);
        TupleDescInitEntry(tupdesc,
                           (AttrNumber) 1,
                           attname,
                           typeoid,
                           -1,
                           0);
    }
    else if (functypclass == TYPEFUNC_RECORD)
    {
        /* XXX can't support this because typmod wasn't passed in ... */
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("could not determine row description for function returning record")));
    }
    else
    {
        /* crummy error message, but parser should have caught this */
        elog(ERROR, "function in FROM has unsupported return type");
    }
 
    return tupdesc;
}
 
/*
 * extract_variadic_args
 *
 * Extract a set of argument values, types and NULL markers for a given
 * input function which makes use of a VARIADIC input whose argument list
 * depends on the caller context. When doing a VARIADIC call, the caller
 * has provided one argument made of an array of values, so deconstruct the
 * array data before using it for the next processing. If no VARIADIC call
 * is used, just fill in the status data based on all the arguments given
 * by the caller.
 *
 * This function returns the number of arguments generated, or -1 in the
 * case of "VARIADIC NULL".
 */
int
extract_variadic_args(FunctionCallInfo fcinfo, int variadic_start,
                      bool convert_unknown, Datum **args, Oid **types,
                      bool **nulls)
{
    bool        variadic = get_fn_expr_variadic(fcinfo->flinfo);
    Datum      *args_res;
    bool       *nulls_res;
    Oid        *types_res;
    int         nargs,
                i;
 
    *args = NULL;
    *types = NULL;
    *nulls = NULL;
 
    if (variadic)
    {
        ArrayType  *array_in;
        Oid         element_type;
        bool        typbyval;
        char        typalign;
        int16       typlen;
 
        Assert(PG_NARGS() == variadic_start + 1);
 
        if (PG_ARGISNULL(variadic_start))
            return -1;
 
        array_in = PG_GETARG_ARRAYTYPE_P(variadic_start);
        element_type = ARR_ELEMTYPE(array_in);
 
        get_typlenbyvalalign(element_type,
                             &typlen, &typbyval, &typalign);
        deconstruct_array(array_in, element_type, typlen, typbyval,
                          typalign, &args_res, &nulls_res,
                          &nargs);
 
        /* All the elements of the array have the same type */
        types_res = (Oid *) palloc0(nargs * sizeof(Oid));
        for (i = 0; i < nargs; i++)
            types_res[i] = element_type;
    }
    else
    {
        nargs = PG_NARGS() - variadic_start;
        Assert(nargs > 0);
        nulls_res = (bool *) palloc0(nargs * sizeof(bool));
        args_res = (Datum *) palloc0(nargs * sizeof(Datum));
        types_res = (Oid *) palloc0(nargs * sizeof(Oid));
 
        for (i = 0; i < nargs; i++)
        {
            nulls_res[i] = PG_ARGISNULL(i + variadic_start);
            types_res[i] = get_fn_expr_argtype(fcinfo->flinfo,
                                               i + variadic_start);
 
            /*
             * Turn a constant (more or less literal) value that's of unknown
             * type into text if required. Unknowns come in as a cstring
             * pointer. Note: for functions declared as taking type "any", the
             * parser will not do any type conversion on unknown-type literals
             * (that is, undecorated strings or NULLs).
             */
            if (convert_unknown &&
                types_res[i] == UNKNOWNOID &&
                get_fn_expr_arg_stable(fcinfo->flinfo, i + variadic_start))
            {
                types_res[i] = TEXTOID;
 
                if (PG_ARGISNULL(i + variadic_start))
                    args_res[i] = (Datum) 0;
                else
                    args_res[i] =
                        CStringGetTextDatum(PG_GETARG_POINTER(i + variadic_start));
            }
            else
            {
                /* no conversion needed, just take the datum as given */
                args_res[i] = PG_GETARG_DATUM(i + variadic_start);
            }
 
            if (!OidIsValid(types_res[i]) ||
                (convert_unknown && types_res[i] == UNKNOWNOID))
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("could not determine data type for argument %d",
                                i + 1)));
        }
    }
 
    /* Fill in results */
    *args = args_res;
    *nulls = nulls_res;
    *types = types_res;
 
    return nargs;
}