# 🛠 Compiler

compiler translator interpretor grammer parser lexer

How to write your own programming language?

Examples
- GNU Compiler Collection - GCC
- LLVM
- Clang
- javascript Compilers - V8 Engine
- CPython - python compiler/interpreter
Guido van Rossum - Benevolent dictator for life BDFL for Python until 2018

Programming is mainly writing correct code for compilers. If you can program in a language means you know how to write instructions for a specific compiler.
Programming languages differ widely because their compilers are written so.

# 🌴 Types of Compilers

Cross-Compiler

compiles code for a target platform(CPU architecture)

compiler for different CPU Architecture
on x86 compiling code for ARM Architecture

Assembler

Translate code to assembly languages

Transpiler - S2S compiler

compiles code from one version to another. Eg: Babel in JS world

Eg: From modern ES2015 to ES5 to support older browsers

Decompiler

compiles from a Low Level Language to High Level Language

Bytecode Compiler

JAV, Python VM

JIT - Just in time Compilers

Bootstrapped Compilers: Self Compiled - compiled by itself

# 🖌 Compiler Design

Translates code from one form to another

# 🎨 Compiler Frontend

Generally a 5 Stages Process Line. Just how a Buddha rice bown is assembles in a restaurant.

# 🏎 Canonicalization

converting to a format more suitable to work with
remove extra spaces etc.

Very similar to Database System Canonicalization of data to 1NF, 2NF or 3NF

# Preprocessing

Macro Substitution
Conditional Compilation

# 🍇 Lexical Analysis / Tokenization

very important Stage and most complex when implementing any programming language

source code is converted to token, so that a hierarical tree could be generated
Can happen in 2 Stages
1. Scanning
  1. convert code blocks to leximes
    1. keywords
    2. literals
    3. identifiers
    4. references
    5. comments
    6. seperators
    7. operators
2. Evaluating
  1. Attackes leximes with values so that they could be used in Parsing stage
  2. Token Name: Token Value Format

Scanning

Scanning is performed using

RegEx
CFG Context-free Grammer
RegEx Languages and
FSM Finite State Automata Schemes

BNF, EBNF
- Intended for consumption by humans
- BNF Python
Python Lexical Analysis
Full Python Grammer
Difference b/w regular grammer and Context free grammer
How to write grammer for a programming language
Chomsky hierarchy of grammer
Allison Parrish
Grammer Parsing Engines
- Tracery for JS

Grammer

Language of languages, Chomsky Hierarchy

CFG - Context Free Grammer

Every production rules of the form

where,

is non-terminal and is terminal character

4-tuple

where,

is called a nonterminal character or a variable
is a finite set of terminals,
is a finite relation from to
start variable

CSG - Context Sensitive Grammar

more general than CFG

A formal grammar 📐

Notation	Meaning
	is a set of nonterminal symbols
	is a set of terminal symbols
	is a set of production rules, and
	is the start symbol

is context-sensitive if all rules in are of the form

CSG formal definition

where,

👉
👉 and
👉

# 🇩🇪 Grammar

Formal Grammer

Finite set of production Rules

Examples, write grammer to match all a, aa, aaaa, aaaaaaa

# 🌲 Parsing / Syntax Analysis

crucial stage in Process

Outputs Parse Tree

# 💻 Symentic Analysis

Outputs Symbol Table

Builds Type checking
Object Binding

# 🖥 Compiler Middle End

Optimizations
Dead code removal
Constant propagation
Rechability Analysis

# 🐲 Compiler Backend

Could be reuses as in cross Compilers

CPU Architecture level Transformation
CPU Scheduling Flags
CPU architecture based Optimization to utilize CPU features like
1. Hypreadthreaded feature
2. Multicore
3. GPUs etc
CPU Heuristics and Algorithms

# 🔎 Overview

# How compilers are used?

Compiler interface usually have a CLI interface. Works just like another CLI tool so as to speak. Take examples of python, node, rust, java, bash, zsh compilers.

# 🐮 Parser Generators

Parser check the grammer and syntax of a natural/computer language. Syntatic Analysis

Compiler-compiler softwares
- YACC
- GNU Bison
  - documentation
  - Generates a parser in C, C++, or java
  - Perl 5
  - GNU OCtave
  - MySQL, PostgresSQL
  - Bash
  - Go - initiall then shifted to their own custom tool
  - PHP, Ruby
ANTLR
CPython uses ASDL

Can generate parser from calculator to complex language
filename.l
4 sections
commenting is not allowed

Bison Input Grammer File structure

%{
Prologue
%}

Bison declarations

%%
Grammar rules
%%
Epilogue

# 🌀 Resources

https://en.wikipedia.org/wiki/Instruction_set_architecture

← Linting CPython →