Snobol4 语言 实战 URL 参数编码解码实战

Snobol4^【1】 语言实战：URL^【2】 参数编码解码^【3】实战

Snobol4 是一种古老的编程语言，由David J. Farber、Ralph E. Griswold 和 Ivan P. Polonsky 在1962年设计。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，但它在处理字符串和文本数据方面仍然有其独特的优势。本文将围绕Snobol4 语言，通过一个实际的案例——URL 参数编码解码，来展示Snobol4 的强大功能。

URL 参数编码解码背景

URL（统一资源定位符）参数编码解码是网络编程中常见的需求。URL 参数通常用于传递查询字符串^【4】，例如在Web表单^【5】提交或URL重写^【6】中。URL 参数编码解码的主要目的是确保参数中的特殊字符^【7】不会破坏URL的格式。

URL 编码

URL 编码将特殊字符转换为百分号后跟两位十六进制数^【8】的形式。例如，空格被编码为 `%20`，而问号被编码为 `%3F`。

URL 解码

URL 解码则是将编码后的字符转换回原始字符。

Snobol4 语言简介

Snobol4 是一种高级编程语言，特别适合于文本处理。它具有以下特点：

- 简洁的语法
- 强大的字符串处理能力
- 内置的文本搜索和替换功能
- 支持正则表达式^【9】

实战：URL 参数编码解码

以下是一个使用Snobol4 实现的URL 参数编码和解码的示例。

URL 编码

```snobol
:encode<sup>【10】</sup> URL-String<sup>【11】</sup>
URL-String . URL-String
| URL-String = ""
0
| URL-String = URL-Char<sup>【12】</sup> URL-Remainder<sup>【13】</sup>
URL-Char = " " | "?" | "&" | "=" | "%" | "+" | "/" | ":" | "@" | "&" | "%" | "" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | "%" | 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