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882f02ed83
Yes, this obfuscates the point of this example, variants only. But glr.cc cannot work (yet?) without locations. This change makes it easier to use this example with glr.cc. * examples/variant.yy (assert): %define it. (locations): Request them. (yylex): Bind the location to the stage.
125 lines
2.4 KiB
Plaintext
125 lines
2.4 KiB
Plaintext
%debug
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%skeleton "lalr1.cc"
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%defines
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%define assert
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%define variant
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%define lex_symbol
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%locations
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%code requires // *.hh
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{
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#include <list>
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#include <string>
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typedef std::list<std::string> strings_type;
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}
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%code // *.cc
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{
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#include <algorithm>
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#include <iostream>
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#include <iterator>
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#include <sstream>
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// Prototype of the yylex function providing subsequent tokens.
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static yy::parser::symbol_type yylex ();
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// Printing a list of strings.
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// Koening look up will look into std, since that's an std::list.
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namespace std
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{
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std::ostream&
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operator<< (std::ostream& o, const strings_type& s)
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{
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std::copy (s.begin (), s.end (),
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std::ostream_iterator<strings_type::value_type> (o, "\n"));
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return o;
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}
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}
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// Conversion to string.
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template <typename T>
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inline
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std::string
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string_cast (const T& t)
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{
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std::ostringstream o;
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o << t;
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return o.str ();
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}
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}
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%token <::std::string> TEXT;
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%token <int> NUMBER;
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%printer { debug_stream () << $$; }
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<int> <::std::string> <::std::list<std::string>>;
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%token END_OF_FILE 0;
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%type <::std::string> item;
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%type <::std::list<std::string>> list;
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%%
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result:
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list { std::cout << $1 << std::endl; }
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;
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list:
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/* nothing */ { /* Generates an empty string list */ }
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| list item { std::swap ($$, $1); $$.push_back ($2); }
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;
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item:
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TEXT { std::swap ($$, $1); }
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| NUMBER { $$ = string_cast ($1); }
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;
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%%
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// The yylex function providing subsequent tokens:
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// TEXT "I have three numbers for you:"
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// NUMBER 1
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// NUMBER 2
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// NUMBER 3
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// TEXT " and that's all!"
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// END_OF_FILE
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static
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yy::parser::symbol_type
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yylex ()
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{
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static int stage = -1;
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++stage;
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yy::parser::location_type loc(0, stage + 1, stage + 1);
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switch (stage)
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{
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case 0:
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return yy::parser::make_TEXT ("I have three numbers for you.", loc);
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case 1:
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case 2:
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case 3:
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return yy::parser::make_NUMBER (stage, loc);
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case 4:
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return yy::parser::make_TEXT ("And that's all!", loc);
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default:
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return yy::parser::make_END_OF_FILE (loc);
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}
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}
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// Mandatory error function
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void
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yy::parser::error (const yy::parser::location_type& loc, const std::string& msg)
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{
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std::cerr << loc << ": " << msg << std::endl;
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}
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int
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main ()
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{
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yy::parser p;
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p.set_debug_level (!!getenv ("YYDEBUG"));
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return p.parse ();
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}
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// Local Variables:
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// mode: C++
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// End:
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