mirror of
https://github.com/GrammaticalFramework/gf-core.git
synced 2026-04-29 06:22:51 -06:00
73 lines
1.5 KiB
C
73 lines
1.5 KiB
C
#include <gu/choice.h>
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#include <gu/seq.h>
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#include <gu/assert.h>
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#include <gu/log.h>
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struct GuChoice {
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GuBuf* path;
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size_t path_idx;
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};
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GuChoice*
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gu_new_choice(GuPool* pool)
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{
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GuChoice* ch = gu_new(GuChoice, pool);
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ch->path = gu_new_buf(size_t, pool);
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ch->path_idx = 0;
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return ch;
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}
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GuChoiceMark
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gu_choice_mark(GuChoice* ch)
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{
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gu_assert(ch->path_idx <= gu_buf_length(ch->path));
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gu_debug("%p@%d: mark", ch, ch->path_idx);
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return (GuChoiceMark){ch->path_idx};
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}
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void
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gu_choice_reset(GuChoice* ch, GuChoiceMark mark)
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{
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gu_assert(ch->path_idx <= gu_buf_length(ch->path));
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gu_debug("%p@%d: reset %d", ch, ch->path_idx, mark.path_idx);
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gu_require(mark.path_idx <= ch->path_idx );
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ch->path_idx = mark.path_idx;
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}
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int
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gu_choice_next(GuChoice* ch, int n_choices)
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{
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gu_assert(n_choices >= 0);
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gu_assert(ch->path_idx <= gu_buf_length(ch->path));
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if (n_choices == 0) {
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return -1;
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}
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int i = 0;
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if (gu_buf_length(ch->path) > ch->path_idx) {
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i = (int) gu_buf_get(ch->path, size_t, ch->path_idx);
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gu_assert(i <= n_choices);
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} else {
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gu_buf_push(ch->path, size_t, n_choices);
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i = n_choices;
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}
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int ret = (i == 0) ? -1 : n_choices - i;
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gu_debug("%p@%d: %d", ch, ch->path_idx, ret);
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ch->path_idx++;
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return ret;
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}
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bool
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gu_choice_advance(GuChoice* ch)
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{
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gu_assert(ch->path_idx <= gu_buf_length(ch->path));
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while (gu_buf_length(ch->path) > ch->path_idx) {
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size_t last = gu_buf_pop(ch->path, size_t);
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if (last > 1) {
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gu_buf_push(ch->path, size_t, last-1);
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return true;
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}
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}
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return false;
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}
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