/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.

 * Use of this file is governed by the BSD 3-clause license that

 * can be found in the LICENSE.txt file in the project root.

 */

#include "Token.h"

#include "CommonTokenStream.h"

using namespace antlr4;

CommonTokenStream::CommonTokenStream(TokenSource *tokenSource) : CommonTokenStream(tokenSource, Token::DEFAULT_CHANNEL) {

}

CommonTokenStream::CommonTokenStream(TokenSource *tokenSource, size_t channel_)

: BufferedTokenStream(tokenSource), channel(channel_) {

}

ssize_t CommonTokenStream::adjustSeekIndex(size_t i) {

  return nextTokenOnChannel(i, channel);

}

Token* CommonTokenStream::LB(size_t k) {

  if (k == 0 || k > _p) {

    return nullptr;

  }

  ssize_t i = static_cast<ssize_t>(_p);

  size_t n = 1;

  // find k good tokens looking backwards

  while (n <= k) {

    // skip off-channel tokens

    i = previousTokenOnChannel(i - 1, channel);

    n++;

  }

  if (i < 0) {

    return nullptr;

  }

  return _tokens[i].get();

}

Token* CommonTokenStream::LT(ssize_t k) {

  lazyInit();

  if (k == 0) {

    return nullptr;

  }

  if (k < 0) {

    return LB(static_cast<size_t>(-k));

  }

  size_t i = _p;

  ssize_t n = 1; // we know tokens[p] is a good one

                 // find k good tokens

  while (n < k) {

    // skip off-channel tokens, but make sure to not look past EOF

    if (sync(i + 1)) {

      i = nextTokenOnChannel(i + 1, channel);

    }

    n++;

  }

  return _tokens[i].get();

}

int CommonTokenStream::getNumberOfOnChannelTokens() {

  int n = 0;

  fill();

  for (size_t i = 0; i < _tokens.size(); i++) {

    Token *t = _tokens[i].get();

    if (t->getChannel() == channel) {

      n++;

    }

    if (t->getType() == Token::EOF) {

      break;

    }

  }

  return n;

}