| #include "./deorummolae.h" |
| |
| #include <array> |
| #include <cstdio> |
| |
| #include "third_party/esaxx/sais.hxx" |
| |
| /* Used for quick SA-entry to file mapping. Each file is padded to size that |
| is a multiple of chunk size. */ |
| #define CHUNK_SIZE 64 |
| /* Length of substring that is considered to be covered by dictionary string. */ |
| #define CUT_MATCH 6 |
| /* Minimal dictionary entry size. */ |
| #define MIN_MATCH 24 |
| |
| /* Non tunable definitions. */ |
| #define CHUNK_MASK (CHUNK_SIZE - 1) |
| #define COVERAGE_SIZE (1 << (DM_LOG_MAX_FILES - 6)) |
| |
| /* File coverage: every bit set to 1 denotes a file covered by an isle. */ |
| typedef std::array<uint64_t, COVERAGE_SIZE> Coverage; |
| |
| /* Symbol of text alphabet. */ |
| typedef int32_t TextChar; |
| |
| /* Pointer to position in text. */ |
| typedef uint32_t TextIdx; |
| |
| /* SAIS sarray_type; unfortunately, must be a signed type. */ |
| typedef int32_t TextSaIdx; |
| |
| static size_t popcount(uint64_t u) { |
| return static_cast<size_t>(__builtin_popcountll(u)); |
| } |
| |
| /* Condense terminators and pad file entries. */ |
| static void rewriteText(std::vector<TextChar>* text) { |
| TextChar terminator = text->back(); |
| TextChar prev = terminator; |
| TextIdx to = 0; |
| for (TextIdx from = 0; from < text->size(); ++from) { |
| TextChar next = text->at(from); |
| if (next < 256 || prev < 256) { |
| text->at(to++) = next; |
| if (next >= 256) terminator = next; |
| } |
| prev = next; |
| } |
| text->resize(to); |
| if (text->empty()) text->push_back(terminator); |
| while (text->size() & CHUNK_MASK) text->push_back(terminator); |
| } |
| |
| /* Reenumerate terminators for smaller alphabet. */ |
| static void remapTerminators(std::vector<TextChar>* text, |
| TextChar* next_terminator) { |
| TextChar prev = -1; |
| TextChar x = 256; |
| for (TextIdx i = 0; i < text->size(); ++i) { |
| TextChar next = text->at(i); |
| if (next < 256) { // Char. |
| // Do nothing. |
| } else if (prev < 256) { // Terminator after char. |
| next = x++; |
| } else { // Terminator after terminator. |
| next = prev; |
| } |
| text->at(i) = next; |
| prev = next; |
| } |
| *next_terminator = x; |
| } |
| |
| /* Combine all file entries; create mapping position->file. */ |
| static void buildFullText(std::vector<std::vector<TextChar>>* data, |
| std::vector<TextChar>* full_text, std::vector<TextIdx>* file_map, |
| std::vector<TextIdx>* file_offset, TextChar* next_terminator) { |
| file_map->resize(0); |
| file_offset->resize(0); |
| full_text->resize(0); |
| for (TextIdx i = 0; i < data->size(); ++i) { |
| file_offset->push_back(full_text->size()); |
| std::vector<TextChar>& file = data->at(i); |
| rewriteText(&file); |
| full_text->insert(full_text->end(), file.begin(), file.end()); |
| file_map->insert(file_map->end(), file.size() / CHUNK_SIZE, i); |
| } |
| if (false) remapTerminators(full_text, next_terminator); |
| } |
| |
| /* Build longest-common-prefix based on suffix array and text. |
| TODO: borrowed -> unknown efficiency. */ |
| static void buildLcp(std::vector<TextChar>* text, std::vector<TextIdx>* sa, |
| std::vector<TextIdx>* lcp, std::vector<TextIdx>* invese_sa) { |
| TextIdx size = static_cast<TextIdx>(text->size()); |
| lcp->resize(size); |
| TextIdx k = 0; |
| lcp->at(size - 1) = 0; |
| for (TextIdx i = 0; i < size; ++i) { |
