Snobol4 语言 解析 HTTP 请求中的头部字段

Snobol4^【1】 语言解析 HTTP 请求头部字段

Snobol4 是一种古老的编程语言，最初在1962年由David J. Farber、Peter J. Deutsch 和 Thomas E. Kurtz 设计。它以其简洁的语法和强大的字符串处理能力而闻名。尽管在现代编程中Snobol4 并不常见，但它在处理文本数据时仍然有其独特的优势。本文将探讨如何使用Snobol4 语言来解析HTTP请求中的头部字段。

HTTP 请求头部简介

HTTP请求头部^【2】是HTTP请求的一部分，它包含了关于请求的元信息，如请求方法^【3】、请求的URL、客户端信息、请求的版本等。以下是HTTP请求头部的一个简单示例：


GET /index.html HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, sdch
Connection: keep-alive


Snobol4 语言基础

在开始解析HTTP请求头部之前，我们需要了解一些Snobol4语言的基础知识。Snobol4是一种基于规则^【4】的编程语言，它使用模式匹配^【5】和规则来处理字符串。

变量^【6】

在Snobol4中，变量使用美元符号（$）开头。例如，`$header` 表示一个变量，用于存储HTTP请求头部。

模式匹配

Snobol4使用模式匹配来匹配字符串。模式匹配通常使用``符号。例如，`` 用于匹配字符串 "GET"。

规则

规则是Snobol4中的核心概念，它定义了如何处理字符串。规则由模式、动作和可选的优先级组成。例如，` > " " > $method` 表示如果找到 "GET"，则将后面的空格后的内容赋值给 `$method` 变量。

解析 HTTP 请求头部

以下是一个使用Snobol4语言解析HTTP请求头部的示例代码：

```snobol
:readline $line
> " " > $method
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