static int
rasqal_join_rowsource_reset(rasqal_rowsource* rowsource, void *user_data)
{
rasqal_join_rowsource_context* con;
int rc;
con = (rasqal_join_rowsource_context*)user_data;
con->state = JS_START;
con->failed = 0;
rc = rasqal_rowsource_reset(con->left);
if(rc)
return rc;
return rasqal_rowsource_reset(con->right);
}
static int
rasqal_distinct_rowsource_reset(rasqal_rowsource* rowsource, void *user_data)
{
rasqal_distinct_rowsource_context *con;
con = (rasqal_distinct_rowsource_context*)user_data;
return rasqal_rowsource_reset(con->rowsource);
}
static rasqal_row*
rasqal_graph_rowsource_read_row(rasqal_rowsource* rowsource, void *user_data)
{
rasqal_graph_rowsource_context *con;
rasqal_row* row = NULL;
con = (rasqal_graph_rowsource_context*)user_data;
if(con->finished)
return NULL;
while(1) {
row = rasqal_rowsource_read_row(con->rowsource);
if(row)
break;
if(rasqal_graph_next_dg(con)) {
con->finished = 1;
break;
}
if(rasqal_rowsource_reset(con->rowsource)) {
con->finished = 1;
break;
}
}
/* If a row is returned, put the GRAPH variable value as first literal */
if(row) {
rasqal_row* nrow;
int i;
nrow = rasqal_new_row_for_size(rowsource->world, 1 + row->size);
if(!nrow) {
rasqal_free_row(row);
row = NULL;
} else {
nrow->rowsource = rowsource;
nrow->offset = row->offset;
/* Put GRAPH variable value (or NULL) first in result row */
nrow->values[0] = rasqal_new_literal_from_literal(con->var->value);
/* Copy (size-1) remaining variables from input row */
for(i = 0; i < row->size; i++)
nrow->values[i + 1] = rasqal_new_literal_from_literal(row->values[i]);
rasqal_free_row(row);
row = nrow;
}
}
return row;
}
static int
rasqal_graph_rowsource_reset(rasqal_rowsource* rowsource, void *user_data)
{
rasqal_graph_rowsource_context *con;
con = (rasqal_graph_rowsource_context*)user_data;
con->finished = 0;
con->dg_offset = -1;
con->offset = 0;
rasqal_graph_next_dg(con);
return rasqal_rowsource_reset(con->rowsource);
}
static rasqal_row*
rasqal_join_rowsource_read_row(rasqal_rowsource* rowsource, void *user_data)
{
rasqal_join_rowsource_context* con;
rasqal_row* row = NULL;
rasqal_query *query = rowsource->query;
con = (rasqal_join_rowsource_context*)user_data;
if(con->failed || con->state == JS_FINISHED)
return NULL;
while(1) {
rasqal_row *right_row;
int bresult = 1;
int compatible = 1;
if(con->state == JS_START) {
/* start / re-start left */
if(con->left_row)
rasqal_free_row(con->left_row);
con->left_row = rasqal_rowsource_read_row(con->left);
#ifdef RASQAL_DEBUG
RASQAL_DEBUG2("rowsource %p read left row : ", rowsource);
if(con->left_row)
rasqal_row_print(con->left_row, stderr);
else
fputs("NONE", stderr);
fputs("\n", stderr);
#endif
con->state = JS_INIT_RIGHT;
}
if(con->state == JS_INIT_RIGHT) {
/* start right */
if(!con->left_row) {
con->state = JS_FINISHED;
return NULL;
}
con->right_rows_joined_count = 0;
rasqal_rowsource_reset(con->right);
}
right_row = rasqal_rowsource_read_row(con->right);
#ifdef RASQAL_DEBUG
RASQAL_DEBUG2("rowsource %p read right row : ", rowsource);
if(right_row)
rasqal_row_print(right_row, stderr);
else
fputs("NONE", stderr);
fputs("\n", stderr);
#endif
if(!right_row && con->state == JS_READ_RIGHT) {
/* right has finished */
/* restart left */
con->state = JS_START;