| if (invese_sa->at(i) == size - 1) { |
| k = 0; |
| continue; |
| } |
| // Suffix which follow i-th suffix. |
| TextIdx j = sa->at(invese_sa->at(i) + 1); |
| while (i + k < size && j + k < size && text->at(i + k) == text->at(j + k)) { |
| ++k; |
| } |
| lcp->at(invese_sa->at(i)) = k; |
| if (k > 0) --k; |
| } |
| } |
| |
| /* Isle is a range in SA with LCP not less than some value. |
| When we raise the LCP requirement, the isle sunks and smaller isles appear |
| instead. */ |
| typedef struct { |
| TextIdx lcp; |
| TextIdx l; |
| TextIdx r; |
| Coverage coverage; |
| } Isle; |
| |
| /* Helper routine for `cutMatch`. */ |
| static void poisonData(TextIdx pos, TextIdx length, |
| std::vector<std::vector<TextChar>>* data, std::vector<TextIdx>* file_map, |
| std::vector<TextIdx>* file_offset, TextChar* next_terminator) { |
| TextIdx f = file_map->at(pos / CHUNK_SIZE); |
| pos -= file_offset->at(f); |
| std::vector<TextChar>& file = data->at(f); |
| TextIdx l = (length == CUT_MATCH) ? CUT_MATCH : 1; |
| for (TextIdx j = 0; j < l; j++, pos++) { |
| if (file[pos] >= 256) continue; |
| if (file[pos + 1] >= 256) { |
| file[pos] = file[pos + 1]; |
| } else if (pos > 0 && file[pos - 1] >= 256) { |
| file[pos] = file[pos - 1]; |
| } else { |
| file[pos] = (*next_terminator)++; |
| } |
| } |
| } |
| |
| /* Remove substrings of a given match from files. |
| Substrings are replaced with unique terminators, so next iteration SA would |
| not allow to cross removed areas. */ |
| static void cutMatch(std::vector<std::vector<TextChar>>* data, TextIdx index, |
| TextIdx length, std::vector<TextIdx>* sa, std::vector<TextIdx>* lcp, |
| std::vector<TextIdx>* invese_sa, TextChar* next_terminator, |
| std::vector<TextIdx>* file_map, std::vector<TextIdx>* file_offset) { |
| while (length >= CUT_MATCH) { |
| TextIdx i = index; |
| while (lcp->at(i) >= length) { |
| i++; |
| poisonData( |
| sa->at(i), length, data, file_map, file_offset, next_terminator); |
| } |
| while (true) { |
| poisonData( |
| sa->at(index), length, data, file_map, file_offset, next_terminator); |
| if (index == 0 || lcp->at(index - 1) < length) break; |
| index--; |
| } |
| length--; |
| index = invese_sa->at(sa->at(index) + 1); |
| } |
| } |
| |
| std::string DM_generate(size_t dictionary_size_limit, |
| const std::vector<size_t>& sample_sizes, const uint8_t* sample_data) { |
| { |
| TextIdx tmp = static_cast<TextIdx>(dictionary_size_limit); |
| if ((tmp != dictionary_size_limit) || (tmp > 1u << 30)) { |
| fprintf(stderr, "dictionary_size_limit is too large\n"); |
| return ""; |
| } |
| } |
| |
| /* Could use 256 + '0' for easier debugging. */ |
| TextChar next_terminator = 256; |
| |
| std::string output; |
| std::vector<std::vector<TextChar>> data; |
| |
| TextIdx offset = 0; |
| size_t num_samples = sample_sizes.size(); |
| if (num_samples > DM_MAX_FILES) num_samples = DM_MAX_FILES; |
| for (size_t n = 0; n < num_samples; ++n) { |
| TextIdx delta = static_cast<TextIdx>(sample_sizes[n]); |
| if (delta != sample_sizes[n]) { |
| fprintf(stderr, "sample is too large\n"); |
| return ""; |
| } |
| if (delta == 0) { |
| fprintf(stderr, "0-length samples are prohibited\n"); |
| return ""; |
| } |
| TextIdx next_offset = offset + delta; |
| if (next_offset <= offset) { |
| fprintf(stderr, "corpus is too large\n"); |
| return ""; |
| } |
| data.push_back( |
