xo-expression2/include/xo/reader/expect_formal_xs.hpp

85 lines
2.5 KiB
C++

/* file expect_formal_xs.hpp
*
* author: Roland Conybeare, Aug 2024
*/
#pragma once
#include "exprstate.hpp"
#include "formal_arg.hpp"
namespace xo {
namespace scm {
/**
* name : type
* ^ ^ ^
* | | formal_2
* | formal_1
* formal_0
*
* formal_0 --on_symbol()--> formal_1
* formal_1 --on_colon_token()--> formal_2
* formal_2 --on_typedescr()--> (done)
**/
enum class formalstatetype {
invalid = -1,
formal_0,
formal_1,
formal_2,
n_formalstatetype,
};
extern const char *
formalstatetype_descr(formalstatetype x);
inline std::ostream &
operator<< (std::ostream & os, formalstatetype x) {
os << formalstatetype_descr(x);
return os;
}
/** @class expect_formal_xs
* @brief parser state-machine for a typed formal parameter
**/
class expect_formal_xs : public exprstate {
public:
expect_formal_xs();
static std::unique_ptr<expect_formal_xs> make();
virtual void on_symbol(const std::string & symbol_name,
exprstatestack * p_stack,
rp<Expression> * p_emit_expr) override;
virtual void on_colon_token(const token_type & tk,
exprstatestack * p_stack
/*rp<Expression> * p_emit_expr*/) override;
// virtual void on_comma_token(...) override;
#ifdef PROBABLY_NOT
virtual void on_rightparen_token(const token_type & tk,
exprstatestack * p_stack,
rp<Expression> * p_emit_expr) override;
#endif
virtual void on_typedescr(TypeDescr td,
exprstatestack * p_stack,
rp<Expression> * p_emit_expr) override;
virtual void print(std::ostream & os) const override;
private:
/** parsing state-machine state **/
formalstatetype formalxs_type_ = formalstatetype::formal_0;
/** populate with {parameter-name, parameter-type}
* as they're encountered
**/
formal_arg result_;
};
} /*namespace scm*/
} /*namespace xo*/
/* end expect_formal_xs.hpp */