


这篇文章解析转换器3:手写PHP转Python编译器的词法部分
一时技痒,自然而然地想搞个大家伙,把整个PHP程序转成Python。不比模板,可以用正则匹配偷懒,这次非写一个Php编译器不可。
上网搜了一下,发现大部分Python to xxx的transpile都是直接基于AST,省略了最重要的Tokenizer,Parser。直接写个Visitor了事。要不然就是基于Antlr之类的生成器,搞一大堆代码,看得令人心烦。
既然大家都不想做这个苦力,我就来试试,手工写一个Php编译器。分Tokenizer,Parser,Visitor三个部分来实现。
翻出《龙书》《虎书》做参考,仔细学了一回PHP,不学不知道,原来PHP有那么多特性,做个编译器真心累人。
词法部分很简单,就是一个自动机。设计了一个结构存放自动机,然后简单粗暴地在自动机上编程,也顾不上什么性能了,就是个一锤子买卖。
写得还算快,调试不是很顺,不过我是不会说的,哈
自动机不复杂,发上来大家看看,敬请指正。
self.statemachine = { 'current': { 'state': 'default', 'content': '', 'line': 0}, 'default': [ {'name': 'open', 'next': 'php', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'<\?'}, {'name': 'open', 'next': 'php', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'<\?php'}], 'php': [ {'name': 'close', 'next': 'default', 'extra': 0, 'token': r'\?>', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'lnum', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'[0-9]+'}, {'name': 'dnum', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'([0-9]*\.[0-9]+)|([0-9]+\.[0-9]*)'}, {'name': 'exponent', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'(([0-9]+|([0-9]*\.[0-9]+)|([0-9]+\.[0-9]*))[eE][+-]?[0-9]+)'}, {'name': 'hnum', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'0x[0-9a-fA-F]+'}, {'name': 'bnum', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'0b[01]+'}, {'name': 'label', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*'}, {'name': 'comment', 'next': 'commentline', 'extra': 1, 'token': r'//', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'comment', 'next': 'commentline', 'extra': 1, 'token': r'#', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'comment', 'next': 'comment', 'extra': 1, 'token': r'/\*', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': 'string1', 'extra': 1, 'token': r'\'', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': 'string2', 'extra': 1, 'token': r'"', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'symbol', 'next': '', 'extra': 0, 'start': 0, 'end': 0, 'cache': '', 'token': r'[\\\{\};:,\.\[\]\(\)\|\^&\+-/\*=%!~$<>\?@]'}], 'string1': [ {'name': 'string', 'next': 'php', 'extra': 0, 'token': r'\'', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': 'escape1', 'extra': 1, 'token': r'\\', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': '', 'extra': 1, 'token': r'', 'start': 0, 'end': 0, 'cache': ''}], 'escape1': [ {'name': 'string', 'next': 'string1', 'extra': 1, 'token': r'.', 'start': 0, 'end': 0, 'cache': ''}], 'string2': [ {'name': 'string', 'next': 'php', 'extra': 0, 'token': r'\'', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': 'escape2', 'extra': 1, 'token': r'\\', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'string', 'next': '', 'extra': 1, 'token': r'', 'start': 0, 'end': 0, 'cache': ''}], 'escape2': [ {'name': 'string', 'next': 'string2', 'extra': 1, 'token': r'.', 'start': 0, 'end': 0, 'cache': ''}], 'commentline': [ {'name': 'comment', 'next': 'php', 'extra': 0, 'token': r'(\r|\n|\r\n)', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'comment', 'next': 'php', 'extra': 0, 'token': r'', 'start': 0, 'end': 0, 'cache': ''}], 'comment': [ {'name': 'comment', 'next': 'php', 'extra': 0, 'token': r'\*/', 'start': 0, 'end': 0, 'cache': ''}, {'name': 'comment', 'next': '', 'extra': 1, 'token': r'', 'start': 0, 'end': 0, 'cache': ''}]}
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Python and C each have their own advantages, and the choice should be based on project requirements. 1) Python is suitable for rapid development and data processing due to its concise syntax and dynamic typing. 2)C is suitable for high performance and system programming due to its static typing and manual memory management.

Choosing Python or C depends on project requirements: 1) If you need rapid development, data processing and prototype design, choose Python; 2) If you need high performance, low latency and close hardware control, choose C.

By investing 2 hours of Python learning every day, you can effectively improve your programming skills. 1. Learn new knowledge: read documents or watch tutorials. 2. Practice: Write code and complete exercises. 3. Review: Consolidate the content you have learned. 4. Project practice: Apply what you have learned in actual projects. Such a structured learning plan can help you systematically master Python and achieve career goals.

Methods to learn Python efficiently within two hours include: 1. Review the basic knowledge and ensure that you are familiar with Python installation and basic syntax; 2. Understand the core concepts of Python, such as variables, lists, functions, etc.; 3. Master basic and advanced usage by using examples; 4. Learn common errors and debugging techniques; 5. Apply performance optimization and best practices, such as using list comprehensions and following the PEP8 style guide.

Python is suitable for beginners and data science, and C is suitable for system programming and game development. 1. Python is simple and easy to use, suitable for data science and web development. 2.C provides high performance and control, suitable for game development and system programming. The choice should be based on project needs and personal interests.

Python is more suitable for data science and rapid development, while C is more suitable for high performance and system programming. 1. Python syntax is concise and easy to learn, suitable for data processing and scientific computing. 2.C has complex syntax but excellent performance and is often used in game development and system programming.

It is feasible to invest two hours a day to learn Python. 1. Learn new knowledge: Learn new concepts in one hour, such as lists and dictionaries. 2. Practice and exercises: Use one hour to perform programming exercises, such as writing small programs. Through reasonable planning and perseverance, you can master the core concepts of Python in a short time.

Python is easier to learn and use, while C is more powerful but complex. 1. Python syntax is concise and suitable for beginners. Dynamic typing and automatic memory management make it easy to use, but may cause runtime errors. 2.C provides low-level control and advanced features, suitable for high-performance applications, but has a high learning threshold and requires manual memory and type safety management.


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