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#ifndef _SUFFIX_ARRAY_H_
#define _SUFFIX_ARRAY_H_
#include <memory>
#include <string>
#include <vector>
#include <boost/filesystem.hpp>
namespace fs = boost::filesystem;
using namespace std;
namespace extractor {
class DataArray;
class PhraseLocation;
class SuffixArray {
public:
// Creates a suffix array from a data array.
SuffixArray(shared_ptr<DataArray> data_array);
virtual ~SuffixArray();
// Returns the size of the suffix array.
virtual int GetSize() const;
// Returns the data array on top of which the suffix array is constructed.
virtual shared_ptr<DataArray> GetData() const;
// Constructs the longest-common-prefix array using the algorithm of Kasai et
// al. (2001).
virtual vector<int> BuildLCPArray() const;
// Returns the i-th suffix.
virtual int GetSuffix(int rank) const;
// Given the range in which a phrase is located and the next word, returns the
// range corresponding to the phrase extended with the next word.
virtual PhraseLocation Lookup(int low, int high, const string& word,
int offset) const;
void WriteBinary(const fs::path& filepath) const;
protected:
SuffixArray();
private:
// Constructs the suffix array using the algorithm of Larsson and Sadakane
// (1999).
void BuildSuffixArray();
// Bucket sort on the data array (used for initializing the construction of
// the suffix array.)
void InitialBucketSort(vector<int>& groups);
void TernaryQuicksort(int left, int right, int step, vector<int>& groups);
// Constructs the suffix array in log(n) steps by doubling the length of the
// suffixes at each step.
void PrefixDoublingSort(vector<int>& groups);
// Given a [low, high) range in the suffix array in which all elements have
// the first offset-1 values the same, it returns the first position where the
// offset value is greater or equal to word_id.
int LookupRangeStart(int low, int high, int word_id, int offset) const;
shared_ptr<DataArray> data_array;
vector<int> suffix_array;
vector<int> word_start;
};
} // namespace extractor
#endif
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