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// file : libbutl/char-scanner.hxx -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef LIBBUTL_CHAR_SCANNER_HXX
#define LIBBUTL_CHAR_SCANNER_HXX
#include <string> // char_traits
#include <iosfwd>
#include <cstdint> // uint64_t
#include <libbutl/export.hxx>
namespace butl
{
// Low-level character stream scanner. Normally used as a base for
// higher-level lexers.
//
class LIBBUTL_EXPORT char_scanner
{
public:
// If the crlf argument is true, then recognize Windows newlines (0x0D
// 0x0A) and convert them to just '\n' (0x0A). Note that a standalone
// 0x0D is treated "as if" it was followed by 0x0A.
//
char_scanner (std::istream& is, bool crlf = true)
: is_ (is), crlf_ (crlf) {}
char_scanner (const char_scanner&) = delete;
char_scanner& operator= (const char_scanner&) = delete;
// Scanner interface.
//
public:
// Extended character. It includes line/column information
// and is capable of representing EOF.
//
class xchar
{
public:
typedef std::char_traits<char> traits_type;
typedef traits_type::int_type int_type;
typedef traits_type::char_type char_type;
int_type value;
std::uint64_t line;
std::uint64_t column;
operator char_type () const {return static_cast<char_type> (value);}
xchar (int_type v, std::uint64_t l = 0, std::uint64_t c = 0)
: value (v), line (l), column (c) {}
};
xchar
get ();
void
unget (const xchar&);
// Note that if there is an "ungot" character, peek() will return
// that.
//
xchar
peek ();
// Tests. In the future we can add tests line alpha(), alnum(),
// etc.
//
static bool
eos (const xchar& c) {return c.value == xchar::traits_type::eof ();}
// Line and column of the furthest seen (either via get() or
// peek()) character.
//
std::uint64_t line {1};
std::uint64_t column {1};
protected:
std::istream& is_;
bool crlf_;
bool unget_ {false};
xchar buf_ = '\0';
bool eos_ {false};
};
}
#endif // LIBBUTL_CHAR_SCANNER_HXX
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