139 lines
4.8 KiB
Plaintext
139 lines
4.8 KiB
Plaintext
process main {
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# Turing machine specification.
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var("B") blank;
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var([
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{"0", "0"}:{"0", "0", "right"},
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{"0", "1"}:{"1", "x", "right"},
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{"1", "1"}:{"1", "1", "right"},
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{"1", "0"}:{"2", "0", "right"},
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{"2", "0"}:{"2", "0", "right"},
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{"2", "1"}:{"3", "1", "right"},
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{"3", "1"}:{"3", "1", "right"},
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{"3", "0"}:{"4", "1", "left"},
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{"3", "B"}:{"4", "1", "left"},
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{"4", "1"}:{"4", "1", "left"},
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{"4", "0"}:{"5", "0", "left"},
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{"5", "0"}:{"5", "0", "left"},
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{"5", "1"}:{"6", "1", "left"},
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{"5", "x"}:{"h", "x", "stay"},
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{"6", "1"}:{"6", "1", "left"},
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{"6", "x"}:{"0", "x", "right"},
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{"6", "0"}:{"0", "0", "right"}
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]) rules;
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var("0") initial_state;
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var({}) initial_tape_left;
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var({
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"0", "0",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1"
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}) initial_tape_right;
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# Perform the computation, stopping when no rule matches.
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call("turing", {blank, rules, initial_state, initial_tape_left, initial_tape_right}) results;
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# Check results.
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val_equal(results.tape_left, {"B"}) a;
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assert(a);
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val_equal(results.tape_right,
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{"x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x",
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"x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x", "x",
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"0", "0", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
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"1", "1"}
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) a;
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assert(a);
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val_equal({results.side, results.pos}, {"right", "55"}) a;
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assert(a);
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val_equal(results.state, "h") a;
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assert(a);
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exit("0");
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}
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template turing {
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alias("_arg0") blank;
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value(_arg1) rules;
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alias("_arg2") initial_state;
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alias("_arg3") initial_tape_left;
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alias("_arg4") initial_tape_right;
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# Head state.
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var(initial_state) state;
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# Tape. Positions go like this: ... L2 L1 L0 R0 R1 R2 ...
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value(initial_tape_left) tape_left;
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value(initial_tape_right) tape_right;
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# Make sure each side of the tape has at least one symbol so we can flip easily.
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tape_left->insert(tape_left.length, blank);
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tape_right->insert(tape_right.length, blank);
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# Head position.
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var("right") side;
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var("0") pos;
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# Enter loop.
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blocker() loop_blk;
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loop_blk->up();
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loop_blk->use();
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# Get symbol under head.
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concat("tape_", side) tape_name;
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alias(tape_name) cur_tape;
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cur_tape->get(pos) symbol;
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# Look for a matching rule.
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rules->try_get({state, symbol}) rule;
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If (rule.exists) {
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# Extract directions from rule.
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rule->get("0") new_state;
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rule->get("1") new_symbol;
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rule->get("2") move;
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# Change head state.
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state->set(new_state);
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# Replace symbol under head.
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cur_tape->remove(pos);
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cur_tape->insert(pos, new_symbol);
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# Branch based on how we move.
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strcmp(move, side) is_outside;
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strcmp(move, "stay") is_stay;
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strcmp(pos, "0") is_zero;
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If (is_outside) {
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# Increment position.
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num_add(pos, "1") new_pos;
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pos->set(new_pos);
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# If the new position is out of range, extend tape.
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strcmp(pos, cur_tape.length) need_extend;
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If (need_extend) {
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cur_tape->insert(pos, blank);
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};
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} elif (is_stay) {
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# Nop.
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getargs();
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} elif (is_zero) {
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# Flip side, leave pos at zero.
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side->set(move);
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} else {
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# Decrement position.
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num_subtract(pos, "1") new_pos;
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pos->set(new_pos);
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};
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# Continue loop.
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loop_blk->downup();
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};
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}
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