CharStream.cpp

/*
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 * This file is derived from the file "scanner.cc", which was part of the
 * V8 project. The original copyright header follows:
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 * Copyright 2006-2012, the V8 project authors. All rights reserved.
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*/
/**
 * Character stream / input file.
 */

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

using namespace solidity;
using namespace solidity::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();
}

char CharStream::setPosition(size_t _location)
{
	solAssert(_location <= m_source.size(), "Attempting to set position past end of source.");
	m_position = _location;
	return get();
}

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

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

std::string_view CharStream::text(SourceLocation const& _location) const
{
	if (!_location.hasText())
		return {};
	solAssert(_location.sourceName && *_location.sourceName == m_name, "");
	solAssert(static_cast<size_t>(_location.end) <= m_source.size(), "");
	return std::string_view{m_source}.substr(
		static_cast<size_t>(_location.start),
		static_cast<size_t>(_location.end - _location.start)
	);
}

std::string CharStream::singleLineSnippet(std::string const& _sourceCode, SourceLocation const& _location)
{
	if (!_location.hasText())
		return {};

	if (static_cast<size_t>(_location.start) >= _sourceCode.size())
		return {};

	std::string cut = _sourceCode.substr(static_cast<size_t>(_location.start), static_cast<size_t>(_location.end - _location.start));
	auto newLinePos = cut.find_first_of("\n\r");
	if (newLinePos != std::string::npos)
		cut = cut.substr(0, newLinePos) + "...";

	return cut;
}

std::optional<int> CharStream::translateLineColumnToPosition(LineColumn const& _lineColumn) const
{
	return translateLineColumnToPosition(m_source, _lineColumn);
}

std::optional<int> CharStream::translateLineColumnToPosition(std::string const& _text, LineColumn const& _input)
{
	if (_input.line < 0)
		return std::nullopt;

	size_t offset = 0;
	for (int i = 0; i < _input.line; i++)
	{
		offset = _text.find('\n', offset);
		if (offset == _text.npos)
			return std::nullopt;
		offset++; // Skip linefeed.
	}

	size_t endOfLine = _text.find('\n', offset);
	if (endOfLine == std::string::npos)
		endOfLine = _text.size();

	if (offset + static_cast<size_t>(_input.column) > endOfLine)
		return std::nullopt;
	return offset + static_cast<size_t>(_input.column);
}