~drizzle-trunk/drizzle/development

/******************************************************

Executes SQL stored procedures and their control structures

(c) 1998 Innobase Oy

Created 1/20/1998 Heikki Tuuri

*******************************************************/

#include "eval0proc.h"

#ifdef UNIV_NONINL

#include "eval0proc.ic"

#endif

/**************************************************************************

Performs an execution step of an if-statement node. */

que_thr_t*

if_step(

/*====*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	if_node_t*	node;

	elsif_node_t*	elsif_node;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_IF);

	if (thr->prev_node == que_node_get_parent(node)) {

		/* Evaluate the condition */

		eval_exp(node->cond);

		if (eval_node_get_ibool_val(node->cond)) {

			/* The condition evaluated to TRUE: start execution

			from the first statement in the statement list */

			thr->run_node = node->stat_list;

		} else if (node->else_part) {

			thr->run_node = node->else_part;

		} else if (node->elsif_list) {

			elsif_node = node->elsif_list;

			for (;;) {

				eval_exp(elsif_node->cond);

				if (eval_node_get_ibool_val(

					    elsif_node->cond)) {

					/* The condition evaluated to TRUE:

					start execution from the first

					statement in the statement list */

					thr->run_node = elsif_node->stat_list;

					break;

				}

				elsif_node = que_node_get_next(elsif_node);

				if (elsif_node == NULL) {

					thr->run_node = NULL;

					break;

				}

			}

		} else {

			thr->run_node = NULL;

		}

	} else {

		/* Move to the next statement */

		ut_ad(que_node_get_next(thr->prev_node) == NULL);

		thr->run_node = NULL;

	}

	if (thr->run_node == NULL) {

		thr->run_node = que_node_get_parent(node);

	}

	return(thr);

}

/**************************************************************************

Performs an execution step of a while-statement node. */

que_thr_t*

while_step(

/*=======*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	while_node_t*	node;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_WHILE);

	ut_ad((thr->prev_node == que_node_get_parent(node))

	      || (que_node_get_next(thr->prev_node) == NULL));

	/* Evaluate the condition */

	eval_exp(node->cond);

	if (eval_node_get_ibool_val(node->cond)) {

		/* The condition evaluated to TRUE: start execution

		from the first statement in the statement list */

		thr->run_node = node->stat_list;

	} else {

		thr->run_node = que_node_get_parent(node);

	}

	return(thr);

}

/**************************************************************************

Performs an execution step of an assignment statement node. */

que_thr_t*

assign_step(

/*========*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	assign_node_t*	node;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_ASSIGNMENT);

	/* Evaluate the value to assign */

	eval_exp(node->val);

	eval_node_copy_val(node->var->alias, node->val);

	thr->run_node = que_node_get_parent(node);

	return(thr);

}

/**************************************************************************

Performs an execution step of a for-loop node. */

que_thr_t*

for_step(

/*=====*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	for_node_t*	node;

	que_node_t*	parent;

	lint		loop_var_value;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_FOR);

	parent = que_node_get_parent(node);

	if (thr->prev_node != parent) {

		/* Move to the next statement */

		thr->run_node = que_node_get_next(thr->prev_node);

		if (thr->run_node != NULL) {

			return(thr);

		}

		/* Increment the value of loop_var */

		loop_var_value = 1 + eval_node_get_int_val(node->loop_var);

	} else {

		/* Initialize the loop */

		eval_exp(node->loop_start_limit);

		eval_exp(node->loop_end_limit);

		loop_var_value = eval_node_get_int_val(node->loop_start_limit);

		node->loop_end_value

                  = (int) eval_node_get_int_val(node->loop_end_limit);

	}

	/* Check if we should do another loop */

	if (loop_var_value > node->loop_end_value) {

		/* Enough loops done */

		thr->run_node = parent;

	} else {

		eval_node_set_int_val(node->loop_var, loop_var_value);

		thr->run_node = node->stat_list;

	}

	return(thr);

}

/**************************************************************************

Performs an execution step of an exit statement node. */

que_thr_t*

exit_step(

/*======*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	exit_node_t*	node;

	que_node_t*	loop_node;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_EXIT);

	/* Loops exit by setting thr->run_node as the loop node's parent, so

	find our containing loop node and get its parent. */

	loop_node = que_node_get_containing_loop_node(node);

	/* If someone uses an EXIT statement outside of a loop, this will

	trigger. */

	ut_a(loop_node);

	thr->run_node = que_node_get_parent(loop_node);

	return(thr);

}

/**************************************************************************

Performs an execution step of a return-statement node. */

que_thr_t*

return_step(

/*========*/

				/* out: query thread to run next or NULL */

	que_thr_t*	thr)	/* in: query thread */

{

	return_node_t*	node;

	que_node_t*	parent;

	ut_ad(thr);

	node = thr->run_node;

	ut_ad(que_node_get_type(node) == QUE_NODE_RETURN);

	parent = node;

	while (que_node_get_type(parent) != QUE_NODE_PROC) {

		parent = que_node_get_parent(parent);

	}

	ut_a(parent);

	thr->run_node = que_node_get_parent(parent);

	return(thr);

}