void
LexIndex_seek(LexIndex *self, Obj *target)
{
FieldType *type = self->field_type;
i32_t lo = 0;
i32_t hi = self->size - 1;
i32_t result = -100;
if (target == NULL || self->size == 0) {
self->tick = 0;
return;
}
else {
if ( !OBJ_IS_A(target, CHARBUF)) {
THROW("Target is a %o, and not comparable to a %o",
Obj_Get_Class_Name(target), CHARBUF.name);
}
/* TODO:
Obj *first_obj = VA_Fetch(terms, 0);
if ( !Obj_Is_A(target, Obj_Get_VTable(first_obj)) ) {
THROW("Target is a %o, and not comparable to a %o",
Obj_Get_Class_Name(target), Obj_Get_Class_Name(first_obj));
}
*/
}
/* Divide and conquer. */
while (hi >= lo) {
const i32_t mid = lo + ((hi - lo) / 2);
const i64_t offset
= (i64_t)Math_decode_bigend_u64(self->offsets + mid);
char *data = self->data + offset;
size_t size = Math_decode_c32(&data);
i64_t comparison;
ViewCB_Assign_Str(self->term, data, size);
comparison = FType_Compare_Values(type, target, (Obj*)self->term);
if (comparison < 0) {
hi = mid - 1;
}
else if (comparison > 0) {
lo = mid + 1;
}
else {
result = mid;
break;
}
}
/* Record the index of the entry we've seeked to, then read entry. */
self->tick = hi == -1 ? 0 /* indicating that target lt first entry */
: result == -100 ? hi /* if result is still -100, it wasn't set */
: result;
S_read_entry(self);
}
void
LexIndex_Seek_IMP(LexIndex *self, Obj *target) {
LexIndexIVARS *const ivars = LexIndex_IVARS(self);
TermStepper *term_stepper = ivars->term_stepper;
InStream *ix_in = ivars->ix_in;
FieldType *type = ivars->field_type;
int32_t lo = 0;
int32_t hi = ivars->size - 1;
int32_t result = -100;
if (target == NULL || ivars->size == 0) {
ivars->tick = 0;
return;
}
else {
if (!Obj_is_a(target, STRING)) {
THROW(ERR, "Target is a %o, and not comparable to a %o",
Obj_get_class_name(target), Class_Get_Name(STRING));
}
/* TODO:
Obj *first_obj = Vec_Fetch(terms, 0);
if (!Obj_is_a(target, Obj_get_class(first_obj))) {
THROW(ERR, "Target is a %o, and not comparable to a %o",
Obj_get_class_name(target), Obj_get_class_name(first_obj));
}
*/
}
// Divide and conquer.
while (hi >= lo) {
const int32_t mid = lo + ((hi - lo) / 2);
const int64_t offset
= (int64_t)NumUtil_decode_bigend_u64(ivars->offsets + mid);
InStream_Seek(ix_in, offset);
TermStepper_Read_Key_Frame(term_stepper, ix_in);
// Compare values. There is no need for a NULL-check because the term
// number is alway between 0 and ivars->size - 1.
Obj *value = TermStepper_Get_Value(term_stepper);
int32_t comparison = FType_Compare_Values(type, target, value);
if (comparison < 0) {
hi = mid - 1;
}
else if (comparison > 0) {
lo = mid + 1;
}
else {
result = mid;
break;
}
}
// Record the index of the entry we've seeked to, then read entry.
ivars->tick = hi == -1 // indicating that target lt first entry
? 0
: result == -100 // if result is still -100, it wasn't set
? hi
: result;
S_read_entry(self);
}
