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// file : libbuild2/build/script/lexer.cxx -*- C++ -*-
// license : MIT; see accompanying LICENSE file
#include <libbuild2/build/script/lexer.hxx>
using namespace std;
namespace build2
{
namespace build
{
namespace script
{
using type = token_type;
build2::script::redirect_aliases lexer::redirect_aliases {
type (type::in_file),
type (type::in_doc),
type (type::in_str),
type (type::out_file_ovr),
type (type::out_file_app),
nullopt};
void lexer::
mode (build2::lexer_mode m,
char ps,
optional<const char*> esc,
uintptr_t data)
{
bool a (false); // attributes
const char* s1 (nullptr);
const char* s2 (nullptr);
bool s (true); // space
bool n (true); // newline
bool q (true); // quotes
if (!esc)
{
assert (!state_.empty ());
esc = state_.top ().escapes;
}
switch (m)
{
case lexer_mode::command_line:
{
s1 = "=!|&<> $(#\t\n";
s2 = "== ";
break;
}
case lexer_mode::first_token:
{
// First token on the script line. Like command_line but
// recognizes variable assignments as separators.
//
s1 = "=+!|&<> $(#\t\n";
s2 = " == ";
break;
}
case lexer_mode::second_token:
{
// Second token on the script line. Like command_line but
// recognizes leading variable assignments.
//
// Note that to recognize only leading assignments we shouldn't
// add them to the separator strings (so this is identical to
// command_line).
//
s1 = "=!|&<> $(#\t\n";
s2 = "== ";
break;
}
case lexer_mode::variable_line:
{
// Like value except we don't recognize '{'.
//
s1 = " $(#\t\n";
s2 = " ";
break;
}
default:
{
base_lexer::mode (m, ps, esc);
return;
}
}
assert (ps == '\0');
state_.push (state {m, data, nullopt, a, ps, s, n, q, *esc, s1, s2});
}
token lexer::
next ()
{
token r;
switch (state_.top ().mode)
{
case lexer_mode::command_line:
case lexer_mode::first_token:
case lexer_mode::second_token:
case lexer_mode::variable_line:
r = next_line ();
break;
default: return base_lexer::next ();
}
if (r.qtype != quote_type::unquoted)
++quoted_;
return r;
}
token lexer::
next_line ()
{
bool sep (skip_spaces ().first);
xchar c (get ());
uint64_t ln (c.line), cn (c.column);
state st (state_.top ()); // Make copy (see first/second_token).
lexer_mode m (st.mode);
auto make_token = [&sep, ln, cn] (type t)
{
return token (t, sep, ln, cn, token_printer);
};
// Handle attributes (do it first to make sure the flag is cleared
// regardless of what we return).
//
if (st.attributes)
{
assert (m == lexer_mode::variable_line);
state_.top ().attributes = false;
if (c == '[')
return make_token (type::lsbrace);
}
if (eos (c))
return make_token (type::eos);
// Expire certain modes at the end of the token. Do it early in case
// we push any new mode (e.g., double quote).
//
if (m == lexer_mode::first_token || m == lexer_mode::second_token)
state_.pop ();
// NOTE: remember to update mode() if adding new special characters.
switch (c)
{
case '\n':
{
// Expire variable value mode at the end of the line.
//
if (m == lexer_mode::variable_line)
state_.pop ();
sep = true; // Treat newline as always separated.
return make_token (type::newline);
}
// Variable expansion, function call, and evaluation context.
//
case '$': return make_token (type::dollar);
case '(': return make_token (type::lparen);
}
// Command line operator/separators.
//
if (m == lexer_mode::command_line ||
m == lexer_mode::first_token ||
m == lexer_mode::second_token)
{
switch (c)
{
// Comparison (==, !=).
//
case '=':
case '!':
{
if (peek () == '=')
{
get ();
return make_token (c == '=' ? type::equal : type::not_equal);
}
}
}
}
// Command operators.
//
if (m == lexer_mode::command_line ||
m == lexer_mode::first_token ||
m == lexer_mode::second_token)
{
if (optional<token> t = next_cmd_op (c, sep))
return move (*t);
}
// Variable assignment (=, +=, =+).
//
if (m == lexer_mode::second_token)
{
switch (c)
{
case '=':
{
if (peek () == '+')
{
get ();
return make_token (type::prepend);
}
else
return make_token (type::assign);
}
case '+':
{
if (peek () == '=')
{
get ();
return make_token (type::append);
}
}
}
}
// Otherwise it is a word.
//
unget (c);
return word (st, sep);
}
token lexer::
word (state st, bool sep)
{
lexer_mode m (st.mode);
// Customized implementation that handles special variable names ($>,
// $<, $~).
//
// @@ TODO: $(<), $(>): feels like this will have to somehow be
// handled at the top-level lexer level. Maybe provide a
// string of one-char special variable names as state::data?
//
if (m != lexer_mode::variable)
return base_lexer::word (st, sep);
xchar c (peek ());
if (c != '>' && c != '<' && c != '~')
return base_lexer::word (st, sep);
get ();
state_.pop (); // Expire the variable mode.
return token (string (1, c),
sep,
quote_type::unquoted, false,
c.line, c.column);
}
}
}
}
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