How Ruby Source Code Gets Executed

Programming languages, such as Ruby, are natural and elegant. But to achieve this elegance, things have to happen under the hood.

Let's see how does a ruby code is compiled and interpreted.

Before moving forward lets see the structure(cross-section) of ruby and its world.

90% of work is done on the surface, so that we focus on developing business value .

The following code will be split into tokens by ruby lexer

 puts 'Welcome to Ruby World'

Tokenized Representation :

 [“puts”,” ”,”'”,”Welcome to Ruby World”,”'”]

Lexed Representation :
Lexer Format:

 [[line number,column],type,token]

 [[1,0]:on_ident,”puts”],
  [1,4]:on_sp,” ”]
  [1,5]:on_t_string_beg,”'”]
  [1,6]:on_t_string_content,”Welcome to Ruby World”]
  [1,28]:on_t_string_end,”'”]]

Once the code generates token & is lexed , now the parser will start its job by taking the lexed representation and create a Abstract syntax tree.


AST:

 [:program,
   [[:command,
    [:@ident, ”puts” , [1,0] ],
     [:args_add_block,
      [[:string_literal,
       [:string_content],[:@string_content, “Welcome to Ruby World”,[1,6]]]]],
 false]]]

Once AST finishes the job the compiler will convert to byte code, Now it is executed/interpreted by VM

This is Implemented in MRI. Ruby uses lex(Lexer) & bison(parser generator).
Implementation of Above code in CLI/Ruby Program :

 require “ripper”
 require “pp”
 src= “puts 'Welcome to Ruby World'”
 puts “source: #{src}”
 puts “tokenized:”
 pp Ripper.tokenize(src)
 puts “lexed:”
 pp Ripper.lex(src)
 puts “parsed:”
 pp Ripper.sexp(src)

Refer Confreaks
Njoy Coding in Ruby !!

Thanks to Santosh Mohanty for writing this post .