File size: 2,112 Bytes
1ce325b |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 |
#ifndef LM_COMMON_NGRAM_H
#define LM_COMMON_NGRAM_H
#include "../weights.hh"
#include "../word_index.hh"
#include <cstddef>
#include <cassert>
#include <stdint.h>
#include <cstring>
namespace lm {
class NGramHeader {
public:
NGramHeader(void *begin, std::size_t order)
: begin_(static_cast<WordIndex*>(begin)), end_(begin_ + order) {}
NGramHeader() : begin_(NULL), end_(NULL) {}
const uint8_t *Base() const { return reinterpret_cast<const uint8_t*>(begin_); }
uint8_t *Base() { return reinterpret_cast<uint8_t*>(begin_); }
void ReBase(void *to) {
std::size_t difference = end_ - begin_;
begin_ = reinterpret_cast<WordIndex*>(to);
end_ = begin_ + difference;
}
// These are for the vocab index.
// Lower-case in deference to STL.
const WordIndex *begin() const { return begin_; }
WordIndex *begin() { return begin_; }
const WordIndex *end() const { return end_; }
WordIndex *end() { return end_; }
std::size_t size() const { return end_ - begin_; }
std::size_t Order() const { return end_ - begin_; }
private:
WordIndex *begin_, *end_;
};
template <class PayloadT> class NGram : public NGramHeader {
public:
typedef PayloadT Payload;
NGram() : NGramHeader(NULL, 0) {}
NGram(void *begin, std::size_t order) : NGramHeader(begin, order) {}
// Would do operator++ but that can get confusing for a stream.
void NextInMemory() {
ReBase(&Value() + 1);
}
static std::size_t TotalSize(std::size_t order) {
return order * sizeof(WordIndex) + sizeof(Payload);
}
std::size_t TotalSize() const {
// Compiler should optimize this.
return TotalSize(Order());
}
static std::size_t OrderFromSize(std::size_t size) {
std::size_t ret = (size - sizeof(Payload)) / sizeof(WordIndex);
assert(size == TotalSize(ret));
return ret;
}
const Payload &Value() const { return *reinterpret_cast<const Payload *>(end()); }
Payload &Value() { return *reinterpret_cast<Payload *>(end()); }
};
} // namespace lm
#endif // LM_COMMON_NGRAM_H
|