PHP的词法分析器 [英] php lexical analyser

问题描述

如何用php编写词法分析器?

How to write a lexical analyser with php?

推荐答案

就像使用其他任何编程语言一样:编码. PHP具有正则表达式 [

As you would in any other programming language: coding it. PHP features Regular Expressions[^] that may help you a lot in the process.

您要扫描哪种语言? PHP?

如果要编写自己的分析器，则需要标识您要扫描的以下语言的词汇标记:

What language do you want to scan? PHP?

If you want to write your own analyzer, you need to identify the following lexical tokens of you language to scan:

1. 注释(//...，#...，/*...*/)
2. 字符串("..."，``...''，处理转义字符串文字)
3. 数字(0，1，...，3.141592653589793238462643，...)
4. 单词(包括关键字)
5. 运算符和标点符号( =>，<<，>>，++，-，... +，-，...

1. Comments (//..., #..., /*...*/)
2. Strings ("...", ''...'', handle escaping within the string literals)
3. Numbers (0, 1, ..., 3.141592653589793238462643, ...)
4. Words (including keywords)
5. Operators and punctuation (=>, <<, >>, ++, --, ... +, -, ...

，... {，} 、. ..)

空格(空格，制表符，nl，cr，...)

, ... {, }, ...)

Spaces (space, tab, nl, cr, ...)

为这些令牌中的每一个编写正则表达式，然后将它们连接到一个正则表达式中，每个子正则表达式都可以作为替代((Comment)|(String)|(Number)|(Word)|(Op)|(Space)|(Error)) .

通过检测子正则表达式组中的哪个正则表达式，使用给定的正则表达式扫描文本，直到找不到匹配项为止.

干杯

安迪

Write the regex for each of these tokens and concatenate them into one regex with each sub-regex as alternative ((Comment)|(String)|(Number)|(Word)|(Op)|(Space)|(Error)).

Scan the text with the given regex until no match is found anymore by detecting which of the sub-regex group is matched.

Cheers

Andi

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