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#include <gu/choice.h>
#include <gu/seq.h>
#include <gu/assert.h>
struct GuChoice {
GuBuf* path;
size_t path_idx;
};
GU_API GuChoice*
gu_new_choice(GuPool* pool)
{
GuChoice* ch = gu_new(GuChoice, pool);
ch->path = gu_new_buf(size_t, pool);
ch->path_idx = 0;
return ch;
}
GU_API GuChoiceMark
gu_choice_mark(GuChoice* ch)
{
gu_assert(ch->path_idx <= gu_buf_length(ch->path));
return (GuChoiceMark){ch->path_idx};
}
GU_API void
gu_choice_reset(GuChoice* ch, GuChoiceMark mark)
{
gu_assert(ch->path_idx <= gu_buf_length(ch->path));
gu_require(mark.path_idx <= ch->path_idx );
ch->path_idx = mark.path_idx;
}
GU_API int
gu_choice_next(GuChoice* ch, int n_choices)
{
gu_assert(n_choices >= 0);
gu_assert(ch->path_idx <= gu_buf_length(ch->path));
if (n_choices == 0) {
return -1;
}
int i = 0;
if (gu_buf_length(ch->path) > ch->path_idx) {
i = (int) gu_buf_get(ch->path, size_t, ch->path_idx);
gu_assert(i <= n_choices);
} else {
gu_buf_push(ch->path, size_t, n_choices);
i = n_choices;
}
int ret = (i == 0) ? -1 : n_choices - i;
ch->path_idx++;
return ret;
}
GU_API bool
gu_choice_advance(GuChoice* ch)
{
gu_assert(ch->path_idx <= gu_buf_length(ch->path));
while (gu_buf_length(ch->path) > ch->path_idx) {
size_t last = gu_buf_pop(ch->path, size_t);
if (last > 1) {
gu_buf_push(ch->path, size_t, last-1);
return true;
}
}
return false;
}
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