I have the following builder that builds Tokens
:
// token_builder.h
class TokenBuilder
{
Keyword m_keyword;
TokenType m_type;
std::string m_symbol;
public:
TokenBuilder& set_keyword(Keyword);
TokenBuilder& set_toktype(TokenType);
TokenBuilder& set_symbol(std::string);
std::unique_ptr<Token>&& build();
};
// token_builder.cpp
TokenBuilder& TokenBuilder::set_keyword(Keyword k)
{
m_keyword = k;
return *this;
}
TokenBuilder& TokenBuilder::set_toktype(TokenType t)
{
m_type = t;
return *this;
}
TokenBuilder& TokenBuilder::set_symbol(std::string sym)
{
m_symbol = sym; // This is the point where it segfaults
return *this;
}
std::unique_ptr<Token>&& TokenBuilder::build()
{
std::unique_ptr<Token> token;
token->m_keyword = m_keyword;
token->m_type = m_type;
token->m_symbol = m_symbol;
return std::move(token);
}
The program halts with SIGSEGV
at the point where I am trying to initialize m_symbol
by calling TokenBuilder::set_symbol
. Here is how main
looks like:
int main()
{
auto token = Token::builder()
.set_keyword(Keyword::IF)
.set_toktype(TokenType::ID)
.set_symbol("if")
.build();
std::cout << token->get_symbol() << std::endl;
}
As you can see, call to set_keyword
and set_toktype
don't result in any errors. But passing the literal "if" (or a std::string
object) to set_symbol
causes the program to crash. Passing by value is intentional. Stepping into set_symbol
and analyzing the state of TokenBuilder
doesn't reveal anything. As expected, m_keyword
is set to Keyword::IF
and m_type
to TokenType::ID
. This is the line that crashes: m_symbol = sym
.
The program above might have other, non-trivial issues (am I using std::move
correctly? returning to C++ after a long time) but this kind of feels like a silly mistake a rookie would make. I am using MinGW-w64 compiler on Windows 10 (64-bit).
Here is the entire code for conveniently copy pasting to your machine:
// src/include/token_builder.h
#ifndef TOKEN_BUILDER_H
#define TOKEN_BUILDER_H
#include <memory>
#include "token.h"
namespace funk
{
class Token;
class TokenBuilder
{
Keyword m_keyword;
TokenType m_type;
std::string m_symbol;
public:
TokenBuilder& set_keyword(Keyword);
TokenBuilder& set_toktype(TokenType);
TokenBuilder& set_symbol(std::string);
std::unique_ptr<Token>&& build();
};
}
#endif
// src/token_builder.cpp
#include "include/token.h"
#include "include/token_builder.h"
namespace funk
{
TokenBuilder& TokenBuilder::set_keyword(Keyword k)
{
m_keyword = k;
return *this;
}
TokenBuilder& TokenBuilder::set_toktype(TokenType t)
{
m_type = t;
return *this;
}
TokenBuilder& TokenBuilder::set_symbol(std::string sym)
{
m_symbol = sym;
return *this;
}
std::unique_ptr<Token>&& TokenBuilder::build()
{
std::unique_ptr<Token> token;
token->m_is_keyword = m_keyword != Keyword::_NONE_;
token->m_keyword = m_keyword;
token->m_type = m_type;
token->m_symbol = m_symbol;
return std::move(token);
}
}
// src/include/token.h
#ifndef TOKEN_H
#define TOKEN_H
#include <memory>
#include "keyword.h"
#include "token_type.h"
#include "token_builder.h"
namespace funk
{
class TokenBuilder;
class Token
{
friend class TokenBuilder;
Keyword m_keyword;
bool m_is_keyword;
std::string m_symbol;
TokenType m_type;
Token();
public:
Keyword& get_keyword ();
bool is_keyword();
std::string& get_symbol();
TokenType& get_type();
static TokenBuilder&& builder();
};
}
#endif // END TOKEN_H
// src/token.cpp
#include <string>
#include <memory>
#include "include/keyword.h"
#include "include/token_builder.h"
#include "include/token_type.h"
namespace funk
{
Keyword& Token::get_keyword()
{
return m_keyword;
}
bool Token::is_keyword()
{
return m_is_keyword;
}
std::string& Token::get_symbol()
{
return m_symbol;
}
TokenType& Token::get_type()
{
return m_type;
}
TokenBuilder&& Token::builder()
{
TokenBuilder builder;
return std::move(builder);
}
}
// src/main.cpp
#include <iostream>
#include "include/buffered_reader.h"
#include "include/token.h"
#include "include/token_builder.h"
int main()
{
using namespace funk;
auto token = Token::builder()
.set_keyword(Keyword::IF)
.set_toktype(TokenType::ID)
.set_symbol("if")
.build();
std::cout << token->get_symbol() << std::endl;
}
Note: I looked up for similar questions on StackOverflow as best as I could but didn't find one that matches my case. If you think it is similar to a question you previously encountered, feel free to mark duplicate and post the link to the original question. Thanks!