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|
%require "3.2"
%language "c++"
%define api.value.type variant
%code
{
// Print a list of strings.
auto
operator<< (std::ostream& o, const std::vector<std::string>& ss)
-> std::ostream&
{
o << '{';
const char *sep = "";
for (const auto& s: ss)
{
o << sep << s;
sep = ", ";
}
return o << '}';
}
}
%define api.token.constructor
%token END_OF_FILE 0
%code
{
namespace yy
{
// Return the next token.
auto yylex () -> parser::symbol_type
{
static int count = 0;
switch (int stage = count++)
{
case 0:
return parser::make_TEXT ("I have three numbers for you.");
case 1: case 2: case 3:
return parser::make_NUMBER (stage);
case 4:
return parser::make_TEXT ("And that's all!");
default:
return parser::make_END_OF_FILE ();
}
}
}
}
%%
result:
list { std::cout << $1 << '\n'; }
;
%type <std::vector<std::string>> list;
list:
%empty { /* Generates an empty string list */ }
| list item { $$ = $1; $$.push_back ($2); }
;
%type <std::string> item;
%token <std::string> TEXT;
%token <int> NUMBER;
item:
TEXT
| NUMBER { $$ = std::to_string ($1); }
;
%%
namespace yy
{
// Report an error to the user.
auto parser::error (const std::string& msg) -> void
{
std::cerr << msg << '\n';
}
}
int main ()
{
yy::parser parse;
return parse ();
}
|
