This document describes the process Ruby code goes through before being executed: 1. Tokenization breaks the code into individual tokens like integers, identifiers, keywords. 2. Parsing uses grammar rules to organize the tokens into an abstract syntax tree (AST) that represents the code structure. 3. Compilation converts the AST into bytecode that the Ruby virtual machine (YARV) can execute for improved performance over interpreting the AST directly.

1. CORE RUBY: HOW IT
WORKS
Back to Basics

2. A Success Story

3. Why Ruby?

4. A Journey To RUBY
My code’s journey through Ruby
Sample.r
b
Tokenize Parse Compile
YARV
instructio
ns
Tokens AST
Nodes

5. Your Code has a long road to take before
Ruby ever runs it.
- Pat Shaughnessy
Starter

6. Tokenization
1 0 . t i m e s d
o
| n |
. t i m e s d
o
| n |
tINTEG
ER
10

7. Tokenization (Cont.)
. t i m e s d
o
| n |
tINTEG
ER
10
t i m e s d
o
| n |
tINTEG
ER
10
.
tINTEG
ER
10
.
tIDENTIFIE
R
times
Keyword_do | |
tIDENTIFIE
R
n

8. Tokenization (Cont.)

9. Parsing
 Ruby uses a parse.c file, which is a parser
generator.
 It consists a parse.y file which contains
grammar rules
 Parser generator:
- input: tokens
- output: tokens that follow the grammar rules
 parse.c file uses LALR (Look-ahead Left
Reversed Rightmost Derivation) Algorithm

10. Parsing (Cont.)

11. Parsing (Cont.)
AST (Abstract Syntax Tree)
program
binary
Integer
5
plus
Integer
5

12. Compilation
 Before Ruby 1.9,
there was no
compiler.
 Using YARV, you
compile your code
into bytecode (like
JVM)
 JVM compiles the
bytecode with JIT
compiler, Ruby
interprets the
bytecode

13. Hey, Isn’t it too complex?

14. Compilation (Cont.)
 Why this extra compiler added from version
1.9?
 Answer: Speed. A compiled program with YARV is
much faster (~ 4.25 times) than traversing AST
nodes.
 Okay, Now what?
 Answer: Now let’s taste the magic of Ruby.
Thanks to “Matz”.
 Enough! Why do we need this actually?
 Isn’t it awesome to know how a language works
internally?

15. From, Dohatec
Thanks, I’m Imtiaz Hossain Emu