Roll the Dice with Crapshoot

Parsing and rolling mathematical expressions for pen & paper gaming.

Transcript

1. Roll The Dice with Crapshoot Bryce Kerley Scottish Ruby Conference Lightning Talks April 8, 2011 Tuesday, October 2, 12
2. Dice Code • 2d4 • Two four-sided dice • 1d100 + 8 • One hundred-sided die plus eight • 4d6v • Four six-sided dice, minus the lowest Tuesday, October 2, 12
3. Dice Language A programming language is […] designed to express computations, […] to express algorithms precisely, or as a mode of human communication. http://en.wikipedia.org/wiki/Programming_language Tuesday, October 2, 12
4. Regular Language In computer science, a regular language is a formal language […] that satisfies the following equivalent properties: • it can be accepted by a deterministic finite state machine •it can be generated by a regular grammar http://en.wikipedia.org/wiki/Regular_language Tuesday, October 2, 12
5. Dice Language 4d6v 3d10^ 2d6 300 + – - Tuesday, October 2, 12
6. Dice Language 4d6v 3d10^ 2d6 300 + – - Expression Tuesday, October 2, 12
7. Dice Language 4d6v 3d10^ 2d6 300 + – - Tuesday, October 2, 12
8. Dice Language 2d6 300 - Tuesday, October 2, 12
9. Dice Language 2d6 300 - BinaryExpression Tuesday, October 2, 12
10. Dice Language 2d6 300 - Tuesday, October 2, 12
11. Dice Language 2d6 300 - Tuesday, October 2, 12
12. Dice Language 2d6 300 - Series Tuesday, October 2, 12
13. Dice Language 2d6 300 - Series Arithmetic Tuesday, October 2, 12
14. Dice Language 2d6 300 - Series Arithmetic Constant Tuesday, October 2, 12
15. Dice Language 2d6 300 - Tuesday, October 2, 12
16. Dice Language Number = digit+; Constant = Number; Drop = ('^' | 'v'); Series = Number 'd' Number Drop?; Arithmetic = ('+' | '-'); UnaryExpression = Series | Constant; BinaryExpression = UnaryExpression (space* Arithmetic space* UnaryExpression)+; Expression = UnaryExpression | BinaryExpression; 100% CERTIFIED REGULAR LANGUAGE Tuesday, October 2, 12
17. Ragel Ragel compiles executable finite state machines from regular languages. Ragel targets C, C++, Objective-C, D, Java and Ruby. http://www.complang.org/ragel/ Tuesday, October 2, 12
18. scan.rl %%{ machine scanner; action _number { @mark_num = p } action number { @num_stack.push atos(data[@mark_num..p-1]) } action constant { @tokens << Tokens::Constant.new(@num_stack.pop) } action series { drop = @drop_current @drop_current = nil sides = @num_stack.pop count = @num_stack.pop @tokens << Tokens::Series.new(count, sides, drop) } action arithmetic { @tokens << Tokens::Arithmetic.new(data[p-1].chr) } action drop { @drop_current = data[p-1].chr } Number = digit+ >_number %number; Constant = Number %constant; Drop = ('^' | 'v') %drop; Series = Number 'd' Number Drop? %series; Arithmetic = ('+' | '-') %arithmetic; UnaryExpression = Series | Constant; BinaryExpression = UnaryExpression (space* Arithmetic space* UnaryExpression)+; Expression = UnaryExpression | BinaryExpression; main := Expression; }%% Actions Language Tuesday, October 2, 12
19. Ragel Tuesday, October 2, 12
20. Ragel scan.rl: 62 lines Tuesday, October 2, 12
21. Ragel scan.rl: 62 lines scan.rb: 330 lines Tuesday, October 2, 12
22. Ragel
                  !   " #  $    % & '        !   #(    #(    ! #(   )     !  * ) +   *  )    ) scan.rl: 62 lines scan.rb: 330 lines scan.pdf: priceless Tuesday, October 2, 12
23. scan.rl action constant { @tokens << Tokens::Constant.new(@num_stack.pop) } action series { drop = @drop_current @drop_current = nil sides = @num_stack.pop count = @num_stack.pop @tokens << Tokens::Series.new(count, sides, drop) } action arithmetic { @tokens << Tokens::Arithmetic.new(data[p-1].chr) } Transform constant, series, and arithmetic elements into Token objects Tuesday, October 2, 12
