LangStudies/Notes.Lecture.1.txt

Following the first lecture of "Building a Parser from scratch"
By Dmitry Soshnikov.


Lecture 1:


Phases:

Data      - Text Content
Processor - Tokenizer
Data      - Tokens
Processor - Parser
Data      - AST


Example of syntaxes :

S-Expression :

(class Point
	(begin 
		
		(def constructor (self x y)
			(begin
				(set (prop self x) x)
				(set (prop self y) y)
			)
		)

		(def calc (self)
			(+  (prop self x)
				(prop self y)
			)
		)
	)
)

(var p (new Point 10 20))

((prop p calc) p)


User Syntax :

class Point
{
	def constructor( x, y )
	{
		this.x = x;
		this.y = y;
	}

	def calc() {
		return this.x + this.y;
	}
}

let 
p = new Point(10, 20);
p.calc();


Tokenizer - Lexial    Analysis : Uses Regular Expressions (Optimal)
Parser	  - Syntactic Analysis : Uses Backus-Naur Form 


Backus-Naur Example :

Program
	: StatementList
	;

StatementList
	: BlockStatement
	| IfStatement
	| FunctionDeclaration
		...
	;

FunctionDeclaration
	: def Identifier ( Arguments ) BlockStatement
	;


Hand-written parsers : 
	Use recursive descent.

Automatically generated
	All kinds of stuff...