1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
%debug
%skeleton "lalr1.cc"
%defines
%define assert
%define variant
%define lex_symbol
%locations
%code requires // *.hh
{
#include <list>
#include <string>
typedef std::list<std::string> strings_type;
}
%code // *.cc
{
#include <algorithm>
#include <iostream>
#include <iterator>
#include <sstream>
// Prototype of the yylex function providing subsequent tokens.
static yy::parser::symbol_type yylex ();
// Printing a list of strings.
// Koening look up will look into std, since that's an std::list.
namespace std
{
std::ostream&
operator<< (std::ostream& o, const strings_type& s)
{
std::copy (s.begin (), s.end (),
std::ostream_iterator<strings_type::value_type> (o, "\n"));
return o;
}
}
// Conversion to string.
template <typename T>
inline
std::string
string_cast (const T& t)
{
std::ostringstream o;
o << t;
return o.str ();
}
}
%token <::std::string> TEXT;
%token <int> NUMBER;
%printer { debug_stream () << $$; }
<int> <::std::string> <::std::list<std::string>>;
%token END_OF_FILE 0;
%type <::std::string> item;
%type <::std::list<std::string>> list;
%%
result:
list { std::cout << $1 << std::endl; }
;
list:
/* nothing */ { /* Generates an empty string list */ }
| list item { std::swap ($$, $1); $$.push_back ($2); }
;
item:
TEXT { std::swap ($$, $1); }
| NUMBER { $$ = string_cast ($1); }
;
%%
// The yylex function providing subsequent tokens:
// TEXT "I have three numbers for you:"
// NUMBER 1
// NUMBER 2
// NUMBER 3
// TEXT " and that's all!"
// END_OF_FILE
static
yy::parser::symbol_type
yylex ()
{
static int stage = -1;
++stage;
yy::parser::location_type loc(0, stage + 1, stage + 1);
switch (stage)
{
case 0:
return yy::parser::make_TEXT ("I have three numbers for you.", loc);
case 1:
case 2:
case 3:
return yy::parser::make_NUMBER (stage, loc);
case 4:
return yy::parser::make_TEXT ("And that's all!", loc);
default:
return yy::parser::make_END_OF_FILE (loc);
}
}
// Mandatory error function
void
yy::parser::error (const yy::parser::location_type& loc, const std::string& msg)
{
std::cerr << loc << ": " << msg << std::endl;
}
int
main ()
{
yy::parser p;
p.set_debug_level (!!getenv ("YYDEBUG"));
return p.parse ();
}
// Local Variables:
// mode: C++
// End:
|
