2006-04-06 00:11:58 +02:00
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/*-------------------------------------------------------------------------
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*
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* domains.c
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* I/O functions for domain types.
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*
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* The output functions for a domain type are just the same ones provided
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* by its underlying base type. The input functions, however, must be
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* prepared to apply any constraints defined by the type. So, we create
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* special input functions that invoke the base type's input function
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* and then check the constraints.
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*
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* The overhead required for constraint checking can be high, since examining
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* the catalogs to discover the constraints for a given domain is not cheap.
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* We have two mechanisms for minimizing this cost:
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* 1. In a nest of domains, we flatten the checking of all the levels
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* into just one operation.
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* 2. We cache the list of constraint items in the FmgrInfo struct
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* passed by the caller.
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*
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* We also have to create an EState to evaluate CHECK expressions in.
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* Creating and destroying an EState is somewhat expensive, and so it's
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* tempting to cache the EState too. However, that would mean that the
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* EState never gets an explicit FreeExecutorState call, which is a bad idea
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* because it risks leaking non-memory resources.
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*
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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2006-07-14 16:52:27 +02:00
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* $PostgreSQL: pgsql/src/backend/utils/adt/domains.c,v 1.2 2006/07/14 14:52:24 momjian Exp $
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2006-04-06 00:11:58 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "commands/typecmds.h"
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#include "executor/executor.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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/*
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* structure to cache state across multiple calls
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*/
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typedef struct DomainIOData
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{
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Oid domain_type;
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/* Data needed to call base type's input function */
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Oid typiofunc;
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Oid typioparam;
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int32 typtypmod;
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FmgrInfo proc;
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/* List of constraint items to check */
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List *constraint_list;
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} DomainIOData;
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/*
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* domain_state_setup - initialize the cache for a new domain type.
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*/
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static void
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domain_state_setup(DomainIOData *my_extra, Oid domainType, bool binary,
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MemoryContext mcxt)
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{
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Oid baseType;
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MemoryContext oldcontext;
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/* Mark cache invalid */
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my_extra->domain_type = InvalidOid;
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/* Find out the base type */
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my_extra->typtypmod = -1;
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baseType = getBaseTypeAndTypmod(domainType, &my_extra->typtypmod);
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if (baseType == domainType)
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ereport(ERROR,
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(errcode(ERRCODE_DATATYPE_MISMATCH),
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errmsg("type %s is not a domain",
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format_type_be(domainType))));
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/* Look up underlying I/O function */
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if (binary)
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getTypeBinaryInputInfo(baseType,
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&my_extra->typiofunc,
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&my_extra->typioparam);
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else
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getTypeInputInfo(baseType,
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&my_extra->typiofunc,
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&my_extra->typioparam);
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fmgr_info_cxt(my_extra->typiofunc, &my_extra->proc, mcxt);
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/* Look up constraints for domain */
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oldcontext = MemoryContextSwitchTo(mcxt);
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my_extra->constraint_list = GetDomainConstraints(domainType);
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MemoryContextSwitchTo(oldcontext);
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/* Mark cache valid */
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my_extra->domain_type = domainType;
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}
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/*
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* domain_check_input - apply the cached checks.
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*
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* This is extremely similar to ExecEvalCoerceToDomain in execQual.c.
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*/
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static void
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domain_check_input(Datum value, bool isnull, DomainIOData *my_extra)
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{
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EState *estate = NULL;
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ListCell *l;
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foreach(l, my_extra->constraint_list)
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{
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DomainConstraintState *con = (DomainConstraintState *) lfirst(l);
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switch (con->constrainttype)
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{
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case DOM_CONSTRAINT_NOTNULL:
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if (isnull)
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ereport(ERROR,
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(errcode(ERRCODE_NOT_NULL_VIOLATION),
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errmsg("domain %s does not allow null values",
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format_type_be(my_extra->domain_type))));
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break;
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case DOM_CONSTRAINT_CHECK:
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{
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ExprContext *econtext;
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Datum conResult;
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bool conIsNull;
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Datum save_datum;
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bool save_isNull;
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if (estate == NULL)
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estate = CreateExecutorState();
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econtext = GetPerTupleExprContext(estate);
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/*
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* Set up value to be returned by CoerceToDomainValue
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* nodes. We must save and restore prior setting of
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* econtext's domainValue fields, in case this node is
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* itself within a check expression for another domain.
