diff options
Separated Turing machine implementation into components
* i.e. separate namespaces and headers for _Tape_ and _State_ functions
* `void` is now used as the `BLANK` field value
Diffstat (limited to 'example/turing/src/machine.h')
-rw-r--r-- | example/turing/src/machine.h | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/example/turing/src/machine.h b/example/turing/src/machine.h new file mode 100644 index 0000000..2404d9a --- /dev/null +++ b/example/turing/src/machine.h @@ -0,0 +1,98 @@ +#ifndef TYPEASVALUE_EXAMPLE_TURING_MACHINE_H_ +#define TYPEASVALUE_EXAMPLE_TURING_MACHINE_H_ + +#include "conditional/cond.h" + +#include "state.h" +#include "tape.h" + +namespace machine { + +// (define (simulate transition tape state position) +// (if (= state FINAL) +// tape +// (let* ((current_symbol (readSymbol position tape)) +// (current_state (transition state current_symbol)) +// (direction (nth MOVE current_state)) +// (next_symbol (nth WRITE current_state)) +// (next_state (nth NEXT current_state)) +// (next_position (cond ((= direction RIGHT) (+ position 1)) +// ((= direction LEFT) (- Position 1)) +// (else position)))) +// (simulate transition +// (writeSymbol position next_symbol tape) +// next_state, +// next_position))) +template < + template<typename, typename> class Transition, + typename State, + typename Tape, + typename Position +> +class simulate { + private: + using current_symbol = tape::readSymbol<Position, Tape>; + using current_state = Transition<State, current_symbol>; + + using direction = tav::Nth<state::field::MOVE, current_state>; + + using next_symbol = tav::Nth<state::field::WRITE, current_state>; + using next_state = tav::Nth<state::field::NEXT, current_state>; + using next_position = tav::Cond< + tav::Branch< + tav::IsEqualValue<direction, tav::Char<'R'>>, + tav::Add<Position, tav::Size<1>> + >, + tav::Branch< + tav::IsEqualValue<direction, tav::Char<'L'>>, + tav::Substract<Position, tav::Size<1>> + >, + tav::Else< + Position + > + >; + + static_assert( + tav::Not<tav::LowerThan<next_position, tav::Size<0>>>::value, + "next position out of bounds" + ); + + public: + using type = tav::Eval<simulate< + Transition, + next_state, + tape::writeSymbol<Position, next_symbol, Tape>, + next_position + >>; +}; + +template < + template<typename, typename> class Transition, + typename Tape, + typename Position +> +struct simulate<Transition, void, Tape, Position> { + typedef Tape type; +}; + +// (define (run program state tape position) +// (simulate (transition program) +// tape +// state +// position)) +template < + typename Program, + typename State, + typename Tape, + typename Position +> +using run = tav::Eval<simulate< + state::transition<Program>::template state, + State, + Tape, + Position +>>; + +} + +#endif // TYPEASVALUE_EXAMPLE_TURING_MACHINE_H_ |