Context-Free Grammars (Cfg) - The Language's Blueprint

This section introduces Context-Free Grammars (CFG), the foundational rulebook for programming languages, detailing its components and importance in syntax analysis.

V (Variables / Non-Terminals): The Abstract Categories

This section introduces Variables (non-terminals) in Context-Free Grammars (CFG), explaining their role as abstract categories that form the foundation of programming languages' syntax.

In Programming: Examples Include

This section covers Syntax Analysis, the critical phase in a compiler where the logical structure of source code is validated using Context-Free Grammars.

T (Terminals): The Concrete Tokens (Words)

This section explains the concept of terminals in programming languages, detailing their role as the basic building blocks of syntax.

In Programming: Examples Include

P (Productions / Production Rules): The Building Instructions

This section discusses the crucial role of production rules in Context-Free Grammars (CFGs) for defining programming languages.

In Programming:

This section covers the syntax analysis phase of a compiler, emphasizing the role of Context-Free Grammars (CFGs) in ensuring code adheres to grammatical rules.

S (Start Symbol): The Grand Goal

Why Cfgs Are Important:

Example Cfg (For A Tiny Arithmetic Calculator, Expanded)

This section provides an in-depth look at Context-Free Grammars (CFG), showcasing their importance in syntax analysis and parsing, especially through an example of a CFG for a basic arithmetic calculator.

Concept Of Parsing - The Syntax Checker

Parsing, also known as syntax analysis, is crucial in compilers to determine if a stream of tokens follows the syntactic rules defined by Context-Free Grammars (CFG).

What Parsing Achieves:

Parse Tree (Concrete Syntax Tree):

Purpose:

Abstract Syntax Tree (Ast):

3. Sentences And Sentential Forms - The Stages Of Derivation

This section discusses the process of derivation in grammars, defining key terms and illustrating the transformation of non-terminal symbols into terminal sentences.

Sentences And Sentential Forms - The Stages Of Derivation

This section discusses the concepts of derivation, sentential forms, sentences, leftmost and rightmost derivations, and ambiguous grammars in the context of context-free grammars.

Derivation:

Sentential Form:

Sentence:

Leftmost And Rightmost Derivations - Following A Path In The Tree

This section discusses the concepts of leftmost and rightmost derivations in the context of grammar parsing, emphasizing their role in constructing parse trees and understanding syntax.

Leftmost Derivation:

Rightmost Derivation (Canonical Derivation):

Ambiguous Grammars - The Confusion In Meaning

This section addresses the challenges of ambiguous grammars in programming languages and their implications for syntax interpretation.

Why Ambiguity Is A Problem:

Classic Example: Arithmetic Expressions Without Precedence/associativity Rules

This section illustrates the ambiguity in arithmetic expressions due to a lack of precedence and associativity rules, highlighting the importance of Context-Free Grammars (CFGs) in unambiguously defining language syntax.

Resolving Ambiguity:

Overview Of Top-Down And Bottom-Up Parsing

This section explores top-down and bottom-up parsing strategies, detailing how they construct parse trees.

Top-Down Parsing (Predictive Parsing):

How It Works:

This section delves into syntax analysis, known as parsing, where the compiler ensures source code is structured according to the grammar rules of a programming language.

Bottom-Up Parsing (Shift-Reduce Parsing):

The Core Actions:

Example Walkthrough: Parsing A + B With Shift-Reduce

This section delves into Shift-Reduce parsing, explaining how parsers use this strategy to interpret and validate expressions in programming languages.

Viable Prefixes And Valid Items - Guiding The Parser's Decisions

This section discusses viable prefixes and items in the context of bottom-up parsing, essential for guiding the parser's decisions during the syntax analysis phase.

Item (Lr(0) Item):

Constructing Lr(0) Sets Of Items - Defining Parser States

This section provides an introduction to constructing LR(0) parser states through the definition of LR(0) items and the operations of CLOSURE and GOTO.

Closure Operation:

Goto Operation:

Building The Canonical Collection Of Lr(0) Items:

Constructing Slr Parsing Tables (Simple Lr)

This section discusses the construction of SLR parsing tables, which enhance LR(0) parsers by incorporating FOLLOW sets to resolve ambiguities.

Generating A Parser Using A Parser Generator Such As Yacc/bison

This section discusses how parser generators like YACC and Bison automate the creation of parsers, making compiler development more efficient by managing complex grammar rules.

Option 2: Top-Down Parsing - The Predictive Approach

Left Factoring - Resolving Ambiguous Choices

This section discusses left factoring as a technique to eliminate ambiguity in grammars used for predictive parsing.

Elimination Of Left Recursion - Avoiding Infinite Loops

This section discusses the concept of left recursion in grammars, explaining how it can lead to infinite loops in top-down parsing and outlining strategies for eliminating it.

Predictive Parsing - The Lookahead-Driven Parser (Ll(1))

This section introduces LL(1) parsing, a technique in top-down parsing that utilizes a single lookahead token to make parsing decisions without backtracking.

Key Sets For Table Construction: First And Follow:

Recursive Descent Parsing - The Hands-On Approach

This section explores recursive descent parsing, a top-down parsing technique that translates grammar rules into functions, allowing for intuitive parsing of programming languages.

Basic Structure Of A Non-Terminal Function (E.g., Parsefactor()):

Generating A Parser Using A Parser Generator Such As Antlr, Javacc, Etc.

This section covers the use of parser generators like ANTLR and JavaCC to automatically create parsers from defined grammars, streamlining compiler development.