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// file : butl/char-scanner -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUTL_CHAR_SCANNER
#define BUTL_CHAR_SCANNER
#include <string> // char_traits
#include <iosfwd>
#include <cstdint> // uint64_t
#include <butl/export>
namespace butl
{
// Low-level character stream scanner. Normally used as a base for
// higher-level lexers.
//
class LIBBUTL_EXPORT char_scanner
{
public:
char_scanner (std::istream& is): is_ (is) {}
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 unget_ {false};
xchar buf_ = '\0';
bool eos_ {false};
};
}
#endif // BUTL_CHAR_SCANNER
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