| std::vector<TextChar>(sample_data + offset, sample_data + next_offset)); |
| offset = next_offset; |
| data.back().push_back(next_terminator++); |
| } |
| |
| /* Most arrays are allocated once, and then just resized to smaller and |
| smaller sizes. */ |
| std::vector<TextChar> full_text; |
| std::vector<TextIdx> file_map; |
| std::vector<TextIdx> file_offset; |
| std::vector<TextIdx> sa; |
| std::vector<TextIdx> invese_sa; |
| std::vector<TextIdx> lcp; |
| std::vector<Isle> isles; |
| std::vector<char> output_data; |
| TextIdx total = 0; |
| TextIdx total_cost = 0; |
| TextIdx best_cost; |
| Isle best_isle; |
| size_t min_count = num_samples; |
| |
| while (true) { |
| TextIdx max_match = static_cast<TextIdx>(dictionary_size_limit) - total; |
| buildFullText(&data, &full_text, &file_map, &file_offset, &next_terminator); |
| sa.resize(full_text.size()); |
| /* Hopefully, non-negative TextSaIdx is the same sa TextIdx counterpart. */ |
| saisxx(full_text.data(), reinterpret_cast<TextSaIdx*>(sa.data()), |
| static_cast<TextChar>(full_text.size()), next_terminator); |
| invese_sa.resize(full_text.size()); |
| for (TextIdx i = 0; i < full_text.size(); ++i) { |
| invese_sa[sa[i]] = i; |
| } |
| buildLcp(&full_text, &sa, &lcp, &invese_sa); |
| |
| /* Do not rebuild SA/LCP, just use different selection. */ |
| retry: |
| best_cost = 0; |
| best_isle = {0, 0, 0, {{0}}}; |
| isles.resize(0); |
| isles.push_back(best_isle); |
| |
| for (TextIdx i = 0; i < lcp.size(); ++i) { |
| TextIdx l = i; |
| Coverage cov = {{0}}; |
| size_t f = file_map[sa[i] / CHUNK_SIZE]; |
| cov[f >> 6] = (static_cast<uint64_t>(1)) << (f & 63); |
| while (lcp[i] < isles.back().lcp) { |
| Isle& top = isles.back(); |
| top.r = i; |
| l = top.l; |
| for (size_t x = 0; x < cov.size(); ++x) cov[x] |= top.coverage[x]; |
| size_t count = 0; |
| for (size_t x = 0; x < cov.size(); ++x) count += popcount(cov[x]); |
| TextIdx effective_lcp = top.lcp; |
| /* Restrict (last) dictionary entry length. */ |
| if (effective_lcp > max_match) effective_lcp = max_match; |
| TextIdx cost = count * effective_lcp; |
| if (cost > best_cost && count >= min_count && |
| effective_lcp >= MIN_MATCH) { |
| best_cost = cost; |
| best_isle = top; |
| best_isle.lcp = effective_lcp; |
| } |
| isles.pop_back(); |
| for (size_t x = 0; x < cov.size(); ++x) { |
| isles.back().coverage[x] |= cov[x]; |
| } |
| } |
| if (lcp[i] > isles.back().lcp) isles.push_back({lcp[i], l, 0, {{0}}}); |
| for (size_t x = 0; x < cov.size(); ++x) { |
| isles.back().coverage[x] |= cov[x]; |
| } |
| } |
| |
| /* When saturated matches do not match length restrictions, lower the |
| saturation requirements. */ |
| if (best_cost == 0 || best_isle.lcp < MIN_MATCH) { |
| if (min_count >= 8) { |
| min_count = (min_count * 7) / 8; |
| fprintf(stderr, "Retry: min_count=%zu\n", min_count); |
| goto retry; |
| } |
| break; |
| } |
| |
| /* Save the entry. */ |
| fprintf(stderr, "Savings: %d+%d, dictionary: %d+%d\n", |
| total_cost, best_cost, total, best_isle.lcp); |
| int* piece = &full_text[sa[best_isle.l]]; |
| output.insert(output.end(), piece, piece + best_isle.lcp); |
| total += best_isle.lcp; |
| total_cost += best_cost; |
| cutMatch(&data, best_isle.l, best_isle.lcp, &sa, &lcp, &invese_sa, |
| &next_terminator, &file_map, &file_offset); |
| if (total >= dictionary_size_limit) break; |
| } |
| |
| return output; |
| } |