24. Tokens Token#eval Turn token into result during evaluation Token#independent Determine if token needs the next token during postfixing Token#inspect <Crapshoot::Tokens::Series dice=4d6 drop=nothing> Tuesday, October 2, 12
25. Parsed Dice 4d6v count: 4 sides: 6 drop: ‘v’ 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Tuesday, October 2, 12
26. Infix & Postfix Tuesday, October 2, 12
27. Infix & Postfix Infix 1 + 2 + 3 + 4 Used for centuries Hard for computers Tuesday, October 2, 12
28. Infix & Postfix Infix 1 + 2 + 3 + 4 Used for centuries Hard for computers Postfix 1 2 + 3 + 4 + Easy for computers Convertible from infix Tuesday, October 2, 12
29. Parsed Dice 4d6v count: 4 sides: 6 drop: ‘v’ 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Tuesday, October 2, 12
30. Postfixed Dice 4d6v count: 4 sides: 6 drop: ‘v’ 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Tuesday, October 2, 12
31. Postfix Evaluation Tuesday, October 2, 12
32. Postfix Evaluation • Series Tuesday, October 2, 12
33. Postfix Evaluation • Series • Roll dice Tuesday, October 2, 12
34. Postfix Evaluation • Series • Roll dice • Do drop Tuesday, October 2, 12
35. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack Tuesday, October 2, 12
36. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack • Constant Tuesday, October 2, 12
37. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack • Constant • Push value to stack Tuesday, October 2, 12
38. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack • Constant • Push value to stack • Arithmetic Tuesday, October 2, 12
39. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack • Constant • Push value to stack • Arithmetic • Pop twice Tuesday, October 2, 12
40. Postfix Evaluation • Series • Roll dice • Do drop • Push result to stack • Constant • Push value to stack • Arithmetic • Pop twice • Push result Tuesday, October 2, 12
41. Postfix Evaluation 4d6v count: 4 sides: 6 drop: ‘v’ 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
42. Postfix Evaluation 15 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
43. Postfix Evaluation 15 3d10^ count: 3 sides: 10 drop: ‘^’ 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
44. Postfix Evaluation 15 5 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
45. Postfix Evaluation 15 5 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
46. Postfix Evaluation 15 5 2d6 count: 2 sides: 6 drop: nil 300 value: 300 + - - Stack Tuesday, October 2, 12
47. Postfix Evaluation 20 2d6 count: 2 sides: 6 drop: nil 300 value: 300 - - Stack Tuesday, October 2, 12
48. Postfix Evaluation 20 9 300 value: 300 - - Stack Tuesday, October 2, 12
49. Postfix Evaluation 20 9 300 value: 300 - - Stack Tuesday, October 2, 12
50. Postfix Evaluation 20 9 300 value: 300 - - Stack Tuesday, October 2, 12
51. Postfix Evaluation 11 300 value: 300 - Stack Tuesday, October 2, 12
52. Postfix Evaluation 11 300 - Stack Tuesday, October 2, 12
53. Postfix Evaluation 11 300 - Stack Tuesday, October 2, 12
54. Postfix Evaluation 11 300 - Stack Tuesday, October 2, 12
55. Postfix Evaluation -289 Stack Tuesday, October 2, 12
56. Result -289 Tuesday, October 2, 12
57. Operator Precedence Harder than no operator precedence Push lame operators like + and - into a stack Tuesday, October 2, 12
58. Try It! http://triskelion.heroku.com/ Tuesday, October 2, 12
59. Fork It* http://github.com/bkerley/crapshoot/ (not updated yet due to conference wifi) Tuesday, October 2, 12
60. Thanks Bryce Kerley http://brycekerley.net/ https://twitter.com/bonzoesc Tuesday, October 2, 12