Parsing for Humans

Presentation for the Amsterdam Ruby user group.

Transcript

1. Parsing For Humans
2. @yorickpeterse (Github, Twitter, Gmail, etc)
3. Olery http://olery.com/
4. Parsing “Analysing a string of symbols according to the rules of a grammar.”
5. 10 + 10
6. number = [0-9]+ operator = “+”
7. Vocabulary Token, AST, Lexer & Parser
8. Token A label for a specific part of the input.
9. 10 [:INTEGER, “10”]
10. Abstract Syntax Tree A tree structure representing the input.
11. Markdown Lists * Item * Nested item
12. (unordered-list (list “Item” (unordered-list (list “Nested item”))))
13. Lexer Takes raw input and returns a sequence of tokens.
14. Parser Takes tokens as input and returns an AST.
15. Available Tools
16. ANTLR, Bison, Coco/R, Flex, Happy, Lemon, jQuery, Parslet, Racc, Ragel, Rexical, Treetop, Yacc
17. Ragel & Racc
18. Ragel “A finite state machine compiler.”
19. “<!--” any* “-->” => { … };
20. $ ragel -R lexer.rl -o lexer.rb
21. Racc “A LALR(1) parser generator.”
22. expression : NUMBER OPERATOR NUMBER { … } ;
23. $ racc -o parser.rb parser.y
24. Oga Parsing XML/HTML in Ruby https://github.com/yorickpeterse/oga
25. Questions?