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*/
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save_datum = econtext->domainValue_datum;
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save_isNull = econtext->domainValue_isNull;
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econtext->domainValue_datum = value;
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econtext->domainValue_isNull = isnull;
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conResult = ExecEvalExprSwitchContext(con->check_expr,
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econtext,
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&conIsNull, NULL);
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if (!conIsNull &&
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!DatumGetBool(conResult))
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ereport(ERROR,
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(errcode(ERRCODE_CHECK_VIOLATION),
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errmsg("value for domain %s violates check constraint \"%s\"",
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format_type_be(my_extra->domain_type),
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con->name)));
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econtext->domainValue_datum = save_datum;
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econtext->domainValue_isNull = save_isNull;
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break;
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}
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default:
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elog(ERROR, "unrecognized constraint type: %d",
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(int) con->constrainttype);
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break;
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}
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}
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if (estate)
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FreeExecutorState(estate);
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}
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/*
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* domain_in - input routine for any domain type.
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*/
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Datum
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domain_in(PG_FUNCTION_ARGS)
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{
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char *string;
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Oid domainType;
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DomainIOData *my_extra;
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Datum value;
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/*
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* Since domain_in is not strict, we have to check for null inputs.
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* The typioparam argument should never be null in normal system usage,
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* but it could be null in a manual invocation --- if so, just return null.
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*/
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if (PG_ARGISNULL(0))
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string = NULL;
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else
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string = PG_GETARG_CSTRING(0);
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if (PG_ARGISNULL(1))
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PG_RETURN_NULL();
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domainType = PG_GETARG_OID(1);
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/*
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* We arrange to look up the needed info just once per series of
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* calls, assuming the domain type doesn't change underneath us.
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*/
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my_extra = (DomainIOData *) fcinfo->flinfo->fn_extra;
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if (my_extra == NULL)
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{
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my_extra = (DomainIOData *) MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
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sizeof(DomainIOData));
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domain_state_setup(my_extra, domainType, false,
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fcinfo->flinfo->fn_mcxt);
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fcinfo->flinfo->fn_extra = (void *) my_extra;
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}
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else if (my_extra->domain_type != domainType)
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domain_state_setup(my_extra, domainType, false,
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fcinfo->flinfo->fn_mcxt);
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/*
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* Invoke the base type's typinput procedure to convert the data.
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*/
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value = InputFunctionCall(&my_extra->proc,
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string,
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my_extra->typioparam,
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my_extra->typtypmod);
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/*
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* Do the necessary checks to ensure it's a valid domain value.
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*/
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domain_check_input(value, (string == NULL), my_extra);
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if (string == NULL)
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PG_RETURN_NULL();
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else
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PG_RETURN_DATUM(value);
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}
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/*
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* domain_recv - binary input routine for any domain type.
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*/
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Datum
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domain_recv(PG_FUNCTION_ARGS)
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{
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StringInfo buf;
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Oid domainType;
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DomainIOData *my_extra;
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Datum value;
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/*
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* Since domain_recv is not strict, we have to check for null inputs.
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* The typioparam argument should never be null in normal system usage,
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* but it could be null in a manual invocation --- if so, just return null.
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*/
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if (PG_ARGISNULL(0))
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buf = NULL;
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else
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buf = (StringInfo) PG_GETARG_POINTER(0);
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if (PG_ARGISNULL(1))
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PG_RETURN_NULL();
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domainType = PG_GETARG_OID(1);
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/*
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* We arrange to look up the needed info just once per series of
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* calls, assuming the domain type doesn't change underneath us.
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*/
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my_extra = (DomainIOData *) fcinfo->flinfo->fn_extra;
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if (my_extra == NULL)
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{
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my_extra = (DomainIOData *) MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
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sizeof(DomainIOData));
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domain_state_setup(my_extra, domainType, true,
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fcinfo->flinfo->fn_mcxt);
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fcinfo->flinfo->fn_extra = (void *) my_extra;
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}
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else if (my_extra->domain_type != domainType)
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domain_state_setup(my_extra, domainType, true,
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fcinfo->flinfo->fn_mcxt);
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/*
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* Invoke the base type's typreceive procedure to convert the data.
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*/
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value = ReceiveFunctionCall(&my_extra->proc,
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buf,
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my_extra->typioparam,
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my_extra->typtypmod);
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/*
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* Do the necessary checks to ensure it's a valid domain value.
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*/
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domain_check_input(value, (buf == NULL), my_extra);
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if (buf == NULL)
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PG_RETURN_NULL();
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else
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PG_RETURN_DATUM(value);
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}
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