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// file : build2/cc/lexer.hxx -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUILD2_CC_LEXER_HXX
#define BUILD2_CC_LEXER_HXX
#include <libbutl/sha256.hxx>
#include <libbutl/char-scanner.hxx>
#include <build2/types.hxx>
#include <build2/utility.hxx>
#include <build2/diagnostics.hxx>
namespace build2
{
namespace cc
{
// Preprocessor-level tokenization of C/C++ source. In other words, the
// sequence of tokens returned is similar to what a real C/C++ compiler
// would see from its preprocessor.
//
// The input is a (partially-)preprocessed translation unit that may still
// contain comments, line continuations, and preprocessor directives such
// as #line, #pragma, but not #include (which is diagnosed). Currently,
// all preprocessor directives except #line are ignored and no values are
// saved from literals. The #line directive (and its shorthand notation)
// is recognized to provide the logical token location.
//
// While at it we also calculate the checksum of the input ignoring
// comments, whitespaces, etc. This is used to detect changes that do not
// alter the resulting token stream.
//
enum class token_type
{
// NOTE: remember to update operator<<() if changing anything here!
//
eos,
dot, // .
semi, // ;
lcbrace, // {
rcbrace, // }
punctuation, // Other punctuation.
identifier,
number, // Number literal.
character, // Char literal.
string, // String literal.
other // Other token.
};
struct token
{
token_type type = token_type::eos;
string value;
// Logical position.
//
path file;
uint64_t line = 0;
uint64_t column = 0;
// Physical position in the stream, currently only for identifiers and
// only if the stream is ifdstream.
//
uint64_t position = 0;
};
// Output the token value in a format suitable for diagnostics.
//
ostream&
operator<< (ostream&, const token&);
class lexer: protected butl::char_scanner
{
public:
lexer (istream& is, const path& name)
: char_scanner (is, false),
name_ (name),
fail ("error", &name_),
log_file_ (name) {}
const path&
name () const {return name_;}
string
checksum () const {return cs_.string ();}
// Note that it is ok to call next() again after getting eos.
//
token
next ()
{
token t;
next (t, skip_spaces (), true);
return t;
}
// As above but reuse the token to avoid a (potential) memory
// allocation. Typical usage:
//
// for (token t; l.next (t) != token_type::eos; )
// ...
//
token_type
next (token& t)
{
next (t, skip_spaces (), true);
return t.type;
}
private:
void
next (token&, xchar, bool);
void
number_literal (token&, xchar);
void
char_literal (token&, xchar);
void
string_literal (token&, xchar);
void
raw_string_literal (token&, xchar);
void
literal_suffix (xchar);
void
line_directive (token&, xchar);
xchar
skip_spaces (bool newline = true);
// The char_scanner adaptation for newline escape sequence processing.
// Enabled by default and is only disabled in the raw string literals.
//
private:
using base = char_scanner;
xchar
peek (bool escape = true);
xchar
get (bool escape = true);
void
get (const xchar& peeked);
// Hashing versions.
//
xchar
geth (bool escape = true);
void
geth (const xchar& peeked);
private:
const path name_;
const fail_mark fail;
// Logical file and line as set by the #line directives. Note that the
// lexer diagnostics still uses the physical file/lines.
//
path log_file_;
optional<uint64_t> log_line_;
sha256 cs_;
};
// Diagnostics plumbing.
//
inline location
get_location (const token& t, const void*)
{
return location (&t.file, t.line, t.column);
}
}
}
#endif // BUILD2_CC_LEXER_HXX
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