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Diffstat (limited to 'entries/jj/tm/tm.nim')
-rw-r--r-- | entries/jj/tm/tm.nim | 189 |
1 files changed, 0 insertions, 189 deletions
diff --git a/entries/jj/tm/tm.nim b/entries/jj/tm/tm.nim deleted file mode 100644 index 71debe4..0000000 --- a/entries/jj/tm/tm.nim +++ /dev/null @@ -1,189 +0,0 @@ -# A simple Turing machine simulator implemented in Nim. - -import std/enumerate - -type Symbol = enum - `_`, `$`, `X`, `0`, `1`, `0*`, `1*`, - noop - -type Tape = seq[Symbol] - -type Direction = enum - L, R, S - -type State = enum - ca, cb, cc, cd, ce, cf, cg, ch, ci - sa, sb, sc, sd, - aa, ab, ac, - aaa, aab, aac, aad, aae, aaf, - aba, abb, abc, abd, abe, abf, - ba, bb, bc, - baa, bab, bac, bad, bae, baf, - bba, bbb, bbc, bbd, bbe, bbf, - za, zb, zc, zd - -type Transition = object - current_state: State - read_symbol: set[Symbol] - next_state: State - write_symbol: Symbol - move_direction: Direction - -# convenience constructor -func δ(a: State, b: set[Symbol], c: State, d: Symbol, e: Direction): Transition = - return Transition(current_state: a, read_symbol: b, next_state: c, write_symbol: d, move_direction: e) - -# safe get for an infinite tape: pretty, right? -func get(tape: var Tape, i: int): Symbol = - for j in tape.len .. i: - tape.add(`_`) - return tape[i] - -# safe set for an infinite tape -func set(tape: var Tape, i: int, s: Symbol) = - for j in tape.len .. i: - tape.add(`_`) - tape[i] = s - -let turing_machine = @[ - δ(ca, {`_`}, cb, `$`, R), - δ(cb, {`_`}, cc, `0`, R), - δ(cc, {`_`}, cd, `$`, R), - δ(cd, {`_`}, ce, `1*`, R), - δ(ce, {`_`}, cf, `$`, R), - δ(cf, {`_`}, cg, `1`, R), - δ(cg, {`_`}, ch, `$`, R), - δ(ch, {`_`}, sa, noop, S), - - δ(sa, {`_`, `X`}, sa, noop, L), - δ(sa, {`$`}, sb, noop, L), - δ(sb, {`0*`, `1*`}, sb, noop, L), - δ(sb, {`0`}, sc, `0*`, R), - δ(sb, {`1`}, sc, `1*`, R), - δ(sb, {`$`}, sd, noop, R), - δ(sc, {`$`, `X`, `0*`, `1*`}, sc, noop, R), - δ(sc, {`_`}, sa, `X`, L), - δ(sd, {`$`, `X`}, sd, noop, R), - δ(sd, {`0*`}, sd, `0`, R), - δ(sd, {`1*`}, sd, `1`, R), - δ(sd, {`_`}, aa, noop, L), - - δ(aa, {`X`, `0`, `1`}, aa, noop, L), - δ(aa, {`$`}, ab, noop, L), - δ(ab, {`0*`, `1*`}, ab, noop, L), - δ(ab, {`0`}, aaa, `0*`, L), - δ(ab, {`1`}, aba, `1*`, L), - δ(ab, {`$`}, ac, noop, R), - δ(ac, {`$`, `X`, `0`, `1`, `0*`, `1*`}, ac, noop, R), - δ(ac, {`_`}, sa, `$`, R), - - δ(aaa, {`0`, `1`}, aaa, noop, L), - δ(aaa, {`$`}, aab, noop, L), - δ(aab, {`0*`}, aac, `0`, R), - δ(aac, {`$`, `X`, `0`, `1`, `0*`, `1*`}, aac, noop, R), - δ(aac, {`_`}, aad, noop, L), - δ(aad, {`0`, `1`}, aad, noop, L), - δ(aad, {`X`}, aa, `0`, L), - δ(aab, {`1*`}, aae, `1`, R), - δ(aae, {`$`, `X`, `0`, `1`, `0*`, `1*`}, aae, noop, R), - δ(aae, {`_`}, aaf, noop, L), - δ(aaf, {`0`, `1`}, aaf, noop, L), - δ(aaf, {`X`}, aa, `1`, L), - δ(aab, {`0`, `1`}, aab, noop, L), - - δ(aba, {`0`, `1`}, aba, noop, L), - δ(aba, {`$`}, abb, noop, L), - δ(abb, {`0*`}, abc, `0`, R), - δ(abc, {`$`, `X`, `0`, `1`, `0*`, `1*`}, abc, noop, R), - δ(abc, {`_`}, abd, noop, L), - δ(abd, {`0`, `1`}, abd, noop, L), - δ(abd, {`X`}, aa, `1`, L), - δ(abb, {`1*`}, abe, `1`, R), - δ(abe, {`$`, `X`, `0`, `1`, `0*`, `1*`}, abe, noop, R), - δ(abe, {`_`}, abf, noop, L), - δ(abf, {`0`, `1`}, abf, noop, L), - δ(abf, {`X`}, ba, `0`, L), - δ(abb, {`$`}, abc, noop, R), - δ(abb, {`0`, `1`}, abb, noop, L), - - δ(ba, {`X`, `0`, `1`}, ba, noop, L), - δ(ba, {`$`}, bb, noop, L), - δ(bb, {`0*`, `1*`}, bb, noop, L), - δ(bb, {`0`}, baa, `0*`, L), - δ(bb, {`1`}, bba, `1*`, L), - δ(bb, {`$`}, bc, noop, R), - δ(bc, {`$`, `X`, `0`, `1`, `0*`, `1*`}, bc, noop, R), - δ(bc, {`_`}, za, noop, L), - - δ(baa, {`0`, `1`}, baa, noop, L), - δ(baa, {`$`}, bab, noop, L), - δ(bab, {`0*`}, bac, `0`, R), - δ(bac, {`$`, `X`, `0`, `1`, `0*`, `1*`}, bac, noop, R), - δ(bac, {`_`}, bad, noop, L), - δ(bad, {`0`, `1`}, bad, noop, L), - δ(bad, {`X`}, aa, `1`, L), - δ(bab, {`1*`}, bae, `1`, R), - δ(bae, {`$`, `X`, `0`, `1`, `0*`, `1*`}, bae, noop, R), - δ(bae, {`_`}, baf, noop, L), - δ(baf, {`0`, `1`}, baf, noop, L), - δ(baf, {`X`}, ba, `0`, L), - δ(bab, {`0`, `1`}, bab, noop, L), - - δ(bba, {`0`, `1`}, bba, noop, L), - δ(bba, {`$`}, bbb, noop, L), - δ(bbb, {`0*`}, bbc, `0`, R), - δ(bbc, {`$`, `X`, `0`, `1`, `0*`, `1*`}, bbc, noop, R), - δ(bbc, {`_`}, bbd, noop, L), - δ(bbd, {`0`, `1`}, bbd, noop, L), - δ(bbd, {`X`}, ba, `0`, L), - δ(bbb, {`1*`}, bbe, `1`, R), - δ(bbe, {`$`, `X`, `0`, `1`, `0*`, `1*`}, bbe, noop, R), - δ(bbe, {`_`}, bbf, noop, L), - δ(bbf, {`0`, `1`}, bbf, noop, L), - δ(bbf, {`X`}, ba, `1`, L), - δ(bbb, {`$`}, bbc, noop, R), - δ(bbb, {`0`, `1`}, bbb, noop, L), - - δ(za, {`0`, `1`}, za, noop, L), - δ(za, {`$`}, zb, noop, R), - - δ(zb, {`0`}, zc, `1`, R), - δ(zb, {`1`}, zb, `1`, R), - δ(zb, {`_`}, zd, `1`, R), - - δ(zc, {`0`}, zc, `0`, R), - δ(zc, {`1`}, zb, `0`, R), - δ(zc, {`_`}, zd, `0`, R), - - δ(zd, {`_`}, sa, `$`, R) -] - -proc print(state: State, tape: Tape, position: int) = - stdout.write($state) - for i, s in enumerate(tape): - if i == position: - stdout.write("[" & $s & "]") - elif s == `$`: - stdout.write(" ") - else: - stdout.write($s) - stdout.write("\n") - -var state = ca -var position = 0 -var tape = @[`_`] - -proc step() = - # print(state, tape, position) - for δ in turing_machine: - if state == δ.current_state and tape.get(position) in δ.read_symbol: - state = δ.next_state - if δ.write_symbol != noop: tape.set(position, δ.write_symbol) - if δ.move_direction == L: position.dec - elif δ.move_direction == R: position.inc - return - echo "Invalid state! crashing" - quit() - -while true: - step() |