This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
defmodule Brainfuck do | |
# opcodes | |
@op_vinc "+" # increment value at memory address | |
@op_vdec "-" # decrement value at memory address | |
@op_pinc ">" # increment memory address | |
@op_pdec "<" # decrement memory address | |
@op_putc "." # output byte at memory address | |
@op_getc "," # input byte into memory address | |
@op_lbeg "[" # loop begin | |
@op_lend "]" # loop end | |
@empty "" | |
def run(program), do: run(program, 0, [0], @empty) | |
# final condition | |
defp run(@empty, addr, mem, output), do: {addr, mem, output} | |
# commands | |
defp run(@op_vinc <> rest, addr, mem, output) do | |
run(rest, addr, mem |> inc_at(addr), output) | |
end | |
defp run(@op_vdec <> rest, addr, mem, output) do | |
run(rest, addr, mem |> dec_at(addr), output) | |
end | |
defp run(@op_pinc <> rest, addr, mem, output) do | |
run(rest, addr+1, mem, output) | |
end | |
defp run(@op_pdec <> rest, addr, mem, output) do | |
run(rest, addr-1, mem, output) | |
end | |
defp run(@op_putc <> rest, addr, mem, output) do | |
run(rest, addr, mem, output <> (mem |> char_at addr)) | |
end | |
defp run(@op_getc <> rest, addr, mem, output) do | |
val = case IO.getn("Input\n", 1) do | |
:eof -> 0 | |
c -> c | |
end | |
run(rest, addr, mem |> put_at(addr, val), output) | |
end | |
# drop every other character | |
defp run(<<_>> <> rest, addr, mem, output), do: run(rest, addr, mem, output) | |
# helpers | |
defp inc_at(list, addr), do: List.update_at(list, addr, &(&1+1 |> rem 255)) | |
defp dec_at(list, addr), do: List.update_at(list, addr, &(&1-1 |> rem 255)) | |
defp put_at(list, addr, val), do: List.replace_at(list, addr, val) | |
defp byte_at(list, addr), do: list |> Enum.at addr | |
defp char_at(list, addr), do: [list |> byte_at addr] |> to_string | |
end |
Thanks to you!
the second part is out, you can read it at http://dev.mikamai.com/post/102283561929/elixir-as-a-parsing-tool-writing-a-brainfuck
@wstucco you might consider adding elixir benchmarks to: https://github.com/kostya/benchmarks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Thanks for your reply!
And i'm glad to read next part this topic :)
I can feel that pattern matching and guard clauses are really elegant, beautiful.