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/*
    This file is part of solidity.

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    You should have received a copy of the GNU General Public License
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    This file is derived from the file "scanner.cc", which was part of the
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    Copyright 2006-2012, the V8 project authors. All rights reserved.
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    * Redistributions of source code must retain the above copyright
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*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Solidity scanner.
 */

#include <liblangutil/CharStream.h>
#include <liblangutil/Exceptions.h>

using namespace std;
using namespace langutil;

char CharStream::advanceAndGet(size_t _chars)
{
    if (isPastEndOfInput())
        return 0;
    m_position += _chars;
    if (isPastEndOfInput())
        return 0;
    return m_source[m_position];
}

char CharStream::rollback(size_t _amount)
{
    solAssert(m_position >= _amount, "");
    m_position -= _amount;
    return get();
}

string CharStream::lineAtPosition(int _position) const
{
    // if _position points to \n, it returns the line before the \n
    using size_type = string::size_type;
    size_type searchStart = min<size_type>(m_source.size(), _position);
    if (searchStart > 0)
        searchStart--;
    size_type lineStart = m_source.rfind('\n', searchStart);
    if (lineStart == string::npos)
        lineStart = 0;
    else
        lineStart++;
    return m_source.substr(lineStart, min(m_source.find('\n', lineStart),
                                          m_source.size()) - lineStart);
}

tuple<int, int> CharStream::translatePositionToLineColumn(int _position) const
{
    using size_type = string::size_type;
    size_type searchPosition = min<size_type>(m_source.size(), _position);
    int lineNumber = count(m_source.begin(), m_source.begin() + searchPosition, '\n');
    size_type lineStart;
    if (searchPosition == 0)
        lineStart = 0;
    else
    {
        lineStart = m_source.rfind('\n', searchPosition - 1);
        lineStart = lineStart == string::npos ? 0 : lineStart + 1;
    }
    return tuple<int, int>(lineNumber, searchPosition - lineStart);
}