pl_exec.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	foreach(s, stmts)
	{
		PLpgSQL_stmt *stmt = (PLpgSQL_stmt *) lfirst(s);
		int			rc = exec_stmt(estate, stmt);

		if (rc != PLPGSQL_RC_OK)
			return rc;
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt			Distribute one statement to the statements
 *				type specific execution function.
 * ----------
 */
static int
exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
{
	PLpgSQL_stmt *save_estmt;
	int			rc = -1;

	save_estmt = estate->err_stmt;
	estate->err_stmt = stmt;

	CHECK_FOR_INTERRUPTS();

	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
			break;

		case PLPGSQL_STMT_ASSIGN:
			rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
			break;

		case PLPGSQL_STMT_PERFORM:
			rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
			break;

		case PLPGSQL_STMT_GETDIAG:
			rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
			break;

		case PLPGSQL_STMT_IF:
			rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
			break;

		case PLPGSQL_STMT_LOOP:
			rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
			break;

		case PLPGSQL_STMT_WHILE:
			rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
			break;

		case PLPGSQL_STMT_FORI:
			rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
			break;

		case PLPGSQL_STMT_FORS:
			rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
			break;

		case PLPGSQL_STMT_SELECT:
			rc = exec_stmt_select(estate, (PLpgSQL_stmt_select *) stmt);
			break;

		case PLPGSQL_STMT_EXIT:
			rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
			break;

		case PLPGSQL_STMT_RETURN:
			rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
			break;

		case PLPGSQL_STMT_RETURN_NEXT:
			rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
			break;

		case PLPGSQL_STMT_RAISE:
			rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
			break;

		case PLPGSQL_STMT_EXECSQL:
			rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
			break;

		case PLPGSQL_STMT_DYNEXECUTE:
			rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
			break;

		case PLPGSQL_STMT_DYNFORS:
			rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
			break;

		case PLPGSQL_STMT_OPEN:
			rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
			break;

		case PLPGSQL_STMT_FETCH:
			rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
			break;

		case PLPGSQL_STMT_CLOSE:
			rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
			break;

		default:
			estate->err_stmt = save_estmt;
			elog(ERROR, "unrecognized cmdtype: %d", stmt->cmd_type);
	}

	estate->err_stmt = save_estmt;

	return rc;
}


/* ----------
 * exec_stmt_assign			Evaluate an expression and
 *					put the result into a variable.
 * ----------
 */
static int
exec_stmt_assign(PLpgSQL_execstate *estate, PLpgSQL_stmt_assign *stmt)
{
	Assert(stmt->varno >= 0);

	exec_assign_expr(estate, estate->datums[stmt->varno], stmt->expr);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_perform		Evaluate query and discard result (but set
 *							FOUND depending on whether at least one row
 *							was returned).
 * ----------
 */
static int
exec_stmt_perform(PLpgSQL_execstate *estate, PLpgSQL_stmt_perform *stmt)
{
	PLpgSQL_expr *expr = stmt->expr;

	(void) exec_run_select(estate, expr, 0, NULL);
	exec_set_found(estate, (estate->eval_processed != 0));
	exec_eval_cleanup(estate);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_getdiag					Put internal PG information into
 *										specified variables.
 * ----------
 */
static int
exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
{
	ListCell   *lc;

	foreach(lc, stmt->diag_items)
	{
		PLpgSQL_diag_item *diag_item = (PLpgSQL_diag_item *) lfirst(lc);
		PLpgSQL_datum *var;
		bool		isnull = false;

		if (diag_item->target <= 0)
			continue;

		var = estate->datums[diag_item->target];

		if (var == NULL)
			continue;

		switch (diag_item->kind)
		{
			case PLPGSQL_GETDIAG_ROW_COUNT:

				exec_assign_value(estate, var,
								  UInt32GetDatum(estate->eval_processed),
								  INT4OID, &isnull);
				break;

			case PLPGSQL_GETDIAG_RESULT_OID:

				exec_assign_value(estate, var,
								  ObjectIdGetDatum(estate->eval_lastoid),
								  OIDOID, &isnull);
				break;

			default:
				elog(ERROR, "unrecognized attribute request: %d",
					 diag_item->kind);
		}
	}

