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我一直在試圖建立在野牛一個小解析器，但是當我嘗試建立我得到它：野牛：使用聯盟語義類型與C++解析器
stone.tab.cc: In member function ‘virtual int yy::StoneParser::parse()’: stone.tab.cc:507:81: error: invalid initialization of non-const reference of type ‘StoneDriver&’ from an rvalue of type ‘yy::StoneParser::semantic_type*’ yyla.type = yytranslate_ (yylex (&yyla.value, &yyla.location, driver));
我懷疑的原因是使用由Bison生成的C++編譯器使用聯合定義的語義類型時存在問題，但似乎無法解決它...
如何使用'union'語義定義生成有效的C++ bison分析器？
stone.yy：
%skeleton "lalr1.cc"
%require "3.0.4"
%defines
%define parser_class_name {StoneParser}
%code requires
{
# include <string>
class StoneDriver;
}
%param { StoneDriver& driver }
%locations
%code
{
# include "StoneDriver.hpp"
}
%union
{
int intVal;
char* stringVal;
}
%token <stringVal> KEY_ENUM
%token <stringVal> KEY_CLASS
%token K_TEST
%token T_ID
%type <stringVal> class
%type <stringVal> enum
%%
input: toplevel_declarations
toplevel_declarations: toplevel_declarations toplevel_declaration
| %empty
toplevel_declaration: class
| enum
class: KEY_CLASS { $$ = "test"; }
enum: KEY_ENUM { $$ = "test"; }
StoneDriver.hpp
#ifndef STONEDRIVER_INCLUDED_HPP
#define STONEDRIVER_INCLUDED_HPP
#include <string>
#include <map>
#include "stone.tab.hh"
class StoneDriver;
//Tell Flex the lexer's prototype ...
#define YY_DECL \
yy::StoneParser::symbol_type yylex (StoneDriver& driver)
// ... and declare it for the parser's sake.
YY_DECL;
//Scans and parses Stone
class StoneDriver
{
public:
//Constructor
StoneDriver();
//Destructor
virtual ~StoneDriver();
std::map<std::string, int> variables;
int result;
// Handling the scanner.
void scan_begin();
void scan_end();
bool trace_scanning;
// Run the parser on file F.
// Return 0 on success.
int parse (const std::string& f);
// The name of the file being parsed.
// Used later to pass the file name to the location tracker.
std::string file;
// Whether parser traces should be generated.
bool trace_parsing;
// Error handling.
void error (const yy::location& l, const std::string& m);
void error (const std::string& m);
};//StoneDriver
#endif
StoneDriver.cpp：
#include "StoneDriver.hpp"
#include "stone.tab.hh"
StoneDriver::StoneDriver()
: trace_scanning (false), trace_parsing (false)
{
variables["one"] = 1;
variables["two"] = 2;
}//constructor
StoneDriver::~StoneDriver()
{
}//destructor
int StoneDriver::parse(const std::string &f)
{
file = f;
scan_begin();
yy::StoneParser parser(*this);
#if YYDEBUG
parser.set_debug_level(trace_parsing);
#endif
int res = parser.parse();
scan_end();
return res;
}//parse
void StoneDriver::error(const yy::location& l, const std::string& m)
{
std::cerr << l << ": " << m << std::endl;
}//error
void StoneDriver::error(const std::string& m)
{
std::cerr << m << std::endl;
}//error
SOLUTION： RICI表明，YY_DECL方法簽名應該被定義像這樣：
int yylex (semantic_type* YYLVAL, location_type* YYLLOC, TYPE1 ARG1, ...)
在我的情況下，神奇的路線是：
#define YY_DECL int yylex(yy::StoneParser::semantic_type* const lval, yy::StoneParser::location_type* location, StoneDriver& driver)
yy::是從我的野牛文件（在我的情況stone.yy）StoneParser是從石頭的定義parser_class_name的命名空間。 yylocation_type是必需的，因爲stone.yy已定義％位置 。StoneDriver&是stone.yy解析背景下， 定義爲%param { StoneDriver& driver }
感謝您的幫助！