diff options
Diffstat (limited to 'example')
| -rw-r--r-- | example/turing/src/machine.h | 92 | ||||
| -rw-r--r-- | example/turing/src/state.h | 20 |
2 files changed, 70 insertions, 42 deletions
diff --git a/example/turing/src/machine.h b/example/turing/src/machine.h index c1338e1..a30c6e3 100644 --- a/example/turing/src/machine.h +++ b/example/turing/src/machine.h @@ -8,21 +8,41 @@ namespace machine { +// (define (updatePosition direction position) +// (cond ((= direction RIGHT) (+ position 1)) +// ((= direction LEFT) (- Position 1)) +// (else position))) +template < + typename Direction, + typename Position +> +using updatePosition = 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 + > +>; + + // (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)))) +// (let ((current_state (transition state +// (readSymbol position tape)))) // (simulate transition -// (writeSymbol position next_symbol tape) -// next_state, -// next_position))) +// (current_state NEXT) +// (writeSymbol position +// (current_state WRITE) +// tape) +// (updatePosition (current_state MOVE) +// position))))) template < template<typename, typename> class Transition, typename State, @@ -30,39 +50,31 @@ template < 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<Position, tav::Size<0>>>::value, + "machine head position out of bounds" + ); - static_assert( - tav::Not<tav::LowerThan<next_position, tav::Size<0>>>::value, - "next position out of bounds" - ); + private: + template <typename Field> + using current_state = typename Transition< + State, + tape::readSymbol<Position, Tape> + >::template get<Field>; public: using type = tav::Eval<simulate< Transition, - next_state, - tape::writeSymbol<Position, next_symbol, Tape>, - next_position + current_state<state::field::NEXT>, + tape::writeSymbol< + Position, + current_state<state::field::WRITE>, + Tape + >, + updatePosition< + current_state<state::field::MOVE>, + Position + > >>; }; @@ -77,8 +89,8 @@ struct simulate<Transition, void, Tape, Position> { // (define (run program state tape position) // (simulate (transition program) -// tape // state +// tape // position)) template < typename Program, diff --git a/example/turing/src/state.h b/example/turing/src/state.h index f5bd7f2..51fe347 100644 --- a/example/turing/src/state.h +++ b/example/turing/src/state.h @@ -9,12 +9,26 @@ namespace machine { namespace state { -struct field { +namespace field { using ID = tav::Size<0>; using READ = tav::Size<1>; using WRITE = tav::Size<2>; using NEXT = tav::Size<3>; using MOVE = tav::Size<4>; +} + +// (define (state_accessor state) +// (lambda (field) +// (nth field state))) +template <typename State> +struct state_accessor { + static_assert( + tav::IsPair<State>::value, + "machine state is invalid" + ); + + template <typename Field> + using get = tav::Nth<Field, State>; }; // (define (state_predicate id read) @@ -54,7 +68,9 @@ struct transition { typename State, typename Symbol > - using state = findState<State, Symbol, States>; + using state = state_accessor< + findState<State, Symbol, States> + >; }; } |