登录查看更多内容

How can you implement a parser in a compiler?

由人工智能和领英社区提供技术支持

A parser is a crucial component of a compiler that analyzes the syntactic structure of a source code and builds an intermediate representation, such as an abstract syntax tree (AST), that can be used for further processing. In this article, you will learn how to implement a parser in a compiler using some common techniques and tools.

在这篇协作文章中查找专家回答

由社区从 6 条内容中精选。了解更多

1 Lexical analysis

The first step of parsing is to break the source code into smaller units called tokens, such as keywords, identifiers, literals, operators, and punctuation. This is done by a lexer or scanner, which can be implemented using regular expressions, finite automata, or specialized tools like Lex or Flex. The lexer reads the source code character by character and matches them with predefined rules to generate tokens and their attributes.

添加您的观点

Viktor Csuvik

Ph.D Student at University of Szeged
举报内容
It is not straightforward what characters should constitute a token, it really depends on the coding style as well. For example CamelCase and snake_case are totally different, thus you should firat examine the used practices in the code and then apply parsing.

已翻译

赞
Aditya Srivastav

Ambassador @Microsoft | Founder @Mahir Insight Institute | Ex-HP & IBM Intern | 5? Python, 5? Java & 2? SQL @HackerRank | Data Science & AI Student | Aspiring Data Scientist
举报内容
Lexical analysis, often referred to as scanning or tokenization, is the first phase in the process of compiling or interpreting a programming language. It involves breaking down the source code into a sequence of lexemes or tokens, which are the smallest units with syntactic meaning in a programming language.

已翻译

赞

2 Syntax analysis

The second step of parsing is to check if the sequence of tokens conforms to the grammar rules of the source language and to construct an AST that represents the hierarchical structure and meaning of the code. This is done by a parser, which can be implemented using various algorithms, such as recursive descent, LL, LR, or LALR. The parser uses a grammar specification, such as Backus-Naur form (BNF) or Extended BNF (EBNF), to guide the parsing process and to handle errors.

添加您的观点

Aditya Srivastav

Ambassador @Microsoft | Founder @Mahir Insight Institute | Ex-HP & IBM Intern | 5? Python, 5? Java & 2? SQL @HackerRank | Data Science & AI Student | Aspiring Data Scientist
举报内容
Syntax analysis, also known as parsing, is the second phase in the compilation process of programming languages. It follows lexical analysis and involves analyzing the structure of the source code according to the grammar rules of the programming language. The primary goal of syntax analysis is to ensure that the code adheres to the correct syntactic structure specified by the language's grammar. Some programming language grammars may introduce ambiguity, where a sequence of tokens can be interpreted in multiple ways. The parser needs to resolve such ambiguities based on predefined rules or through additional information provided by the language specification.

已翻译

赞

3 Semantic analysis

The third step of parsing is to perform additional checks and transformations on the AST to ensure that the code is semantically correct and consistent. This may include type checking, name resolution, scope analysis, constant folding, or other optimizations. This is done by a semantic analyzer, which can be implemented using various techniques, such as attribute grammars, symbol tables, or intermediate code generation. The semantic analyzer may modify the AST or generate a new intermediate representation, such as three-address code or quadruples.

添加您的观点

Aditya Srivastav

Ambassador @Microsoft | Founder @Mahir Insight Institute | Ex-HP & IBM Intern | 5? Python, 5? Java & 2? SQL @HackerRank | Data Science & AI Student | Aspiring Data Scientist
举报内容
Semantic analysis is the third phase in the compilation process of programming languages, following lexical analysis and syntax analysis. Its primary objective is to ensure that the code adheres to the intended meaning or semantics of the programming language. While syntax analysis checks for correct language structure, semantic analysis focuses on the correctness of the program's meaning. One of the fundamental tasks of semantic analysis is type checking. It involves ensuring that operations and expressions in the code are applied to compatible data types. For example, attempting to add a string to an integer may result in a type error.

已翻译

赞

4 Parser generators

One way to simplify the implementation of a parser in a compiler is to use a parser generator, which is a tool that automatically generates a parser from a grammar specification. Some examples of parser generators are Yacc, Bison, ANTLR, or JavaCC. These tools can save time and effort by handling the details of the parsing algorithm, the error recovery, and the AST construction. However, they may also have some limitations, such as requiring a specific grammar format, generating a large or inefficient code, or having a steep learning curve.

添加您的观点

Aditya Srivastav

Ambassador @Microsoft | Founder @Mahir Insight Institute | Ex-HP & IBM Intern | 5? Python, 5? Java & 2? SQL @HackerRank | Data Science & AI Student | Aspiring Data Scientist
举报内容
Parser generators are tools that automate the generation of parsers for programming languages or other formal grammars. These tools take a formal grammar specification as input and produce a parser code in a programming language such as C, C++, Java, or Python. Using parser generators simplifies the process of building parsers for complex languages, and it is often more efficient than writing a parser by hand.

已翻译

赞

5 Parser testing

Another important aspect of implementing a parser in a compiler is to test its correctness and performance. This can be done by using various methods, such as unit testing, integration testing, regression testing, or benchmarking. Some tools that can help with parser testing are JUnit, PyTest, CUnit, or Google Test. These tools can provide a framework for writing and executing test cases, comparing expected and actual outputs, measuring code coverage, or reporting errors and failures.

添加您的观点

Aditya Srivastav

Ambassador @Microsoft | Founder @Mahir Insight Institute | Ex-HP & IBM Intern | 5? Python, 5? Java & 2? SQL @HackerRank | Data Science & AI Student | Aspiring Data Scientist
举报内容
Parser testing is a critical aspect of the software development process, particularly when working with parsers that interpret and analyze the structure of a programming language or data format. The primary goal of parser testing is to ensure that the parser accurately and efficiently processes input according to the specified grammar rules. Implement a suite of regression tests to ensure that changes or updates to the parser do not introduce new bugs or regressions. This involves running previously successful tests after each code modification.

已翻译

赞

6 Parser debugging

The final aspect of implementing a parser in a compiler is to debug its problems and improve its quality. This can be done by using various techniques, such as logging, tracing, debugging, or profiling. Some tools that can help with parser debugging are GDB, Valgrind, Visual Studio, or Eclipse. These tools can provide features for setting breakpoints, inspecting variables, stepping through code, or analyzing memory and CPU usage.

添加您的观点

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

添加您的观点

Computer Science

+ 关注

给文章评分

我们借助人工智能创建了此文章。您认为这篇文章怎么样？

很棒不太好

举报此文章

查看全部

How can you implement a parser in a compiler?

1

2

3

4

5

6

7

1 Lexical analysis

2 Syntax analysis

3 Semantic analysis

4 Parser generators

5 Parser testing

6 Parser debugging

7 Here’s what else to consider

Computer Science

给文章评分

感谢您的反馈

更多Computer Science相关文章

更多相关阅读内容

How can you implement a parser in a compiler?

1

2

3

4

5

6

7

1 Lexical analysis

2 Syntax analysis

3 Semantic analysis

4 Parser generators

5 Parser testing

6 Parser debugging

7 Here’s what else to consider

Computer Science

给文章评分

感谢您的反馈

查看其他技能