/* if all right table returned no bindings, return left row */
if(!con->right_rows_joined_count) {
/* otherwise return LEFT or RIGHT row only */
if(con->join_type == RASQAL_JOIN_TYPE_LEFT) {
/* LEFT JOIN - add left row if expr fails or not compatible */
if(con->left_row) {
con->right_rows_joined_count++;
row = rasqal_join_rowsource_build_merged_row(rowsource, con, NULL);
break;
}
}
}
/* restart left by continuing the loop */
continue;
}
/* state is always JS_READ_RIGHT at this point */
con->state = JS_READ_RIGHT;
/* now may have both left and right rows so compute compatibility */
if(right_row) {
compatible = rasqal_row_compatible_check(con->rc_map,
con->left_row, right_row);
RASQAL_DEBUG2("join rows compatible: %s\n", compatible ? "YES" : "NO");
}
if(con->constant_join_condition >= 0) {
/* Get constant join expression value */
bresult = con->constant_join_condition;
} else if(con->expr) {
/* Check join expression if present */
rasqal_literal *result;
int error = 0;
result = rasqal_expression_evaluate2(con->expr, query->eval_context,
&error);
#ifdef RASQAL_DEBUG
RASQAL_DEBUG1("join expression result: ");
if(error)
fputs("type error", DEBUG_FH);
else
rasqal_literal_print(result, DEBUG_FH);
fputc('\n', DEBUG_FH);
#endif
if(error) {
bresult = 0;
} else {
error = 0;
bresult = rasqal_literal_as_boolean(result, &error);
#ifdef RASQAL_DEBUG
if(error)
RASQAL_DEBUG1("filter boolean expression returned error\n");
else
RASQAL_DEBUG2("filter boolean expression result: %d\n", bresult);
#endif
rasqal_free_literal(result);
}
}
if(con->join_type == RASQAL_JOIN_TYPE_NATURAL) {
/* found a row if compatible and constraint matches */
if(compatible && bresult && right_row) {
con->right_rows_joined_count++;
/* consumes right_row */
row = rasqal_join_rowsource_build_merged_row(rowsource, con, right_row);
break;
}
} else if(con->join_type == RASQAL_JOIN_TYPE_LEFT) {
/*
* { merge(mu1, mu2) | mu1 in Omega1 and mu2 in Omega2, and mu1
* and mu2 are compatible and expr(merge(mu1, mu2)) is true }
*/
if(compatible && bresult) {
con->right_rows_joined_count++;
/* No constraint OR constraint & compatible so return merged row */
/* Compute row only now it is known to be needed (consumes right_row) */
row = rasqal_join_rowsource_build_merged_row(rowsource, con, right_row);
break;
}
#if 0
/*
* { mu1 | mu1 in Omega1 and mu2 in Omega2, and mu1 and mu2 are
* not compatible }
*/
if(!compatible) {
/* otherwise return LEFT or RIGHT row only */
if(con->join_type == RASQAL_JOIN_TYPE_LEFT) {
/* LEFT JOIN - add left row if expr fails or not compatible */
if(con->left_row) {
con->right_rows_joined_count++;
row = rasqal_join_rowsource_build_merged_row(rowsource, con, NULL);
if(right_row)
rasqal_free_row(right_row);
break;
}
}
}
#endif
/*
* { mu1 | mu1 in Omega1 and mu2 in Omega2, and mu1 and mu2 are
* compatible and for all mu2, expr(merge(mu1, mu2)) is false }
*/
/* The above is handled using check for
* !con->right_rows_joined_count earlier, to generate a row
* once.
*/
} /* end if LEFT JOIN */
if(right_row)
rasqal_free_row(right_row);
} /* end while */
if(row) {
rasqal_row_set_rowsource(row, rowsource);
row->offset = con->offset++;
rasqal_row_bind_variables(row, rowsource->query->vars_table);
}
return row;
}