/*
  Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

#include "paddle/string/piece.h"

#include <string.h>

#include <algorithm>
#include <iosfwd>
#include <stdexcept>

namespace paddle {
namespace string {

Piece::Piece() : data_(NULL), size_(0) {}

Piece::Piece(const char* d, size_t n) : data_(d), size_(n) {
  if (d == NULL && n != 0)
    throw std::invalid_argument("Piece requires len to be 0 for NULL data");
}

Piece::Piece(const char* s) : data_(s) { size_ = (s == NULL) ? 0 : strlen(s); }

Piece::Piece(const std::string& s) : data_(s.data()), size_(s.size()) {}

char Piece::operator[](size_t n) const {
  if (n >= len()) throw std::invalid_argument("index out of Piece length");
  return data_[n];
}

int Compare(Piece a, Piece b) {
  const size_t min_len = (a.len() < b.len()) ? a.len() : b.len();
  int r = memcmp(a.data(), b.data(), min_len);
  if (r == 0) {
    if (a.len() < b.len())
      return -1;
    else if (a.len() > b.len())
      return 1;
  }
  return r;
}

bool operator==(Piece x, Piece y) {
  return ((x.len() == y.len()) &&
          (x.data() == y.data() || memcmp(x.data(), y.data(), x.len()) == 0));
}

bool operator!=(Piece x, Piece y) { return !(x == y); }

bool operator<(Piece x, Piece y) { return Compare(x, y) < 0; }
bool operator>(Piece x, Piece y) { return Compare(x, y) > 0; }

bool operator<=(Piece x, Piece y) { return Compare(x, y) <= 0; }
bool operator>=(Piece x, Piece y) { return Compare(x, y) >= 0; }

bool HasPrefix(Piece s, Piece x) {
  return ((s.len() >= x.len()) && (memcmp(s.data(), x.data(), x.len()) == 0));
}

bool HasSuffix(Piece s, Piece x) {
  return ((s.len() >= x.len()) &&
          (memcmp(s.data() + (s.len() - x.len()), x.data(), x.len()) == 0));
}

Piece SkipPrefix(Piece s, size_t n) {
  if (n > s.len())
    throw std::invalid_argument("Skip distance larger than Piece length");
  return Piece(s.data() + n, s.len() - n);
}

Piece SkipSuffix(Piece s, size_t n) {
  if (n > s.len())
    throw std::invalid_argument("Skip distance larger than Piece length");
  return Piece(s.data(), s.len() - n);
}

Piece TrimPrefix(Piece s, Piece x) {
  return HasPrefix(s, x) ? SkipPrefix(s, x.len()) : s;
}

Piece TrimSuffix(Piece s, Piece x) {
  return HasSuffix(s, x) ? SkipSuffix(s, x.len()) : s;
}

bool Contains(Piece s, Piece sub) {
  return std::search(s.begin(), s.end(), sub.begin(), sub.end()) != s.end();
}

size_t Index(Piece s, Piece sub) {
  auto e = std::search(s.begin(), s.end(), sub.begin(), sub.end());
  return e != s.end() ? e - s.data() : Piece::npos;
}

size_t Find(Piece s, char c, size_t pos) {
  if (pos >= s.len()) {
    return Piece::npos;
  }
  const char* result =
      reinterpret_cast<const char*>(memchr(s.data() + pos, c, s.len() - pos));
  return result != nullptr ? result - s.data() : Piece::npos;
}

size_t RFind(Piece s, char c, size_t pos) {
  if (s.len() == 0) return Piece::npos;
  for (const char* p = s.data() + std::min(pos, s.len() - 1); p >= s.data();
       p--) {
    if (*p == c) {
      return p - s.data();
    }
  }
  return Piece::npos;
}

Piece SubStr(Piece s, size_t pos, size_t n) {
  if (pos > s.len()) pos = s.len();
  if (n > s.len() - pos) n = s.len() - pos;
  return Piece(s.data() + pos, n);
}

std::ostream& operator<<(std::ostream& o, Piece piece) {
  return o << piece.ToString();
}

}  // namespace string
}  // namespace paddle
