Rename calc++.cc -> nask_parse.cpp, add lexer/parser

[hangingman]

ref #32

• calc++.cppをリネームし、コマンド引数をgetoptで設定するようにした
• lexer/parserを仮に設定し字句解析と構文解析が動作することを確認した

最終的なBNF

program
: stmts { $$ = ast::Program($1); }
;
stmts
: stmt { $$ = std::list<ast::Statement>(); $$.push_back($1); }
| stmts stmt { $$ = $1; $1.push_back($2); }
;
stmt
: IDENT COLON { $$ = ast::LabelStmt($1); }
| IDENT ASSIGN exp { $$ = ast::DeclareStmt($<std::string>1, $3); }
| LBRACKET CONFIG CONST_STRING RBRACKET { $$ = ast::ConfigStmt($<std::string>2, $<std::string>3); }
| OPCODE mnemonic_args { $$ = ast::MnemonicStmt($1, $2); }
;
mnemonic_args
: exp { $$ = std::list<ast::ExpNode>(); $$.push_back($1); }
| mnemonic_args COMMA exp { $$ = $1; $$.push_back($<ast::ExpNode>2); }
;
exp: factor CMP factor { $$ = ast::CmpNode( $<std::string>1, $2,  $<std::string>3); }
| factor '+' factor { $$ = ast::CalcNode($<std::string>1, "+", $<std::string>3); }
| factor '-' factor { $$ = ast::CalcNode($<std::string>1, "-", $<std::string>3); }
| factor '*' factor { $$ = ast::CalcNode($<std::string>1, "*", $<std::string>3); }
| factor '/' factor { $$ = ast::CalcNode($<std::string>1, "/", $<std::string>3); }
| factor '%' factor { $$ = ast::CalcNode($<std::string>1, "%", $<std::string>3); }
| factor { $$ = ast::ImmediateNode($<std::string>1);  }
;
factor:
| "number"
| "hex"
| "ident"
| "const_string"
;