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_if				Evaluate a bool expression and
 *					execute the true or false body
 *					conditionally.
 * ----------
 */
static int
exec_stmt_if(PLpgSQL_execstate *estate, PLpgSQL_stmt_if *stmt)
{
	bool		value;
	bool		isnull;

	value = exec_eval_boolean(estate, stmt->cond, &isnull);
	exec_eval_cleanup(estate);

	if (!isnull && value)
	{
		if (stmt->true_body != NIL)
			return exec_stmts(estate, stmt->true_body);
	}
	else
	{
		if (stmt->false_body != NIL)
			return exec_stmts(estate, stmt->false_body);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_loop			Loop over statements until
 *					an exit occurs.
 * ----------
 */
static int
exec_stmt_loop(PLpgSQL_execstate *estate, PLpgSQL_stmt_loop *stmt)
{
	for (;;)
	{
		int			rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel) != 0)
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run the loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, so propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unrecognized rc: %d", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_while			Loop over statements as long
 *					as an expression evaluates to
 *					true or an exit occurs.
 * ----------
 */
static int
exec_stmt_while(PLpgSQL_execstate *estate, PLpgSQL_stmt_while *stmt)
{
	for (;;)
	{
		int			rc;
		bool		value;
		bool		isnull;

		value = exec_eval_boolean(estate, stmt->cond, &isnull);
		exec_eval_cleanup(estate);

		if (isnull || !value)
			break;

		rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel))
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unrecognized rc: %d", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_fori			Iterate an integer variable
 *					from a lower to an upper value.
 *					Loop can be left with exit.
 * ----------
 */
static int
exec_stmt_fori(PLpgSQL_execstate *estate, PLpgSQL_stmt_fori *stmt)
{
	PLpgSQL_var *var;
	Datum		value;
	Oid			valtype;
	bool		isnull;
	bool		found = false;
	int			rc = PLPGSQL_RC_OK;

	var = (PLpgSQL_var *) (estate->datums[stmt->var->varno]);

	/*
	 * Get the value of the lower bound into the loop var
	 */
	value = exec_eval_expr(estate, stmt->lower, &isnull, &valtype);
	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->typioparam,
							var->datatype->atttypmod, isnull);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("lower bound of FOR loop cannot be NULL")));
	var->value = value;
	var->isnull = false;
	exec_eval_cleanup(estate);

	/*
	 * Get the value of the upper bound
	 */
	value = exec_eval_expr(estate, stmt->upper, &isnull, &valtype);
	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->typioparam,
							var->datatype->atttypmod, isnull);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("upper bound of FOR loop cannot be NULL")));
	exec_eval_cleanup(estate);

	/*
	 * Now do the loop
	 */
	for (;;)
	{
		/*
		 * Check bounds
		 */
		if (stmt->reverse)
		{
			if ((int4) (var->value) < (int4) value)
				break;
		}
		else
		{
			if ((int4) (var->value) > (int4) value)
				break;
		}

		found = true;			/* looped at least once */

		/*
		 * Execute the statements
		 */
		rc = exec_stmts(estate, stmt->body);

		if (rc == PLPGSQL_RC_RETURN)
			break;				/* return from function */
		else if (rc == PLPGSQL_RC_EXIT)
		{
			if (estate->exitlabel == NULL)
				/* unlabelled exit, finish the current loop */
				rc = PLPGSQL_RC_OK;
			else if (stmt->label != NULL &&
					 strcmp(stmt->label, estate->exitlabel) == 0)
			{
				/* labelled exit, matches the current stmt's label */
				estate->exitlabel = NULL;
				rc = PLPGSQL_RC_OK;
			}

			/*
			 * otherwise, this is a labelled exit that does not match the
			 * current statement's label, if any: return RC_EXIT so that the
			 * EXIT continues to propagate up the stack.
			 */

			break;
		}
		else if (rc == PLPGSQL_RC_CONTINUE)
		{
			if (estate->exitlabel == NULL)
				/* anonymous continue, so re-run the current loop */
				rc = PLPGSQL_RC_OK;
			else if (stmt->label != NULL &&
					 strcmp(stmt->label, estate->exitlabel) == 0)
			{
				/* label matches named continue, so re-run loop */
				estate->exitlabel = NULL;
				rc = PLPGSQL_RC_OK;
			}
			else
			{
				/*
				 * otherwise, this is a named continue that does not match the
				 * current statement's label, if any: return RC_CONTINUE so
				 * that the CONTINUE will propagate up the stack.
				 */
				break;
			}
		}

		/*
		 * Increase/decrease loop var
		 */
		if (stmt->reverse)
			var->value--;
		else
			var->value++;
	}

	/*
	 * Set the FOUND variable to indicate the result of executing the loop
	 * (namely, whether we looped one or more times). This must be set here so
	 * that it does not interfere with the value of the FOUND variable inside
	 * the loop processing itself.
	 */
	exec_set_found(estate, found);

	return rc;
}


/* ----------
 * exec_stmt_fors			Execute a query, assign each
 *					tuple to a record or row and
 *					execute a group of statements
 *					for it.
 * ----------
 */
static int
exec_stmt_fors(PLpgSQL_execstate *estate, PLpgSQL_stmt_fors *stmt)
{
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	Portal		portal;
	bool		found = false;
	int			rc = PLPGSQL_RC_OK;
	int			i;
	int			n;

	/*