CompileMe (Lexical and Syntax analyzer (python))
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CompileMe
I have been full of passion for the field of programming since I was in high school, and I actually joined the College of Engineering, Computer and Systems Department, and I had that question throughout my studies: How does the computer understand those instructions and codes? How can some of hardware and software elements understand what I want to do and what i'm trying to tell him to do? what is going on in the background !! After I studied the Compiler , I wanted to build my own one. so ... after a lot of research, experimentation, and attempts, I did it, and I am proud of the result, and I aspire to continue and develop it
welcome to my simple compiler CompileMe
before we start i would like to show you the idea of how the compiler works
Introduction
The input Python code that can come from different sources like a file, I/O stream, or string format is first read by the reader, then fed into the lexer and parser, constructing the Abstract Syntax Tree (AST). The AST is fed into the compiler. More specifically, the CPython lexer constructs the Concrete Syntax Tree (CST) from the input Python code, and the CPython parser constructs the AST from the CST. This procedure is shown in the figures below. Our focus of this article is the lexer and parser, which are colored in blue.
Understanding Lexical and Syntax Analyzers in Programming Languages
Programming languages serve as the foundation for software development, allowing developers to communicate instructions to computers effectively. Two essential components of a compiler or interpreter play a crucial role in this process: the lexical analyzer and the syntax analyzer. These components work hand in hand to transform human-readable code into machine-executable instructions. In this article, we will delve into the concepts of lexical and syntax analyzers, exploring their functions, differences, and significance in the realm of programming languages.
Lexical Analyzer:
The lexical analyzer, also known as a lexer or scanner, is the first phase of a compiler or interpreter. Its primary task is to read the source code and break it down into individual tokens. Tokens are the smallest units of meaning in a programming language, such as keywords, identifiers, operators, and literals. The lexical analyzer eliminates whitespace and comments, simplifying the code for further processing.
The lexical analysis involves regular expressions and finite automata to recognize patterns in the source code. Tokens generated by the lexer serve as input for the subsequent phase, the syntax analyzer.
Syntax Analyzer:
The syntax analyzer, commonly referred to as a parser, comes into play after the lexical analysis. Its primary purpose is to examine the sequence of tokens generated by the lexer and determine whether they form a valid program according to the language's grammar rules. The syntax analyzer constructs a hierarchical structure called a syntax tree or parse tree, representing the grammatical structure of the program.
Parsing involves the use of context-free grammars, which define the syntactic rules of the programming language. The syntax analyzer checks whether the sequence of tokens conforms to these rules and produces an error if the code contains syntax errors. If the code is syntactically correct, the syntax tree is handed over to the next phase for semantic analysis and code generation.
Differences Between Lexical and Syntax Analyzers:
Scope of Analysis:
Lexical Analyzer: Focuses on individual tokens and their categorization.
Syntax Analyzer: Examines the overall structure and organization of tokens to ensure they adhere to the language's grammar.
Unit of Output:
Lexical Analyzer: Produces tokens as output.
Syntax Analyzer: Generates a hierarchical structure, such as a syntax tree, as output.
Error Handling:
Lexical Analyzer: Detects and reports errors related to token formation.
Syntax Analyzer: Identifies and reports errors related to the arrangement and structure of tokens.
Processing Techniques:
Lexical Analyzer: Uses regular expressions and finite automata.
Syntax Analyzer: Utilizes context-free grammars and parsing techniques.
Conclusion:
In summary, lexical and syntax analyzers are integral components of the compilation process, each playing a distinct role in transforming human-readable code into machine-executable instructions. The lexical analyzer focuses on breaking down the code into tokens, while the syntax analyzer ensures that these tokens follow the grammatical rules of the programming language. Understanding the functions and differences between these analyzers is essential for anyone delving into the world of compiler construction and programming language design.
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